Is the end of fire season expected soon?

So while we can't argue that the worst of fire season is behind us, it should be noted there are still fires burning across portions of the Inland Northwest. Here's is what satellite information was showing on the last day of September:

MODIS Visible Satellite Imagery from 9/30/15

While these fires are far from the raging infernos we saw earlier this summer, it's still rather impressive for the end of September or beginning of October.  However, as we all know this year is different. First off, look at these precipitation totals since the beginning of April

Idaho Precipitation % of normal 4/2/15-10/1/15

Washington Precipitation % of normal 4/2/15-10/1/15

That is a lot of red and dark red shading over the Inland Northwest which correlates with meager precipitation amounts ranging 25-70% of normal. That's pretty dry. In fact, since the beginning of April through the beginning of October it was the driest period on record for both Spokane and Boundary Dam, WA (extreme NE corner of the state).

So combine the record dry conditions with nearly record warmth for both sites and it is no wonder the fire season has been so long. Here is a look at the temperatures for both sites.

So obviously record warm and dry conditions led to our active fire season, but unlike a typical year, things just aren't winding down as quickly as we are accustomed to. Climatologically, the days of active fires will be limited. We say that because the shorter days are leading to cooler temperatures and higher relative humidity levels  (both items are generally detrimental to good fire growth) while the chances for measurable precipitation are rising quickly. Climatologically the chance of measurable rain ranges from 20-25% over locations where the fires are currently burning. However by the end of the month those chances nearly double. So despite these facts, look at the latest fire danger ratings for the Inland Northwest:

Current Fire danger ratings

That map shows the fire danger is still high (yellow) or even very high (orange) across a sizable portion of the Inland Northwest, with moderate conditions (light green) found everywhere east of the Cascades. So what does that mean? According to the Wildland Fire Assessment System (WFAS) a high fire danger means, "All fine dead fuels ignite readily and fires start easily from most causes. Unattended brush and campfires are likely to escape. Fires spread rapidly and short-distance spotting is common. High-intensity burning may develop on slopes or in concentrations of fine fuels. Fires may become serious and their control difficult unless they are attacked successfully while small.

So is this danger level unusual for the beginning of October? Since 2006 (earliest year of  the graphical archive), the current fire danger has only been matched one time. That was in 2012. All other years saw low to moderate fire danger ratings across the area.

So what was the fire weather like in 2012? This satellite picture tells the story

MODIS Satellite imagery from 10/4/12

Just like this year, there were quite a few fires burning during the beginning of October. In fact, based on the satellite image, they were much bigger and included the Wenatchee Complex (southwest of Wenatchee) and the St. Mary's Misson Rd fire south of Omak. So what happened that year? The dry weather and fires continued to burn through the middle of the month, but several days of rain (not necessarily heavy) and cooler temperatures put an end to that fire season.

So what did the weather pattern look like for the end of that fire season? Well leading up to the end of the fire season, the upper-level pattern exhibited a large ridge parked right off the BC/WA coast with dry northwest flow over the region. Also, note the low-pressure area off the California Coast.

Early October 2012 500 mb pattern. 

So how does the pattern look for most of this week? Although it's far from identical, it does have some similarities, including the low near California, and the ridge over the Pacific Northwest.

500 mb pattern for Monday afternoon (10/5/15)

So what did the weather pattern that led to the end of the fire weather year in 2012 look like? The ridge broke down quite quickly and was replaced swift southwest flow into the Pacific Northwest and a deep low over the Gulf of Alaska. Again this brought cooler temperatures, periods of light rain (moderate in places), as well as significant cloud cover.

Mid-October 2012 500 mb pattern (Oct12-14)

How about this year? Is anything similar expected? Again although not a perfect match, there are some good similarities including a deep Gulf of Alaska low and deep southwest flow pointed into the Pacific Northwest from the eastern Pacific.

500 mb forecast for Oct 10, 2015

So how is our confidence in this solution and will this be the end of the fire season?  There are a few additional tools we can look at. One of the more interesting ones is called the NOMADS ensemble probability tool. This tool queries 21 GFS ensemble members or model runs and calculates the chances of any given parameter. Using this tool we can look at things such as what is our chance of seeing over a tenth of an inch of rain in a day?  When asking that particular question, here is the answer for the Grizzly Complex located over northern Shoshone County, ID.

The probability of seeing 0.10" of rain or more in 24 hrs over northern Shoshone County. 

So if you key in on the clustering of the blue bars, you can see that there is some consensus that by next weekend (10/10 and 10/11) that the weather pattern will support an increasing chance of rain (it peaks at 25% for the 24 hrs between 5pm Saturday through 5pm Sunday). Notice also that there is a small chance of light rain during the middle of the week.

Stay tuned and we shall see if this will truly be the end of a historically warm and dry fire season across the Inland Northwest.

Does Monday still look like a severe day?

A few days have come and gone since our last post about the potential severe weather event for the first day of June. So how are things looking now that the event is nearing? Well according to the water vapor imagery below, it's looking pretty good. See the swirl off the northern California Coast? That's the deep low-pressure system which will deliver the active weather as it moves toward the Inland Northwest. Why is this low important? Well for a good thunderstorm day we need three key ingredients: lift, instability, and moisture. The low will provide us with the first ingredient.

Animated water vapor imagery. Note the swirl off the Northern California coast. 

The models are very consistent in taking this low from its current position off the California Coast toward the Washington/Oregon border by afternoon and then toward the Washington/BC border by evening. This pattern resembles the typical negative tilted pattern we associate with severe weather in the Inland Northwest. The track of the low will ensure that the region will be subject to strong lifting potential beginning in southern Washington and central Idaho in the morning and spreading northward through the day. 

500 mb forecast with precipitable water forecast

Notice the shading in the 500 mb map above? That represents the precipitable water forecast. The greens, blues, and purples depict where the juiciest air will be located, Initially the pool of moisture, currently over far northern Oregon, will shift northward tonight and then become enhanced with even more moisture from the incoming low. How much moisture will we see? We forecast that using  a parameter termed precipitable water. Precipitable water is a figure used to represent how much water the atmosphere is holding. The precipitable water forecasts are expected to reach  values are forecast to exceed an inch over portions of the Inland Northwest by afternoon. How unusual is that? According to the graphic below, it would be placed in the 97.5-99th percentile for this time of year. So it will be far from typical. 

Precipitable Water anomaly

So with the two key pieces in place, what about the third, instability? Well it looks like that piece of the puzzle will be realized as well. If you recall our previous blog post, one of the ways to measure potential instability is looking at the lifted index values. If we see negative lifted index values, that indicates potential instability. So as early as 5 am, we begin to see some of this instability. Notice the yellow and orange shading over southeast Washington? This is enough instability to support thunderstorms even without the benefit of daytime heating. 

5am Monday Lifted Index Forecast

How about later in the day? Suffice it to say the instability will not be lacking. The entire region is expected to see negative lifted index values, with the best instability represented by the -6 to -8 values over extreme eastern Washington and north Idaho. That's about as good of a lifted index as you can expect to see over the region. 

5 pm Monday Lifted Index Forecast

So with all the pieces in place what would we expect to happen? We think there will be a band of showers and thunderstorms early in the morning spreading across the Washington/Oregon border, which should slowly work their way northward through the morning. How extensive this band will be remains rather uncertain. One of the weather models is forecasting the radar to look like the image below. Notice the nice cluster of showers and thunderstorms near the Blue Mountains in SE Washington. This coincides nicely with the good pocket of instability forecast by another model.  

7 am simulated radar image

By midday, this band is expected to drift farther north, but could lose some of its definition and strength.  

11 am simulated radar

However, the first band which moves through will further moisten and destabilize the atmosphere before the strong upper-level disturbance tracks toward our region. So what will the afternoon look like? This is far from certain, and there are as many answers as there are high-resolution models. Here's just one of the forecasts for 5 pm. 

5 pm simulated radar

That is a pretty impressive simulation with strong thunderstorms located across the northern portions of Washington as well as in the southern Idaho Panhandle. However recall that the best instability (or lifted index values) were located over the Idaho Panhandle. So we have better faith in the eastern portions of this radar simulation verifying. Another thing we can look at is an ensemble of simulated radar returns. The image below shows where the greatest risk will be for the biggest thunderstorms (chances of having a 40 dbz or stronger radar echo). The regions shaded in purple have the best chances (over 90%) followed closely by the reds (over 70%). This would highlight two areas. The Cascade crest and over the southeast corner of Washington and the southern Idaho Panhandle.

Ensemble chances for 40dbz or higher echoes

So what will the main risk of severe weather involve tomorrow? Based on the instability, the biggest risk looks to be large hail. If we look at the model soundings they are likely a little too moist to support widespread wind damage, however, we still expect to see some strong wind potential with a few of the storms. 

So what is the typical weather we experience with this type of upper-level pattern? We can utilize a fascinating tool produced by the Cooperative Institute for Precipitation Systems (CIPS) at Saint Louis University. They created a tool that makes an analog of the 15 closest weather patterns (since 1980) to what the forecast weather pattern is supposed to be. So below we see the forecast for tomorrow in red compared to the mean of the top 15 analogs (or pattern matches). This looks like a pretty good fit.

500 mb forecast for tomorrow (red) plotted against the 15 top weather analogs since 1980

So what weather was experienced on those days? Interestingly enough, quite a bit. Of those 15 days that matched Mondays expected weather, there were widespread severe reports. Most of them were related to hail, but a good sample of the reports were related to wind as well. Also, notice there were 3 tornado reports in the Inland Northwest. We do not expect to see tornadoes on Monday, as the wind patterns are not quite right to support violently rotating storms, however, they have occurred in this weather pattern before. 

Severe reports from the top 15 analog days to Monday's weather pattern

The other risk we see tomorrow will be for flash flooding. The storms which develop tomorrow will obviously contain copious amounts of moisture. And more importantly they could be slow movers. 

The risk of heavy rains will likely continue through Monday night before tapering off. Here's a look at the 24-hour precipitation forecast from 4 different weather models.

Precipitation forecast from 11am Mon-11am Tue

That's a lot of precipitation (purple amounts are above  0.75") and there is a fairly consistent message that the bulk of it will occur across the northern quarter of Washington, the Cascade Crest, and over the Idaho Panhandle. Since much of this will be attributed to thunderstorms, there is likely to be a high variability over short distances, with some areas likely to receive much heavier amounts. 

Stay tuned for updates to the forecast as this will likely be a very active weather pattern. 

Is it still looking wet for this Memorial Day Weekend?

So a couple days have passed since our last blog post about the weather outlook for the Inland Northwest for the upcoming Memorial Day weekend. Consequently, our confidence in what sort of weather to expect should be increasing. Recall that in the last post, there were suggestions that this could be a very wet weekend. In fact, perhaps the wettest Memorial Day weekend since 1997 and the second wettest on record (since 1970). So is that still the case?

Saturday 500 mb height

Above is the 500 mb map for Saturday from the GFS. This is a similar setup to the maps we explored earlier this week with a deep low centered over the Pacific Northwest. So is this GFS run an outlier or do other model agree with the solution?

4 different models showing 500 mb heights for Saturday (upper left model did not come in fully)

Here's is a look at 4 models compared to each other and they all show a low focused somewhere over the Pacific Northwest on Saturday. So where is this low on Sunday?

500 mb maps for Sunday

Again there is great agreement that there will be a low focused somewhere over the Pacific Northwest. The top 2 models take the low into southern Oregon, whereas the bottom two models drop the low into southern Oregon. Now, what the positioning of the low on Memorial Day?

500 mb maps for Monday

Again all the models keep the low over the region, however, the consensus is to drop the low south of the Washington/Oregon border.

So our confidence in this event is quite high. We are certain this low will form and move over portions of the Inland Northwest however how long it will remain over the area and where its precipitation  band will set up is the big question. Looking at the GFS for the Saturday and Sunday yields a significant northwest to southeast orientated band of precipitation.

48 hr precipitation amounts for Saturday-Sunday (latest model run )

This is quite similar to the previous model run we looked at a couple days ago(see below). Both model runs show a similarly oriented band of precipitation, however,  the latest version has the band a little farther to the west leaving places such as Sandpoint and Colville much drier than the previous forecast.

Rainfall forecast for Saturday and Sunday (Monday's model run)

Obviously wherever this band sets up will determine who gets a lot of rain and who doesn't. If we decide to consult another model solution it also shows a similar NW-SE band setting up, but this time it's displaced even further west. If this solution were to pan out even Spokane would miss out on the bulk of the rain as would the Silver Valley. 

Another Saturday-Sunday 48 hr precipitation forecast

So given these uncertainties it will be hard to pinpoint exactly where the band will take up residence. This is where ensemble model forecast can sometimes help to pinpoint the band (s) of heavy precipitation. So once again referring to the GEFS/NAEFS ensemble forecasts we see that it maintains a NW-SE oriented band of heavy precipitation as well. However the model has backed off from previous runs which suggested this would be a 99-99.9 percentile event for this time of year. Nonetheless the model still suggests this is potentially a 90-97 percentile event which is still significant. 

NAEFS/GEFS Ensemble 48 hr rainfall Sat-Sun

So what about the temperature forecast? We are holding onto our thoughts of hitting near 70° each day in Spokane this weekend, however if the band hits our area what will our temperature be? To say there is some uncertainty in this forecast would be an understatement. The 12z run of the GFS (dark blue line) has our high hitting the mid-70s that day. How about the 18z run of the GFS? A chilly mid-50s! That is about as uncertain as things can get. Its pretty much the same story for other parts of the Inland Northwest including Moses Lake (bottom meteogram)

Meteogram for Spokane

Meteogram for Moses Lake

This forecast remains a problematic one. Suffice it to say a good portion of the Inland Northwest is going to see a soggy beginning to the holiday weekend. Specifically where that will be, we still can't say with good confidence.  We expect the wettest day of the three-day weekend will be Saturday with a gradual improvement expected after that.

How unusual will this next episode of warm and wet weather be for the Inland Northwest?

By now you have likely heard that this is going to be a wet and warm remainder of the week across the Inland Northwest. This wet spell of weather is expected to continue into early next week. So why is this? Well, most of it can be attributed to yet another atmospheric river event. While most atmospheric rivers come and go, this event will be a little different, as we will likely be impacted by a trio of rivers. The first arrived yesterday into last night. The next is expected to unleash its torrent of moisture on Friday and the last will likely impact the region on late Sunday. The video below shows the expected sequence of events. The atmospheric rivers are denoted by the blue, purple and red colors

So what does this mean for the area. Well, it will translate to several things. The most obvious is it will result in very wet weather. Here's the estimated rainfall we are forecasting between today and Sunday night.

Rainfall forecast between today-Sunday night

These are some pretty hefty totals. Notice the reds and oranges spread across the Cascade Crest and extreme northeast Washington/north Idaho. These locations could potentially amass a few spots of 3-6" of precipitation, most of which will fall as rain. While these amounts are impressive, the question is just how rare are they? We get atmospheric rivers all the time this time of year. Certainly it can't be that unusual, can it? Well, if put into perspective for the time of year and amount of precipitation it actually turns out to be a very rare event. One of the new tools in our weather toolkit consists of quantifying an event based on climatology. In other words, how common is a weather event for a given time of year? For this event, we will look at the amount of rainfall expected over a 3-day period (between today-Sunday). Below you will see an image from one of our ensemble models showing the approximate amount of precipitation (black contours or isohyets) combined with the rarity of the forecast amount (the color shading). What's interesting, in this case, is northern California is covered with isohyets in excess of 3 inches, while over the Inland Northwest we see a small area of 1.5"-2+"  inches over extreme northeast Washington and north Idaho (the amount is smoothed and will not catch the locally higher amounts we forecast over the mountains). Despite the lighter rain totals over our neck of the woods, it's actually a less common event as shown by the blue and dark green shading. The blue shaded areas are locations where this event places in the 99.9 percentile (or 1 out of 1000 events)  for all rainfall events between December 22 and March 22nd (between 1985-2012). The dark green shaded areas, which cover a good portion of the Inland Northwest represent a 99.5 percentile event (1 out of 500 events). So technically speaking we will experience the most unusually heavy precipitation in the western US this weekend.

Ensemble precipitation forecast (Thu-Sun) combined with the relative rarity of the amount.

The other unusual weather phenomena we are expecting this weekend will be the warmth. If we once again choose to utilize a percentile ranking of the warmth for this event it's rare, but nowhere close to as rare as the rainfall. Here's a look at the forecast temperature and the respective percentile (for the period between January 27-February 17)  for the temperatures at 850 mbs (around 4500' above sea level) on Friday afternoon. The image below is showing temperatures in the lower to middle 40s (4-6°C)  pale yellow which indicates roughly the 90th percentile (1 out of 10 events). So really it's not rare at all. Temperatures at this level will be significantly cooler than what we experienced on the 25th of January when our 4500' temperature surged into the lower to middle 50s.

Climatology rarity of 850 mb temperature for Friday afternoon (2/6/15)

What will make this an unusual event though is the duration of the mild temperatures. Right now for the Spokane area we are forecasting 4 consecutive days of high temperatures right around 50° (see image below). The last time we saw that many 50°F or warmer days between December and early February (2/10) was in 1963! The longest stretch on record is 6 days set in 1917. A 3-day stretch of low-temperatures of 40°F or warmer is also rare for this time of year. Between tonight and Saturday night, we are forecasting lows at or above that mark. Surprisingly, the last time we saw three nights of lows ≥ 40°F was earlier this winter (in early December). Before that, we had only seen 3 or more consecutive nights of 40°F or warmer lows 7 times since 1881.

7-day outlook for the Spokane area Thursday (on left) through Wednesday (right)

Just the latest chapter in what has been an unusually mild and relatively snow-free winter.

Spring Skiing in January?

If you've looked at the forecast lately, you'll notice that we're expecting warmer temperatures next week.  Temperatures are forecast to be in the 40s, with even some lower 50s in places (i.e. the Palouse and Lewiston area).

Why will it be so warm?  Very strong high pressure will develop over the western US in the next few days.  But we often see that.  So what's so special about this?

The image below shows the temperatures at about 5000' above sea-level this morning.

Temperature at 5000 feet MSL on Thursday.

You'll notice that the warmest air (red shading) is over California, as well as in the lee of the Canadian Rockies.  Now here's the same image on Saturday afternoon:

Temperature forecast at 5000 feet MSL Saturday

Notice those bright red colors off the coast of northern California?  Where did that come from?  The wind will be "offshore" at this time, which means it will be blowing from the northeast, coming from Nevada and eastern Oregon, to the Pacific Ocean.  As it does this, it descends from the Sierra Nevada mountains down to sea level.  Air that descends warms due to compression.  So this warm air didn't move here from somewhere else, it was created by the wind flowing from the Sierra's (e.g. 8000 feet elevation) down to sea level.

Now here's the forecast of what will happen to that warm air on Monday:

Temperature forecast at 5000 feet MSL Monday morning

You can see that the warm air has spread northward, along the coast, and into the Inland Northwest.  

OK, so just how warm are we talking?  Well, in addition to keeping track of all of the record high and low temperatures at various cities, we also keep track of historical temperatures on our weather balloons.  So here's the January record high temperatures at 5000' MSL for various western locations, along with the computer model forecasts:

Site	Max 5000’ MSL Temperature	Model 1	Model 2	Model 3
Oakland	19°C	18.3°C	18.3°C	18.2°C
Medford	18°C	17.6°C	17.2°C	17.6°C
Salem	19°C	15.5°C	18.9°C	18.5°C
Quillayute	16.5°C	11.3°C	16.3°C	14.8°C
Spokane	14.5°C	11.2°C	12.6°C	14.1°C

The three models differ a bit in their forecast, but they all have very warm temperatures at 5000'.  Some records (going back to 1948) could be broken.  How warm are these?  The forecast of 14.1°C at Spokane, if it verifies, would be the same as what we normally see on April 6th!!!

So what does this mean?  The answer is somewhat complicated.  Here's the forecast high temperatures for Monday:

These are about 10 degree above normal for the end of January.  But this forecast could easily be very wrong.  You'll notice that much of the western Basin (i.e. Moses Lake), and the northern valleys (e.g. Omak, Colville, Bonners Ferry) are in light blue (40-45F) while the mountains (e.g. the area between Republic and Colville) are in green (45-50F).  What gives?

The northern and Cascade valleys have snow on the ground.  Any melting of snow could lead to fog and low cloud formation.  And this would keep the valley temperatures cooler (i.e. little or now sunshine).  But if that fog doesn't form, then the temperatures could easily be 10 degrees warmer than forecast.

Typically, for a mid-winter warm spell, we need wind.  The wind helps to mix the atmosphere, taking warm air aloft and mixing it with the cold air near the surface.  But in this case, there won't be much if any wind.  So we won't have any "mechanical mixing" to stir the atmosphere. The sun will have to do all the work by itself to warm up the near-surface temperatures.  With the low sun angle of late January, this is a tough task.  Not impossible, but difficult.

Meanwhile, the mountains will be above any fog formation and they should see abundant sunshine.  So confidence is high that they will be warm.   Here's the minimum temperature forecast:

Notice that the mountains are as warm as the valleys?  The mountains won't just be warm during the day, but they'll probably be above freezing during the nighttime hours as well.  And this will likely last for 3 or 4 days.  A week cold front in the middle of next week will cool things down some, but it will still be warmer than normal for late January.

So we'll get a taste of early spring next week, especially in the mountains.  There's a big bust potential for the valley temperatures, especially north of I-90.  But if you're going skiing, make sure you bring the sunscreen and don't over-dress.

Severe Weather Tomorrow??? It's a Possibility.

We have all heard of the calm before the storm, today could be just another chapter in that book. This afternoon will feature highs in the 70's and 80's under mostly sunny skies. Come tomorrow the chance for showers and thunderstorms will be on the rise as an area of low pressure approaches the Inland Northwest. Temperatures will continue on the warm side of normal, but increased moisture will push ahead of the low pressure center increasing our chances for convective activity or thunderstorms. In this post we will evaluate the chances for thunder around the region and the potential timing through various weather maps and products.

So lets start out with today and move forward from there. Our current pattern has a ridge of high pressure directly over the Inland Northwest keeping conditions calm and pleasant. The ridge also allows for warm southwesterly flow to advect into our area bringing above normal temperatures today. We will take a look at the current set up in the following image.

 11am PDT Infared satellite map with 500mb heights

From the image we can see the area of low pressure to our west and the current ridge over us. The ridge is also diverting much of the cloud cover to our north. As the low slowly moves onshore the ridge will continue to be shifted to the east allowing clouds to move east of the Cascades. Not only will this bring increased cloud cover for tomorrow afternoon, but also increased moisture through the atmospheric column allowing better instability. So lets take a look at the increased moisture moving in. This can be accomplished in a couple of manners, but we will look at Precipitable Water or PWATs in the atmospheric column.

Precipitable Water values from 11am today (left image) and 5pm Thursday (right image)

The images above show the increase in atmospheric moisture from today to tomorrow from the North American Model (NAM). For much of the Inland NW we will see an increase of nearly a quarter of an inch of precipitable water. Another method to address the amount of moisture would be the change in forecast soundings which show temperature and dewpoints up through the atmosphere. Next we will examine the forecast soundings to see the change in moisture from today to tomorrow.

NAM forecast soundings from 2pm today (left image) and 2pm Thursday (right image)

From the sounding you can see the major differences in the amount of moisture present. The red line would indicate the temperatures and the green indicates the dewpoint which reflects the amount of moisture in the atmosphere. For the left image a dry layer is noted around 500mb (where the green line moves away from the red) whereas for tomorrow (right image) much more moisture is present (green and red lines are closer throughout the image). So from these two examples the change in moisture can easily be noted, but will we have the instability to promote the thunderstorms? We will now at these parameters that promote thunderstorms.

For thunderstorms to occur, many things need to be present including lift (forcing), moisture and instability (atmospheric stability). We will first look at the lift for the area and the one way to do this is to compare from today's conditions to tomorrow. Below is an image looking at the Q vector convergence in the upper atmosphere or Div-Q. Div-Q is a generalized way to assess the lifting potential in a portion of the atmosphere.

Upper level Div Q from 11am today (left image) and 5pm Thursday (right image)

From comparing the images we can see the major differences concerning forcing. Tomorrow the low will move onshore bringing a good amount of forcing ultimately aiding in thunderstorm development. With the right image being for 5pm tomorrow, we will most likely be looking at a case that will unfold more in the late afternoon and evening hours rather than early in the afternoon. Would this be a good or a bad thing with it unfolding in the evening? For now it looks good. We have been hitting our high temperatures in the late afternoon/early evening which would be the best time for the stronger storms, so this would also would aid in thunderstorm development. We have already looked at the moisture profiles for the area and have concluded that higher amounts of moisture will be in place. Finally we will look at one of the convective parameters that are normally consulted to address thunderstorm potentials which is CAPE or the Convective Available Potential Energy. First we will once again look at the NAM model. It has been the most aggressive when it comes to CAPE values, but paints a similar picture to the others as to the areas with the best chances for seeing thunderstorms.

NAM CAPE values for 5pm Thursday

From the NAM we can see a broad area with values surpassing 1000J/kg and localized areas greater than 1500J/kg (blue and green shading). If you remember around a week ago on the afternoon of June 3rd we had thunderstorms for much of the area. These storms were also working with around 1000J/kg of CAPE. With the NAM being on the upper end of model perspective lets take a look at another one. Next we will examine the model often used by the Storm Prediction Center (SPC) in Norman, OK which is the SREF or the Short Range Ensemble Forecast.

SREF CAPE values for 5pm tomorrow

Although not as colorful as the NAM, the SREF is also showing higher values for eastern Washington and into the Idaho Panhandle. It also has peak values in the 1000J/kg to 1250J/kg range. So we do have some consistency among short range models of the potential for higher amounts of CAPE. So with all of this in mind, now comes the million dollar? will we see thunderstorms and if so, how strong will they be? Concerning the chance for thunderstorms, it is a given. We will see thunderstorms tomorrow. The next question is where? As we can see, the best forcing will be in the eastern third of Washington and the Idaho Panhandle so these are the locations with the best chances. We do not want to omit the chance for the east slopes of the Cascades or the Basin, but the threat will not be as great as the other locations. From the SPC, they create a calibrated outlook of the thunderstorm chances for a location so lets take a look at what they think.

SPC calibrated thunderstorm probabilities between 5am-5pm Thursday

So from the SPC, they highlight a 40% chance for much of northeast Washington into the Idaho Panhandle.  These are some of the higher values I have seen from this for our area so it would lead me to think the chance for thunderstorms is essentially a slam dunk.  Finally the big one.....will any of the storms be severe? Here at the office we seem to think the potential is definitely there for strong storms. Comparing to last week, we had similar CAPE values, but tomorrow we actually have better dynamics to support storms. The SPC also does a product for the chances of severe storms and here it is.

SPC severe thunderstorm probabilities for 5pm Thursday

While the chances for severe storms do not look very high, they still highlight the potential for portions of the area. This product usually only has slight chances for us when severe events do occur, so the potential is there. The region will want to keep an eye on the skies tomorrow as active weather looks to be a given.