Saturday, February 27, 2010

Severe Weather Awareness Week--March 8-12, 2010

As we begin to think about spring we need to think about severe weather as the seasons transition!!!  Situational Awareness is the key to being able to avoid injury and survive a severe weather event!!!

Severe Weather Awareness Week will be observed March 8-12, 2010.  MesoExtreme will post a severe weather safety tip from the NWS throughout severe weather awareness week.  In the meantime, you can peruse the NWS Pleasant Hill Severe Weather Awareness website at http://test.crh.noaa.gov/eax/?n=severewx-awareness and the Missouri State Emergency Management Agency website at http://sema.dps.mo.gov/semapage.htm .

One MAJOR change this year is on tornado safety.  I repost the following information from the NWS Pleasant Hill in regards to tornado safety:

1) If you can drive away from the tornado, do so. On average tornadoes move from one location to another at 35-45 mph so driving away though may be the first course of action.

2) If you can't drive away from the tornado (as in the case of driving directly towards the tornado on a divided highway, or stuck in slow moving traffic), abandon your vehicle and seek shelter in a nearby sturdy structure such as a house or other well built structure.

3) If no buildings are available, their really are no good options. At this point every person needs to decide for themselves whether they will:
             a) remain in their car with their seatbelt buckled, leaning down to get below the window line, or
             b) abandon the vehicle for the shelter of a culvert or lay flat, face down in a ditch or low spot.          
Again, at this point there are no good options and the best thing is to not be there in the first place. ~ CS

Tuesday, February 23, 2010

Washington DC~Snow Storm February 2010

I received these photos of our Sentinals at the Tomb of the Unknown Soldier in an e-mail and do not have a person to credit.  The top three photos are not my photos and I do not take credit for them.  I post the photos only as a rememberance of the sacrifices our military personnel have made and are continuing to make for our freedom every day!!  If anyone knows the source of the photos, please let me know so I can give credit where credit is due.

The text of the e-mail indicated they were taken during the major snowstorm several weeks ago in our nations capitol that shut down the city.  These are our military personnnel who guard the tomb and have done so since 1937 without fail.  It was reported the Sentinels were ordered to abandon their post during Hurricane Isabel, which was not true!  They maintained their post through the Hurricane!



Here are some photos my wife and I took in DC when the weather was a bit calmer.


Photos courtesy of Heidi Sloan ~ http://www.memoriesbyheidi.com/

God Bless our Troops!!!! ~ CS

Monday, February 22, 2010

FCST: 2/27-28/2010 SNOW Northern MO AGAIN????

The long range GFS is hinting at another winter storm affecting the area late into the weekend (Sat-Sun).  This will likely change over the coming days, but it is something to keep an eye on as we head toward the end of the week!  Here is a look at the GFS forecast hours 144-180 (Saturday evening through Monday morning).  The Upper Left is 500mb Hgt/Vort, Upper Right is 1000-500mb Thickness, Lower Left is 700mb Hgt / RH and Lower Right is 12 Hr Precip/850mb temp. ~ CS





Sunday, February 21, 2010

NOW: 2/21/2010 Snow storm winding down

A potent late winter storm affected the area beginning Saturday evening and continued through the day on Sunday.  A convective band of snow lined up from MCI to STJ and to the east northeast from there.  This was a very classic track and set up for the local area with a deformation zone/TROWAL forming on the north and northwest side of the low pressure center.  This produced snowfall rates at 1" to 2" per hour during the mid to late afternoon hours.  Snowfall accumulations met the forecasted totals of 5" to 10" with local reoprts of 12" of snow.


Currently, the area of low pressure is located over southeast Missouri and continues to lift off to the ENE.  This will allow the snow to taper off to flurries, but usher in strong north winds in the 20 to 25 mph range which will cause blowing and drifting of snow.  Here is a look at the surface map valid as of 12 a.m. CST February 22, 2010:


Looking at current radar trends indicate there is a band of light snow spinning around the backside of the storm from near Maryville, MO to Topeka, KS.  This band of snow should clear the local area by 9 p.m. CST.  I am expecting only minor additional accumulations.  Here is a look at the current surface map / radar returns:


Roads in northern MO are snow covered and slick.  Travel is highly discouraged at this time until road crews can get the roads cleared of snow and treated.  This will be complicated by the pesky north wind.  County roads are nearly impassable across the area.  Exercise extreme caution if you must venture our this evening.  Have an emergency travel kit, blankets, snow shovel and cell phone with you. ~ CS

NOW: 2/21/2010 SNOW North Missouri

A potent late winter storm is taking shape for the local area today. A strong area of low pressure is currently located over N. Central OK and S. Central KS and is expected to take a classic snow storm track for the local area. This track is across southern MO and northern AR, south of the I-44 corridor and northeast south of St. Louis.

Copious amounts of gulf moisture are being drawn into the system which will potentially lead to significant snow accumulations over the local area.  Here is a look at this mornings water vapor imagery, current surface analysis and short term forecast (18Z Sunday) analysis:



One fly in the ointment is the time of year the storm is occurring in. Late winter storms have the tendency to have decent warm air advection occur ahead of the storm, before colder Canadian air can be wrapped into it on the back side. This warm air advection brings in warmer air a few thousand feet above the surface (850mb level) and melts the snow crystals as it falls…the precip falls as rain and with surface temps below freezing it freezes on contact. We are seeing this in areas from KC south and east along I-70 as freezing rain has been the dominant precipitation type. Some locales from KC south and east could see .25 to .50 inches of ice accretion. It appears the warm air advection will not move much further north during this storm, but it is something to watch as the storm progresses. We should be all snow through the duration of the event!  Here is a look at the NAM 850mb temps for this afternoon:



Snowfall will continue through the day today, possibly heavy at times, with total snowfall accumulations in the 5” to 8” range with locally higher amounts. The higher amounts will occur within convective bands of the snow. The convective banding is hard to determine with prognostic models and will need to be nowcasted based on radar trends. Snow ratios appear to be in the 10:1 category where 1” of liquid precip equals 10” of snow. This will be a heavy, wet snow and any blowing and drifting will be minimized, but some may occur.  Here is a look at the HPC snowfall / ice accumulation probability composite maps:

Cold Canadian air will be brought in behind the system to usher in the new work week.  Highs in the local are are forecasted to be in the mid 20's with gusty northwest winds with wind chills in the single digits.  Here are the forecasted high temperatures for Monday:


The National Weather Service has continued the Winter Storm Warning through midnight tonight for snow. Here is the map of the current watches and warnings valid for Sunday afternoon:

~ CS ~

Saturday, February 20, 2010

Saturday, February 20, 2010 FCST: 2/20-22/10 SNOW Illinois

To add to what Corey has already noted, the main question at this time remains exactly where the low pressure system will track tomorrow, but current models paint the low tracking in the vicinity of KSTL and points ENE near somewhere in the vicinity of the I-70 corridor. The NAM and GFS have come into better agreement in regards to which areas are likely to see best forcing and dynamics to produce the highest snowfall totals of 6+ inches. QPF values still look to be on the order of 0.50" to 1.25", with an interesting notation that the Canadian GEM is painting values of upwards of 2.00" into far West Central Illinois through 00Z Monday.

However, one caveat that needs to be considered, as noted in Corey's discussion, is the ultimate location of the 540 freezing line. Most of the models show the line residing near the US 24 corridor, with an outlier still being the WRF, having the line residing roughly along a line from Keokuk, IA to Paxton, IL. With these dynamic systems containing ample gulf moisture and strong WAA, it's not uncommon for the models do have difficulty resolving the exact precipitation types that will befall a given area closer to the rain-snow boundary. This can immensely cut down on forecast snowfall totals on the southern periphery of the heaviest snowfall axis.

The 06Z GFS paints the axis of heaviest snowfall accumulations of 6-12" along an axis 25 miles either side of a line from Keokuk, IA to just east of Rockford, IL. However, the 06Z NAM paints the axis of heaviest snowfall accumulations of 6-12" along an axis 30 miles either side of a line from Lorraine, IL to near Wenona, IL, reflecting a more southerly bias. Much of Northwest and North Central Illinois is likely to experience one of the more significant snowfalls of the season.

JLR

FCST: 2/20-22/10 SNOW Northern MO

A potent later winter storm is taking aim on the local area.  Currently an area of low pressure is located in the southwest US.  This area of low pressure is currently located over northern AZ and is forecasted to track into Colorado and weaken.  Another area of low pressure is forecast to form near AMA and track out of the TX panhandle region into the central plains later this evening and into Sunday.  This will be a our next snow producer here in KS-MO.  Here is a look at the current surface chart:

 As the system enters the plains it is going to pull an abundant amount of warm moist air from the Gulf of Mexico.  The storm system and attendant moisture can be seen on the water vapor imagery from this morning:


This storm system is progged to take a classic track for a prolific snow maker for northern Missouri and areas of adjacent Northeast Kansas, Southeastern Nebraska and Southern Iowa.  Remember from the Christmas Eve storm the classic track is basically along and south of the I-44 corridor to near Jefferson City and over to the south of St. Louis.  Here is a look at the progged track of the surface low from HPC:


This setup normally yields very heavy snow accumulations for the local area.  This storm system looks to be no different.  The Gulf of Mexico is indeed wide open and moisture will not be an issue with this storm system.  I agree with Jesse's last post on the snowfall ration being aruond 10:1, which means 1" of rain will produce 10" of snow.  I see no reason to disagree with this ration ATTM.  Here is a look at the QPF for Days 1-3:

  
However, one thing quite concerning is the sharp temperature gradient that will occur with this storm.  This happens many times with late winter storms.  The track of this storm and the strength of the warm air advection ahead of the storm will determine precipitation type.  The model progs are currently forecasting the 540 line to be situated across northern Missouri just south of the US 36 corridor Sunday morning.  The 540 thickness line is a "rough" guide for the transition from rain to snow.  The 850mb and warmest vertical temperature below freezing line is oriented to the north of the 540 thickness line.  In addition, the other critical thickness lines are dissecting the local area along and just south or north of the US 36 corridor.  Here is a look at the on-going Warm Air Advection ahead of the system.  These are the current temps and dewpoints for the region:

Temperatures
Dewpoints
Here is a look at the forecasted temperatures for Sunday morning:

Here is the GFS BUFKIT sounding for KSTJ at 9 a.m. Sunday morning:

The NWS in Pleasant Hill has issued a Winter Storm Warning for Snow effective from 6 p.m. Saturday to Midnight Monday for all of northern Missouri.  The WSW is for snow with accumulations in the 6" to 8" range with locally higher amounts.  Here is a look at the HPC snow fall probabilities:


4" Probabilities

8" Probabilities

 ~ CS ~

Friday, February 19, 2010

FCST: 2/21/10 Snow

Unfortunately, since the system has not come ashore and currently sits just off the coast of California, it looks like we'll have to wait until the 12Z (Saturday, February 20th) suite of model runs are available to get a better handle on the track of the system. Once the raw upper air data becomes available, more definitive forecasts can be ascertained.

At this point in time, I would infer that near or just north of a Kansas City to Chicago axis will fall in the preliminary band of heavier snow accumulations of six (6) or more inches. This is the region most likely to see QPF values of 0.50" to 1.00" in some locations, wherein the most favored synoptic lift coalesces with an entrenched arctic air mass, enumerating water-to-snow ratios on the order of at least 10:1.

The Gulf of Mexico will remain patulous as a robust LLJ transports more moisture northward whilst the shortwave advances across the Southern Plains. This robust WAA is likely to cut down on total snowfall amounts in the southern periphery of the currently progged heavier snowfall axis.

As the system passes off to the east, more cold, Canadian air will filter into the Midwest to usher in a new work week.  ~ JR

FCST: 2/21/2010 Western and Northern Missouri

Adding thoughts....new blog up by late Saturday morning with the latest data.....as for now...NWS EAX has us in a winter storm watch with 3" to 6" possible....more later...also watch for Jesse Risley's thoughts on the pending winter storm for NW IL.....~ CS

Thursday, February 18, 2010

FCST: 2/19/10 SNOW NW Missouri

EDIT (0415Z):  Quick look at the RUC and SREF for tomorrow's little weather event has me sticking to the forecast posted earlier.  The temperature profile of the column is going to be the key to the accumulations.  I am thinking a 1" to2", possibly isolated 3" amounts are possible mainly on grassy surfaces. 
Here is the latest surface/radar map:


Here is a look at the SREF liquid precipitation forecast for 3 p.m. Friday as well as the 2M temps:


Notice the location of the freezing line at 3 p.m. Friday.

Old Discussion
An area of low pressure, currently situated over SE CO and NW OK, will bring a round of winter weather to the KS and MO region beginning late Thursday night and through the day on Friday.  Here is a look at the current surface map:


Accumulations will be dependant on the form of precipitation that falls.  Based on information right now, I am looking at 1" to possibly 2" in the local area, mostly on grassy surfaces.    The HPC has us in a slight chance of 4" accumulations for Friday. Here is a look at their probability map:

High temperatures are forecasted to be near or just above freezing during most of the event.  I am expecting limited impacts on travel, but there will be slick spots, especially on bridges and overpasses.


Precipitation along and north of the US 36 corridor should fall in the form of a slushy snow as the vertical temperature profiles will be at or near freezing.  There is an outside chance we may see the precip changeover to rain during the day, but this will be difficult to determine until the event begins and we get real data on the actual temps of the column.  KSTJ model soundings is indicating a rain-snow mix after 1 p.m. CST Friday.  The 850mb freezing line is just north of the KC Metro on the GFS and NAM and the 1000-500 mb thickness line is south of the metro.  Tough thermal profile forecast to say the least, which makes it very difficult in determining precipitation type and associated change over timing.
 

Points south of here, especially south of the MO River may have a more rain than snow from this event as warm advection will be more pronounced in these areas.  Another potentially stronger and more significant winter storm will affect the KS-MO region late into the weekend.  I will put a blog up Friday evening with my thoughts on this storm system.  At this time moderate to heavy snow accumulations are possible north of I-70 during this event. ~ CS

Sunday, February 14, 2010

FCST: Valentine's Day Snow

A quick blog update to discuss the storm system affecting our area this morning into this evening.  An area of low pressure is currently sitting over southeast Missouri with a cold front trailing into northern Arkansas and southern Oklahoma.  Another area of low pressure is visible on the water vapor loop in southeastern NE and northeastern Kansas.  This surface low and associated trough is going to bring snow to the area throughout the day today. 

Currently, snow is falling in southeast NE and SW Iowa with some areas reporting visibility down to less than 1/2 mile due to blowing snow.  Snowfall accumulations are only going to be in the 1" to 3" range with isolated 4" amounts (especially east of the local area), but the pressure gradient tightens behind the surface trough and northwest winds will increase to the 25 to 30 mph range.  Some METARS and other station reports are reporting gusts to 42 to 45 mph in southeast NE with significant reduction in visibilities.  Temperatures will bottom out in the single digits this evening across the local area.  ~ CS

NWS EAX has issued a winter weather advisory for snow and blowing snow through 6 p.m. this evening.

Water Vapor Image
EAX forecasted snow amounts for the CWA

Friday, February 12, 2010

CHASER CON 2010 on Severe Studios

CHASERCON 2010 gathering is being broadcast free of charge at http://www.severestudios.com/.  2/3 of http://www.stormchaselive.com/ is attending (Chris and Steve).  Enjoy fellas, wish I was with you! ~ CS

Friday, February 5, 2010

FCST: 2/7-9/2010 SNOW

EDIT (0450Z/9): Forecast verified as Cameron officially received 4" of snow during this event.  I measured 5.5" on the north side of town in Dekalb County.  There were isolated reports of 6" to the south and northwest of town.


EDIT (2045Z/7): Forecast remains on track for a broad area of 2" to 5" accumulations across the local area (less north and more south).  Some areas will receive 5" to 6", especially south and east of Cameron, depending on banding of the snow.  Areas to the south and northeast of the KC Metro have the best chance of seeing 6" plus snowfall accumulations.  NWS in Pleasant Hill has issued a Winter Weather Advisor for the local area through midnight Tuesday morning. ~ CS

EDIT (0030Z/7): 18Z model runs are in and I have taken a look at them.  I still think our 3" to 6" forecast is still on track for the local area, with most of it coming during the day Monday.  The 0Z runs will be out later this evening and I will take a look at them to see if there is much difference from run to run.  Our snow maker will be the disturbance in the northern stream, the southern stream storm does not appear to it will have much affect on our accumulations due to how far south it is tracking.  However, the Christmas eve storm tracked south on the model runs 24 to 36 hours out and we all know what happened there.  No watches or advisories at this time for the local area, but there are winter storm watches to our south and east by one county.  Any minor shift in the storm track will change this.  Keep abreast of the latest information from the NWS in Pleasant Hill as we head into this evening and through the day Sunday!  I will add more thoughts this evening after the 0Z model runs are out! ~ CS


HPC 4" Snow Probabilities--6 p.m. Sunday to 6 p.m. Monday


EDIT (1745Z/6): Current model data takes the southern storm across southern Arkansas and northern Louisiana through the period.  This shifts the heavier snow into central and southern MO, where 6" plus of snow, with some locales receiving close to 8" to 10" of snow.  The northern storm will not be as prolific of a snow maker, but nonetheless, 3" to 6" of snow look possible for the local area.  Any northward shift in this track will put us into the heavier snow accumulations.  Stay abreast of the latest winter weather information from the NWS in Pleasant Hill as these winter storm systems approach.  ~ CS

Here is a look at the current upper low track based on the latest model progs:



Old Discussion and Graphics
A more significant winter storm is poised to affect the area during the late Sunday-Tuesday time frame.  Two shortwaves, one in the northern stream and one in the southern stream, will be the culprit for this round of wintry weather.  Accumulations will depend on how these two shortwaves track, interact and their timing.  At this time, based on the 0Z model runs, the local area could see 3" to 6" of snow....this will need to be watched as the weekend progresses. ~ CS

500mb absolute vorticity forecast map at 6 a.m. Monday morning:


Here are the latest snow fall probabilities from the HPC:

4" probabilities

8" probabilties

Wednesday, February 3, 2010

FCST: Snow 2-5 NW MO

EDIT: Our forecast verified as we received 3" of a wet snow in Cameron, Dekalb County.  Heavier amounts were in the southern part of the KC Metro as a convective band of snow developed and produced snowfall rates of 2" per hour for a brief time.  Some accumulations in this area exceeded 8".  ~ CS


Models are in decent agreement that we will have wintery precipitation Thursday night into Friday evening in the local area.  Accumulations do not appear to be much at this time, maybe the 1" to 3", with locally higher amounts, range as things look right now.  However, this will be something we need to watch the next few model runs. 

HPC 4" Snow Probability--Thursday 6 a.m. to Friday 6 a.m.

HPC 4" Snow Probability--Friday 6 a.m. to Saturday 6 a.m.

A more significant system may affect us on Monday.  The latest model runs are forecasting a deeper and stronger system which my give us a shot at a little more accumulating snow during this time frame.  However, this is only one model run and we will be looking at consistency as we move toward the weekend. ~ CS