The National Weather Service has issued a WINTER STORM WARNING for the Denver metro area ahead of tomorrow’s storm.  The models continue to indicate a favorable track for the storm to dump decent snows across the Front Range.  Latest numbers bump up the totals to about 5-10″ across the region.  Gusty winds will not only create very cold wind chills, but will blow the fluffy snow around pretty good.

Snow looks to start around daybreak and should last through about midnight.  While some convective snow is possible thanks to the dynamics, the snow should steadily fall at a light to moderate rate through the day.  Heavier amounts will be along the Palmer Divide and in the western suburbs where up to a foot will be possible.  Gusty winds will create blowing snow, mainly in the plains.

For here in Westminster, I am going with half a foot starting as the sun rises with snow falling through the evening hours.  Conditions will deteriorate rapidly after the front rolls through with temperatures and snow both falling through the day on Thursday.  Gusty winds will create some visibility issues in the plains and parts of the immediate foothills.

Temperatures will remain cold, dropping into the teens through the day on Thursday with overnight lows below zero both Thursday and Friday.  Wind chills will be extreme with the wind, so bundle up heavily if heading outside.

I work all day tomorrow, but will be posting periodic updates and intend to shoot some of the storm as my time allows, so stay tuned.

Sitting down before bed and with the lack of anything else to pass the time while my sleepytime vanilla tea kicks in, I opted to pour over the forecast models on Thursday’s storm system which continues to present our best chance for snow along the Front Range so far in the 2010/2011 season.

The GFS continues to be the favorite in terms of snowfall potential with tonight’s runs making the 42hr (noonish Thurs) through 54hr (midnight Fri) look good for Denver with about 0.75″ of liquid which would definitely put us in the Advisory criteria with about 5-10″ city-wide.  The NAM is a bit less, but concentrates just over 0.50″ of liquid in the midday Thursday realm with much lighter amounts on either side of that.  It still holds a good potential for accumulating snow, even as its a couple inches shy of the GFS.  Both of those models slide the surface low across southern Colorado which does put the metro area into a very favorable low-level pattern for upslope and snow potential.  The NAM does try to close off the low at the upper levels which would definitely aid in snowfall production, but it seems more likely that the system will remain open as it swings through.

Again, cold temperatures remain the big story with this system as highs on Friday will barely make the teens.  Thursday’s high will no doubt be reached before sunrise with temperatures plummeting after the front passes through early in the morning.  I figure low 20s and dropping from there throughout the day.  Overnight lows, below zero both Thursday and Friday nights.

Given the trends of the GFS and the NAM, I am a bit more optimistic for a low-end decent snowfall with totals ranging from 3-6″ with higher amounts south and west where the upslope will be better f ocused for a longer duration of time.  Obviously this isn’t a back-breaker and would barely qualify as significant, but the trends are leaning more toward snow than they were a couple days ago and it does maintain a slim chance that we could see higher amounts if a few things fall better into place.

NWS Boulder hasn’t issued any watches, but I wouldn’t be surprised to see at least a Winter Weather Advisory go up at some point tomorrow as later models come out.  Right now, I think 3-6″ is a safe bet with up to 10″ in a few metro locations south and west of the city, but I would also caution that the possibility remains for those predictions to go up a bit, especially if the system does close off, slow down, and track along the southern Colorado border.

Stay tuned…

OMG, an update to my blog!  It’s hard to post anything of note when the weather here has been so quiet!  Seriously, it was sunny and 50 on Christmas and most of the days surrounding it.  While its been nice, it also been boring and that’s lead to the lack of updates.

First off, it’s worth a note of a big event in my personal life.  While I don’t often make such updates here, this falls under the big enough to brag about!

Tony & Dania Laubach; December 17, 2010

I got married!  My now wife and I took the vows in front of over 100 people in Denver, Colorado on Friday, December 17.  A host of my Colorado chasing buddies along with friends and family attended this event!  After nearly 7 years of dating, the time had come!  Figuring after 6 chase seasons, she can endure a few more!

On to weather… forecast models have indicated a major change in our weather for several days now.  The hope obviously would be for this storm to triple or better the 1.5″ of snow on record for this winter season here in Denver.  While saying such a thing doesn’t make this a major snowstorm, it promises to drop temperatures 40-50 degrees.  The GFS and European models have varied differently on the placement of this system which will ultimately determine the snow potential with this storm, but best case scenario even with a proper snow track would be a 6-12″ snowfall, and that’s being optimistic.

Here’s what I know for (nearly) certain…

Temperatures will fall, and they will fall hard.  Wednesday’s readings will be the warmest of the week with highs in the mid to upper 50s.  Depending on the arrival of the front will determine when those temperatures will fall on Thursday.  Regardless, I don’t foresee Thursday’s highs getting out of the 30s during the day.  More than likely, the official high for the day will be between midnight and 6am with temperatures falling from the mid 30s into the 20s during the daylight hours.

Thursday night and Friday will hold the coldest time period with lows below zero and highs in the mid teens.  Forecasts indicate Friday high in the upper teens, but that has steadily dropped with each run, so temperatures closer to 10 wouldn’t be out of the question.  Lows overnight will be near or just below zero again with subsequent nights in the single-digits.

Here’s what remains in question…

Snow potential with this system is (sadly) the highest of the season so far.  And given the whopping 1.5″ of snow for the season, any amounts with this storm will look much bigger than they really are.  Regardless, I think this storm has the potential to be a significant snow maker for the Front Range as opposed to a major winter storm.

The first question is the storm track.  The GFS has a more favorable track to bring snow to the Front Range, but its duration will likely be 12 hours or less, thus keeping snowfall amounts in the 6-12″ range.  It does hold the storm around about 6 hours longer then the European which wants to eject the storm north and east in a hurry.

The European model holds the cold, but doesn’t do a lot for us in terms of snow.  It tracks the system northeast across Colorado and ejects it quickly into Nebraska and gives us a couple hour window post-frontal for some light snow.  This scenario looks more likely between the two right now, but will await to see if the models come together on a solution in the next 48 hours.

Given the storm still being a few days out, there is room to move around with this forecast.  Right now, I am sadly leaning toward the European model for this system and expect the bitter cold with a couple inches of snow.  I hope the GFS becomes the favored solution which will nudge up those snowfall totals a bit starting late Wednesday night through Thursday.

Stay tuned… if anything, it’ll make the weather a bit less boring, at least for a few days.

The massive storm system barreling across the central U.S. had a minimum central pressure of 28.24" or 956 mb (equivalent to the minimum pressure of a Category 3 hurricane).

While it was no record breaker in terms of severe weather outbreaks, it toasted the former record for the lowest recorded pressure in a non-tropical system measured in the U.S.

In terms of severe weather, the storm system produced the wind expected, but it lacked the strong, damaging tornadoes; a fortunate thing.  In all, there were 265 strong wind reports, 7 of which exceeded the 70mph threshold.  There were two dozen tornado reports as well, so there were indeed tornadoes, but most were weak and short lived.

Most of the tornadoes were concentrated across Indiana, Ohio, and Kentucky, with a string of tornado reports very close to my hometown.  One tornado report which is reported to be in Pickaway County was listed near a township located closer to Dayton, so I am not sure about that.

0144 PM     TORNADO          1 W FIVE POINTS         39.67N 83.20W
10/26/2010                   PICKAWAY           OH   TRAINED SPOTTER

            POSSIBLE TORNADO. PATH ABOUT ONE EIGHTH OF A MILE LONG.
            SIX TELEPHONE POLES SNAPPED. ROOF BECAME DETACHED FROM
            BARN AND SIDING TORN OFF SEVERAL HOUSES.

However a strong of reports from an embedded cell launched across northern Pickaway County into southern portions of the Columbus metro area.

Several reports of wind damage were collected, including this one from Circleville..

0152 PM     TSTM WND DMG     CIRCLEVILLE             39.60N 82.94W
10/26/2010                   PICKAWAY           OH   LAW ENFORCEMENT

            TREES DOWN COUNTY WIDE POSSIBLE BLDG COLLAPSE NR
            COMMERCIAL POINT

The air force base just north of Circleville clocked a 63mph wind gust with the squall line as it barrelled through.

0213 PM     TSTM WND GST     3 NNE DUVALL            39.81N 82.93W
10/26/2010  M63.00 MPH       FRANKLIN           OH   AWOS

            RECORDED AT RICKENBACKER INTERNATIONAL AIRPORT /KLCK/

NWS at Wilmington clocked a 72mph wind gust..

0113 PM     TSTM WND GST     WILMINGTON              39.44N 83.83W
10/26/2010  M72.00 MPH       CLINTON            OH   OFFICIAL NWS OBS

            AT NWS WILMINGTON.

And lastly, I enjoyed this report..

1245 PM     TSTM WND GST     BELLBROOK               39.64N 84.09W
10/26/2010  E60 MPH          GREENE             OH   TRAINED SPOTTER

            BLOWING HER BIG TRUCK SIDEWAYS...HARD TO STAY ON ROAD.

As far as I know, there were no significant tornadoes with today’s event as the instability expected to generate the pre-frontal supercells never materialized and thus was lacking to create the strong tornado environments.  That was fortunate as it would’ve made for a deadly day had such storms developed.

Nearly 300 severe weather reports with today's historical storm system.

High risk Of severe thunderstorms, including a large swatch of damaging winds and possible strong tornadoes.

Parts of my homestate were included in a HIGH RISK issued this morning by the Storm Prediction Center.  The risk highlighted is mainly for a damaging wind event due to a squall line expected to move through the region ahead of a very dynamic storm system.  However, an isolated strong tornado is also possible and was highlighted as well (see graphic below).

Threats; 15% tornadoes, hatched to include threat for strong tornadoes and 60% wind, hatched indicated potential for extreme wind events.

The main threat area does not include my hometown of Circleville, however it does remain in the moderate risk area for the potential later in the day as the squall line should move through with wind potential, however the instability axis remains further to the west and north and should allow for weakening of the overall system by the time it impacts south-central Ohio and points east and south.

The main threat area includes most of Indiana and parts of northwestern Ohio, including Van Wert which was hit by an F4 tornado on November 12, 2002.  The Van Wert storm was a fairly discrete storm ahead of the main line as opposed to embedded within a squall line, but had a similar setup overall with a rather low instability, extreme shear/dynamics.  A similar situation today could lead to the development of similar storms in the area, and those would hold the biggest tornado threats as opposed to anything in the line.

However, as the 1999 Circleville F3 proved, tornadoes can indeed happen in the line.  While not as likely as a discrete storm ahead of the line, there remains the possibility of tornado developing in embedded supercells in the main squall.  I believe that scenario is more likely today as opposed to discrete supercells and hence why I think SPC went with the higher-end tornado probs to cover that scenario given the extreme shear involved.  However as the day progresses, the instability should increase as well as the chances for some pre-line storms, and thus I believe the 15%-hatched is warranted to account for such events.  Those will be the storms that hold the biggest threat for strong tornadoes as opposed to anything in the line itself.

Another area of concern with today’s setup is the storm speeds and lack of cover time they will allow.  Ongoing warnings across Indiana and Illinois right now show storm speeds upwards of 60-80mph.  Storms moving at those speeds will not allow for a lot of warning time and may increase wind threats with the downward momentum of air crashing to the ground.  Again, hence the 60%-hatched wind threat as there are likely to be various reports of 80+mph wind gusts within this system.

I gave some consideration to flying out to chase this event, however given the unreasonable conditions for chasing (i.e. storm speeds, squall line, etc), it didn’t seem prudent for me to make the trip for what would virtually be a 1-and-done scenario.  Also, I believe the highest threat areas today will remain well north and west of my hometown, so while that sounds rather selfish and moronic, I didn’t feel the need to be out for this event.  But without question, 60mph storms embedded within a line and the extreme unpredictability of discrete storm development ahead of the line (and their forwards speeds) lead me to not hop a plane.

Those in the highest threat areas need to remain alert today as conditions will change rapidly and warning times will be on the low side.  Because of the nature of this system, any storm, particularly those that may develop in front of the line, hold significant potential to rotate and produce fast moving, damaging tornadoes with little advanced warning.  That scenario makes days like today very dangerous and certainly warrants the higher threat levels to be issued.

Stay safe all!