February 1-5, 2011 Arctic Blast/Winter Storm Discussion

[wxman666]

Winter storm warning has been issued

...WINTER STORM WARNING IN EFFECT FROM NOON TODAY TO NOON CST
FRIDAY...

Mr. T...where did you see that? I'm still seeing watch on HGX's website.

[wxman666]

Never mind.

[Mr. T]

Full product:

...WINTER STORM WARNING FOR ALL OF SOUTHEAST TEXAS FROM NOON CST
THURSDAY TO NOON CST FRIDAY...

.AN UPPER LEVEL STORM SYSTEM APPROACHING FROM THE WEST WILL
COMBINE WITH INCREASING MOISTURE AND COLD TEMPERATURES IN THE
LOWER ATMOSPHERE TO GENERATE A MIX OF SNOW...SLEET...AND FREEZING
RAIN ACROSS SOUTHEAST TEXAS THURSDAY AFTERNOON THROUGH FRIDAY
MORNING.

442 AM CST THU FEB 3 2011

...WINTER STORM WARNING IN EFFECT FROM NOON TODAY TO NOON CST
FRIDAY...

THE NATIONAL WEATHER SERVICE IN HOUSTON/GALVESTON HAS ISSUED A
WINTER STORM WARNING FOR SNOW...SLEET AND FREEZING RAIN...WHICH
IS IN EFFECT FROM NOON TODAY TO NOON CST FRIDAY. THE WINTER STORM
WATCH IS NO LONGER IN EFFECT.

AN UPPER LEVEL STORM SYSTEM APPROACHING FROM THE WEST WILL
COMBINE WITH INCREASING MOISTURE AND COLD TEMPERATURES IN THE
LOWER ATMOSPHERE TO GENERATE A MIX OF SNOW...SLEET...AND FREEZING
RAIN ACROSS SOUTHEAST TEXAS THIS AFTERNOON THROUGH FRIDAY
MORNING. THE PRECIPITATION IS EXPECTED TO BEGIN DURING THE EARLY
AFTERNOON NEAR THE COAST...AND SPREAD AREA WIDE BY EVENING. THE
WINTRY MIX WILL CONTINUE THURSDAY NIGHT THEN TAPER OFF LATE
MORNING FRIDAY.

PRECIPITATION TYPE: VERY LIGHT SNOW AND SLEET IS EXPECTED AT THE
ONSET OF THE EVENT THURSDAY ACROSS ALL OF SOUTHEAST TEXAS.
THURSDAY NIGHT AND FRIDAY MORNING...A MIX OF SLEET AND SNOW IS
EXPECTED TO THE WEST OF A LINE FROM MATAGORDA TO DOWNTOWN HOUSTON
TO NORTHERN LIBERTY COUNTY...WITH ALL SNOW ACROSS THE NORTHWEST
HALF OF THE AREA. EAST OF THIS LINE...FREEZING RAIN IS EXPECTED
TO MIX IN WITH THE SLEET AND SNOW MAINLY BEFORE MIDNIGHT. OVER
SOUTHERN BRAZORIA... SOUTHERN GALVESTON...CHAMBERS...AND SOUTHERN
LIBERTY COUNTIES MOSTLY ICE IS EXPECTED. AFTER MIDNIGHT THESE
AREAS MAY HAVE A SLEET AND SNOW MIX. FREEZING RAIN MIXED WITH
SLEET AND SNOW MAY STILL BE POSSIBLE FOR MOST OF CHAMBERS COUNTY
AND SOUTHERN MOST GALVESTON COUNTY INCLUDING GALVESTON ISLAND.
PRECIPITATION MAY CONTINUE TO CHANGE OVER TO ALL SNOW AFTER 6AM
FRIDAY EXCEPT FOR THE IMMEDIATE COAST WHERE SLEET MAY MIX WITH
THE SNOW. PRECIPITATION SHOULD COME TO AN END NEAR OR SHORTLY
AFTER NOON FRIDAY.

AMOUNTS: IN THE SNOW AND SLEET AREA...ACCUMULATIONS OF 1 TO
3 INCHES ARE EXPECTED WITH ISOLATED TOTALS AROUND 4 INCHES. THE
BEST CHANCE OF 4 INCH ACCUMULATIONS WILL BE ACROSS THE PINEY
WOODS AND LAKES AREA OF EAST TEXAS. IN THE FREEZING RAIN THREAT
AREA...ICE ACCUMULATIONS OF 1/10 TO 1/4 INCH ARE EXPECTED.

IMPACTS: DUE TO EVAPORATIVE COOLING IN THE VERY DRY AIRMASS...
TEMPERATURES WILL RUN 5 TO 7 DEGREES COLDER WITH THIS EVENT THAN
DURING THE LAST FEW WINTER WEATHER EVENTS TO IMPACT THIS AREA.
THESE COLDER TEMPERATURES WILL RESULT IN A MUCH HIGHER LIKELIHOOD
OF ROADS BECOMING ICED OVER...EVEN WITH LIGHT PRECIPITATION
AMOUNTS. THIS WILL ESPECIALLY BE THE CASE WITH ELEVATED SURFACES
LIKE BRIDGES AND OVERPASSES. ROAD CONDITIONS ARE EXPECTED TO
DETERIORATE BEGINNING AROUND SUNSET THURSDAY. IN ADDITION...POWER
OUTAGES WILL BE POSSIBLE ESPECIALLY IN THE FREEZING RAIN THREAT
AREA.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

ROADS...BRIDGES...AND OVERPASSES IN THE WATCH AREA MAY BECOME
SLICK AND HAZARDOUS. ACCUMULATION OF SNOW OR ICE ON ROADWAYS...
BRIDGES AND OVERPASSES MAY MAKE TRAVEL TREACHEROUS. EXERCISE
CAUTION IF TRAVEL IS NECESSARY. IN ADDITION...POWER OUTAGES WILL
BE POSSIBLE.

[Txdreamer62]

David Paul seems to think up to 5" of accumulation in some areas around Houston. Anyone have some idea when they think we'll start seeing the first signs of it today? I have an appt. Downtown at 3. I'm wondering if I should cancel.

[Andrew]

I see some light precip on the Houston radar most likely virga but you never know

[Txdreamer62]

I see some light precip on the Houston radar most likely virga but you never know

yep Galveston already reporting light sleet. Starting earlier than I thought it would.

[Mr. T]

Very light sleet falling in Galveston at the moment. Reported by storm spotter

[srainhoutx]

Good Morning. Here is a sight you will not see everyday...

[Mr. T]

HGX's thoughts for today. They also hint at another interesting pattern developing around next wednesday

522 AM CST THU FEB 3 2011

...WINTER STORM WARNING FOR ALL OF SOUTHEAST TEXAS FROM THIS
AFTERNOON THROUGH FRIDAY MORNING...

.DISCUSSION...
MID AND HIGH CLOUDS HAVE HELD TEMPS THIS MORNING IN THE MID TO
UPPER 20S FOR MUCH OF SE TX WITH LOW 30S ALONG THE COAST. RADAR
HAS BEEN PICKING UP SOME VERY LIGHT RETURNS OVER PORTIONS OF SE
TX BUT NOTHING HITTING THE GROUND AT THIS TIME. UPPER LEVEL LOW
OVER THE DESERT SW AND S ROCKIES IS ACTUALLY DIGGING A LITTLE
MORE TO THE SOUTH. MODELS ARE ALL ON TRACK WITH PUSHING THE UPPER
LOW ACROSS BIG BEND AND INTO C TX TONIGHT. THIS STORM TRACK WILL
SUPPORT THE THREAT FOR FROZEN PRECIPITATION OVER MUCH OF SE TX
FROM THIS AFTERNOON THROUGH FRIDAY MORNING. A WINTER STORM
WARNING HAS BEEN ISSUED FOR THE POSSIBILITY OF SNOW ACCUMULATIONS
GREATER THAN 2 INCHES AND ICE MORE THAN 0.05 INCHES.

TIMING OF PRECIPITATION...EXPECT PRECIPITATION TO BEGIN THIS
AFTERNOON BUT HOW MUCH ACCUMULATIONS IS STILL DEBATABLE. MUCH OF
THE PRECIP WILL HAVE TO GO INTO EVAPORATIVE COOLING AND WET
BULBING TO SATURATE THE BOUNDARY LAYER WHICH IS CURRENTLY DRY.
SFC DEWPOINTS ARE STILL IN THE UPPER TEENS. THE NET EFFECT OF
THIS WILL BE TO RAISE THE DEWPOINTS BUT ALSO DECREASE THE
TEMPERATURE. SNOW WILL BE THE MAIN PRECIP TYPE FOR MUCH OF THE
AREA THIS AFTERNOON AND TONIGHT. AREAS NEAR AND SOUTH OF A
CLEVELAND TO HOUSTON TO EDNA LINE OR ALONG US HWY 59 CAN EXPECT A
MIX OF SNOW AND SLEET BEFORE CHANGING OVER TO SNOW. THE TRICKY
PART OF THE FORECAST IS CLOSER TO THE COAST. WARM ADVECTION WITH
ISENTROPIC LIFT NEAR 850MB MAY BE STRONG ENOUGH FOR TEMP PROFILES
TO WARM ABOVE FREEZING IN THIS LAYER. SHOULD THIS HAPPEN FREEZING
RAIN WILL BE THE MORE LIKELY PRECIPITATION TYPE. THIS WILL BE
ESPECIALLY TRUE FOR AREAS FROM GALVESTON ISLAND INTO CHAMBERS
COUNTY. AREAS FROM MATAGORDA TO ANGLETON TO NORTHERN GALVESTON
COUNTY WILL MOST LIKELY STILL HAVE A SLEET/SNOW MIX. BY FRIDAY
MORNING...PRECIP IS EXPECTED TO BE ALL SNOW EXCEPT FOR MAYBE
CHAMBERS COUNTY AND GALVESTON ISLAND WHERE A SNOW/SLEET MIX WILL
BE POSSIBLE. PRECIP SHOULD THEN END AFTER 18Z FRI.

ACCUMULATIONS...THIS IS ALSO QUITE TRICKY BUT STILL THINK GIVEN
MODEL QPF OUTPUT 1-3 INCHES OF SNOW AREA WIDE LOOKS GOOD. THE
PROBLEM COMES WHEN CONSIDERING ANY PRECIP BANDS THAT MAY FORM.
LOOKING AT CROSS SECTIONS...FRONTGENETIC LIFT WILL BE QUITE
STRONG AND COUPLED WITH AREAS OF CONDITIONAL SYMMETRIC
INSTABILITY. 4KM WRF AND NAM INDICATE PRECIP BANDS IN BOTH
SIMULATED REFLECTIVITY AND QPF OUTPUT. GIVEN THIS MESOSCALE
FORCING WITH STRONG UPPER LEVEL QG FORCING AND ASCENT FROM THE
UPPER LOW AND JET...QUITE POSSIBLE FOR BANDS TO FORM WITH
ENHANCED PRECIP AMOUNTS. THIS MEANS ISOLATED BANDS OF 4 INCHES
COULD BE POSSIBLE ESPECIALLY IF THERE IS SOME WEAK CONVECTIVE
ACTIVITY WITHIN THE BANDS. SPC HAS EVEN PUT PART OF THE AREA IN A
GENERAL THUNDERSTORM OUTLOOK. IT IS THIS CONCERN THAT THE WINTER
STORM WARNING WAS ISSUED. THAT BEING SAID...CONCERNED THAT THE
GFS HAS A QPF MINIMUM OVER THE AREA AT 06Z FRI WHEN LIFT WILL BE
INCREASING AND MODEL SOUNDINGS FAVOR PRECIP EXCEPT FOR IN THE
LOWER LEVELS WHERE MOISTENING MAY NEED TO OCCUR. MOISTURE STILL
EXISTS DESPITE THIS WITH PW AROUND 0.8 INCHES. SHOULD THE
FREEZING RAIN DEVELOP WITH THE WARM ADVECTION AT 850MB...THINK
THAT COASTAL AREAS THROUGH CHAMBERS CO COULD SEE A GOOD 1/10 TO
1/4 INCH OF ICE ESPECIALLY IF A SOLID BAND SETS UP OVER THE AREA.

THE OTHER REASON FOR THE WARNING IS THAT SE TX HAS BEEN RATHER
COLD AND ALL SURFACES HAVE HAD TIME TO FREEZE. THIS MEANS ANY
SNOW OR ICE THAT FALLS WILL ACCUMULATE AND CAUSE SIGNIFICANT
PROBLEMS FOR ROADS...BRIDGES AND OVERPASSES. TRAVEL ACROSS SE TX
WILL BE A PROBLEM FOR ALL MOTORISTS.

WEEKEND SHOULD HAVE A DECENT ENOUGH WARM UP THAT ANY REMAINING
ICE OR SNOW SHOULD MELT. THERE MAY BE A DAY OR TWO OF
TEMPERATURES WELL ABOVE FREEZING MAINLY SUNDAY. MODELS ARE HAVE A
TOUGH TIME WITH THE NEXT FRONT. LATEST 00Z GFS/ECMWF ARE CLOSE
ENOUGH WITH A FRONTAL PUSH MONDAY MORNING. CHANGES TO THE
FORECAST WERE MADE TO REFLECT THIS...MAINLY TO MAX/MIN TEMPS.
PRECIP LOOKS MINIMAL AS MOISTURE RETURN IS LIMITED. NEXT
WEDNESDAY COULD BE INTERESTING AGAIN AS THE AIRMASS WILL BE COLD
AGAIN WITH ANOTHER SHORTWAVE TROUGH MOVING ACROSS. MENTION 20
POPS FOR RAIN AS TEMPS AT THIS TIME ARE ABOVE FREEZING. AGAIN
WITH THE MODELS HAVING A TOUGH TIME WITH THE INITIAL FRONTAL
PUSH...THE EXTENDED FORECAST WILL BE SUBJECT TO SOME CHANGES.

39

[cristina99]

Good morning! Yes, David Paul has mentioned anywhere north of I-10 or Houston could see 3-5" of the white stuff. That went up from yesterday. And the chance has also gone up to 80%!!! I hope those that are having doubts, change their minds. I mean today is D-day! Bring the snow on - don't see how my office will make us go to work tomorrow, but what do I know. Another co-worker said if she doesn't feel comfortable getting on the roads (no matter how short of a drive it is) she's using a personal day - think I will do the same thing. It's coming!

[srainhoutx]

SPC Day One Outlook:

...WESTERN GULF COAST...
LOW PROBABILITIES FOR THUNDERSTORMS ALSO APPEAR TO EXIST ACROSS
PARTS OF EASTERN TEXAS AND UPPER TEXAS COASTAL AREAS INTO LOUISIANA
LATE THIS EVENING INTO EARLY FRIDAY...WHEN MID-LEVEL LAPSE RATES
APPEAR LIKELY TO STEEPEN WITH THE APPROACH OF THE CLOSED LOW.
FORECAST SOUNDINGS SUGGEST THAT THIS WILL CONTRIBUTE TO WEAK
CAPE...BASED WITHIN A SATURATED ENVIRONMENT NEAR OR ABOVE 700
MB...WITHIN THE MIXED PHASE LAYER FAVORABLE FOR THE DEVELOPMENT OF
CHARGE SEPARATION...AND CLOUD TO GROUND LIGHTNING.

[wxman57]

Initial observations of current conditions along the coast would indicate that the Canadian was wrong with it's moisture projection and start time and the low position offshore. Euro was too early bringing in the precip. Dew points are quite low and offshore winds would suggest the low would form farther offshore per the GFS/NAM. That would mean accumulations would be toward the lower end of estimates rather than the high end. A trace to 2" appears most likely across much of Houston, rather than any 3-5 inches or 6-8 inch isolated amounts.

Heading in to work now, will take a good look at soundings once there. They may shed some light on precip amounts.

[Katdaddy]

Thunder snow may be possible in SE TX.....interesting day ready to unfold

[Mr. T]

Initial observations of current conditions along the coast would indicate that the Canadian was wrong with it's moisture projection and start time and the low position offshore. Euro was too early bringing in the precip. Dew points are quite low and offshore winds would suggest the low would form farther offshore per the GFS/NAM. That would mean accumulations would be toward the lower end of estimates rather than the high end. A trace to 2" appears most likely across much of Houston, rather than any 3-5 inches or 6-8 inch isolated amounts.

Heading in to work now, will take a good look at soundings once there. They may shed some light on precip amounts.

Galveston already had some sleet, though. And the Euro and CMC only predicted very light amounts right along the coast at this point. I disagree, especially with banding prospects possible.

I also see some virga developing across NE counties right now, which would suggest that moisture is beginning to pool well inland.

[Mr. T]

I'm looking at the 0z CMC, and it doesn't have the heaviest precip arriving until later on this afternoon

I don't understand what you're talking about, wxman...

Also, dewpoints are much higher than the GFS suggests right now. Upper teens instead of lower teens. Again, suggesting to me that the GFS does not have a great handle on the amount of moisture advecting into the area right now.

[srainhoutx]

Just took the trash out. Brrrr...24.8F up here at this time...

[Katdaddy]

I will be interested what Jeff has to say this morning. Onward to downtown for work which may be end a little early today

[PaulEInHouston]

Morning all...League City checking in. RH rising quickly...hovering near freezing here. Seems winds have increased as well. Radar showing some returns east of the bay supporting reports of light sleet in GLS area.

TIME TEMP WIND SPD WIND GUST WIND DIR HUMIDITY PRESSURE RAIN
Current 32.8 °F 8.1 17.3 NNW 66% 30.400 0.00
30 minutes ago 33.1 °F 5.8 8.1 NNW 66% 30.406 0.00
45 minutes ago 33.0 °F 9.2 11.5 N 65% 30.408 0.00
60 minutes ago 33.2 °F 5.8 9.2 NW 65% 30.404 0.00
75 minutes ago 33.1 °F 10.4 13.8 NNW 65% 30.414 0.00
90 minutes ago 33.3 °F 6.9 11.5 NNW 64% 30.409 0.00
120 minutes ago 33.2 °F 9.2 16.1 NNW 63% 30.427 0.00

[texaskaz]

Whoo hoo! Realized we brought sleds home from New Mexico trip and they are hanging in garage! Gonna go find me an empty retention pond wall! Bring it on! I am near Hooks and will let ya'll know along the way what we get

[MRG93415]

Whoo hoo! Realized we brought sleds home from New Mexico trip and they are hanging in garage! Gonna go find me an empty retention pond wall! Bring it on! I am near Hooks and will let ya'll know along the way what we get

Hubby and I laughing at ya (In the good way)...We say bring it on Texaskaz and have yourself a ball.....