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

[ticka1]

I don't see any moisture or snow in any forecast in the houston area for thursday or friday.

Ticka1...the icons have not been updated yet. Here's the link.

http://forecast.weather.gov/MapClick.php?zoneid=TXZ213

Okay that's what i was looking for....sorry its too early and I dreamed about snow last night...

[srainhoutx]

I'll post the entire discussion. You're right, Tyler. One of the better discos in a while from HGX. SPS (Special Weather Statement) and updated HWO (Hazardous Weather Outlook) coming shortly as well from HGX. Interesting...we are finally nearing this loooong tracked pattern/event...time for some coffee....

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
444 AM CST MON JAN 31 2011

...ARCTIC AIRMASS TO MOVE INTO SE TEXAS TUESDAY...

.DISCUSSION...
TODAY WILL BE THE LAST DAY FOR ABOVE NORMAL TEMPERATURES AS AN
ARCTIC COLD FRONT IS EXPECTED TO PUSH ACROSS SE TX ON TUESDAY.
MAX TEMPS IN THE 70S TODAY WILL QUICKLY GIVE WAY TO FALLING TEMPS
ON TUESDAY BEHIND THE COLD FRONT. TEMPERATURES ON WEDNESDAY WILL
BE SOME 30-40 DEGREES COLDER. THIS IS JUST THE BEGINNING OF A
COMPLEX FORECAST FOR THIS COMING WORK WEEK.

UPPER AIR ANALYSIS SHOWS ONE SHORTWAVE TROUGH PUSHING OUT OF THE
AREA WITH ANOTHER SHORTWAVE OVER CALIFORNIA THAT WILL MOVE ACROSS
THE S ROCKIES TONIGHT AND INTO TX TOMORROW. THIS SHORTWAVE WILL
PROVIDE STRONG DIVERGENCE FROM A 130KT 300MB JET ON TUESDAY. SFC
LOW SHOULD FORM ON THE ARCTIC FRONT IN W TX AT 06Z TUE AND MOVE
IN TO ARK BY 18Z TUE WITH THE FRONT TRAILING IT. MOIST WARM
SECTOR WILL BE IN PLACE BUT INSTABILITY LOOKS TO BE SOMEWHAT
LIMITED. GIVEN THE STRONG FORCING...STILL THINK THERE WILL BE A
FEW THUNDERSTORMS TO MOVE ACROSS THE AREA ALONG THE FRONT. AN ISO
SEVERE STORM WILL BE POSSIBLE WITH DAMAGING WINDS/HAIL AS THE
MAIN THREATS. LOW LEVEL SHEAR MAY BE STRONG ENOUGH TO SUPPORT
ROTATING STORMS WITH IN A LINE OF STORMS ALONG THE FRONT BUT
INSTABILITY MAY BE WEAK ENOUGH TO SUPPORT THESE STORM STRUCTURES.

THE COLD FRONT SHOULD PUSH THROUGH SE TX BY 18Z-21Z TUE WITH
TEMPERATURES FALLING QUICKLY INTO THE 40S BY THE AFTERNOON.
TEMPERATURES WILL CONTINUE TO FALL INTO THE 20S TUE NIGHT AND WED
MORNING. HARD FREEZES WILL BE LIKELY WED...THU AND FRI MORNINGS
WITH WARNINGS POSSIBLE EACH MORNING. STRONG NORTHERLY WINDS AND
CLOUD COVER WILL KEEP TEMPERATURES FROM WARMING MUCH DURING THE
DAY WED THROUGH FRI. MAX TEMPS IN THE UPPER 30S/LOW 40S LOOK
REASONABLE AND THIS UNDERCUTS GFS GUIDANCE SOME DURING THIS TIME
FRAME. MIN TEMPS LOOK REASONABLE WITH MIN TEMPS IN THE UPPER
TEENS FOR NORTHERN SE TX BY THU MORNING.

THE FORECAST THURSDAY NIGHT THROUGH FRIDAY NIGHT BECOMES MORE
CHALLENGING WITH CHANGES IN THE UPPER LEVEL PATTERN. WATER VAPOR
SHOWS A STRONG SHORTWAVE TROUGH OVER MONTANA/CANADA BORDER WITH
A JET STREAK COMING INTO THE BACK SIDE OF IT OVER THE CANADIAN
ROCKIES. ALL OF THE MODELS DROP THIS TROUGH SOUTHWARD THROUGH THE
ROCKIES NEAR THE 4 CORNERS REGION BY WED. THE MODELS THEN BEGIN
TO DIVERGE IN THEIR SOLUTIONS WITH THE ECMWF/CANADIAN HOLDING THE
TROUGH OVER THE S ROCKIES WITH THE GFS/NAM BEING MORE
PROGRESSIVE. THE GFS ENSEMBLE IS SOMEWHERE BETWEEN THE TWO MODEL
CAMPS BUT CLOSER TO THE SLOWER ECMWF/CANADIAN SOLUTIONS. BY 12Z
FRI...THE GFS HAS THE TROUGH OVER C TX WITH STRONG QG FORCING AND
LARGE SCALE ASCENT OVER SE TX. THE SAME CAN BE SAID WITH THE
ECMWF/CANADIAN SOLUTIONS BUT DELAYED BY 6 TO 12 HRS. THE
COMBINATION OF WEAK ISENTROPIC LIFT AND FRONTOGENETIC LIFT WITH
THE LARGE SCALE ASCENT WILL BE FAVORABLE FOR PRECIP BANDS TO FORM
OVER SE TX. GIVEN THE ARCTIC AIRMASS IN PLACE...POSSIBLE THAT
PRECIP WILL FALL AS SNOW LOOKING AT MODEL SOUNDINGS. CLOSER TO
THE COAST...PRECIP MAY TRANSITION FROM RAIN TO SLEET TO SNOW
DEPENDING ON HOW TEMPERATURE AND MOISTURE PROFILES EVOLVE. THERE
IS STILL QUITE A BIT OF UNCERTAINTY WITH THE DEVELOPMENT OF FROZEN
PRECIP. THERE ARE STILL TIMING ISSUES WITH THE TROUGH AND WHEN
THE BEST LIFT OCCURS COMBINED WITH THE RIGHT TEMP/MOISTURE
PROFILES. BOUNDARY LAYER MOISTURE MAY BE LACKING AT FIRST WITH
SFC DEWPOINTS IN THE TEENS TO LOW 20S. EVAPORATIVE COOLING/WET
BULBING OCCURRING WITH THE STRONG ASCENT MAY HELP ELIMINATE THIS
DRY AIR IN THE LOW LEVELS. THIS SCENARIO MAY BE MORE FAVORABLE
WITH A SLOWER PROGRESSION OF THE TROUGH LIKE THE ECMWF. THERE IS
STILL PLENTY OF TIME TO MONITOR THIS SITUATION BUT FOR NOW PRECIP
WILL BE KEPT AS A MIX OF RAIN/SNOW TO START...SNOW OVER INLAND
AREAS WHERE/WHEN FREEZING TEMPS OCCUR...WITH A MIX AGAIN DURING
THE DAY FRI. WILL LEAVE OUT MENTION OF SLEET IN THE FORECAST AS
DETAILS WILL CHANGE AND WILL TRY TO NAIL DOWN THESE DETAILS WITH
FUTURE FORECASTS.

TEMPERATURES BEGIN TO MODIFY OVER THE WEEKEND WITH A BROAD LONG
WAVE TROUGH OVER MUCH OF THE CENTRAL U.S. TEMPERATURES MAY SLOWLY
CLIMB BACK TO NORMAL AFTER BEING 20 DEGREES BELOW NORMAL FOR MUCH
OF THE COMING WEEK. A SPECIAL WEATHER STATEMENT (SPS) WILL BE
ISSUED TO DISCUSS SPECIFIC HAZARDS WITH THE UP COMING ARCTIC
OUTBREAK AND THE HAZARDOUS WEATHER OUTLOOK (HWO) WILL ONLY
HIGHLIGHT THESE HAZARDS.

[wxman666]

Special Weather Statement
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
508 AM CST MON JAN 31 2011

TXZ163-164-176>179-195>200-210>214-226-227-235>238-312215-
HOUSTON-TRINITY-MADISON-WALKER-SAN JACINTO-POLK-BURLESON-BRAZOS-
WASHINGTON-GRIMES-MONTGOMERY-LIBERTY-COLORADO-AUSTIN-WALLER-
HARRIS-CHAMBERS-WHARTON-FORT BEND-JACKSON-MATAGORDA-BRAZORIA-
GALVESTON-
INCLUDING THE CITIES OF...CROCKETT...TRINITY...GROVETON...
MADISONVILLE...HUNTSVILLE...SHEPHERD...COLDSPRING...LIVINGSTON...
CORRIGAN...ONALASKA...CALDWELL...LAKE SOMERVILLE...
COLLEGE STATION...BRYAN...BRENHAM...NAVASOTA...THE WOODLANDS...
CONROE...WILLIS...LIBERTY...CLEVELAND...DAYTON...COLUMBUS...
EAGLE LAKE...WEIMAR...SEALY...BELLVILLE...HEMPSTEAD...
PRAIRIE VIEW...BROOKSHIRE...HOUSTON...PASADENA...KATY...TOMBALL...
HUMBLE...WINNIE...MONT BELVIEU...ANAHUAC...EL CAMPO...WHARTON...
PIERCE...SUGAR LAND...MISSOURI CITY...RICHMOND...ROSENBERG...
EDNA...BAY CITY...PALACIOS...PEARLAND...LAKE JACKSON...ALVIN...
ANGLETON...FREEPORT...LEAGUE CITY...TEXAS CITY...FRIENDSWOOD...
GALVESTON
508 AM CST MON JAN 31 2011

...ARCTIC COLD FRONT TO ARRIVE TUESDAY WITH WINTRY PRECIPITATION
POSSIBLE FRIDAY...

AN ARCTIC COLD FRONT IS EXPECTED TO PUSH THROUGH SOUTHEAST TEXAS
DURING THE DAY TUESDAY. A LINE OF STRONG TO SEVERE THUNDERSTORMS
WILL DEVELOP ALONG IT TUESDAY MORNING WITH SOME STORMS PRODUCING
DAMAGING STRAIGHT LINE WINDS. STRONG NORTHERLY WINDS WILL BE
EXPECTED BEHIND THE FRONT AND A WIND ADVISORY MAY BE NEEDED FOR
MUCH OF THE AREA. THIS WILL USHER A MUCH COLDER AIRMASS INTO THE
AREA WITH TEMPERATURES FALLING INTO THE 40S BY TUESDAY AFTERNOON.
MINIMUM TEMPERATURES BY WEDNESDAY MORNING WILL BE IN THE LOW TO
MID 20S INLAND...UPPER 20S TO NEAR 30 ALONG THE COAST. A HARD
FREEZE WARNING MAY BE NEEDED. FREEZING TEMPERATURES WILL BE
POSSIBLE EACH NIGHT THROUGH THE END OF THE WEEK. RESIDENTS OF
SOUTHEAST TEXAS NEED TO MAKE NECESSARY PREPARATIONS TO PROTECT
PROPERTY AND LIFE FROM THE FREEZING TEMPERATURES. PIPES NEED TO
BE PROTECTED TO PREVENT BURSTING. PLANTS AND TENDER VEGETATION
WILL NEED PROTECTION FROM THE HARSH COLD. ENSURE THAT ELDERLY
PEOPLE AND CHILDREN ARE ALSO WELL PROTECTED AND HAVE SHELTER FROM
THE COLD CONDITIONS.

NWS METEOROLOGISTS WILL ALSO CONTINUE TO MONITOR A POSSIBLE
WINTER PRECIPITATION EVENT THURSDAY NIGHT THROUGH FRIDAY NIGHT.
THERE IS STILL LARGE UNCERTAINTY WITH REGARD TO THE TIMING OF THE
EVENT. AN UPPER LEVEL DISTURBANCE IS EXPECTED TO MOVE ACROSS THE
REGION EARLY FRIDAY MORNING THROUGH THE DAY TIME HOURS.
TEMPERATURES FRIDAY MORNING WILL BE WELL BELOW FREEZING SO SNOW
WILL BE THE MAIN PRECIPITATION TYPE. THE FROZEN PRECIPITATION
TYPE LARGELY DEPENDS ON MOISTURE AND TEMPERATURE PROFILES IN THE
LOWEST LEVELS OF THE ATMOSPHERE. THERE IS STILL SOME UNCERTAINTY
AS TO WHETHER THESE PARAMETERS WILL BE MET. RESIDENTS OF
SOUTHEAST TEXAS ARE ENCOURAGED TO CONTINUE TO MONITOR FORECASTS
FOR ANY CHANGES AND FOR UPDATED INFORMATION ON POSSIBLE HAZARDS
FROM ANY FROZEN PRECIPITATION.

39

$$

[Mr. T]

We're going to have it all this week. Heavy rain, isolated severe weather, hard freezes, and a slight chance of snow

Here are record lows at IAH for the coming week. We definitely stand a chance to break some of these

Feb 2 (Wednesday): 14 in 1951
Feb 3 (Thursday): 23 in 1951
Feb 4 (Friday): 22 in 1996
Feb 5 (Saturday): 23 in 1996

[cristina99]

Good morning! David Paul is FINALLY talking about this winter event - and warning people to use today to get prepared. I can't believe it. It's going to be so exciting. Just getting ready for work. Will check in when I can. David Paul showed Wed and Thursday highs not getting out of the 30s. Amazing. We are experiencing spring like storms, then go right back into deep winter. wow . . ..

[wxman666]

Good morning! David Paul is FINALLY talking about this winter event - and warning people to use today to get prepared. I can't believe it. It's going to be so exciting. Just getting ready for work. Will check in when I can. David Paul showed Wed and Thursday highs not getting out of the 30s. Amazing. We are experiencing spring like storms, then go right back into deep winter. wow . . ..

I will be talking to my dad when he wakes up and see what he wants me to do. He'll need to know today is the day to prepare.

[wxman57]

Projected soundings from the GFS do indicate a vertical column of sub-freezing air from the surface up to near the moon Thursday night. It appears that the surface wave/low on the front may be close enough to the coast such that there will be enough moisture for precipitation. That would mean snow Thursday night to around sunrise Friday. Probably just a dusting due to limited moisture, but I guess that would do for most of you.

I spent a few hours up in my attic yesterday spreading insulation out so that my water pipes would be covered better. I may do a bit more of that before Wednesday. At least we got 3 good bike rides in over the weekend with temps near 70. Probably no biking next weekend with highs in the 40s on Saturday and rain Sunday. Still waiting for that first 80 degree day to show up on the IAH meteogram...

[jabcwb2]

Projected soundings from the GFS do indicate a vertical column of sub-freezing air from the surface up to near the moon Thursday night. It appears that the surface wave/low on the front may be close enough to the coast such that there will be enough moisture for precipitation. That would mean snow Thursday night to around sunrise Friday. Probably just a dusting due to limited moisture, but I guess that would do for most of you.

I spent a few hours up in my attic yesterday spreading insulation out so that my water pipes would be covered better. I may do a bit more of that before Wednesday. At least we got 3 good bike rides in over the weekend with temps near 70. Probably no biking next weekend with highs in the 40s on Saturday and rain Sunday. Still waiting for that first 80 degree day to show up on the IAH meteogram...

When I went to bed last night, there was a 20% chance of precip. When I woke up this morning, a 30% chance! Keep up the good work, Mother Nature!!!

[Portastorm]

30% chance of snow here as well in AUS on Thursday night.

Glad Wxman57 got his cycling in this weekend. Sure was beautiful.

[MRG93415]

David Paul mentioned Snow possibilities for Thursday and Friday and a better chance for Friday BUT he doesnt seem to concerned about it and doesnt think it will effect the traffic...

[C2G]

David Paul mentioned Snow possibilities for Thursday and Friday and a better chance for Friday BUT he doesnt seem to concerned about it and doesnt think it will effect the traffic...

That's good news for me, because I have to show up regardless.
Guess the dynamics are more impressive in the DFW area?
Although what they're saying isn't anything that incredible.

National Weather Service Fort Worth Texas
1131 PM CST sun Jan 30 2011


Finally we have been internally discussing the potential for
another system by next weekend for a couple days now. Basically
the upper level pattern leaves an upper low at the base of the
trough to our west. Models have been showing flashes of bringing
this low through in tact Fri-sun. Most have now settled on
bringing this through in the Friday timeframe now...but few are
very bullish with moisture profiles. The pattern is similar to the
Christmas Dec 2004 snowstorm in south Texas...and models showed
that low having little moisture too until it was too late. Either
way we are closely watching this system to see where it tracks...
and believe if the 500 mb pattern verifies like the European model (ecmwf)/Gem/GFS
show...it will find the moisture. Have introduced 20 percent
chance of snow Friday and Friday night...but much uncertainty
still exists.

[srainhoutx]

David Paul mentioned Snow possibilities for Thursday and Friday and a better chance for Friday BUT he doesnt seem to concerned about it and doesnt think it will effect the traffic...

David only mentioned that after the SPS was issued. At 4:30AM his forecast had nothing but a vocal mention of a very slight chance of rain and maybe some sleet.

[srainhoutx]

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0644 AM CST MON JAN 31 2011

VALID 311300Z - 011200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF CENTRAL TX...

...TX...
EARLY MORNING WATER VAPOR IMAGERY SHOWS A POWERFUL MID/UPPER LEVEL
TROUGH DIGGING SOUTH-SOUTHEASTWARD ACROSS AZ AND NORTHWEST MEXICO.
AS THIS SYSTEM TURNS EASTWARD LATER TODAY...PERSISTENT SOUTHWESTERLY
LOW LEVEL WINDS ACROSS TX WILL SLOWLY MOISTEN THE BOUNDARY LAYER AND
YIELD A MARGINALLY UNSTABLE AIR MASS WITH MUCAPE VALUES AROUND 500
J/KG. A CAPPING INVERSION AND WEAK LIFT WILL SUPPRESS ORGANIZED DEEP
CONVECTION THROUGH THE DAY...BUT INCREASING LARGE SCALE FORCING AND
CONVERGENCE ALONG A SOUTHWARD-MOVING SURFACE COLD FRONT WILL LIKELY
RESULT IN SCATTERED THUNDERSTORM DEVELOPMENT OVER PORTIONS OF
NORTH-CENTRAL TX AFTER DARK. THE MAJORITY OF THESE STORMS ARE
EXPECTED TO DEVELOP ALONG AND NORTH OF THE COLD FRONT AND REMAIN
ELEVATED. NEVERTHELESS... STEEP MID LEVEL LAPSE RATES AND FAVORABLE
DEEP LAYER VERTICAL SHEAR WILL SUPPORT A RISK OF HAIL IN THE
STRONGER CELLS. IF ANY STORMS ARE ABLE TO DEVELOP SOUTH OF THE
FRONT...LOCALLY DAMAGING WINDS WOULD ALSO BE POSSIBLE. OVERALL
INTENSITY OF CONVECTION SHOULD SLOWLY DIMINISH OVERNIGHT...BUT
COVERAGE WILL CONTINUE TO EXPAND ACROSS NORTH/CENTRAL TX AND
SOUTHERN OK THROUGH 12Z.

..HART/GRAMS.. 01/31/2011

[srainhoutx]

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1209 AM CST MON JAN 31 2011

VALID 011200Z - 021200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
PLAINS...LOWER MS VALLEY AND CNTRL GULF COAST STATES...

...SRN PLAINS/LOWER MS VALLEY/CNTRL GULF COAST...
AN IMPRESSIVE UPPER-LEVEL TROUGH ACROSS WEST AND CNTRL TX WILL LIFT
QUICKLY NEWD TOWARD THE ARKLATEX TUESDAY. AT THE SFC...A STRONG COLD
FRONT IS FORECAST TO MOVE EWD ACROSS EAST TX IN WHICH A SQUALL-LINE
MAY BE ONGOING AT DAYBREAK TUESDAY MORNING JUST AHEAD OF THE
BOUNDARY. STRONG VERTICAL SHEAR ASSOCIATED WITH A COUPLET OF THE LOW
AND MID-LEVEL JETS SHOULD SUPPORT A SEVERE THREAT AS THE LINE MOVES
INTO FAR EAST TX...WRN/NRN LA AND SRN/ERN AR AROUND MIDDAY. ALTHOUGH
A TORNADO THREAT WILL BE POSSIBLE WITH STRONGER STORMS EMBEDDED IN
THE LINE...SFC DEWPOINTS WILL ONLY BE IN THE 50S F ACROSS THE OZARKS
SUGGESTING THE PRIMARY THREAT WOULD BE WIND DAMAGE WITH A FAST
MOVING CONVECTIVE SYSTEM. IN SPITE OF THE WEAK INSTABILITY...HAVE
INCLUDED AREAS AS FAR NORTH AS LITTLE ROCK FOR THE SLIGHT RISK. IN
THE ARKLATEX AND SRN OZARKS...THE SHEAR-ENVIRONMENT SHOULD BE
FAVORABLE FOR ROTATING STORMS ESPECIALLY AS SFC TEMPS WARM TUESDAY
AFTERNOON ON THE WEST SIDE OF A WELL-DEFINED AND CONCENTRATED 60 TO
70 KT LOW-LEVEL JET.

FURTHER SOUTH SOUTHEAST ALONG THE MOIST AXIS IN THE LOWER MS
VALLEY...SFC DEWPOINTS SHOULD REACH THE LOWER TO MID 60S F WHERE THE
WARM SECTOR SHOULD BE OF HIGHER QUALITY THAN TO THE NORTH. THE
GREATEST INSTABILITY SHOULD BE LOCATED ACROSS SE LA WHERE FORECAST
SOUNDINGS SUGGEST MUCAPE PARCELS COULD APPROACH 1000 J/KG BY TUESDAY
AFTERNOON AS SFC TEMPS WARM. A CLUSTERING OF SEVERE REPORTS WITH A
FEW TORNADOES...WIND DAMAGE OR HAIL WILL BE POSSIBLE IN THE SRN MS
AND THE MS DELTA ESPECIALLY IF A SQUALL-LINE CAN ORGANIZE AND
PERSIST INTO THE EARLY EVENING. STRONG DEEP LAYER SHEAR WITH
ENHANCED LOW-LEVEL SHEAR PROFILES ON THE SRN EDGE OF THE LOW-LEVEL
JET SHOULD BE SUFFICIENT FOR ROTATING STORMS. THE TORNADO THREAT
COULD BECOME ENHANCED BUT THIS MAY DEPEND UPON IF STORMS CAN REMAIN
DISCRETE OR IF ROTATING STORMS CAN BE MAINTAINED WITHIN THE LINE
ITSELF. FOR THE OVERNIGHT PERIOD...MODEL FORECASTS KEEP A CONVECTIVE
SYSTEM GOING ACROSS AL AND THE FL PANHANDLE BUT THE CURRENT THINKING
IS THAT ANY SEVERE POTENTIAL SHOULD REMAIN CLOSE TO THE COAST CLOSER
TO THE GREATEST INSTABILITY.

..BROYLES.. 01/31/2011

[srainhoutx]

Morning e-mail from Jeff...

Dangerous winter weather heading for the state of Texas.

Preparations for an extended period of very cold air should be completed today.

Major winter storm to affect W and N TX tonight and Tuesday into the central plains

Winter precipitation possible across the entire TX coast (including S TX) Thursday and Friday.

Discussion:

Long advertised arctic outbreak is on the move this morning with the very cold air mass now crossing the US border over Montana and North Dakota. Current temperatures are -27 in northern Montana with the leading edge of the arctic front in central Wyoming. Strong blocking along the US west coast with ridging building deep into Alaska will force the -30 to -40 degree air mass over NW Canada southward into the US central plains over the next 24-36 hours. Appears record cold temperatures are on the way to much of the plains along with a major blizzard for the central plains and Great Lakes. Overnight lows forecast to drop into the -5 to -10 range over the Texas panhandle and possibly the lower teens to single digits over N TX. Sub-zero wind chills will be likely as far south as Waco by Wednesday.

Will break the impacts down by time periods to try and help layout an extremely difficult and changeable forecast.

Tuesday:

Powerful arctic boundary will reach the TX panhandle this evening and sweep southward across N TX by sunrise. Shallow but very cold air mass will undercut the warm Gulf surface layer with widespread rainfall/thunderstorms. Temperatures prior to the front will reach the mid-upper 60’s and then fall rapidly into the 30’s behind the front. Rain will change to freezing rain/sleet/snow from NW to SE over N TX during the day on Tuesday while a large blizzard develops from W TX into OK. Travel to W TX and N TX/OK on Tuesday will be extremely dangerous with heavy blowing snow on 40-45mph winds and temperatures in the teens and 20’s.

Tuesday night:

Arctic cold front blasts into the Gulf of Mexico with very strong cold air advection in progress. Winds will howl post front 20-35mph with gust to 40mph driving wind chills into the teens all across coastal Texas and to near zero as far south as Waco. Freezing line will advance to the US 59 corridor by mid evening and then to the coast with mid 20’s for all locations north of a line from Huntsville to Sugar Land to Victoria by Wednesday morning. This will be a damaging advective freeze for sensitive vegetation. Wind advisories may be required for parts of the area.

Wednesday:

Arctic dome deepens toward 900mb with low level moisture likely trapped near the surface keeping skies mostly cloudy. Strong north winds will continue to drive very cold air southward off the snow pack over W and N TX/OK. Will likely see very little warming to maybe freezing NW of a line from Conroe to Hempstead to Victoria. SE of this line highs may reach the mid 30’s. Wind chills will be in the teens. Clouds may clear out some Wednesday night allowing lows for Thursday morning to bottom out in the teens N of HWY 105, low 20’s along the US 59 corridor, and upper 20’s/low 30’s along the coast.

Forecast for Thursday onward is subject to major changes due to high uncertainty when dealing with forecasting winter precipitation in coastal Texas. There will be significant changes over the next few days to what is described below, it is the best prediction at this time with the model data available.

Thursday:

Upper level energy over the northern Rockies currently dives SSW into the SW US and then begins to move eastward toward TX. Arctic dome deepens toward 850-700mb (5,000-20,000 ft deep) with the center of the arctic high over western OK/KS. GFS is the fastest with this trough ejecting over TX while the ECMWF and CMC are the slowest. The CMC is by far the wettest with the GFS and ECMWF drier. Expect weak isentropic lift to begin midday Thursday thickening the mid level cloud deck. Soundings for CRP and VCT by Thursday evening show a saturated mid to low level profile completely below freezing, but all sounding sites show a very dry sub-cloud layer near the surface. Expect lifting processes and frontogenic forcing to develop meso scale banding of precipitation by Thursday afternoon/evening. Initial precipitation will likely evaporate before reaching the ground helping to moisten the near surface layer. Then once the dry layer is removed, precipitation will start to reach the ground. With the point forecast soundings showing a sub-freezing layer through the entire column for nearly all sites by Thursday afternoon/evening P-type will be snow, except maybe a period of IP (sleet) right along the coast. Expect highs near freezing along and N of I-10 and in the mid 30’s south of I-10

Thursday night:

Upper level trough moves toward/across Texas depending on which model you follow (GFS is the fastest with the ECMWF the slower and the GFS ensembles nearly splitting the difference). The faster GFS produces a quick shot of snow while the slower ECMWF and CMC would produce impressive snowfall totals across all of coastal Texas. Slower solution would allow greater time for the air mass to moisten and a longer period of meso scale snow banding to develop with higher snowfall rates. Surface layer will be in the mid to upper 20’s so what falls will accumulate and after days of sub-freezing temperatures the ground is going to be very cold. GFS shows best snowfall accumulation along a line from Victoria to W of Corpus Christi to McAllen on the order of 2-4 inches in this area. Still too early to be certain on any kind of accumulations as there are questions with moisture quality and how far inland the deeper moisture penetrates. This potential event has similarities to both the Dec 04 snowstorm and the snow event in Dec 1989 with the position of the upper and surface features. I am a little concerned about the amount of moisture available (usually it is the other way around, we do not have the cold air), but the models have been trending wetter with more QPF with each run adding confidence that something will fall later this week.

Friday:

Winter weather event will likely be ongoing Thursday night-Friday with potential for snow and some accumulations. Will go well below GFS guidance on highs and keep temperatures at or below freezing given falling precipitation, clouds, and possible snow accumulations for all areas including the coastal areas. Precipitation should gradually end from west to east Friday as the upper level trough moves over E TX and into LA allowing lift to decrease. Should the slower ECMWF and CMC models verify the best chances for snow will be on Friday and Friday night.

Preparations:

Residents across Texas should take the last warm day today to make the needed preparations for an extended period of cold weather. Protect/shelter sensitive tropical vegetation, hours of sub-freezing temperatures will damage or kill unprotected sensitive plants. Advective nature of the freeze with strong north winds will reduce the “greenhouse effect” of wrapping plants, so make sure coverings are strongly fastened with multiple layers.

Wrap exposed outside pipes and disconnect all water hoses from exterior wall connects. Turn off sprinkler systems and cover back flow preventer pipes which suffered greatly in the freeze last January. It might be a good idea to shut off the water supply to the entire sprinkler system to prevent freezing and bursting of the back flow pipes. Interior pipes should be fine with this event, but to be on the safe side open exterior facing cabinets to allow house warmth against the interior plumbing.

Pets and livestock should be sheltered is possible. Hours of sub-freezing temperatures and wind chills ranging from the single digits to teens will produce highly uncomfortable conditions for animals exposed for long periods of time.

Travel:

Dangerous/life threatening conditions will be developing over portions of W TX into the central plains tonight/Tuesday with full scale blizzard conditions as far south as southern OK. Surface travel is strongly discouraged in this region as significant snowfall and strong north winds of 30-40mph will blow and drift snow likely closing interstates and stranding vehicles. Temperatures over parts of OK and the TX panhandle will fall below zero with wind chills as low as -35 degrees making exposure to the outside air extremely dangerous. Aviation travel will likely be heavily impacted on Tuesday as major airports across the Midwest and plains struggle against heavy snow, low visibilities, and very cold air. Both Chicago and DFW will likely have major weather impacts/delays which will ripple into the rest of the system.

[cristina99]

okay, checking in before I get to work. Come on snow!!! I still think the meterologists on tv are a little conseravative about the temps. I think my mom is finally starting to believe it. I will check in close to noon. Again, this is so exciting!!!

[srainhoutx]

Here is a US Hazard map you will not see very often...

[srainhoutx]

The 12Z suite has started:

NCEP Operational Status Message
Mon Jan 31 13:33:34 2011 GMT
NOUS42 KWNO 311333
ADMNFD

SENIOR DUTY METEOROLOGIST NWS ADMINISTRATIVE MESSAGE
NWS NCEP CENTRAL OPERATIONS CAMP SPRINGS MD
1330Z MON JAN 31 2011
NCEP 12Z MODEL CYCLE STARTED ON TIME WITH GOOD US/CAN UPPER AIR
DATA COVERAGE...
12Z RAOB RCEAP..
NKX/72293 - 10142; GROUND EQUIP PROBLEMS..
ZAC/76526 - SHORT TO 432MB..
ASY/70414 - NOT AVAILABLE FOR THE NAM..
A CRITICAL WEATHER DAY (CWD) PERIOD WILL BE INITIATED AT 0600Z
TODAY (MONDAY) JAN 31TH 2011 AND WILL BE SCHEDULED TO EXPIRE AT
1200Z (THURSDAY) FEB 3 2011.
NCEP, NWSTG, NWS SOUTHERN, CENTRAL, EASTERN REGIONS AND THE NCF
WILL PARTICIPATE IN THIS CWD TO ENSURE A RELIABLE FLOW OF DATA.
THE CWD IS IN SUPPORT OF FORECAST OPERATIONS CONCERNING THE
POSSIBLE DANGEROUS AND POTENT WINTER STORM AFFECTING MUCH OF THE
CENTRAL AND NORTHEASTERN PART
OF THE US THRU THURSDAY MORNING.
ALSO, USERS CAN GET AN UPDATED CWD STATUS ON THE NCEP WEB PAGE:
HTTP://WWW.NCO.NCEP.NOAA.GOV/PMB/CWD/
$$
SHRUELL/SDM/NCO/NCEP

[srainhoutx]

The front is moving in faster on the NAM and even faster than that on the HiresSREF. 1056mb High pressure building S from MT @ hour 30.

[Andrew]

I was looking at the cmc and it seems like it would be able to support sleet and or freezing rain but defiantly not snow. That is colder than the last couple runs