More cold air on the way next week!?

[wxman57]

Yes, could be 3-6" of snow in Dallas. For us, it still looks like the air aloft will be too warm in the lower 10,000ft. Coldest air aloft is present at the start of the precip. But as the low forms along the coast, lots of warmer air is transported over Houston. So a slight chance of mixed precip as the precip begins on Wednesday, changing quickly to an all very cold rain event.

[sleetstorm]

I am praying that the models are wrong that warm air advection will not impede the formation of sleet and snow for southeast Texas. I pray that the cold air advection is much deeper over southeast Texas.

[wxman57]

I am praying that the models are wrong that warm air advection will not impede the formation of sleet and snow for southeast Texas. I pray that the cold air advection is much deeper over southeast Texas.

Yeah, and the Saints will win the superbowl, too. Checking the 12Z GFS, it's predicting similar surface temps during the 1.1" of precip Wed/Thu. HOWEVER, I do see a significant difference in the temps aloft after running a few model projections. In fact, temps aloft Thursday morning are now indicated to be very near freezing all the way up, with a slow warming by noon Thursday. If this was to happen, then we could see precip start out as sleet/snow here Wednesday evening/Thursday morning.

Not ready to forecast that as the most likely scenario, but something that can't be ruled out.

[TexasMetBlake]

It's interesting that the NWS from Fort Worth and Austin/San Antonio have snow/sleet in the likely category for Robertson, Milam, Leon and Lee Counties. Yet, the Houston office has cold rain for Burleson and Brazos Counties. The Houston office, to be fair, does mention in the AFD that they'll need to watch for the possibility.

One of two things is going to happen here. I'm calling it first...

1. Going into Wednesday night, the forecast will be for the snow/ice line to be north of or cutting right through Montgomery County. As the event kicks in, there may be SOME sleet or snow mixed in with the rain in northern Harris County and the board will light up with how wrong the forecast was.

2. The models will dramatically shift showing colder than expected conditions. I've seen this happen and a watch or advisory will be issued.

With all that said, any time you have a coastal low, you have to be prepared for the possibility of an inversion or some type of warm layer being pulled in with the anticyclonic flow around the low. I still think it's a bit to early to say who is going to get what. I mean that guy from the Houston Examiner yesterday, if left up to him, would already have TXDOT out sanding all the freeways outside the beltway. However, to comepletely rule out snow or ice as far south as Harris County is not wise either. Unfortunately, not all the pieces of the puzzle have revealed themselves yet. The wait continues...

[harpman]

I was born in New Orleans and have suffered through many miserable seasons. This win is SO sweet, you folks just don't know!!!

[biggerbyte]

The only way, in this case, to get an accurate forecast for the upcoming event, is to wait until Wednesday evening. There are too many variables to make a call. Having said that, I will say that I don't see how we in s.e Texas could have anything like the potentials for DFW, but it is still to early to say that we will not see some sleet of more than just the scattered variety. Everything everyone is saying at this point can be nothing more than mere speculation.

Wednesday night... Let's make the call.

[don]

2. The models will dramatically shift showing colder than expected conditions. I've seen this happen and a watch or advisory will be issued.

I was thinking of the same possible scenario that we've seen happen in the past when the models (especially the GFS) first shows a colder solution at first and then trends warmer.All to switch back over to its original colder solution right before the event,I guess that is an OUTSIDE possibility if the models are underestemating the strength of the cold air even by a little...

[wxman57]

The only way, in this case, to get an accurate forecast for the upcoming event, is to wait until Wednesday evening. There are too many variables to make a call. Having said that, I will say that I don't see how we in s.e Texas could have anything like the potentials for DFW, but it is still to early to say that we will not see some sleet of more than just the scattered variety. Everything everyone is saying at this point can be nothing more than mere speculation.

Wednesday night... Let's make the call.

It's easy for a meteorologist to make a perfect forecast if he's allowed to wait until the event is happening to issue our forecast. However, we don't have that luxury. We must make a 3-5 day forecast for our clients, regardless of our confidence in the potential event. A forecast is always what the meteorologist thinks is most likely to happen. For now, that "most likely" event would be cold rain with a little sleet mixed in at firs.

[C2G]

I was born in New Orleans and have suffered through many miserable seasons. This win is SO sweet, you folks just don't know!!!

Happy for you folks and believe me WE do know.
Can you recall the last time a Houston NFL team played in the Super Bowl, me neither?
Glad to see you and I are on the same page wxman.......I definitely know I'm headed in the right direction.

Cloud2ground Mon Feb 08, 2010 12:44 am It appears the Houston areas best chances come at the onset of the moisture shield moving in.
Appears the big D could get some measurable snowfall.

wxman57 Mon Feb 08, 2010 8:06 am That said, there may be a chance of frozen precip in Houston, but not as the precip ends (which would be typical). As the precip starts on Wednesday morning, vertical profiles indicate that moisture falling from above 6000 ft may fall as sleet or even snow.

[brazoria_county22]

this dosent make it to the coast right or near brazoria county...just harris county and points north and west right?

[srainhoutx]

E-mail update from Jeff...

Same story this entire winter will play out again this week...but it is a far cry from the 2.0-3.0 feet of snow dumped on the mid-Atlantic this weekend.

Cold and wet middle to end of the week with some threat of winter precip. over our N and W counties.

Next in the series of southern stream storm systems will affect the area today into tonight with increasing chances for showers this afternoon and a threat for thunderstorms...some strong tonight. Low level moisture continues to increase this morning with 40kt low level jet overhead. Expect surface dewpoints to make a run toward the lower 60's by this afternoon ahead of the approaching arctic front. Arctic boundary surging down the plains will arrive tonight. Lift along the boundary will create a favorable environment for showers and thunderstorms from around 300pm to about midnight. Very strong cold air advection develops post front with falling temperatures and gusty NW winds. This same system will head on eastward and produce another 6-12" of snow over the mid-Atlantic on top of an already robust snowpack.

Highs will struggle to reach 50 on Tuesday...as a matter of fact today will likely be the warmest for the next 2 weeks with 60's not seen again until toward the end of the month. The rest of this week will be in the 40's...maybe 30's for highs. Cold and dry air mass entrenches into the region early Tuesday...low clouds may break up by afternoon, however active southern stream will spill high level cirrus back over the region by early evening Tuesday and that will be the last time we see the sun until maybe this weekend...although that is even questionable.

Entrenched arctic high and continued cold air advection will likely result in a freeze Wednesday AM. Next item of interest is the next system which pulls across TX Wed-Fri with the cold and dry arctic air in place. Models continue to waffer widely with the track of the surface and upper level lows, the air column temperature profiles, and the surface temperatures as well as P-type concerns. It appears guidance is trending toward the colder and stronger GFS solution of the past several days which does raise some concern for P-type issues across our western and northern counties through the period. GFS has has the deeper coastal low with strong coastal winds again and tidal rises along the coast...same ole story.

For now will keep everything liquid, but any slight deviation of the upper low southward or slightly colder/drier air would support a chance of sleet/snow/freezing rain/rain into portions of SE TX Thursday AM-Friday AM. Will undercut guidance on highs for Thursday and show nearly steady temperatures in the upper 30's. Travel N and W of the area could become an issue by early Thursday as a full blown winter storm looks likely over W and portions of NW TX.

System should exit the area Friday with perhaps some late afternoon clearing. Third system will line up and affect the state by next Sunday. Once again little air mass modification is expected with continued filtering of cold air southward. This system looks to spread more ice and snow from NM across OK into the mid-Atlantic.

Long range outlook shows a little drier pattern for next week...but still cold with below normal temperatures east of the Rockies.

[wxdata]

Late morning update from SPC

"NO SUBSTANTIAL CHANGES TO PREVIOUS OUTLOOK.VERTICAL SHEAR WILL BE SUFFICIENT FOR EMBEDDED BOW/SUPERCELL
STRUCTURES...THOUGH THE MAGNITUDE OF THE SEVERE THREAT WILL BE TEMPERED BY THE WEAK INSTABILITY. CONVECTION SHOULD EVOLVE INTO A BAND OF THUNDERSTORMS ALONG THE COLD FRONT THIS AFTERNOON ACROSS SE TX AND THEN PROGRESS EWD ACROSS SRN LA OVERNIGHT. INSTABILITY WILL LIKELY BE ROOTED JUST ABOVE A RESIDUAL SHALLOW STABLE LAYER INLAND FROM THE COAST...WHICH SUGGESTS THAT ANY WIND DAMAGE THREAT WILL BE MARGINAL."

Tornado probability:

[Aquaria]

Can anyone give me an idea of what we may be looking at in the Tyler/Longview area? A lot of times DFW gets hammered, and we squeak by with a flurry or two, so I wasn't sure if the potential you mentioned for Dallas really applied to us. Thanks!

[srainhoutx]

Can anyone give me an idea of what we may be looking at in the Tyler/Longview area? A lot of times DFW gets hammered, and we squeak by with a flurry or two, so I wasn't sure if the potential you mentioned for Dallas really applied to us. Thanks!

Aquaria, I suspect it is just a bit too soon to know the 'finer details' as we are still a couple of days out from the event. As we know things can and often do change regarding storm tracks. Keep an eye on the Forum and I suspect that things will become a bit more clear in about 24-36 hours. In the mean time here is what the HPC is thinking...

EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
115 PM EST MON FEB 08 2010

VALID 12Z THU FEB 11 2010 - 12Z MON FEB 15 2010

...SOUTHERN SNOW POSSIBLE THURSDAY THROUGH SATURDAY...

TELECONNECTIONS WITH A STRONG POSITIVE ANOMALY IN THE MID-LEVELS
OVER NORTHEAST CANADA /BETWEEN 3 AND 4 STANDARD DEVIATIONS ABOVE
NORMAL/ FAVORS PROGRESSIVE CLOSED CYCLONES UNDER ITS BASE IN THE
LOWER 40S LATITUDE. THIS ALLOWS US TO DISCARD THE 00Z CANADIAN
WHICH LEAVES A CLOSED CYCLONE QUASI-STATIONARY IN THE NORTHERN
PLAINS/UPPER MIDWEST LATE IN THE PERIOD. SHORTWAVE ENERGY IN THE
SOUTHERN STREAM IS EXPECTED TO REMAIN PROGRESSIVE ACROSS THE
SOUTHERN TIER OF THE COUNTRY THROUGH THE FORESEEABLE FUTURE. DUE
TO THE PROGRESSION EXPECTED IN THE NORTHERN AND SOUTHERN STREAMS
AS WELL AS QUESTIONS REGARDING FUTURE INTERACTIONS BETWEEN THE TWO
STREAMS... CONFIDENCE IN THE FORECAST LATE THIS WEEKEND INTO EARLY
NEXT WEEK IS LOW IN ANY PARTICULAR PIECE OF DETERMINISTIC
GUIDANCE...WHICH IS LIKELY TO SHOW RUN-TO-RUN AND DAY-TO-DAY
DIFFERENCES REGARDING PROGRESSION AND PHASING. BOTH THE 06Z GEFS
MEAN AND 00Z ECMWF ENSEMBLE MEANS ARE IN REASONABLE AGREEMENT
THROUGH THE PERIOD. IN ORDER TO RESOLVE DETAIL ISSUES...CHOSE TO
COMPROMISE BETWEEN THE 00Z ECMWF AND 06Z GEFS MEAN
SOLUTIONS...WITH SOME MODIFICATIONS MADE PER 00Z MULTI-MODEL
ENSEMBLE LOW PRESSURE AREA CLUSTERING...SUCH AS THIS WEEKEND NEAR
FLORIDA AND LATE IN THE PERIOD IN THE GULF OF MEXICO.

DEEP CYCLONE MOVING BY THE PACIFIC NORTHWEST SATURDAY/SUNDAY...
A COMPROMISE OF THE 06Z GEFS MEAN/00Z ECMWF KEPT THIS SYSTEM
WITHIN THE MIDDLE OF THE ENSEMBLE SPREAD POSITION-WISE. HEAVY
PRECIPITATION IS EXPECTED WITH THE SYSTEM FROM WASHINGTON
STATE/THE OLYMPIC PENINSULA NORTHWARD TO VANCOUVER ISLAND. AT
THIS TIME...THE CASCADES ARE EXPECTED TO HAVE LESSER AMOUNTS...BUT
ONLY A SLIGHT SHIFT TO THE SOUTH WOULD BRING MUCH HEAVIER
PRECIPITATION INTO THE MOUNTAIN RANGE.

GREAT LAKES...
AS A STRONG AND DEEP CYCLONE MOVES OFFSHORE THE NORTHEAST AND
RETROGRADES INTO ATLANTIC CANADA...COLD AIR WITHIN THE CYCLONIC
FLOW ON ITS BACK/SOUTHWEST SIDE SETS THE STAGE FOR LAKE EFFECT
SNOWS THROUGH THE PERIOD.

SOUTHERN STREAM SYSTEM MOVING THROUGH FLORIDA FRIDAY...
THE ECMWF SHOWS A TWO DAY TREND TOWARDS SLOWING THIS SYSTEM
DOWN...AND ITS 00Z SOLUTION LIES WITHIN THE SOUTHERN PORTION OF
THE ENSEMBLE ENVELOPE. TO ACCOUNT FOR THE TREND...TOOK THE LOW ON
A SLOWER/MORE NORTHERLY PATH...WITHIN THE NORTHWEST SIDE OF THE
00Z MULTI-MODEL ENSEMBLE LOW ENVELOPE. THIS SYSTEM IS EXPECTED TO
BE QUITE WET ALONG THE GULF COAST AND FLORIDA...WITH STRONG
THUNDERSTORMS POSSIBLE ACROSS THE FLORIDA PENINSULA TO THE SOUTH
OF ITS TRACK AS THE LOW PASSES THROUGH. MEASURABLE SNOW IS
POSSIBLE WITHIN ITS NORTHERN PERIPHERY FROM TEXAS EASTWARD ACROSS
THE DEEP SOUTH INTO SOUTH CAROLINA FROM THURSDAY INTO SATURDAY AS
1000-500 HPA THICKNESS VALUES WITH THE PREFERRED MODEL BLEND ARE
ANTICIPATED TO BE BELOW 5400 METERS.
ROTH

[TexasMetBlake]

For such a "big" snow event for Dallas, their AFD doesn't sound like they are taking it to seriously...

AS FOR THE THURSDAY SYSTEM...NAM/ECMWF ARE MORE CONSERVATIVE WITH
QPF BUT IT DOES LOOK LIKE WE WILL SEE A WINTER MIX. AFTERNOON
TEMPERATURES WILL BE ABOVE FREEZING ACROSS ALL OF NORTH TEXAS...SO
EVEN THOUGH WE HAVE ALMOST A HALF INCH OF SNOW FALL POSSIBLE IN
THE NORTHEAST...IT WILL MELT RATHER THAN ACCUMULATE. ISOLATED
TRAVEL PROBLEMS MAY OCCUR THURSDAY MORNING WHEN FREEZING
TEMPERATURES ARE EXPECTED NORTH OF A LINE FROM LAMPASAS TO
CANTON...AND AGAIN AFTER MIDNIGHT THURSDAY NIGHT THROUGH SUNRISE
FRIDAY.

[TexasMetBlake]

The low, according to HPC, wants to track right over head. It should also be mentioned that the HPC has no hatched areas across Texas for significant snowfall. Grant it, they only go out to day 3, but that will be something to watch for...



It will be interesting to see the Updated Storm Tracks from the HPC around 19Z.

[wxdata]

MESOSCALE DISCUSSION 0111
NWS STORM PREDICTION CENTER NORMAN OK
1245 PM CST MON FEB 08 2010

AREAS AFFECTED...S CNTRL THROUGH SERN TX

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 081845Z - 082045Z

THUNDERSTORMS DEVELOPING FROM S-CNTRL THROUGH SERN TX MAY POSE A
RISK FOR ISOLATED MARGINALLY SEVERE HAIL AND PERHAPS AN ISOLATED
BRIEF TORNADO THIS AFTERNOON. THREAT DOES NOT APPEAR SUFFICIENT FOR
A WW AT THIS TIME...BUT TRENDS WILL CONTINUE TO BE MONITORED.

EARLY THIS AFTERNOON A QUASI-STATIONARY FRONT EXTENDS FROM CNTRL LA
WWD THROUGH NERN TX WHERE IT INTERSECTS A COLD FRONT THAT STRETCHES
SWWD THROUGH CNTRL AND SWRN TX. SWLY 40-50 KT LOW-LEVEL JET WILL
ADVECT NEAR 60 F DEWPOINTS THROUGH WARM SECTOR OF S-CNTRL AND SERN
TX BENEATH MODEST LAPSE RATES RESULTING IN MLCAPE AOB 500 J/KG.
STORMS DEVELOPING WITHIN PRE-FRONTAL CONFLUENT ZONE HAVE EXHIBITED
SOME SUPERCELL CHARACTERISTICS DURING THE PAST HOUR. THE STORMS ARE
PROBABLY SLIGHTLY ELEVATED...BUT MAY BECOME SURFACE BASED AS
TEMPERATURES WARM THROUGH THE UPPER 60S. THE 0-1 KM STORM RELATIVE
HELICITY WITHIN THE MORE UNSTABLE PORTION OF THE WARM SECTOR RANGES
FROM 200-400 M2/S2...SUFFICIENT FOR LOW-LEVEL MESOCYCLONES.
HOWEVER...TENDENCY SHOULD BE FOR HODOGRAPHS TO SLOWLY DECREASE IN
SIZE FROM THE WEST AS THE LOW-LEVEL JET SHIFTS EAST. THE MARGINAL
THERMODYNAMIC ENVIRONMENT SHOULD FURTHER SERVE AS A LIMITING FACTOR
FOR A MORE ROBUST SEVERE THREAT.

[wxman57]

Can anyone give me an idea of what we may be looking at in the Tyler/Longview area? A lot of times DFW gets hammered, and we squeak by with a flurry or two, so I wasn't sure if the potential you mentioned for Dallas really applied to us. Thanks!

Here's a place where you can check the latest GFS predictions of snowfall accumulations:

http://wxcaster.com/gis-gfs-snow-overla ... TIONID=SHV

For Tyler, the current 12Z GFS predicts about 8-10" of snow for you. I think you're in the running for some interesting weather later this week.

[Portastorm]

wxdata, glad you posted that. Radar is lighting up just to our north and west here in AUS. Just saw some towering CB just west of town on my way back to the office from lunch.

[wxdata]

San Antonio NWS:

Pea hail reported near Bastrop in Bastrop CO reported by EM at 110 PM

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
103 PM CST MON FEB 8 2010

TXZ173-191>194-206>208-082000-
BASTROP-CALDWELL-COMAL-GUADALUPE-HAYS-LEE-TRAVIS-WILLIAMSON-
103 PM CST MON FEB 8 2010

...STRONG THUNDERSTORMS WERE AFFECTING BASTROP...CALDWELL...
COMAL...GUADALUPE...HAYS...LEE...TRAVIS AND WILLIAMSON COUNTIES...

AT 1258 PM CST...NWS METEOROLOGISTS ARE TRACKING ISOLATED STRONG
THUNDERSTORMS FROM NEAR LOCKHART TO BASTROP AND NEAR
GEORGETOWN...MOVING NORTHEAST AT 20 MPH.

PEOPLE IN BASTROP...CALDWELL...HAYS...NORTHEASTERN COMAL...
NORTHEASTERN GUADALUPE...TRAVIS...WESTERN LEE AND WILLIAMSON
COUNTIES...INCLUDING THE FOLLOWING LOCATIONS...LOCKHART AND
BASTROP...SHOULD MONITOR THE WEATHER SITUATION CLOSELY. LISTEN FOR
POSSIBLE WARNINGS AND BE PREPARED TO TAKE APPROPRIATE ACTION SHOULD
SEVERE WEATHER THREATEN.