Texas winter wx thread (2009-2010)

[srainhoutx]

Well the day shift did a little more explaining...

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
830 AM EST THU FEB 18 2010

VALID 12Z MON FEB 22 2010 - 12Z THU FEB 25 2010


THE MAIN PLAYERS IN THIS MEDIUM RANGE PERIOD WILL CONTINUE TO BE
AN ACTIVE SUBTROPICAL JET ASSOCIATED WITH EL NINO...AND A STRONGLY
NEGATIVE NAO. THE INTERACTION OF ENERGY FROM THE SRN PORTION OF A
DEEP CANADIAN POLAR VORTEX TRAPPED WITHIN THE LARGE AREA OF ABOVE
NORMAL HEIGHTS WITH SRN STREAM ENERGY BE AN IMPORTANT FACTOR IN
DETERMINING THE TRACK OF YET ANOTHER POSSIBLE MID ATLANTIC/NEW ENG
SNOWSTORM.

UPDATED PRELIM PROGS LEFT EARLY PRELIM ALONE EXCEPT FOR MINOR
COSMETIC CHANGES. OUR PREFERENCE FOR MOSTLY GEFS MEAN SEEMS WELL
FOUNDED WHEN WE COMPARE THE 00Z/18 GEFS MEAN TO THE NEW 00Z/18
ECMWF ENSEMBLE MEAN. THERE ARE NO MAJOR DISAGREEMENTS BETWEEN THE
THE 00Z/18 GEFS AND ECMWF MEANS. THE TWO AREAS OF HIGHEST
UNCERTAINTY CONTINUE TO BE 1) WHERE PACIFIC WESTERLIES UNDERCUT
THE AREA BELOW THE STRONG WRN CANADIAN RIDGE...AND 2) THE GREAT
LAKES/OH VLY AS WE WRESTLE WITH HOW MUCH HEIGHT FALL LEAKS SSE OUT
OF OUT OF A DEEP...SWD DRIFTING POLAR VORTEX IN N CENTRAL CANADA
BY MON. THE HEIGHT FALLS LEAKING SWD INTO THE GREAT LAKES/OH VLY
EARLY NEXT WEEK ARE CRITICAL IN DETERMINING WHETHER THE SYS
APPROACHING THE E COAST MON/TUE GOES OUT FARTHER S AND FAIRLY
FLAT...OR WHETHER THE PRIMARY LOW TAKES A TRACK MORE NWD INTO THE
OH VLY AS PER YESTERDAYS 12Z MODELS. PREFER THE EARLY PRELIM
APPROACH OF STAYING IN THE MIDDLE OF THE ROAD GIVEN THE
FLIP-FLOPPING OF MODELS MENTIONED IN THE EARLY DISCUSSION. A
CONDENSED VERSION OF THAT DISCUSSION FOLLOWS BELOW.

USED AN EVEN BLEND OF THE 00Z/18 ECMWF AND 00Z/18 GEFS MEAN FOR
THE PRELIMINARY FRONTS AND PRESSURES FOR DAY 3...WITH 2/3 GEFS
MEAN AND 1/3 DETERMINISTIC ECMWF THEREAFTER. THE 00Z/17 GFS AND
GEM GLOBAL WERE NORTH WITH THE MAJOR WAVE CROSSING THE EAST DURING
THE FIRST HALF OF THE PERIOD...AND ARE NOW SOUTH...WHILE THE
00Z/17 ECMWF AND UKMET WERE SOUTH AND ARE NOW NORTH WITH THE SAME
FEATURE. THIS FLIP-FLOPPING ARGUES FOR A MIDDLE OF THE ROAD
SOLUTION...WHICH THE HEAVY EMPHASIS ON THE GEFS MEAN AFFORDS THIS
PACKAGE.

CISCO/FLOOD

[iorange55]

I don't know if I have ever seen so many models saying such different stuff.

[gofrogs2]

CBS 11 is saying snow for next week tuesdy for dallaas fort worth.

[iorange55]

I'm calling for 5 inches of idk.

[DentonGal]

I'm calling for 5 inches of idk.

HA! Best forecast I've seen today!

[jasons2k]

Morning update from Jeff Lindner:

Cold but at least sunny weather of this week will be replaced by warmer and wetter weather over the weekend before more cold arrives early next week.

Discussion:

High level moisture is on the increase as old polar high moves eastward allowing the sub-tropical jet stream to spill into the region. Most areas have had a freeze the last 4 mornings. SE surface winds will return today allowing a very slow increase in moisture at the low levels into the weekend ahead of the next front penciled in for Sunday evening. A heavily suppressed short wave will move mainly south of the region Friday. Guidance does not produce much QPF with this system over the land areas of SE TX with most of the activity over the NW Gulf and beyond. Best chances for rain will be along the coast and offshore Friday.

This wave moves eastward Friday night with no air mass change. SE winds will increase over the weekend allowing at least upper 50 to near 60 degree dewpoints to arrive into the area for the first time in a while. Next storm system will approach on Sunday with a strong cold front. Area looks to get into the warm sector for a change on Sunday as Gulf opens up. Forecast soundings for IAH and VCT becoming increasingly unstable during the day as moisture increases and temperatures warm into the lower 70’s. Strong cold front will arrive into this air mass Sunday evening. Forecasted CAPE values of 500-1000 J/kg does support some strong to severe storms Sunday afternoon/evening. Will be watching this period fairly closely as cells may attempt to get going in the warm sector prior to the front and have a severe threat. With that said…the Gulf has been worked over hard this winter with several cold air intrusions, and the models may be overdoing the progged instability. Plenty of time to watch between now and Saturday evening.

Next forecast concern is how cold behind the Sunday front and if there will be any precipitation next week in the cold air. Models are in horrible disagreement with the upper air and surface features. Developing high latitude omega block off the W Canada coast would allow some bitter cold air the move southward….however the GFS breaking this pattern down quickly and transitions into a fast split zonal flow over the US which would support the cold air heading southward to get deflected eastward. The EURO model is more aggressive with a cold air plunge due south and much more amplified southern stream trough Tues/Wed next week with lots of cold air and precip over TX. GFS does have some support from the CMC and several of the ensemble members, but I am not sure it is handling the cold air well…as this model usually does not handle cold arctic domes well.

Given all the uncertainty, will go with a colder solution than the GFS with highs back into the 50’s on Monday and possibly the 40’s on Tues/Wed. Will bring a slight rain chance into the forecast starting Tuesday and keep P-type all liquid for now. If the models start trending toward the more stable EURO…then much colder for next week with highs in the 30’s and 40’s and we would have to entertain the idea of P-type issues Tues/Wed. Not really needing to be said…the forecast beyond Sunday is extremely low confidence.

Climo:

So how cold has this cold winter been? Per the NWS the average Dec 1-Feb 15 temp. for KIAH has been 49.1 degrees or the 7th coldest on record and currently the first 15 days of Feb are the 8th coldest on record. More astounding is the fact that Galveston is currently running an impressive 8.0 degrees below average for the month of Feb. By far this has been one of the coldest winters of the past decade and likely for many since the late 1980’s.

Spring Outlook:

The outlook for the March-May period for TX will continue to favor the wetter and colder pattern of this winter. El Nino indicators have shown a gradual cooling of the current ENSO in progress with conditions heading toward neutral by early summer. This corresponds well with above average rainfall and continued cooler conditions. One interesting aspect is all this cold air affects on the Gulf water temps. Temperatures are running above 2.0 degrees colder than last year at this time over the Gulf. With all the cold and stable air in place it has been hard to get severe weather going along the Gulf coast this winter. During such El Nino winter severe threats and tornadoes are fairly common along the US Gulf coast. The combination of poor moisture quality over the Gulf and a very suppressed sub-tropical jet has resulted in all the “action” being out over the central Gulf of Mexico. This activity in this very active pattern should begin to lift northward over the next month, but the colder than average water temperatures may help mitigate much of a severe weather season until the Gulf warms a bit and the cold air intrusions abate.

[gofrogs2]

What the new gfs saying.

[cperez1594]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BROWNSVILLE TX
954 AM CST THU FEB 18 2010

.SHORT TERM /TODAY THROUGH FRIDAY/...WEAKENING MID LEVEL TROUGH
CURRENTLY TREKKING ACROSS NORTHERN MEXICO WITH VORTS RACING OUT
AHEAD OF IT IN SOUTHWESTERLY FLOW ALOFT. LIGHT RAIN ON RADAR TO THE
SOUTHWEST SHOULD REACH THE REGION WITHIN THE NEXT COUPLE HOURS. SOME
STRONGER VORT MAXIMA COULD BRING ENOUGH LIFT AND INSTABILITY TO
CAUSE A LIGHTNING STRIKE OR TWO OVERNIGHT TONIGHT. BEST CHANCE FOR
MEASURABLE ACCUMULATION WILL BE BETWEEN MIDNIGHT AND NOON
TOMORROW...WITH TOTAL ACCUMULATION OF UP TO AN INCH POSSIBLE. UPDATE
ARRIVING SOON WITH HIGHER POPS TODAY.
&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...NO IMMEDIATE CHANGES
PLANNED. THE LONGER RANGE MODELS ARE A BIT UNCERTAIN WITH THE
MONDAY COLD FRONT. THE 00Z ECMWF IS A BIT STRONGER RIGHT NOW WITH
A COLD FRONT PUSHING THROUGH BUT WITH LESS CHANCE OF OVER RUNNING
PRECIP ON TUESDAY. THE 06Z GFS ON THE OTHER HAND SHOWS A WEAKER
FRONTAL PASSAGE ON MONDAY BUT SHOWS A BETTER CHANCE OF SOME OVER
RUNNING PRECIPITATION ON TUESDAY. THE GFS FOLLOWS UP WITH A
STRONGER SECONDARY SURGE NEXT THURSDAY AND SOME SUSPECT HEAVY
PRECIP OVER THE GULF. WILL TAKE A LOOK AT THE 12Z GFS WHEN IT
COMES IN AND SEE IF THE MODELS MATCH UP ANY BETTER. THE CURRENT
FORECAST IS BASED MORE ON A GFS SOLUTION. &&

They might be seeing something

[Nederlander]

[srainhoutx]

The problem is the under cutting of the W Canadian Ridge. We have the EC and UKMET in one corner, while the GFS, CMC, NOGAPS say not dice. The surge of moisture/convection near the dateline seems to suggest a stronger +PNA and an active STJ. We shall see.

[iorange55]

The 12z GFS looks more interesting

[wxman57]

The 12z GFS looks more interesting

Out to 144 hrs, it's much stronger with the wave coming into California and the southwest U.S. early next week. This is an indication that it will predict more precip and probably cooler temps over Texas late next week then the last run.

[Nederlander]

The 12z GFS looks more interesting

yea.. panhandle gets blasted at 144hrs..

[srainhoutx]

The 12z GFS looks more interesting

Out to 144 hrs, it's much stronger with the wave coming into California and the southwest U.S. early next week. This is an indication that it will predict more precip and probably cooler temps over Texas late next week then the last run.

http://www.nco.ncep.noaa.gov/pmb/nwprod ... _144.shtml

[iorange55]

Next week...next week...next week. my my my.

[Nederlander]

wow ... plenty of moisture to work with..

[wxman57]

Next week...next week...next week. my my my.

For now, looks like it shows just cold rain (maybe sleet, too) across the D-FW Metroplex next Wed/Thu. It may be starting to catch on, but it's still lost.

[Portastorm]

Terrible, terrible run!

More cold rain for Austin and Houston. Forget it! Who needs that?!?!

Might as well be 75 and sunny so Wxman57 can do his cycling and Portastorm's kids won't have their baseball games rained out.

Next, please.

[iorange55]

Next week...next week...next week. my my my.

For now, looks like it shows just cold rain (maybe sleet, too) across the D-FW Metroplex next Wed/Thu. It may be starting to catch on, but it's still lost.

Yeah, was more looking at the moisture supply, and the solution it looks to be headed towards. Could be another very interesting week. Just hope the cold air goes all the way down into Texas.

[Nederlander]

agreed portastorm.. id rather 70's over mid 30's and pouring rain... we just need to get that cold air to plunge a little further south and we're golden