January Weather Discussion: Slight Chance Severe Storms

[vci_guy2003]

Where are you at, mw?

[wxman666]

will continue to post during storm if im able (electricity) with updates precip should start about this time tommorrow night
wet bulb temps are going to be important and thunder appears likely too....

I noticed that in the NWS forecast. Be sure to stock up on supplies and avoid travel!

[Mr. T]

Winter storm watch for Lufkin

Winter precipiation added for HGX counties all the way down to San Jacinto and Walker Counties.

This morning's 0z GFS and Euro have came in a bit colder in the upper levels for this storm which has warrented this change in the forecast.

SHV and HGX coordinated this morning, so I'm curious to see if HGX puts a winter weather advisory for northern counties of SE TX. SHV is going for snow and sleet for Lufkin sunday morning with a changeover to all snow sunday night. If you want to see some snow this season, you could take the quick trip up US 59 to see it!

[vci_guy2003]

lol, if it snows/sleets any farther south, Tim Heller will have egg on his face

[Mr. T]

lol, if it snows/sleets any farther south, Tim Heller will have egg on his face

Looks like that HGX forecaster a few days ago may have been absolutely correct with his assertion that models were not handling the cold air well and snow would be possible for northern areas of the HGX zone...

If so, I'll have egg on my face as well. But, a tasty egg at that... If things look to pan out as currently forecasted, Lufkin is only like 90 miles away . Took a trip up there for the April 07 event, and I just might do that for this one as well.

[Mr. T]

Unless something unanticipated transpires. How much further south would that wave of low pressure have to move to allow all of southeast Texas a good opportunity at getting frozen precipitation?

The cold air would have to be about another 150-200 miles farther south.

Well, with this morning's model changes, it's oh so close but no cigar

[Mr. T]

In HGX's morning discussion, they do mention that a possible winter storm watch/warning or winter weather advisory may be needed later, but only the mention of winter precip in the zones and grids for now...

Otherwise, a heavy rain event is on the way for Houston with 1-2 inches of rain expected with isolated totals up to 4" according to the NWS. There's even a minor severe weather threat for coastal counties.

This should be a fun and very interesting system to track

[srainhoutx]

Well good morning. I see we had some changes with the over night full package of guidance. This is going to be a very interesting 36 hours or so...

[Mr. T]

Well good morning. I see we had some changes with the over night full package of guidance. This is going to be a very interesting 36 hours or so...

Definitely

Here's a SPS for the situation:

540 AM CST SAT JAN 8 2011

...LOCALLY HEAVY RAINFALL POSSIBLE LATE TONIGHT AND SUNDAY
MORNING...

A STRONG UPPER LEVEL STORM SYSTEM WILL COMBINE WITH INCREASING
MOISTURE TO RESULT IN RAIN AND ISOLATED THUNDERSTORMS OVER THE
AREA BEGINNING AROUND MIDNIGHT TONIGHT AND LASTING THROUGH
SUNDAY MORNING.

LOCALLY HEAVY RAINFALL WILL BE POSSIBLE AREA WIDE. RAINFALL
AMOUNTS ARE EXPECTED TO AVERAGE 1 TO 2 INCHES WITH ISOLATED TOTALS
OF 2 TO 4 INCHES. MINOR LOCALIZED FLOODING OF STREETS...FEEDER
ROADS...SECONDARY ROADS...AND LOW WATER CROSSINGS WILL BE
POSSIBLE. IN ADDITION...STORMS COULD PRODUCE FREQUENT LIGHTNING
AND GUSTY WINDS.

ON SUNDAY NIGHT...THERE IS A CHANCE OF SOME VERY LIGHT FREEZING
RAIN OR SNOW FLURRIES AFFECTING AREAS NORTH OF A COLLEGE STATION
TO NEW WAVERLY TO SHEPHERD LINE. MINOR ICING OF BRIDGES AND
OVERPASSES WILL BE POSSIBLE.

LISTEN TO NOAA WEATHER RADIO OR YOUR LOCAL MEDIA FOR THE LATEST
UPDATES ON THIS SITUATION.

[ticka1]

You early birds rock! Thanks Srainhoutx and Mr T. - Never say never until the weather unfolds real-time. Mostly likely all we will get is rain but then again - everyone said the Miracle Christmas snow that happend a couple of years ago wasn't going to happen....so with that - I will be glued to this forum since i'm home sick in bed with a cold.

[Mr. T]

I'm going to post the whole AFD here since it's one of the best one's we have seen in a while:

DISCUSSION...
A COLD FRONT IS PUSHING SOUTH THROUGH THE CWA EARLY THIS MORNING
JUST NOW REACHING THE COASTAL ZONES. THE OB AT KHOU SHOWED THE SFC
DEWPOINT DROPPING FROM 45 TO 35 IN THE LAST HOUR WITH AN INCREASE
IN WIND TO 13 KTS. ANOTHER NICE DAY IS IN STORE FOR TODAY EXCEPT
THAT TEMPS WILL BE 5-10 DEGREES COOLER THAN YESTERDAY IN THE WAKE
THE FRONT. EXPECT MOSTLY SUNNY SKIES THIS MORNING...WITH MID
LEVEL CLOUDS SPREADING WEST TO EAST ACROSS THE AREA THIS AFTN.

POTENT UPPER LEVEL LOW NOW OVER SOUTHERN ARIZONA WILL MOVE EAST
ACROSS TEXAS TONIGHT AND SUNDAY BRINGING A VARIETY OF IMPACTS TO
THE AREA. A 40-50 KT LOW LEVEL JET WILL DEVELOP TONIGHT RESULTING
IN A RAPID INCREASE IN MOISTURE TO THE AREA. PWS ARE FORECAST TO
REACH 1.1-1.5 INCHES OVER THE SRN HALF OF THE AREA TUESDAY
MORNING. FLOW ALOFT BECOMES STRONGLY DIFFLUENT LATE TONIGHT AND
SUNDAY MORNING. A SFC BOUNDARY WILL SET UP ALONG THE COAST WITH AN
850 MB BOUNDARY SETTING UP OVER THE NRN PORTION OF THE CWA. BEST
LOW LEVEL CONVERGENCE WILL BE FOCUSED ALONG THESE TWO BOUNDARIES.
LOCALLY HEAVY RAINFALL IS LIKELY ESPECIALLY ACROSS THE SRN HALF
THE AREA LATE TONIGHT/SUNDAY MORNING. WIDESPREAD RAINFALL AMOUNTS
OF 1-2 INCHES ARE EXPECTED WITH ISOLATED TOTALS OF 2-4 INCHES
ESPECIALLY OVER THE SRN HALF OF THE CWA. WILL MENTION LOCALLY
HEAVY RAINFALL IN GRIDS AND HWO WITH POTENTIAL FOR MINOR FLOODING.
TREMENDOUS AMOUNTS OF LOW LEVEL SHEAR ARE FORECAST BY THE MODELS
(HELICITIES > 800 M2/S2). MODELS CONTINUE TO SUGGEST THE
POSSIBILITY OF THE WARM FRONT SURGING INLAND OVER THE COASTAL
ZONES FOR A FEW HOURS FROM AROUND 10-16Z SUNDAY. SPC DAY 2 OUTLOOK
HAS A SEE TEXT FOR THE COASTAL ZONES. THE DYNAMICS FAVOR THE
DEVELOPMENT OF A SQUALL LINE WHICH WILL AFFECT THE COASTAL AND
MARINE ZONES DURING THE MORNING HOURS SUNDAY WITH STRONG WINDS AND
WATERSPOUTS BEING THE PRIMARY THREAT. WILL MENTION SEVERE THREAT
IN THE HWO BUT NOT THE GRIDS. ELEVATED INSTABILITY WILL FAVOR
ISOLATED THUNDER FOR INLAND AREAS AS WELL. THE HEAVY RAIN AND
STORMS ARE EXPECTED TO END BY EARLY AFTN WITH WRAP AROUND PRECIP
LINGERING OVER NRN ZONES INTO THE AFTERNOON.

IN ADDITION TO THE HEAVY RAIN AND SEVERE POTENTIAL...STRONG WINDS
ARE LIKELY TO IMPACT THE COASTAL AND MARINE AREAS...WITH ELEVATED
TIDES AS WELL. SEE MARINE DISCUSSION BELOW FOR MORE DETAILS. A
WIND ADVISORY MAY BE NEEDED LATE TONIGHT/EARLY SUNDAY FOR COASTAL
AREAS.

WINTER WEATHER IS ANOTHER THREAT AS WELL OVER OUR NE ZONES. THE
GFS BUFR SOUNDING AT KLFK INDICATES PRECIP STARTING OFF AS A
SNOW/SLEET MIX LATE TONIGHT...THEN CHANGING TO RAIN FOR A FEW
HOURS IN THE MORNING BEFORE SWITCHING BACK TO A WINTER MIX IN THE
AFTN. 00Z NAM SHOWED A MOSTLY RAIN EVENT WHILE THE ECMWF WAS A
GOOD COMPROMISE BETWEEN THE GFS/NAM. THE MAIN AREA OF CONCERN IS
HOUSTON...MADISON...TRINITY...AND NORTHERN POLK COUNTIES. WILL
FORECAST A MIX OF RAIN...SLEET AND SNOW DURING THE DAY SUNDAY IN
THIS AREA...WITH SOUNDINGS SUPPORTING VERY LIGHT FREEZING
RAIN/FREEZING DRIZZLE OR SNOW FLURRIES SUNDAY EVENING. IF THE
CHANGEOVER OCCURS IN THE MORNING...THE POTENTIAL EXISTS FOR HEAVY
SLEET OR WET SNOW TO FALL IN THIS AREA WITH SIGNIFICANT ACCUMULATIONS.
HAVE HELD OFF ON A WATCH FOR NOW BUT MAY NEED ONE IN A LATER
FORECAST PACKAGE. FURTHER SOUTH AND WEST...THERE IS THE POTENTIAL
FOR SNOW FLURRIES OR VERY LIGHT FREEZING RAIN TO IMPACT AREAS AS
FAR SOUTH AND WEST AS COLLEGE STATION...HUNTSVILLE...AND
LIVINGSTON SUNDAY EVENING. HOWEVER...PRECIP AT THIS POINT WOULD BE
VERY LIGHT WITH ACCUMULATIONS EITHER NON-EXISTENT OR STAYING IN
THE ADVISORY RANGE.

THE WEATHER WILL TURN SHARPLY COLDER SUNDAY WITH THE ARRIVAL OF
THE STORM WITH MAX TEMPS OCCURRING EARLY IN THE DAY MOST AREAS.
COLDER WEATHER WILL PERSIST THROUGH THE MIDDLE OF NEXT WEEK. THE
SECONDARY MODIFIED ARCTIC COLD FRONT WILL PUSH THROUGH SE TX
TUESDAY MORNING. COLDER AIRMASS WILL SPREAD INTO THE AREA IN THE
WAKE OF THE FRONT WITH DEWPOINTS DROPPING TO THE TEENS/LOW 20S.
HAVE COMPROMISED BETWEEN COLDER ECMWF AND GFS FOR TEMPS. IF SKIES
CAN CLEAR ENOUGH THAN A HARD FREEZE WILL BE POSSIBLE OVER THE NRN
ZONES TUE NIGHT AND POSSIBLY AGAIN WED NIGHT. FURTHER SOUTH...ONLY
A LIGHT FREEZE IS EXPECTED AT THIS TIME. ISENTROPIC LIFT WILL
BEGIN WEDNESDAY AND PERSIST INTO THURSDAY...WITH MID LEVEL CLOUD
DECK FORMING. ALTHOUGH SOUNDINGS WOULD SUPPORT SLEET AND POSSIBLY
SNOW THIS PERIOD...HAVE LEFT PRECIP OUT OF THE FORECAST AS LOW
LEVELS ARE VERY DRY. MAX TEMPS WEDNESDAY WILL LIKELY STAY IN THE
30S WITH THE CLOUD COVER. WARM ADVECTION WILL BEGIN IN EARNEST THU
NIGHT AS SFC HIGH MOVES EAST AND ANOTHER SHORTWAVE APPROACHES
FROM THE WEST. EXPECT SHOWERS ON FRIDAY FOLLOWED BY MUCH WARMER
TEMPS FOR NEXT WEEKEND.

35

[srainhoutx]

Nice write up by Forecaster 35. I know he is amped. After looking at the 06Z WRF, I'd not be suprised to see a WWA/WWS issued sometime later this morning. Dynamics are very impressive with feature. A cold pocket aloft extends further S and W as well when the surface low nears our area. Should be interesting to go from heavy rain transitioning to a wintry mix. Although not "historic cold", it's going to feel mighty chilly this coming week...

[srainhoutx]

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0644 AM CST SAT JAN 08 2011

VALID 081300Z - 091200Z

...NO SVR TSTM AREAS FORECAST...

...S TX AREA THIS EVENING/TONIGHT...
THE MIDLEVEL LOW NOW OVER THE AZ/MEXICO BORDER WILL ACCELERATE EWD
TO THE BIG BEND/LOWER RIO GRANDE VALLEY REGION OF TX BY THE END OF
THE PERIOD. CYCLOGENESIS IS EXPECTED FROM THE LOWER RIO GRANDE
VALLEY TO THE MIDDLE TX COAST TONIGHT...IN ADVANCE OF THE
APPROACHING MIDLEVEL TROUGH. STRENGTHENING LOW-LEVEL WAA ON THE
NOSE OF A 40-50 KT LLJ AND GRADUAL MOISTENING WILL CONTRIBUTE TO A
FAVORABLE ENVIRONMENT FOR THUNDERSTORM DEVELOPMENT BEGINNING THIS
EVENING NEAR THE RIO GRANDE...AND SPREADING EWD TO THE MIDDLE TX
COASTAL PLAIN EARLY SUNDAY.

SURFACE TEMPERATURES WILL WARM INTO THE 70S WITH BOUNDARY LAYER
DEWPOINTS IN THE MID 60S...BUT MODEST MIDLEVEL LAPSE RATES AND A
PRONOUNCED CAP WILL LIMIT WARM SECTOR MLCAPE TO 500-1000 J/KG.
DESPITE THE MODEST INSTABILITY...VERY STRONG WAA WILL LIKELY SUPPORT
AN EXPANSIVE THUNDERSTORM CLUSTER OVERNIGHT ACROSS S TX AND THE
MIDDLE TX COAST. THERE WILL BE A SMALL SPATIAL WINDOW OF
OPPORTUNITY FOR SURFACE-BASED ROTATING STORMS /MAINLY TONIGHT/
WITHIN THE LARGER MCS...ALONG THE N EDGE OF THE MID 60S DEWPOINTS
AND S EDGE OF THE STRONGER LOW-LEVEL SHEAR IN ADVANCE OF THE SURFACE
LOW. A MARGINAL THREAT FOR LARGE HAIL/DAMAGING WINDS WILL ACCOMPANY
THE INITIAL CONVECTION CLOSER TO THE RIO GRANDE THIS EVENING...WHILE
AN ISOLATED TORNADO CANNOT BE RULED OUT...ESPECIALLY CLOSER TO THE
COAST OVERNIGHT IN THE MOIST WAA REGIME.

..THOMPSON/HURLBUT.. 01/08/2011

[PaulEInHouston]

Morning SRain and all fellow members ...new member here and love the weather too. I'm down in League City and have a home station setup here...been running now for about 4 months.

I am in agreement on the threat for heavy rain and possible severe potential, although I think the progged coastal low will form/track bit farther south off the coast...hopefully keeping the bulk of the really bad stuff along or just off the near shore Upper Texas coastal waters. Of course, that's just my opinion, lol. What I'm interested in really is the timing of the arrival of the ULL over southern AZ now along with it's track, be it through the central part of the state or farther South, and the coastal low track as well.

This is a very interesting setup from a timing and placement standpoint of both features. What are your thoughts? I also noticed that HGX mentioned poss of frozen precip on/about Wed/Thur time frame but not much moisture to work with...

[srainhoutx]

Welcome PaulEInHouston. Certainly an interesting event unfolding. As always, the eventual track of the H5 as well as the surface low will be key to how everything unfolds. I will say that the trends of the past 24 hours do raise an eyebrow with the slight shifting further S every run. It should be an interesting storm to track and as I stated several times this week, look for some unexpected surprises.

[PaulEInHouston]

Thanks...have followed you on the Storm2k site as well...great insight into things. I'm a pretty much newbie, but have kind of conducting a test on myself from a local forecasting standpoint over last few months and haven't been doing too badly. I'm really trying to learn more of the model readings, learning not to believe in them too much, and also concentrating more on soundings, satellite products and the like for big weather maker scenarios like this.

[srainhoutx]

I am a firm believer in using all the 'tools in the tool box', so to speak. We have a great group of folks here that are very knowledgeable in all aspects of analysis. We are fortunate to have such folks that are willing to share their experiences/expertise and that’s what makes our Weather Forum a great venue. Again welcome, and enjoy your time here. Latest RUC data is 'sniffing' an area near Corpus Christi/Aransas Pass and up to the Middle TX Coast fairly strongly for Coastal Low Development. We’ll see how it plays out in the next 12-24 hours.

[randybpt]

Well looks like the GFS was on to something after all. Man if it.was just bout 5-7 degrees colder we would have ourselves a heck of a snow storm tomorrow. Wonder what ever happened to the really bitter cold that was to build up over canada is it still sitting in siberia. Thanks.to everyone staying up and updating on this weather event. But still looks like nothing but liquid snow for us.....im sure disappointed I can't use my snow machine this year........Get me just one night of low 20s and low.humidity

[PaulEInHouston]

Randy, agreed here, but the dynamics of this whole system are still in question, especially placement of the approaching H5 and surface low formation. While it does appear too warm for any frozen stuff, I wouldn't rule out later in the day Sunday. Only reason I mention this is the noticeable WV/moisture available that continues to stream from the Pacific across Mexico and onward. The southern jet branch/overrunning will have a lot to do with how this all plays out as well after the main rain maker passes early tomorrow morning. Just my 2cents worth.

[srainhoutx]

12Z NAM suggests the best dynamics for wintry weather would be across the DFW area and points E. NE TX/N LA look to be the sweet spot via that model through hour 36. There are hint's of a robust cold pocket associated with the H5 feature very near College Station, though. The NAM is very wet across TX as well.