January Weather Discussion: Slight Chance Severe Storms

[wxman57]

Any frozen precip showing for our area? We're having UIL competition Friday night with kids traveling to the event on buses. Just wondering if there's going to be a chance of ice. Thanks.

Currently, it appears that the threat from freezing rain/sleet will be up north, meaning near Dallas and northward into Oklahoma. The timing would be Wednesday night through Thursday morning. By Friday, all indications are that high pressure will build across Texas, with much colder air and no precip. So just cold weather for Friday evening for the bus trip.

[wxman57]

Euro and Canadian are suggestive of a very shallow sub-freezing layer (meaning freezing rain, not snow) pushing at least to central Texas by Wednesday afternoon/evening. That sets the stage for the trof axis to pass during the day on Thursday, providing the lifting for precip. I've seen these types of setup before. Generally, the sub-freezing air is too shallow for snow to form, so you get a mix of sleet and freezing rain. It's possible the air column aloft deepens enough as the trof exits on Thursday afternoon for the freezing rain and sleet to briefly change to snow as the precip ends.

Most likely areas would include northeast Texas (Dallas) north through central OK and east to Arkansas. I don't see anything to indicate a threat of freezing rain south to Houston, as I just don't think the sub-freezing air will reach Houston until after the precip ends on Thursday afternoon.

Oh, and one caveat about ALL the models. They did fairly well with last week's much deeper cold air. We could use the models to estimate the frontal position and vertical profile 3-5 days in advance. That won't be true with a shallower Arctic airmass. The models may be off on the southward extend of the front by 200-500 miles. They'll try to drive it back to the north as a warm front Wednesday night/Thursday morning, indicating nothing but rain in advance of the upper trof. Beware!

[biggerbyte]

If I may just interject... Sambucol, I would wait until about Tuesday or Wednesday to get verification on that. Wxman is giving you a projection based on current models. It is not a forecast. If you have something to do that hinges on good weather, I'd suggest you check back. At this early stage, that projection could still come true. Heck, being where we are, it probably will. However, that is six days away. We've been over this subject many times. He did say, "currently it appears". I'm stressing the point. This seems to be really important for you.

Good luck..

BB

[srainhoutx]

Mighty chilly in the source regions...

[Ptarmigan]

Interesting that the GFS model the one that does up to 16 days forecast is not showing any freeze, while Canadian and Euro shows a freeze coming.

[Portastorm]

Ed, I checked the storm database for a Feb. 94 ice storm in Austin and nothing shows. I was here (Austin) then as well and don't remember anything, although sometimes I can't remember what I ate for lunch yesterday so that doesn't matter too much!

There was a major ice storm in Feb 94 in northeast-east Texas where temps dropped some 60 degrees and some areas saw as much as up to 4 inches of ice/sleet.

But you are correct about the ramps on and off I-35 in downtown. They still ice over easily and the upper deck of I-35 is usually the first thing to close down when ice happens in Austin.

1992? 1993? 1995?

Sorry, I checked the NCDC storm database and no reports in those years. Maybe it was in January?

[srainhoutx]

Beneficial rains tonight for those areas that need it the most regarding our ongoing drought…

[biggerbyte]

Yes... Tonight and Sunday look very wet.

[Andrew]

Busy couple of days but got the yard done. Looks like the forums are going to be busy for the next couple of days also. Waiting on 00z but here are the pressures for Canada to go along with Srain's post.

[srainhoutx]

The 00Z NAM suggests N Central/NE TX will see the most rainfall from our tomorrow event. We shall see. That model also suggests a deepening trough...

[Andrew]

00z colder:

[sleetstorm]

We still cannot seem to get any frozen or freezing precipitation with this next feasible arctic outbreak here in southeast Texas. Bummer. We receive precipitation without cold enough temperatures and amply icy temperatures with no moisture or no adequate moisture, yet not both simultaneously.

[wxman57]

We still cannot seem to get any frozen or freezing precipitation with this next feasible arctic outbreak here in southeast Texas. Bummer. We receive precipitation without cold enough temperatures and amply icy temperatures with no moisture or no adequate moisture, yet not both simultaneously.

It's very unlikely that the GFS will be a source for identifying any freezing/frozen precip with a shallow layer of Arctic air this week. I'd look toward the Canadian and Euro for picking up on the upper-level features better, though they'll both likely do a poor job with surface features (front location, precip) as well. What I see in the Euro and hinted at in the Canadian is a very shallow layer of sub-freezing air across TX/OK Wednesday night. You can tell it's shallow by how far north the 850mb (5000ft) freezing line is compared to the likely surface freezing line. I think there's an increasing risk of freezing rain/sleet from NE TX (Dallas area, maybe a bit south of there) north through OK next Wed night/Thu. I don't see any such threat for us even hinted at.

[srainhoutx]

HPC says all the operational models are out to lunch...

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
722 AM EST SUN JAN 16 2011

VALID 12Z THU JAN 20 2011 - 12Z SUN JAN 23 2011


VERY POOR MODEL AND RUN TO RUN AGREEMENT THIS FORECAST PERIOD. ALL
OPERATIONAL MODEL FORECASTS ARE SUSPECT. USE OF LAGGED AVERAGE
FORECASTS EXAMINING MODEL RUN TO RUN CONSISTENCY YIELDS A SLIGHTLY
BETTER AGREED UPON ECMWF SOLUTION WHICH LOOKS CLOSEST TO THE 00Z
ECMWF MEAN. THIS WAS USED AS A BASE WITH MANUAL ADJUSTMENTS.

HIGH PRESSURE BUILDING INTO THE GREAT BASIN SHOULD BRING AN
OFFSHORE/SANTA ANA EVENT TO CA WED INTO THURS. A DIFUSE AREA OF
LOW PRESSURE SHOULD DEVELOP ALONG THE GLFMEX COAST FRI AND INTO
SAT AND MOVE OFFSHORE OF THE EAST COAST SAT AND SUN. RAIN
POTENTIAL ALONG THE GULF COAST AND SOUTHEAST COAST FRI AND SAT
WITH THE POSSIBILITY OF MORE WINTRY WEATHER ACROSS THE NRN EDGE OF
THE PRECIPITATION SHIELD IN THE INTERIOR PIEDMONT AND FOOTHILLS
AND POSSIBILY THE MID ATLC COASTAL PLAIN AS PER ECMWF ENS MEAN.
LOW CONFIDENCE FORECAST.

AN OVERALL BROAD TROUGH SETTING UP COAST TO COAST WILL KEEP MOST
OF CONUS BELOW NORMAL LATE WEEK AND WEEKEND.

ROSENSTEIN

[srainhoutx]

Meanwhile we do have some wet weather to follow today...

01162011 day1otlk_1300.gif

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0637 AM CST SUN JAN 16 2011

VALID 161300Z - 171200Z

...NO SVR TSTM AREAS FORECAST...

THE 12Z SOUNDINGS FROM BRO AND CRP CONFIRM THAT WHILE QUITE
MOIST...THE AIR MASS MOVING INLAND ACROSS S TX CONTAINS MINIMAL
INSTABILITY. NEVERTHELESS AS THE TROUGH NOW MOVING EWD INTO S TX
CONTINUES TO WEAKEN AND SHIFTS INTO NWRN GULF...THERE IS SUFFICIENT
SUPPORT FOR EMBEDDED THUNDERSTORMS. THIS CONVECTIVE THREAT WILL
SHIFT EWD ACROSS S TX TO SWRN LA BY THIS EVENING. MOST ACTIVE
THUNDERSTORMS SHOULD REMAIN OFFSHORE WHERE INSTABILITY WILL BE A
LITTLE GREATER.

..HALES/BOTHWELL.. 01/16/2011

[srainhoutx]

FYI: Some special sounding data will be launched around 18Z across TX/OK/AR/LA. There is even a suggestion of Winter RECON missions to better evaluate the situation ahead this week. Those are strong hints that there is certainly something ahead that requires as much data as possible...

NOUS42 KWNO 161339
ADMNFD

SENIOR DUTY METEOROLOGIST NWS ADMINISTRATIVE MESSAGE
NWS NCEP CENTRAL OPERATIONS CAMP SPRINGS MD
1337Z SUN JAN 16 2011..CORRECTION...RELEASE SONDES TODAY NOT
TOMORROW...
THE 12Z NCEP MODEL PRODUCTION STARTED ON TIME..
12Z RAOB RECAP...
KPP/78970 - 10142; GROUND EQUIP PROBLEMS...
NCEP HPC IS REQUESTING 18Z SOUNDINGS FOR TODAY 1/16 FROM THE
FOLLOWING STATES TX..LA..OK..AR..THIS WOULD INCLUDE THE FOLLOWING
UPPER AIR SITES..72249 FWD..72250 BRO..72251 CRP..72261 DRT..72265
MAF..72363 AMA..72364 EPZ..72240 LCH..72248 SHV..72233 LIX..72340
LZK..72357 OUN..
74646 LMN..

THE REASON FOR THE REQUEST FOLLOWS...
IT WOULD BE BENEFICIAL TO THE MODEL GUIDANCE IF ALL UPPER AIR
SITES IN OKLAHOMA, ARKANSAS, TEXAS, AND LOUISIANA WERE ABLE TO
LAUNCH AN 18Z SET OF BALLOONS/RADIOSONDES TODAY 1/16 TO HELP
BETTER INITIALIZE THE INTERACTION BETWEEN A SOUTHERN STREAM TROUGH
MOVING OUT OF MEXICO AND A NORTHERN STREAM TROUGH EMERGING EAST OF
THE ROCKIES. THIS SHOULD RESULT
IN LESS SPREAD IN THE DETERMINISTIC GUIDANCE COUPLED WITH THE
SCHEDULED WINTER WEATHER RECON.
A CRITICAL WEATHER DAY IS NOT EXPECTED IN THE NEXT 3 DAYS.
$$
SHRUELL/SDM/NCO/NCEP

This was the CARCAH assignment (Winter RECON) issued yesterday for today/tomorrow...

000
NOUS42 KNHC 151930
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
0230 PM EST SAT 15 JANUARY 2011
SUBJECT: WINTER STORM PLAN OF THE DAY (WSPOD)
VALID 16/1100Z TO 17/1100Z JANUARY 2011
WSPOD NUMBER.....10-046

I. ATLANTIC REQUIREMENTS
1. FLIGHT ONE -- TEAL 70
A. A66/ DROP 10 (BOGGY)/ 17/1200Z
B. AFXXX 09WSA TRACK66
C. 17/0730Z
D. 10 DROPS AS PUBLISHED ON TRACK
E. AS HIGH AS POSSIBLE/ 17/1400Z

2. OUTLOOK FOR SUCCEEDING DAY:
A. POSSIBLE A66/ DROP 10 (BOGGY)/ 18/0000Z
B. POSSIBLE A62/ DROP 10 (TORRY)/ 18/1200Z

II. PACIFIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. SUCCEEDING DAY OUTLOOK.....NEGATIVE.
3. REMARK: G-IV WINTER STORM MISSION TASKED
IN WSPOD 10-045 WILL FLY AS SCHEDULED.
SEF

[srainhoutx]

The 12Z GFS suggest why some additional data is needed. Note the troughiness to our W as well as several areas of Upper Air disturbances dropping S along the trough axis and to our W and N.

[weatherguy425]

12z GFS also shows another potential** winter storm for texas around the 28th/29th. Has the Euro come out yet?

[srainhoutx]

12z GFS also shows another potential** winter storm for texas around the 28th/29th. Has the Euro come out yet?

Euro will start around noon with images slowly coming in just beyong 1 PM via the PSU site. The Euro main page should update around 1 PM as well. Oh, and the Canadian (GEM) has a mess around hour 180 besides the mid week threat.

[srainhoutx]

HGX thinking we'll have a very messy afternoon/evening...


AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1138 AM CST SUN JAN 16 2011

.DISCUSSION... /ISSUED 1052 AM CST SUN JAN 16 2011/ INITIAL ROUND
OF RAINFALL IS GRADUALLY TAPERING OFF AT LATE MORNING. GPSMET DATA
SHOWS PLENTY OF MOISTURE IN PLACE WITH PWS RUNNING 1.0-1.2 INCHES.
KHGX VWP SHOWS A 30-35 KT LOW LEVEL JET WHICH WILL CONTINUE TO
TRANSPORT MOISTURE INTO THE AREA. WATER VAPOR IMAGERY SHOWS A
SECOND SHORTWAVE NOW OVER WEST TEXAS. THIS DISTURBANCE WILL CROSS
THE AREA THIS AFTN/EVENING RESULTING IN AN ENHANCEMENT IN RAINFALL
ONCE AGAIN. SOME ISOLATED THUNDER IS EXPECTED AS WELL AS A POCKET
OF VERY COLD 500 MB TEMPS (-20 TO -22C) MOVES OVER THE CWA.
LOCALLY HEAVY RAINS WILL BE POSSIBLE WITH THE NEXT ROUND AS WELL.
MADE SOME ADJUSTMENTS TO POPS OTHERWISE NO CHANGES TO FORECAST.


Also notice the Mountain Waves associated with a strong Northerly flow dropping S from the Rockies in Far W TX/S NM...