Deep South Winterwx Discussion 2015-2016

[Stormcenter]

A very long detailed discussion from the NWS in New Orleans this morning.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW ORLEANS LA
613 AM CST TUE FEB 1 2011

.SHORT TERM...VERY ACTIVE DIFFICULT FORECAST IN STORE FOR THE
REGION. SEVERE WEATHER STILL LOOKS PROBABLE FOR TODAY WHILE WINTER
WEATHER CONCERNS ARE STARTING TO INCREASE FOR OUR EXTREME NE WHICH
DOES INCLUDE THE BATON ROUGE METRO. FOG...WINDS...AND MARINE
CONCERNS ARE ALSO ABUNDANT IN THE FIRST 36 HRS OF THE FCST.

THE MAJOR PLAYER FOR TODAYS WEATHER WHICH WILL BRING US OUR SVR AND
BE AN HISTORIC...YES HISTORIC WINTER STORM...FOR THE PLAINS AND MID
MS VALLEY IS REALLY WRAPPING UP IMPRESSIVELY IN TX RIGHT NOW. SFC LOW
IS DEEPENING QUICKLY WITH SLP DOWN TO 1002MB NEAR CRP AT 10Z. WV/IR
SATELLITE IMAGE SHOWS A NICE BAROCLINIC LEAF DEVELOPING OVER THE
PLAINS.

FOR TODAY AND TONIGHT...NOT MUCH HAS CHANGED IN THE THINKING AND
SEVERE WEATHER IS STILL PROBABLE TODAY ALTHOUGH WIDESPREAD SEVERE
WEATHER IS NOT ANTICIPATED. THINGS WILL GET GOING VERY QUICKLY
BEGINNING AROUND MIDDAY. THE MAIN SYSTEM IS SWINGING THROUGH THE SRN
PLAINS RIGHT NOW AND WILL BECOME NEGATIVELY TITLED AS IT MOVES INTO
THE LOWER/MID MS VALLEY. THE SFC LOW WILL DEEPEN AND MOVE TO THE NE
THROUGH THE LOWER MS VALLEY. THE SFC LOW APPEARS TO BE TRENDING A
TAD FURTHER SOUTH AND THIS WILL TRANSLATE INTO STRONGER SFC WINDS
OVER THE LAND AND THUS WE HAVE ISSUED A WIND ADV FOR THE ENTIRE CWA
FOR THIS AFTN. AS THE SFC LOW MOVES INTO NRN MS/ERN AR IT WILL DRIVE
A COLD FRONT THROUGH LA AND SHOULD BE ON THE DOORSTEP OF OUR CWA
RIGHT AROUND 18Z. THIS IS GOING TO BE A VERY PROGRESSIVE SYSTEM THAT
WILL DRIVE THE COLD FRONT COMPLETELY THROUGH THE CWA DURING THE AFTN
AND SHOULD BE WELL INTO THE GULF BY SUNRISE WED MORNING. THERE WILL
BE SHRA AND TSRA AHEAD OF THE FRONT SOME SVR BUT MORE ON THAT LATER.
AS SOON AS THE FRONT MOVES THROUGH MUCH COLDER AIR WILL QUICKLY MOVE
IN BEHIND IT WITH TEMPS LIKELY FALLING BETWEEN 25 TO 40 DEGREES FROM
HIGHS TODAY AND LOWS TOMORROW MORNING. LOWS WILL FALL BELOW FREEZING
FOR MUCH OF THE CWA NORTH OF THE I 10/12 CORRIDOR AND IN THE EXTREME
NW LOWS COULD FALL INTO THE LOWER 20S FOR A FEW HOURS SO A HARD
FREEZE WARNING HAS BEEN ISSUED FOR THE EXTREME NW. IN ADDITION WE
MAY HAVE TO LOOK AT A WIND CHILL ADV FOR SOME AREAS TONIGHT.

AS FOR STRONG/SVR RISK...THERE IS CONCERN THAT THE RISK MAY BE
INCREASING FOR ALL OF THE REGION NOW AND NOT JUST THE NW. DEWPOINTS
HAVE RISEN DRAMATICALLY IN THE GULF WITH 65-68 READINGS OVER MUCH OF
THE NRN GULF AND EVEN A FEW 70 DEWPOINTS FURTHER OUT IN THE GULF. IF
THOSE DEWPOINTS CAN MOVE INLAND THEN THE LIKELIHOOD OF THE MARINE
LAYER INHIBITING SVR WEATHER WILL BE FAR LESS. TO KEEP FROM GETTING
INTO ALL OF THE DETAILS I WILL TRY TO KEEP THIS SHORT PART
SHORT...INSTABILITY IS STILL THE MAIN ISSUE TODAY WITH SHOWALTERS
NEAR -3 AND MLCAPE UP TO 500 J/KG. THE SYNOPTIC PATTERN IS STILL
VERY FAVORABLE...AND DYNAMICALLY THINGS ARE QUITE IMPRESSIVE. THE
KINEMATIC FIELD IS OFF THE CHART WITH HELICITY VALUES WELL ABV WHAT
IS NEEDED. THE WINDS VEER ALL THE WAY FROM THE SFC TO H7 SO MODE IS
NOT MUCH OF AN ISSUE. IF CONVECTION FIRES AHEAD OF THE FRONT THEN
THE TORNADO RISK WILL INCREASE BUT IF CONVECTION REMAINS MOSTLY
CONFINED TO RIGHT AHEAD OF THE FRONT THEN DAMAGING STRAIGHT LINE
WINDS WILL BE THE PRIMARY CONCERN BUT TORNADOES ARE STILL POSSIBLE.
HEAVY RAIN IS STILL AN ISSUE AS ABUNDANT MOISTURE IS IN PLACE.

WED WILL BE QUIET BUT COLD AND BLUSTERY AS WINDS FROM THE NW TO N
POSSIBLY GUSTS TO NEAR 25 MPH. HIGHS MAY REMAIN NEAR 40 IN THE FAR
NORTH AND WITH THESE WINDS IT WILL FEEL MUCH COLDER. WITH HIGHS NOT
CLIMBING MUCH AND H925 TEMPS REMAINING BELOW FREEZING FOR THE NRN
3RD/HALF OF THE CWA IT COULD SET THE STAGE FOR WINTER WEATHER THU
AND FRI.

.LONG TERM...THE MAIN CONCERN IN THE EXTENDED IS THE THREAT OF
WINTER WEATHER POSSIBLY AS EARLY AS THU MRNG AND REMAINING IN PLAY
THROUGH FRI NIGHT. THE MDLS ARE IN GENERAL AGREEMENT BUT THERE IS
ENOUGH DIFFERENCES IN THE DETAILS THAT CAUSE MAJOR PROBLEMS WITH
WHAT WE COULD SEE IN THE NWRN 3RD/QUARTER OF THE CWA. THE GFS IS THE
LEAST IMPRESSIVE FROM A WINTER WEATHER STANDPOINT WHILE THE 00Z NAM
HAD A FULL BLOWN ICE STORM FOR MCB AND BTR. THE ECMWF WAS RIGHT IN
THE MDL HINTING AT A BETTER CHANCE OF WINTER WEATHER IN THE FAR NW
THAN THE GFS. THE SREF WAS IN MORE AGREEMENT WITH THE NAM AND ECMWF
AND THE CANADIAN APPEARS TO BE MORE INLINE WITH THE 00Z AS WELL WITH
POSSIBLE ICE STORM. FIRST OFF WE WILL SAY CONFIDENCE IS LOW BUT IT
IS INCREASING THAT WE WILL SEE SOME TYPE WINTER PRECIP IN THE FAR NW.

THU THROUGH FRI NIGHT...THIS IS THE BIG PROBLEM AREA IN THE
FORECAST. COLD AIR WILL ALREADY IN PLACE IN THE LL AND AT THE SFC
BUT AS A SFC LOW DEVELOPS IN THE GULF H85 TEMPS WILL BEGIN TO WARM.
WE WILL STILL BE ENTRENCHED IN SW FLOW CARRYING PAC MOISTURE. THE
ELONGATED L/W TROUGH WILL START TO FINALLY PUSH EAST LATE THU
KEEPING THE AREA UNDER BROAD LIFT OVER THE ENTIRE REGION THU THROUGH
FRI. PRECIP LOOKS TO RETURN TO THE REGION AS EARLY AS THU MORNING.
THE PROBLEM WE HAVE IS NORTH OF A LINE FROM BATON ROUGE TO MOUNT
HERMAN. DEWPOINTS WILL BE WELL BELOW FREEZING AND H925 TEMPS LOOK TO
RANGE FROM -4 TO 0. SNOW DOES NOT LOOK LIKELY AS THE FCST SNDGS SHOW
A RATHER THICK WARM LAYER(ABOUT 3-6K FT THINK) WITH TEMPS AS HIGH AS
3C JUST ABV H9. THIS WOULD SUGGEST PARTIAL MELTING IF NOT COMPLETE
MELTING BEFORE MOVING BACK IN THE COLD AIR. FURTHER NOW INTO SWRN MS
THE WARM LAYER IS NOT QUIET AS THICK SO PARTIAL MELTING MAY BE THE
MAIN PLAYER THERE. WITH WET BULBING TAKING PLACE AND DEWPOINTS NOT
FORECAST TO GET OUT OF THE 20S AND H925 TEMPS EXPECTED TO REMAIN
BELOW FREEZING AFTER THE COLD FRONT TODAY THROUGH 12/15Z FRI THERE
IS A VERY GOOD CHANCE WE WILL SEE SLEET AND EVEN POSSIBLY FREEZING
RAIN. I BELIEVE THE MDLS ARE WELL OVERESTIMATING THE SFC TEMP WITH
THE AMOUNT OF PRECIP THEY ARE TRYING TO DEVELOP AND DEWPOINTS IN THE
20S. THIS IS STILL 3-4 DAYS AWAY SO WE WILL BE WATCHING THIS VERY
CLOSE. AN SPS SHOULD BE ISSUED LATER THIS MORNING/TODAY AND WE COULD
END UP NEEDING SOME TYPE OF WINTER WEATHER WATCH WED FOR THE FAR
NE.

THE CAVEAT HERE WITH THE FORECAST FOR THU AND FRI IS ALOT WILL
DEPEND ON THE TRACK OF THE SFC LOWS..TODAYS AND ESPECIALLY THE
GULF LOW THU/FRI. SO WITH THAT THIS FORECAST COULD END UP CHANGING
SIGNIFICANTLY WITH ONLY MINOR CHANGES IN THE SFC LOW AND LL TEMPS.

THE DISTURBANCE MOVES THROUGH FRI NIGHT AND FINALLY COOLS OFF THE
UPPER LVL TO POSSIBLY ALLOW LIGHT SNOW TO DEVELOP FRI NIGHT OVER THE
NW BUT THIS SHOULD BE FAIRLY LIGHT AND ON THE BACK END OF THE
SYSTEM. THIS WEEKEND LOOKS TO BE QUIET AND COOL.&&

[BigB0882]

Sounds interesting. I would much rather snow than ice but we will take what we can get around here!

[Ivanhater]

NWS New Orleans has freezing rain in the forecast for parts of SE Louisiana and South Mississippi Not good

Does end with snow though. NWS Mobile/Pensacola still taking a wait and see, they want to get the severe wx threat over before they focus on this system. Could get nasty around the Gulf coast later this week.

Thursday...Mostly cloudy. Slight chance of light rain or light freezing rain and light sleet. Highs in the lower 40s. Northeast winds 5 to 10 mph. Chance of precipitation 50 percent.

Thursday Night...Cloudy. Light rain or light freezing rain and light sleet. Lows in the lower 30s. Chance of precipitation 70 percent.

Friday...Cloudy. ...Light rain or light freezing rain likely in the morning then light rain likely in the afternoon. Highs in the mid 40s. Chance of precipitation 70 percent.


Friday Night...Mostly cloudy. Chance of light rain and snow in the evening...then a slight chance of light rain and snow after midnight. Lows in the upper 20s. Chance of precipitation 30 percent.

[BigB0882]

Damn you, warm layer, damn you!

The 12z NAM may have nudged the snow back a bit south and east. Just a bit. It looks like Baton Rouge would be right on the edge, could be an inch or two, could be nothing, that close! Better trend though, looks more widespread than the 06z, perhaps. What do you guys think? Looks better?

[Agua]

Sounds interesting. I would much rather snow than ice but we will take what we can get around here!

You ever suffered an ice storm? Its miserable. You can sit around in the dark for days and look at your family.

[BigB0882]

I was just talking about a little sleet and possible freezing rain. At this point I don't feel like a severe ice storm is a worry as temps are progged to be in the mid to low 40's, so any icing will be gone rather quickly once temps get above freezing. Have any models shown a major icing event for the coast?

[Ivanhater]

I was just talking about a little sleet and possible freezing rain. At this point I don't feel like a severe ice storm is a worry as temps are progged to be in the mid to low 40's, so any icing will be gone rather quickly once temps get above freezing. Have any models shown a major icing event for the coast?

Canadian is showing a big ice storm even close to the coast. However, I still don't think the models have a clue what to do with this air mass. Arctic front blasting through Houston right now and I mean blasting. Huge snow pack is getting set down to our North and NW right now.

[Ivanhater]

Many of us will like the 12z Nam

[CYCLONE MIKE]

Not sure if this has been posted yet but just in case I found this on the NWS site. It is HPC's experimental snowfall and freezing rain forecast for up to 72 hrs. Check out what it shows in deep south for friday. Just click on day 3 on right side....

http://www.hpc.ncep.noaa.gov/pwpf_24hr/ ... obs_zr.php

[Ivanhater]

Not sure if this has been posted yet but just in case I found this on the NWS site. It is HPC's experimental snowfall and freezing rain forecast for up to 72 hrs. Check out what it shows in deep south for friday. Just click on day 3 on right side....

http://www.hpc.ncep.noaa.gov/pwpf_24hr/ ... obs_zr.php

Wow, this shows freezing rain accumulation

[CYCLONE MIKE]

Thanks for posting the pic Mike. I don't know how you guys do that. Copying and pasting links is my limit.

[bella_may]

You guys are quiet. I'm getting worried lol

[BigB0882]

I heard the thunder, the squall line is at my door. Currently 69 degrees. Let's see how fast it drops. Maybe I should go sit out in my car, too, haha

[bella_may]

I heard the thunder, the squall line is at my door. Currently 69 degrees. Let's see how fast it drops. Maybe I should go sit out in my car, too, haha

Suppose to be at my house at about 2 or 3. Stay safe everyone!!

[Brent]

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BIRMINGHAM AL
1225 PM CST TUE FEB 1 2011

ALZ011>015-017>050-021230-
AUTAUGA-BARBOUR-BIBB-BLOUNT-BULLOCK-CALHOUN-CHAMBERS-CHEROKEE-
CHILTON-CLAY-CLEBURNE-COOSA-DALLAS-ELMORE-ETOWAH-FAYETTE-GREENE-HALE-
JEFFERSON-LAMAR-LEE-LOWNDES-MACON-MARENGO-MARION-MONTGOMERY-PERRY-
PICKENS-PIKE-RANDOLPH-RUSSELL-SHELBY-ST CLAIR-SUMTER-TALLADEGA-
TALLAPOOSA-TUSCALOOSA-WALKER-WINSTON-
1225 PM CST TUE FEB 1 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE COUNTIES SERVED BY THE
NATIONAL WEATHER SERVICE OFFICE IN BIRMINGHAM.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

A MASSIVE STORM SYSTEM WILL AFFECT A GOOD PORTION OF THE EASTERN
UNITED STATES THIS AFTERNOON. THERE IS A SMALL CHANCE THAT THIS
SYSTEM COULD PRODUCE STRONG DAMAGING WINDS...ISOLATED
TORNADOES...HAIL AND LOCALLY HEAVY RAIN ACROSS CENTRAL ALABAMA.
STORMS ARE CURRENTLY MOVING INTO THE SOUTHERN AND WESTERN SECTIONS
OF CENTRAL ALABAMA AHEAD OF THE COLD FRONT. THESE STORMS WILL WORK
THEIR WAY EASTWARD AS THE FRONT MOVES EASTWARD. THE FRONT ENTERS
WESTERN ALABAMA AS EARLY AS 5 PM AND EXITS INTO GEORGIA BEFORE
MIDNIGHT. THE SEVERE THREAT EXIST FOR ALL OF CENTRAL ALABAMA EXCEPT
FOR FAR NORTHEASTERN PORTIONS OF CENTRAL ALABAMA. THE BEST CHANCE
FOR TORNADOES EXIST NEAR AND SOUTH OF A LINE FROM TUSCALOOSA TO
CLANTON TO TUSKEGEE BEGINNING AROUND AS 2 PM IN THE SOUTHWEST.

IN ADDITION...STRONG GUSTY WINDS ARE ALSO POSSIBLE ON TUESDAY
AND INTO WEDNESDAY MORNING WITH POSSIBLE GUSTS TO 35 MPH.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

GRADIENT WINDS MAY LAST INTO WEDNESDAY WITH A FEW GUSTS OF 25 TO 30
MPH POSSIBLE.

TEMPERATURES ARE GOING TO VITAL FOR WEDNESDAY NIGHT THROUGH FRIDAY
NIGHT...AS WINTRY PRECIPITATION WILL BE POSSIBLE. ON WEDNESDAY NIGHT
THE THREAT FOR FREEZING RAIN WILL BE LIMITED TO SOUTH OF THE
INTERSTATE 85 CORRIDOR AS TEMPERATURES WILL BE NEAR FREEZING...AS
MOISTURE MOVES OUT OF THE AREA.

FOR THURSDAY NIGHT...A WINTRY MIX WILL BE POSSIBLE FOR AREAS ALONG
OR NORTH OF SELMA TO HEFLIN LINE. SOUTH OF THIS LINE...GENERALLY
RAIN WILL OCCUR. BY FRIDAY AND INTO FRIDAY NIGHT...THE THREAT FOR
WINTRY MIX WILL MOVE SOUTH AND IMPACT MOST OF CENTRAL ALABAMA.
CONFIDENCE ON THE WINTRY PRECIPITATION REMAINS LOW AT THIS TIME AND
SUBJECT TO CHANGE AS THE SYSTEM APPROACHES.

.SPOTTER INFORMATION STATEMENT...

ACTIVATION OF STORM SPOTTERS AND EMERGENCY MANAGEMENT PERSONNEL MAY
BECOME NECESSARY THIS AFTERNOON ESPECIALLY WEST AND SOUTH.

$$

[BigB0882]

And just like that the squall line is done. I'm not good at guessing temp drops but its only been about 10 minutes and it is noticeably cooler.

[BigB0882]

How much ice does it take to cause problems?

Looking at the GFS, they show .26 of sleet and .18 of Freezing rain. Then it goes to rain with another .80 but if the temps are off at all it could remain as freezing rain for some or most of that .80 Is under half an inch of freezing rain enough to cause big problems? I'm thinking mostly trees and power lines, hopefully roadways wont be too big of a deal as we will get above freezing a few hours later.

The latest text from the NAM is all rain for my area. Weird how it never quite matches up with their snow maps. Temps, please trend a bit colder...please...

Oh, and while we are busy focusing on a possible Thur/Fri event, the GFS is showing another event for the deep south (skims LA, mostly MS, AL, GA) around the 8th, not that far off, actually.

[northjaxpro]

BigB0882, ice accumulations of 1/4 inch or more will create some major problems not only for the roadways, but with power lines and tree limbs.

[northjaxpro]

Oh, and while we are busy focusing on a possible Thur/Fri event, the GFS is showing another event for the deep south (skims LA, mostly MS, AL, GA) around the 8th, not that far off, actually.

Yep. I have been paying close attention to the next arctic surge which Euro is forecasting to blast down this time more across the Eastern 2/3 of the CONUS by the end of next week. Also, another possible winter storm may be setting up to affect those areas you mentioned and possibly affect the snow weary residents of the Mid Atlantic and Northeast US next week as well.

[BigB0882]

One more question! Sorry, still learning a lot, especially about winter weather.

How much does .26 QPF of sleet usually measure out to? I know snow has a ration of 10:1 (slightly less down here, usually) but what about sleet?