Jump to content
  • Member Statistics

    17,586
    Total Members
    7,904
    Most Online
    23Yankee
    Newest Member
    23Yankee
    Joined

Major National Winter Storm Dec 25-28


Recommended Posts

DISCRETE SUPERCELLS CAPABLE OF ALL THREATS OF SEVERE WEATHER

/INCLUDING THE POTENTIAL FOR LONG-TRACKED TORNADOES/ MAY BE POSSIBLE

AS THE AFOREMENTIONED MID-UPPER LEVEL JET APPROACHES...SUBSEQUENTLY

STRENGTHENING DEEP LAYER SHEAR PROFILES AND PROMOTING STRONG

ROTATION. VISIBLE IMAGERY SUGGESTS CLEARING MAY OCCUR OVER PORTIONS

OF SE TX...CNTRL/SRN LA/MS/AL...WHERE THE GREATEST POTENTIAL

SURFACE-BASED DESTABILIZATION AND CONSEQUENTLY TORNADIC POTENTIAL

WILL EXIST LATER THIS MORNING INTO THE AFTERNOON. HOWEVER...IMPLIED

SUBSIDENCE /DEMARCATED BY SIGNIFICANT DRYING ON WV IMAGERY OVER THE

WRN GULF/ MAY VERY TEMPORARILY DELAY THE DEVELOPMENT IN DISCRETE

SUPERCELLS ACROSS THE WARM SECTOR UNTIL FORCING FOR ASCENT QUICKLY

ARRIVES WITH THE E TX SHORT WAVE. AS SUCH...THE EXPECTED LIMITED

TEMPORAL THREAT OF DISCRETE CELLS WILL PRECLUDE AN UPGRADE TO HIGH

RISK ATTM...THOUGH THE CATEGORICAL THREAT WILL BE REEVALUATED AT

20Z.

Link to comment
Share on other sites

  • Replies 440
  • Created
  • Last Reply

WAA along and south of the warm front has really facilitated strong convection across MS/AL this morning. Soundings from LCH show that LFC values have risen substantially in the wake of BL saturation while Td's have cooled to the low 60s. This might help curb the tornado threat somewhat as the surface cyclone is moving about an hour faster than what 00Z models like the NAM had been forecasting last night. Basically, the window for substantial atmospheric destabilization in advance of the big round later this afternoon is looking to be somewhat protracted based upon latest events.

I'm not sure what you mean. The dewpoint in Lake Charles is up to 66 at the latest hourly ob. Although dewpoints in the area should remain stagnant or even drop a couple degrees due to boundary layer mixing, the temps should rise well into the mid 70s given the clear skies in the warm sector. The only reason why the LFC was so high on the 12z sounding was because of two reasons: 1) it was taken at 12z, so the boundary layer wasn't well mixed and 2) the mid levels were quite warm at 12z, but this should cool as the trough approaches from the west. If anything, I'm more concerned now given that the warm sector is considerably clearer than I had anticipated yesterday.

Link to comment
Share on other sites

And if my eyes aren't deceiving me each one seems to have some rotation in it according to my radar scope. Quite ominous.

Yes. We saw very similar signatures for the 3 long-lived tornadic supercells that hit northern Illinois on 5 June 2010, when we had a series of these smaller, rotating cells coalesce into larger supercells. There are already signs of that happening at this time, and the environment ahead of them is quite supportive of strong to violent tornadoes.

Link to comment
Share on other sites

BULLETIN - EAS ACTIVATION REQUESTED

TORNADO WARNING

NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX

1039 AM CST TUE DEC 25 2012

THE NATIONAL WEATHER SERVICE IN LEAGUE CITY HAS ISSUED A

* TORNADO WARNING FOR...

EXTREME NORTHEASTERN HARRIS COUNTY IN SOUTHEAST TEXAS...

SOUTHEASTERN MONTGOMERY COUNTY IN SOUTHEAST TEXAS...

NORTHWESTERN LIBERTY COUNTY IN SOUTHEAST TEXAS...

* UNTIL 1115 AM CST

* AT 1037 AM CST...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM

CAPABLE OF PRODUCING A TORNADO. THIS DANGEROUS STORM WAS LOCATED

NEAR ROMAN FOREST...OR 8 MILES NORTHEAST OF KINGWOOD...AND MOVING

EAST AT 55 MPH.

* LOCATIONS IMPACTED INCLUDE...

PATTON VILLAGE...WOODBRANCH...ROMAN FOREST...SPLENDORA...PLUM

GROVE AND DAYTON LAKES.

Link to comment
Share on other sites

I'm not sure what you mean. The dewpoint in Lake Charles is up to 66 at the latest hourly ob. Although dewpoints in the area should remain stagnant or even drop a couple degrees due to boundary layer mixing, the temps should rise well into the mid 70s given the clear skies in the warm sector. The only reason why the LFC was so high on the 12z sounding was because of two reasons: 1) it was taken at 12z, so the boundary layer wasn't well mixed and 2) the mid levels were quite warm at 12z, but this should cool as the trough approaches from the west. If anything, I'm more concerned now given that the warm sector is considerably clearer than I had anticipated yesterday.

You know, you are right, so I should stick with my original thoughts. I am on a learning curve here. :santa: Recent satellite imagery shows very pronounced clearing all over the warm sector from LA into the southern two-thirds of MS, and it does appear to be occurring a bit more rapidly when what I envisioned based upon model data.

I think SPC may have a High Risk at 20Z. (Edit: Dacula beat me to the punch; see below.)

Link to comment
Share on other sites

According to James Spann, SPC is considering a High Risk upgrade this afternoon.

DISCRETE SUPERCELLS CAPABLE OF ALL THREATS OF SEVERE WEATHER

/INCLUDING THE POTENTIAL FOR LONG-TRACKED TORNADOES/ MAY BE POSSIBLE

AS THE AFOREMENTIONED MID-UPPER LEVEL JET APPROACHES...SUBSEQUENTLY

STRENGTHENING DEEP LAYER SHEAR PROFILES AND PROMOTING STRONG

ROTATION. VISIBLE IMAGERY SUGGESTS CLEARING MAY OCCUR OVER PORTIONS

OF SE TX...CNTRL/SRN LA/MS/AL...WHERE THE GREATEST POTENTIAL

SURFACE-BASED DESTABILIZATION AND CONSEQUENTLY TORNADIC POTENTIAL

WILL EXIST LATER THIS MORNING INTO THE AFTERNOON. HOWEVER...IMPLIED

SUBSIDENCE /DEMARCATED BY SIGNIFICANT DRYING ON WV IMAGERY OVER THE

WRN GULF/ MAY VERY TEMPORARILY DELAY THE DEVELOPMENT IN DISCRETE

SUPERCELLS ACROSS THE WARM SECTOR UNTIL FORCING FOR ASCENT QUICKLY

ARRIVES WITH THE E TX SHORT WAVE. AS SUCH...THE EXPECTED LIMITED

TEMPORAL THREAT OF DISCRETE CELLS WILL PRECLUDE AN UPGRADE TO HIGH

RISK ATTM...THOUGH THE CATEGORICAL THREAT WILL BE REEVALUATED AT

20Z.

Link to comment
Share on other sites

mcd2209.gif

MESOSCALE DISCUSSION 2209

NWS STORM PREDICTION CENTER NORMAN OK

1102 AM CST TUE DEC 25 2012

AREAS AFFECTED...SWRN/W-CNTRL/S-CNTRL OK...WRN NORTH TX

CONCERNING...BLIZZARD

VALID 251702Z - 252100Z

SUMMARY...BLIZZARD CONDITIONS ARE DEVELOPING ACROSS

SWRN/W-CNTRL/S-CNTRL OK...AND WILL CONTINUE THROUGH AROUND 22-23Z.

NLY WINDS OF 25-35 MPH WITH FREQUENT GUSTS OF 40-45 MPH WILL COMBINE

WITH SNOWFALL RATES OF 1-1.5 IN/HR TO GENERATE NEAR-ZERO

VISIBILITIES AND WHITEOUT CONDITIONS.

Link to comment
Share on other sites

A lot of damage reports coming in across the HGX forecast area. Many trees down and roofs off buildings mainly N of Metro Houston. I've had S winds gusting to 45+kts for at least 3 hours now.

Yikes, that'll do some damage.

1530 80 LOVELADY HOUSTON TX 3113 9545 LOVELADY FIRECHIEF REPORT WIND GUST OF 80 MPH (HGX)

Link to comment
Share on other sites

URGENT - WINTER WEATHER MESSAGE

NATIONAL WEATHER SERVICE MEMPHIS TN

1110 AM CST TUE DEC 25 2012

...BLIZZARD CONDITIONS EXPECTED TO IMPACT PARTS OF THE MIDSOUTH

FROM LATE TODAY...THROUGH CHRISTMAS NIGHT AND INTO EARLY

WEDNESDAY...

.A STRONG UPPER LEVEL LOW PRESSURE SYSTEM CURRENTLY ACROSS TEXAS

WILL TRACK INTO THE MIDSOUTH BY THIS EVENING. RAIN WILL SPREAD

OVER MOST OF THE MIDSOUTH THIS AFTERNOON...POSSIBLY MIXED WITH

SLEET AND SNOW ACROSS NORTHEAST ARKANSAS AND THE MISSOURI BOOTHEEL.

PRECIPITATION ACROSS NORTHEAST ARKANSAS AND THE MISSOURI BOOTHEEL

WILL CHANGE OVER TO ALL SNOW BY EARLY EVENING. PERIODS OF HEAVY

SNOW WILL BE POSSIBLE DURING THE NIGHT. IN ADDITIONAL TO THE HEAVY

SNOW...STRONG NORTH WINDS GUSTING UP TO 45 MPH ARE

EXPECTED...CAUSING SEVERE REDUCTIONS IN VISIBILITIES...ALONG WITH

BLOWING AND DRIFTING CONDITIONS.

ARZ008-009-017-018-026>028-035-MOZ113-115-TNZ001-002-019-048-

260115-

/O.CON.KMEG.BZ.W.0001.121225T2100Z-121226T1500Z/

RANDOLPH-CLAY-LAWRENCE-GREENE-CRAIGHEAD-POINSETT-MISSISSIPPI-

CROSS-DUNKLIN-PEMISCOT-LAKE-OBION-DYER-LAUDERDALE-

INCLUDING THE CITIES OF...WALNUT RIDGE...PARAGOULD...JONESBORO...

HARRISBURG...BLYTHEVILLE...WYNNE...KENNETT...CARUTHERSVILLE...

UNION CITY...DYERSBURG

1110 AM CST TUE DEC 25 2012

...BLIZZARD WARNING REMAINS IN EFFECT FROM 3 PM THIS AFTERNOON TO

9 AM CST WEDNESDAY...

* VISIBILITIES AT TIMES DOWN TO LESS THAN A QUARTER OF A MILE.

* SNOW ACCUMULATIONS...6 TO 10 INCHES...WITH LOCALLY HIGHER

AMOUNTS.

* TIMING...RAIN WILL CHANGE OVER TO SNOW LATE THIS AFTERNOON AND

INTO THE EARLY EVENING HOURS. SNOW WILL BECOME HEAVY AT TIMES

TONIGHT.

* WINDS...SUSTAINED WINDS AROUND 25 TO 30 MPH WITH GUSTS OF 35

TO 45 MPH.

* IMPACTS...SNOW AND BLOWING SNOW WILL SIGNIFICANTLY REDUCE

VISIBILITIES. TRAVEL WILL BECOME HAZARDOUS.

.PRECAUTIONARY/PREPAREDNESS ACTIONS...

A BLIZZARD WARNING MEANS SEVERE WINTER WEATHER CONDITIONS ARE

EXPECTED OR OCCURRING. FALLING AND BLOWING SNOW WITH STRONG WINDS

AND POOR VISIBILITIES ARE LIKELY. THIS WILL LEAD TO WHITEOUT

CONDITIONS...MAKING TRAVEL EXTREMELY DANGEROUS. DO NOT TRAVEL. IF

YOU MUST TRAVEL...HAVE A WINTER SURVIVAL KIT WITH YOU. IF YOU GET

STRANDED...STAY WITH YOUR VEHICLE.

&&

$$

ARZ036-048-049-058-MSZ001-007-008-010-011-TNZ003-004-020-021-

049>051-088-089-260115-

/O.CON.KMEG.WW.Y.0002.121226T0300Z-121226T1500Z/

CRITTENDEN-ST. FRANCIS-LEE AR-PHILLIPS-DESOTO-TUNICA-TATE-COAHOMA-

QUITMAN-WEAKLEY-HENRY-GIBSON-CARROLL-TIPTON-HAYWOOD-CROCKETT-

SHELBY-FAYETTE-

INCLUDING THE CITIES OF...WEST MEMPHIS...FORREST CITY...HELENA...

SOUTHAVEN...OLIVE BRANCH...TUNICA...CLARKSDALE...MARTIN...

DRESDEN...PARIS...HUMBOLDT...MILAN...HUNTINGDON...COVINGTON...

BARTLETT...GERMANTOWN...COLLIERVILLE...MEMPHIS...MILLINGTON...

SOMERVILLE

1110 AM CST TUE DEC 25 2012

...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 9 PM THIS

EVENING TO 9 AM CST WEDNESDAY...

* SNOW AND SLEET ACCUMULATIONS...SNOW ACCUMULATIONS OF ONE TO

THREE INCHES WITH LOCALLY HIGHER AMOUNTS. A BRIEF MIXTURE OF ICE

PELLETS...WITH ACCUMULATIONS OF LESS THAN A TENTH OF AN INCH

WILL ALSO BE POSSIBLE.

* TIMING...RAIN WILL CHANGE OVER TO SNOW AFTER MIDNIGHT AND

CONTINUE THROUGH EARLY WEDNESDAY MORNING.

* IMPACTS...TRAVEL WILL BECOME HAZARDOUS...ESPECIALLY ON

SECONDARY ROADS BEGINNING LATE THIS EVENING THROUGH TOMORROW

MORNING. GUSTY WINDS UP TO 40 MPH WILL ALSO REDUCE

VISIBILITIES AT TIMES DOWN TO LESS THAN A HALF OF A MILE.

.PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER WEATHER ADVISORY MEANS THAT PERIODS OF SNOW AND SLEET

WILL CAUSE TRAVEL DIFFICULTIES. BE PREPARED FOR SLIPPERY ROADS

AND LIMITED VISIBILITIES FROM BLOWING SNOW. USE CAUTION WHEN

TRAVELING...ESPECIALLY IN OPEN AREAS.

&&

$$

SJM

Link to comment
Share on other sites

Moderate risk for tomorrow in the Carolinas.

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1112 AM CST TUE DEC 25 2012

VALID 261200Z - 271200Z

...THERE IS A MDT RISK OF SVR TSTMS OVER CENTRAL AND ERN PARTS OF

THE CAROLINAS...

...THERE IS A SLGT RISK OF SVR TSTMS FROM NRN/CENTRAL FL AND SRN GA

NWD INTO SRN VA...

...A SIGNIFICANT SEVERE WEATHER EPISODE IS POSSIBLE ON WEDNESDAY

OVER PARTS OF THE CENTRAL AND ERN CAROLINAS...

...SYNOPSIS...

PROGRESSIVE UPPER FLOW PATTERN IS FORECAST TO CONTINUE TOMORROW AS A

VIGOROUS COLD UPPER LOW /CURRENTLY OVER THE SRN PLAINS/ IS FORECAST

TO MOVE RAPIDLY FROM THE TN VALLEY TO THE SRN MIDDLE ATLANTIC REGION

DURING THE PERIOD. VERY LARGE 12 HR 500 MB HEIGHT FALLS OF 180 M

AND STRONG WINDS ALOFT WILL ACCOMPANY THIS SYSTEM...WITH 90-100 KT

500 MB WINDS AND 60-70 KT FLOW AT 850 MB.

AT THE SURFACE...MODELS INDICATE THAT THE PRIMARY LOW WILL DEVELOP

OVER NRN GA AND DEEPEN AS IT MOVES NEWD EAST OF THE

APPALACHIANS...MOVING ACROSS THE NC PIEDMONT DURING THE LATE

AFTERNOON/EVENING AND CONTINUING ACROSS THE DELMARVA REGION LATER AT

NIGHT. A STRONG COLD FRONT EXTENDING SWD FROM THE LOW WILL SURGE

EWD TOWARD THE ATLANTIC COAST AND SEWD ACROSS THE FL

PENINSULA...MOVING OFFSHORE INTO THE ATLANTIC WATERS OVERNIGHT. A

WARM FRONT EXTENDING FROM THE NC COAST SWWD ACROSS CENTRAL GA WILL

GRADUALLY LIFT NWD...EXTENDING FROM NERN NC INTO THE PIEDMONT BY

LATE AFTERNOON. THESE BOUNDARIES AND SURFACE LOW WILL PROVIDE THE

PRIMARY LOW LEVEL FOCUSING MECHANISMS FOR STRONG/SEVERE THUNDERSTORM

DEVELOPMENT.

...CENTRAL/ERN CAROLINAS...

A STRONG/SEVERE BROKEN QLCS WITH EMBEDDED BOW ECHOES AND POSSIBLE

SUPERCELLS/MESO-VORTICES IS EXPECTED TO BE ONGOING AT THE START OF

THE PERIOD...EXTENDING FROM NRN GA SWD INTO THE GULF OF MEXICO SOUTH

OF THE TLH. AS THE AFOREMENTIONED WARM FRONT LIFTS NWD...LOW LEVEL

MOISTURE WILL INCREASE INLAND WITH LOW/MID 60S F SURFACE DEW POINTS

SPREADING INTO THE WARM SECTOR. ALTHOUGH CLOUDS AND AREAS OF

LIGHTER PRECIPITATION WILL INHIBIT DIABATIC HEATING...THE AIR MASS

IS EXPECTED TO DESTABILIZE WITH MLCAPE REACHING 1000 J/KG IN PARTS

OF THE WARM SECTOR. VERY STRONG DYNAMIC FORCING FOR LARGE SCALE

ASCENT WITHIN THE LEFT EXIT REGION OF THE CYCLONIC UPPER LEVEL JET

WILL OVERSPREAD THE WARM SECTOR DURING THE MORNING. THIS WILL

ENHANCE CONVECTIVE STORM INTENSITY WITHIN THE QLCS AND SUPPORT

ADDITIONAL INITIATION OF DISCRETE CELLS AND CLUSTERS IN THE WEAKLY

CAPPED WARM SECTOR.

VERY STRONG DEEP LAYER SHEAR OF 50-70 KT IN THE LOWEST 6 KM WILL BE

SUPPORTIVE OF UPDRAFT ROTATION AND BOWING SEGMENTS CAPABLE OF

PRODUCING MORE WIDESPREAD DAMAGING WIND GUSTS AND POTENTIAL FOR

TORNADOES ALONG THE QLCS. GIVEN THE VERY STRONG LOW LEVEL SHEAR AND

SRH /200-500 M2 PER S2 FOR RIGHT-MOVING SUPERCELLS/ AND EXPECTED

RAPID STORM MOTION...THERE WILL ALSO BE POTENTIAL FOR SEVERAL

LONG-TRACK STRONG TORNADOES ASSOCIATED WITH ANY DISCRETE PERSISTENT

SUPERCELLS THAT MAY FORM THROUGH THE AFTERNOON AND EARLY EVENING.

THE SEVERE THREAT WILL GRADUALLY END FROM THE WEST AS THE LOW AND

COLD FRONT CONTINUE TO MOVE RAPIDLY NEWD/EWD THROUGH THE EVENING

HOURS.

...GA SWD INTO NRN/CENTRAL FL

A THREAT FOR DAMAGING WIND GUSTS AND ISOLATED HAIL WILL EXTEND SWD

FROM PARTS OF SRN/ERN GA INTO NRN/CENTRAL FL AS THE LINE OF

CONVECTION MOVES EWD DURING THE DAY. THE RISK IS EXPECTED TO

GRADUALLY DIMINISH WITH SWD EXTENT AS THE PRIMARY DYNAMIC FORCING

MOVES EWD/NEWD ACROSS THE CAROLINAS AND MIDDLE ATLANTIC REGION.

..WEISS.. 12/25/2012

Link to comment
Share on other sites

Details are very sketchy, but TWC is reporting a fatality from winds (thunderstorm?) in the Houston metro area.

We've already heard of one weather-related fatality in northwest Harris County. It happened around 9:30am in the 17600 block of North Eldridge Parkway. Authorities say a young male driver heading down the street came across a fallen tree, and when he decided to move the broken limbs off the road, another tree snapped and fell on top of him.

http://abclocal.go.com/ktrk/story?section=news/local&id=8931442

Link to comment
Share on other sites

That's a lot of clearing in LA...

And...oh boy...hello dry punch

HOWEVER...IMPLIED

SUBSIDENCE /DEMARCATED BY SIGNIFICANT DRYING ON WV IMAGERY OVER THE

WRN GULF/ MAY VERY TEMPORARILY DELAY THE DEVELOPMENT IN DISCRETE

SUPERCELLS ACROSS THE WARM SECTOR UNTIL FORCING FOR ASCENT QUICKLY

ARRIVES WITH THE E TX SHORT WAVE.

23hvN.png

Link to comment
Share on other sites

HOWEVER...IMPLIED

SUBSIDENCE /DEMARCATED BY SIGNIFICANT DRYING ON WV IMAGERY OVER THE

WRN GULF/ MAY VERY TEMPORARILY DELAY THE DEVELOPMENT IN DISCRETE

SUPERCELLS ACROSS THE WARM SECTOR UNTIL FORCING FOR ASCENT QUICKLY

ARRIVES WITH THE E TX SHORT WAVE.

The storms are linear at this point, the discrete cells ahead of the line are too tightly packed to produce long track tornadoes. HRRR keeps it this way.

I am done rooting for tornadoes.

Link to comment
Share on other sites

Looks like we might have a PDS watch coming...

A NEW TORNADO WATCH WILL BE NEEDED TO REPLACE CURRENT WW 692 PRIOR

TO 19Z...WITH THE POTENTIAL FOR THIS NEW WW TO BE A PDS GIVEN A

SIGNIFICANT INCREASE IN EFFECTIVE SRH THIS AFTERNOON AS THE LLJ

STRENGTHENS ACROSS THE LOWER MS VALLEY.

Link to comment
Share on other sites

mcd2210.gif

MESOSCALE DISCUSSION 2210

NWS STORM PREDICTION CENTER NORMAN OK

1204 PM CST TUE DEC 25 2012

AREAS AFFECTED...E/SE TX AND CENTRAL/SRN LA

CONCERNING...TORNADO WATCH 692...694...

VALID 251804Z - 251930Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 692...694...CONTINUES.

SUMMARY...TORNADO THREAT WILL CONTINUE TO INCREASE ACROSS SE TX INTO

SWRN AND CENTRAL LA ACROSS WW 694...WITH A TORNADO POTENTIAL ALSO

INTO THE FAR SRN EXTENT OF SVR WW 693.

A NEW TORNADO WATCH WILL BE NEEDED TO REPLACE CURRENT WW 692 PRIOR

TO 19Z...WITH THE POTENTIAL FOR THIS NEW WW TO BE A PDS GIVEN A

SIGNIFICANT INCREASE IN EFFECTIVE SRH THIS AFTERNOON AS THE LLJ

STRENGTHENS ACROSS THE LOWER MS VALLEY.

DISCUSSION...LATE THIS MORNING...THERE HAS BEEN AN INCREASE IN CG

LIGHTNING STRIKES ACROSS SE THROUGH EAST CENTRAL TX TO NWRN LA INVOF

A SURFACE LOW NOW LOCATED IN FAR EAST CENTRAL TX /NEAR JASPER TX/.

THIS LIGHTNING AND SIMILAR INCREASE IN REFLECTIVITIES EXTENDED SSWWD

ALONG A DRY LINE/PACIFIC FRONT THROUGH SE TX/UPPER TX COAST /TO THE

N-SW OF THE HOUSTON METRO AREA/. TSTMS /MAINLY ELEVATED/ ALSO

EXTENDED NEWD OF THE SURFACE LOW INTO NWRN LA. THIS INCREASE IN TSTM

DEVELOPMENT IS LIKELY INDICATIVE OF THE ARRIVAL OF STRONG FORCING

FOR ASCENT WITHIN THE EXIT REGION OF A 90-100 KT MIDLEVEL JET

ACCOMPANYING THE POWERFUL SRN PLAINS SHORTWAVE TROUGH. SUBSEQUENT

AND EXPECTED STRENGTHENING OF A SSWLY LLJ WAS EVIDENT OVER

SWRN-CENTRAL LA PER 17Z LCH WSR-88D VAD SHOWING 60 KT AT 1 KM AGL.

THE STRONG VERTICALLY VEERING WINDS HAVE GREATLY ENHANCED THE

EFFECTIVE SRH VALUES UP TO 400-600 M2/S2 TO SUPPORT AN INCREASED

TORNADO THREAT...EXPECTED TO SPREAD EWD THIS AFTERNOON INTO THE SRN

PART OF THE LOWER MS VALLEY...WITHIN THE WARM SECTOR.

LATE MORNING SURFACE ANALYSES SHOWED THE LOW HAS CONTINUED TO DEEPEN

AND AT 17Z WAS LOCATED INVOF JASPER TX. A WARM FRONT HAS MOVED

STEADILY NWD AND EXTENDED EWD THROUGH CENTRAL LA...SRN MS /N OF

KMCB/...TO THE N OF KMOB AND INTO THE WRN FL PANHANDLE. GIVEN THE

LOCATION OF THE WARM FRONT...THE SRN EXTENT OF SVR WATCH 693 WILL

ALSO HAVE A TORNADO POTENTIAL AS STORMS WILL BE SFC-BASED OR NEAR

SFC-BASED.

MEANWHILE...THE WARM FRONT HAS MOVED N OF WW 692...THOUGH THE WARM

SECTOR ACROSS THIS WW HAS ONLY SLOWLY DESTABILIZED THUS FAR DUE TO

THE MIXING RELATED DECREASE IN THE DEWPOINTS. 18Z SLIDELL SPECIAL

SOUNDING INDICATED AN INVERSION LOCATED BETWEEN 700-800 MB AND THIS

SHOULD CONTINUE TO INHIBIT DEEPER CU DEVELOPMENT UNTIL THE ARRIVAL

OF GREATER ASCENT WITH THE EXIT REGION OF THE IMMEDIATELY UPSTREAM

MIDLEVEL JET. SOME VEERING OF LOW LEVEL WINDS ACROSS SWRN LA SHOULD

ADVECT RICHER MOISTURE INTO SERN LA/SRN MS SUPPORTING STRONGER

DESTABILIZATION TO SUPPORT AN ENVIRONMENT FAVORABLE FOR

SUSTAINED...DEEP UPDRAFTS.

..PETERS/EDWARDS.. 12/25/2012

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.

×
×
  • Create New...