National Weather Service Raw Text Product

Displaying AFOS PIL: AFDJAN Received: 2012-12-25 22:51 UTC


851 
FXUS64 KJAN 252251
AFDJAN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
451 PM CST TUE DEC 25 2012

.DISCUSSION..

...SEVERE WEATHER OUTBREAK ONGOING THIS AFTERNOON INTO EARLY
EVENING...

TORNADIC SUPERCELLS AND A DANGEROUS ORGANIZED SQUALL LINE 
ARE CURRENTLY ONGOING EAST AND SOUTHEAST MISSISSIPPI. NUMEROUS
DAMAGE REPORTS HAVE BEEN RECEIVED IN ASSOCIATION WITH THIS ACTIVITY
AS IT RACES TO THE EAST/NORTHEAST AT 60MPH. STRONG TORNADOES REMAIN
POSSIBLE IN MORE DISCRETE CELLS AHEAD AND ALONG THE SOUTHERN FLANK OF
THE SQUALL LINE ACROSS SE MS THROUGH THE EARLY EVENING GIVEN ~1000
J/KG SBCAPE AND 0-1KM EFFECTIVE SRH VALUES 400-500 M2/S2 IN PLACE PER
SPC MESOANALYSIS FROM A VIGOROUS AND NEGATIVELY TILTED S/WV TROUGH
OVER THE LOWER MS VALLEY.

FOR THE EXPECTED CONVECTIVE EVOLUTION THIS AFTN INTO TONIGHT...

WARM FRONTAL PLACEMENT EXTENDS JUST SOUTH OF MERIDIAN MISSISSIPPI 
CURVING WESTWARD TOWARDS CRYSTAL SPRINGS WITH A QUICKLY ADVANCING 
COLD FRONT TO THE WEST. THE SURFACE LOW IS CURRENTLY NEAR
ALEXANDRIA, LA AND IS EXPECTED TO SHIFT NE ACROSS CENTRAL MS AND NE
MS THROUGH TONIGHT POSSIBLY PULLING THE WARM FRONT NORTH TO MERIDIAN
AND EXPANDING THE WARM SECTOR CAUSING TO PROLONG THE TORNADIC AND
SEVERE WEATHER RISK IN EAST MS THROUGH EARLY EVENING. CONTINUED RISKS
OF STRONG TORNADOES ACROSS FAR E/SE MS, STRAIGHT LINE WINDS, AND HIGH
RAINFALL RATES WILL OCCUR IN THIS ENVIRONMENT. IT APPEARS THE ~90KT
AVERAGE H7-H5 JET ON THE BACK SIDE OF THE SQUALL LINE SHOULD PROVIDE
ENOUGH MOMENTUM TO PUSH SQUALL LINE CLEAR OF NORTHERN PINE BELT
REGION BY THIS TIME WITH DRY SLOT INTRUSION ON THE BACKSIDE. ADDITIONAL
STORMS AND SEVERE HAZARDS RISK WILL STILL CONTINUE ACROSS FAR SE/COASTAL
MS THROUGH MID EVENING AS WELL. IT IS NOT OUTSIDE OF THE REALM OF
POSSIBILITIES THAT ADDITIONAL STORMS COULD DEVELOP BEHIND THE LINE
GIVEN SUCH STRONG FORCING. A WIND AND HAIL RISK COULD BE ASSOCIATED
WITH THESE STORMS BUT TORNADO RIK WILL BE REDUCED AS SHEAR WILL BE
DECREASING. MOMENTUM OF OVERALL SQUALL LINE AS INCREASED FROM THIS
MORNING AND FLASH FLOODING CONCERN IS DECREASING BUT STILL POSSIBLE AS
THE EVENING PROGRESSES. HAVE BEGUN TO CLEAR TORNADO WATCH BEHIND THE
COLD FRONT.

ON THE NORTHERN SIDE OF THIS SYSTEM FOR TONIGHT...WRAP AROUND 
MOISTURE AND COLD SURFACE TEMPERATURES ACROSS NE MS AND SE AR WILL 
ALLOW FOR LIGHT RAIN TO CHANGE OVER TO A RAIN/SNOW MIX AND THEN 
ALL SNOW ACROSS THE NW PORTIONS OF THE ARKLAMISS DELTA. SNOW MAY BE
MODERATE AT TIMES AND ACCUMULATE ON ELEVATED SURFACES. ACCUMULATIONS
ARE NOT EXPECTED TO BE MORE THAN ONE HALF OF ONE INCH ACROSS PORTIONS
OF THE DELTA. SOME SNOW FLURRIES COULD BE POSSIBLE ALONG AND NORTH OF
HIGHWAY 82 FARTHER EAST THROUGH EARLY WEDNESDAY MORNING AS THE COLD
AIR SPREADS EAST. SNOW SHOWERS/FLURRIES WILL COME TO AN END WEDNESDAY
MORNING AS SYSTEM PULLS OFF TO THE NORTHEAST. 

FOR THURSDAY...COLD AIRMASS AND HIGH PRESSURE WILL SETTLE INTO THE 
REGION THURSDAY. LOWS THURSDAY MORNING WILL BE QUITE COLD WITH 
WIDESPREAD MID 20 READINGS EXPECTED. HIGHS WILL STRUGGLE TO REACH 
INTO THE UPPER 40S AND LOW 50S THURSDAY AFTN. SLOW MODERATION WILL 
TAKE PLACE GOING INTO FRIDAY MORNING AS ANOTHER H5 S/WV AND SFC LOW 
AID IN RETURN SE FLOW AND WEAK ISENTROPIC UPGLIDE TO ALLOW FOR 
SLIGHT CHANCE RAIN SHOWERS FRIDAY AFTN. /ALLEN/


&&

.AVIATION...SEVERE SQUALL LINE MAKING ITS WAY THROUGH EASTERN MISSISSIPPI
AT THIS TIME THIS WILL IMPACT KMEI/KNMM WITH WIND GUSTS OF 50-60 KT,
HEAVY DOWNPOURS, AND HIGH TURBULENCE. ADDITIONAL STRONG STORMS ARE
HEADING TOWARDS KHBG WITH POSSIBLE TORNADIC CIRCULATIONS THROUGH
25/2330Z. SQUALL LINE AND IMPACTFUL WEATHER WILL CLEAR EASTERN TAF
SITES THROUGH 26/00-01Z. STRONG WINDS BEHIND THE COLD FRONT WILL
CONTINUE THROUGH MUCH OF THE EVENING FROM THE WEST AT 20 KT WITH
GUSTS TO 30 KTS AT TIMES. MVFR/IFR CONDS WILL CONTINUE ACROSS NRN
SITES THROUGH THE OVRNGT AS LIGHT RAIN CHANGES OVER TO SNOW. SOME
LIGHT ACCUMULATIONS CAN BE EXPECTED ON ELEVATED SURFACES. WINDS WILL
REDUCE THROUGH THE DAY WEDNESDAY BUT LOW MVFR/IFR CIGS WILL HANG ON
ACROSS N/CNTRL AREAS. /ALLEN/


&&

.PRELIMINARY POINT TEMPS/POPS...
JACKSON       35  43  25  49 /  73   3   0   3 
MERIDIAN      38  45  27  51 /  95   5   0   3 
VICKSBURG     34  42  25  47 /  51   2   0   3 
HATTIESBURG   35  50  28  52 /  90   4   0   4 
NATCHEZ       34  43  25  49 /  30   2   0   3 
GREENVILLE    31  41  25  43 /  95   9   0   3 
GREENWOOD     34  40  24  46 /  95  10   0   3 

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...FLASH FLOOD WATCH UNTIL MIDNIGHT CST TONIGHT FOR MSZ029>033-
     037>039-043>046-048>052-054>058-062>066-072>074.

     WIND ADVISORY UNTIL 6 AM CST WEDNESDAY FOR MSZ018-019-025>027-
     034>036-040>042-047-053-059-060.

LA...WIND ADVISORY UNTIL 6 AM CST WEDNESDAY FOR LAZ007>009-015-016-
     023>026.

AR...WIND ADVISORY UNTIL 6 AM CST WEDNESDAY FOR ARZ074-075.

&&

$$

ALLEN