Flash Flood and Hail in Mississippi, May 30 to 31, 2012

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE JACKSON MS
1115 AM CDT WED MAY 30 2012

...SEVERE STORMS POSSIBLE THIS AFTERNOON WITH AN ADDITIONAL RISK LATER ON
THURSDAY...

.UPDATE...LATEST SATELLITE IMAGERY SHOWS AN OUTFLOW BOUNDARY
ASSOCIATED WITH AN MCV...WHICH CAME FROM SOME CONVECTION IN THE
SOUTHERN PLAINS OVERNIGHT. IT WAS MOVING TOWARD THE MS RIVER OVER
NORTHEAST LOUISIANA. ALSO A WEAK SURFACE BOUNDARY WAS NOTED ACROSS
THE NORTHWEST DELTA REGION. THESE FEATURES WILL HELP TO PROVIDE A
LOW LEVEL MECHANISM  FOR SOME POSSIBLE SEVERE WEATHER ACROSS THE
REGION FOR THIS AFTERNOON. HIGH RES MODELS FOCUS STORMS SPREADING
ACROSS THE REGION FROM THE WEST NORTHWEST FOR THIS AFTERNOON. ALSO A
SERIES OF WEAK DISTURBANCES WAS MOVING THROUGH THE SOUTHERN STREAM
FROM THE SOUTHERN PLAINS. UPPER AIR ANALYSIS SHOWS AN AREA OF
DIVERGENCE ALOFT MOVING TOWARD THE REGION FROM THE SOUTHERN PLAINS
WITH SOME APPROACHING SUBTROPICAL JET ENERGY. AT THIS TIME AREA
RADARS WERE SHOWS SOME ISOLATED TO SCATTERED ACTIVITY FROM ARK TO
NORTHEAST TEXAS. THE LOW LEVEL LOOKED PRETTY CAPPED THIS MORNING IN
UPPER AIR AND SATELLITE IMAGERY FOR MOST OF THE REGION. AREA
SOUNDINGS WERE PRETTY DRY COMPARED TO YESTERDAY. LOW LEVEL FLOW WAS
RATHER WEAK WITH MIDLEVEL FLOW AROUND 15 TO 20 KNOTS AND UPPER WEST
NORTHWEST FLOW AT 30 TO 35 KNOTS. CAPES AT JAN WERE OVER 3000.
DCAPES WERE OVER 1000. SO WITH THIS IN MIND HAVE DELAY THE START OF
THE CONVECTION IN THE GRIDS BY LOWERING THE POPS FOR LATE THIS
MORNING...BUT KEPT THE SAME DECENT POPS FOR THIS AFTERNOON. THE
PRIME TIME FOR CONVECTION STILL LOOKS TO BE BETWEEN NOON AND 7 PM.
MAIN RISK WILL CONTINUE TO HAIL AND DAMAGING WINDS. CURRENT HIGHS
STILL LOOK TO BE ON TRACK./17/

./PREVIOUS DISCUSSION...407 AM CDT WED MAY 30 2012
SHORT TERM...FORECAST FOCUS WILL BE ON CONVECTIVE POTENTIAL TODAY
AND THEN AGAIN LATER THU-THU NGT AS THE MAIN SYSTEM AND STRONG COLD
FRONT MOVE THROUGH THE REGION.

MAIN PLAYERS TODAY WILL BE THE STALLING FRONT OVER THE N/NE CWA AND
THE S/WV(MCV) THAT MOVES E/SE INTO THE AREA FROM THE SOUTHERN PLAINS
COMPLEX. ALL THE LATEST MODEL DATA SHOW THE SLOW MOVING SFC FRONT
JUST N/NE OF THE CWA MAKING SOME LOW PROGRESS EARLY TODAY AND
STALLING OVER A PORTION OF THE AREA. WITH MORE OF A NE PUSH TO THE
LOW LEVEL FLOW...THE STALLING FRONT WILL TAKE AN INTERESTING
ORIENTATION WITH A MUCH MORE PRONOUNCED SE SAG OVER THE NE/E-CENTRAL
PART OF THE CWA. WITH MORE OF THIS BOUNDARY INTO THE CWA...LOOK FOR
BETTER LOW LEVEL CONVERGENCE ASSOCIATED WITH THIS FEATURE. THE OTHER
MAJOR PLAYER IS THE REMNANT MCV THAT WILL MOVE THROUGH THE CWA FROM
THE CURRENT SOUTHERN PLAINS STORM COMPLEX. LOOK FOR THE COMBINATION
OF THESE FEATURES TO SUPPORT A MORE FAVORABLE SETUP OVER THE CWA FOR
STORMS TODAY. THE GLOBAL MODELS INDICATE THESE SUCH FEATURES BUT
OFFER DIFFERING SOLUTIONS IN HOW PRECIP DEVELOPS. WHAT GUID IS MOST
CONSISTENT AND REPRESENTS THE MASS FIELDS IN ITS QPF OUTPUT IS THE
HI-RES MODELS. ALL FOUR (SPC WRF/NSSL WRF/NMM/ARW NCEP WRF'S) ARE IN
SOLID AGREEMENT ON CONVECTIVE POTENTIAL TODAY AND DEVELOP QUITE A
BIT OF STORMS OVER THE CWA. THIS MULTI CONSENSUS OUTPUT MAKES SENSE
AND WILL BE THE PRIMARY BASIS FOR THE NEXT 12-24 HRS OF THE FORECAST.

ALL MODELS CONTINUE TO SHOW COOLING ALOFT AND LINGERING LOW LEVEL
WARMTH TODAY. THIS WILL RESULT IN VERY STEEP LAPSE RATES WITH 29-30
VERTICAL TOTALS. THIS THERMO SETUP WILL YIELD AN UNSTABLE
ENVIRONMENT AS TEMPS RISE TO THE LOWER 90S AND COMBINE WITH
MID/UPPER 60S SFC DEWPTS. LOOK FOR A RANGE OF 2000-3000 J/KG OF
ML/SBCAPE WITH LI'S (-9 TO -12) SUPPORTING ROBUST UPDRAFTS AS MID
LEVEL FORCING INCREASES FOR AFTERNOON. LOW LEVEL FLOW BELOW 700MB
WILL BE WEAK BUT STRONGER MID/UPPER FLOW WILL EXIST IN RESPONSE TO
THE S/WV. MID LEVEL FLOW OF 20-25KTS WILL BE POSSIBLE AND HIGHER
VALUES ARE NOT OUT OF THE QUESTION DEPENDING ON INFLUENCES OF THE
MCV. LIMITATIONS ARE ANY ENHANCED CAPPING AND LINGERING DRY AIR
WHICH WAS AROUND YESTERDAY AND SUPPRESSED EVEN CLOUD DEVELOPMENT.
OVERALL...LOOK FOR A FAIRLY EVEN MIX OF SVR HAIL AND DAMAGING WIND
GUSTS BASED OFF THE MULTI-CELL APPEARANCE OF THE HI-RES CONVECTIVE
STORM MODE. DMG WIND COULD DOMINATE IF STRONGER FLOW DEVELOPS ALOFT
AND A WELL DEVELOPED COLD POOL GETS GOING. AS FOR HAIL...QUARTER TO
GOLFBALL SIZE FITS THE THERMO SETUP WITH A FEW LARGER STONES
POSSIBLE IF THINGS SETUP JUST RIGHT. AS FOR TIMING...THINGS COULD
GET GOING AS EARLY AS 11AM BUT THE MAIN TIMEFRAME LOOKS TO BE
BETWEEN NOON AND 7PM.

AS FOR FORECAST SPECIFICS...GUID POPS WERE WAY TOO LOW AND VALUES
WERE SIGNIFICANTLY INCREASED. POPS WILL BE IN THE 40-60% RANGE WHICH
I FEEL IS A MUCH BETTER REPRESENTATION OF WHAT'S EXPECTED. GUID HIGH
TEMPS WERE DECENT AND FIT THE TREND OF A QUICK WARMUP WITH THE UPPER
END JUST A TAD LESS THAN PREV DAYS. AS FOR TONIGHT...HAVE LOWERED
POPS ACROSS THE N HALF DUE TO EXPECTED EARLY START TO THE STORMS
TODAY. WHILE SOME LOW END CHANCES WILL EXIST TONIGHT...MOST OF THIS
PERIOD WILL BE IN THE LULL BEFORE ACTIVITY INCREASES FOR THU
AFTERNOON.

FOR THU-THU NGT...MODELS CONTINUE TO BE IN DECENT AGREEMENT ON THE
POTENT UPPER TROUGH AND STRONG LATE SEASON COLD FRONT TO MOVE
THROUGH THE CWA. STORM EVOLUTION IS NOT AS CLEAR DUE TO THE COMPLEX
EVOLUTION OF THE NEAR TERM STORM SYSTEMS. HOWEVER...CONDITIONS WILL
EXIST FOR MORE STORMS DUE TO INCREASING MOISTURE AND STRONG LIFT.
INCREASING WIND FIELDS WILL ALSO ADD TO THE SITUATION AND AS
EVERYTHING COMBINES...MORE SEVERE STORMS WILL BE POSSIBLE. AT THIS
POINT...LATE THU AFTERNOON AND EVENING SEEM TO BE THE MAIN TIME FOR
THE MOST ROBUST STORMS AND GREATEST COVERAGE OF STORMS. DAMAGING
WINDS AND HAIL WILL BE THE PRIMARY RISK. HOWEVER...WIND SHEAR WILL
INCREASE THU NGT AND THERE COULD BE A PERIOD WHERE A TORNADO OR TWO
MAY BE POSSIBLE. JUST SOMETHING TO KEEP AN EYE ON. /CME/

.LONG TERM... (FRIDAY THROUGH WEDNESDAY)
THE LONG TERM PORTION OF THE FORECAST WILL FEATURE A BRIEF BREAK
FROM ABOVE NORMAL TEMPS FRIDAY INTO SATURDAY...FOLLOWED BY
MODERATING CONDITIONS FOR THE LATE WEEKEND INTO EARLY NEXT WEEK.

LATEST GUIDANCE HAS SPED UP THE TIMING OF THE COLD FRONT...WITH THE
BOUNDARY PUSHING EAST OF THE CWA BY DAYBREAK FRIDAY AND LINGERING
SHOWER ACTIVITY MOVING OUT OF THE AREA BEFORE NOON. THE ASSOCIATED
UPPER TROUGH WILL SHIFT EASTWARD AND SET UP SHOP OVER THE ATLANTIC
SEABOARD OVER THE WEEKEND AND INTO NEXT WEEK...WITH UPPER RIDGING
BUILDING OVER THE GREAT PLAINS. THIS WILL PLACE THE AREA IN
NORTHWEST FLOW ALOFT. UNFORTUNATELY...OR FORTUNATELY DEPENDING UPON
ONES PERSPECTIVE...THE SURFACE HIGH PRESSURE AXIS WILL HAVE ALREADY
SHIFTED EAST THE REGION BY LATE SATURDAY. THUS THE RESPITE FROM
SUMMERLIKE TEMPERATURES WILL BE RATHER BRIEF AS RETURN FLOW
COMMENCES LATE SATURDAY/SUNDAY.

THE HIGH CENTER WILL REMAIN SITUATED OVER THE EASTERN GULF THROUGH
NEXT WEEK...WITH PWATS RETURNING TO AROUND 1.5 INCHES AS EARLY AS
SUNDAY. AS UPPER DISTURBANCES TRAVERSE THE REGION IN NORTHWESTERLY
FLOW...ISOLATED CONVECTION WILL BE POSSIBLE ALONG THE PERIPHERY OF
THE SURFACE RIDGE. 00Z GUIDANCE INDICATES ISOLATED RAIN CHANCES WILL
INITIALLY BE CONFINED TO NORTHERN SECTIONS OF THE CWA...WITH BETTER
CHANCES ACROSS THE REMAINDER OF THE AREA BY WEDNESDAY. MEANWHILE
DAYTIME HIGH TEMPS IN THE LOW TO MID 90S WILL MAKE A RETURN.

WITH RESPECT TO FORECAST DETAILS...TEMPERED MEX POPS AND TENDED
TOWARD ECMWF FOR LATE THIS WEEKEND AND EARLY NEXT WEEK. GIVEN THE
INFLUENCE OF NWLY FLOW ALOFT...MORE THAN ONE ROUND OF PRECIPITATION
WILL BE POSSIBLE IN THIS TIME PERIOD...BUT NOT PARTICULARLY
CONFIDENT IN GOING AS HIGH AS THE GFS IS FOR EACH PERIOD AS IT IS
DIFFICULT TO PIN DOWN A FAVORED TIME FRAME THIS FAR OUT.
OTHERWISE...NO SIGNIFICANT ADJUSTMENTS WERE MADE TO MEX TEMPS DURING
THE PERIOD. /DL/

&&

AVIATION...VFR CONDITIONS HAVE RESUMED ACROSS THE AREA WITH SKC
ONGOING ACROSS TAF SITES. CONVECTION EXPECTED TO DEVELOP THIS AFTN
AND PUSH GENERALLY E/SE ACROSS THE AREA. TIMING LOOKS TO BE AS EARLY
AS 17Z. STORMS COULD BRING GUSTY WINDS AND HAIL ALONG WITH MVFR TO
IFR VIS RESTRICTIONS. AFTER STORMS PASS(LIKELY AFTER 00-02Z)...VFR
CONDITIONS EXPECTED TO PREVAIL FOR NEARLY ALL OF THE NIGHT PERIOD.
/28/

&&

.PRELIMINARY POINT TEMPS/POPS...
JACKSON       94  69  88  66 /  62  30  48  73
MERIDIAN      95  68  89  67 /  48  25  33  69
VICKSBURG     93  69  87  61 /  59  31  56  71
HATTIESBURG   96  71  89  71 /  35  20  32  49
NATCHEZ       91  71  86  65 /  52  26  45  65
GREENVILLE    94  70  88  61 /  61  28  71  68
GREENWOOD     94  68  89  62 /  59  31  65  73

&&

.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&

17/28/CME/DL

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE JACKSON MS
430 AM CDT WED MAY 30 2012

ARZ074-075-LAZ007>009-015-016-023>026-MSZ018-019-025>066-072>074-
310930-
ASHLEY-CHICOT-MOREHOUSE-WEST CARROLL-EAST CARROLL-RICHLAND-
MADISON LA-FRANKLIN LA-CATAHOULA-TENSAS-CONCORDIA-BOLIVAR-
SUNFLOWER-LEFLORE-GRENADA-CARROLL-MONTGOMERY-WEBSTER-CLAY-LOWNDES-
CHOCTAW-OKTIBBEHA-WASHINGTON-HUMPHREYS-HOLMES-ATTALA-WINSTON-
NOXUBEE-ISSAQUENA-SHARKEY-YAZOO-MADISON MS-LEAKE-NESHOBA-KEMPER-
WARREN-HINDS-RANKIN-SCOTT-NEWTON-LAUDERDALE-CLAIBORNE-COPIAH-
SIMPSON-SMITH-JASPER-CLARKE-JEFFERSON-ADAMS-FRANKLIN MS-LINCOLN-
LAWRENCE-JEFFERSON DAVIS-COVINGTON-JONES-MARION-LAMAR-FORREST-
430 AM CDT WED MAY 30 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL MISSISSIPPI...
NORTHEAST LOUISIANA...AND EXTREME SOUTHEAST ARKANSAS.

.DAY ONE...TODAY AND TONIGHT

SEVERE STORMS WILL BE POSSIBLE TODAY AS A DISTURBANCE MOVING OUT OF
SOUTHERN ARKANSAS COMBINES WITH A STALLED BOUNDARY. THE MAIN TIME FOR
THIS SEVERE ACTIVITY WILL BE FROM AROUND MIDDAY TO 7 PM. THE MAIN
RISK WILL BE FOR DAMAGING WIND GUSTS AND HAIL UP TO GOLF BALL SIZE.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

SEVERE STORMS WILL AGAIN BE POSSIBLE LATE THURSDAY AFTERNOON INTO
THURSDAY NIGHT AS A POTENT DISTURBANCE AND STRONG COLD FRONT MOVE
THROUGH THE REGION. THE PRIMARY RISKS WILL BE DAMAGING WIND GUSTS AND
QUARTER SIZED HAIL OR LARGER. ONE OR TWO TORNADOES CAN NOT BE RULED
OUT FOR THURSDAY NIGHT AS WIND SHEAR INCREASES. LOCALLY HEAVY
RAINFALL WILL ALSO BE POSSIBLE...ESPECIALLY WHERE STORMS MOVE
REPEATEDLY OVER THE SAME AREAS.

.SPOTTER CALL TO ACTION STATEMENT...
THE ACTIVATION OF STORM SPOTTERS...HAM RADIO OPERATORS...AND
EMERGENCY MANAGEMENT PERSONNEL IN SUPPORT OF SEVERE WEATHER
OPERATIONS WILL LIKELY BE NEEDED TODAY AND AGAIN LATE THURSDAY INTO
THURSDAY NIGHT.

FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT
WWW.SRH.NOAA.GOV/JAN.

CME

ARZ074-075-MSZ018-034-301730-
ASHLEY AR-CHICOT AR-WASHINGTON MS-BOLIVAR MS-
1149 AM CDT WED MAY 30 2012

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE JACKSON MS
1149 AM CDT WED MAY 30 2012

A LINE OF STRONG THUNDERSTORMS CAPABLE OF PRODUCING PENNY TO NICKEL
SIZE HAIL AND 40 TO 50 MPH WINDS WAS LOCATED ACROSS EASTERN ARKANSAS
AT 1147 AM CDT...MOVING EAST AT 35 MPH. THIS LINE OF STORMS IS
SENDING AN OUTFLOW BOUNDARY TO THE EAST SOUTHEAST. THIS WILL HELP TO
GENERATE ADDITIONAL STORMS ACROSS THE NORTHWEST DELTA OF MISSISSIPPI
AND PORTIONS OF EXTREME SOUTHEAST ARKANSAS THROUGH THE EARLY
AFTERNOON. GIVEN SUFFICIENT DAYTIME HEATING...STORMS THAT DEVELOP
WILL ALSO BE CAPABLE OF PRODUCING 40 TO 50 MPH WINDS AND HAIL TO THE
SIZE OF NICKELS.

VERY HEAVY RAIN IS ALSO POSSIBLE WITH THESE STORMS.

PEOPLE IN BOLIVAR...WASHINGTON...CHICOT AND ASHLEY COUNTIES SHOULD
MONITOR THESE STORMS CLOSELY.

LAT...LON 3411 9067 3353 9078 3311 9071 3302 9116
      3303 9211 3320 9214 3341 9199 3339 9147
      3357 9145 3352 9126 3360 9114 3371 9121
      3368 9104 3373 9115 3378 9099 3397 9110
      3396 9098 3409 9088 3412 9096
TIME...MOT...LOC 1647Z 267DEG 32KT 3444 9119 3399 9137
          3387 9187

JC