Special Weather Statement, NWS Jackson, MS

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
1117 AM CDT MON SEP 2 2013

.UPDATE...

HAVE MADE A FEW MORE CHANGES SINCE THE EARLIER UPDATE. THE MOST
SIGNIFICANT UPDATE WAS TO REMOVE THE RISK FOR SEVERE STORMS ALONG
THE HIGHWAY 82 CORRIDOR IN THE GRAPHICS/HWO FOR THIS AFTERNOON/
EVENING. HAVE ALSO SHIFTED BETTER NEAR TERM POPS FARTHER SOUTH AND
CUT BACK ON TODAY'S TEMPERATURES A LITTLE MORE IN CURRENT RAIN AREA.

THE COMPLEX OF SHOWERS/THUNDERSTORMS ACROSS NORTHWEST PORTIONS OF
THE ARKLAMISS HAS DIMINISHED SOME...AND CLOUDS/RAIN ARE KEEP THE
AIRMASS MORE STABLE...THUS LIMITING ANY CONCERN FOR SEVERE STORMS.
HOWEVER...CONTINUED REGENERATION OF CONVECTION ON THE UPSTREAM SIDE
OF THE COMPLEX HAS RAISED SOME CONCERN FOR HEAVY RAINFALL AND MINOR
FLOODING IN THE BOLIVAR/SUNFLOWER COUNTY AREA FOR THE NEXT HOUR OR SO
AND WE ARE MONITORING THIS FOR THE NEAR TERM.

OTHERWISE...SHALLOW OUTFLOW FROM THIS COMPLEX IS MOVING SOUTH WITHOUT
DEEP CONVECTIVE DEVELOPMENT IN THE CAPPED AIRMASS. WITH CONTINUED
DAYTIME HEATING AND DESTABILIZATION...THE RISK FOR STORMS TO DEVELOP
WILL INCREASE ALONG THE BOUNDARY AS IT STALLS SOUTH AND EAST OF THE
CURRENT COMPLEX...BUT THE MOST RECENT HRRR/WRF GUIDANCE CONTINUE TO
BE BEARISH WITH TSTM DEVELOPMENT LATER THIS AFTERNOON/EVENING...SO
HAVE NOT RAISED POPS VERY MUCH. A FEW STRONG PULSE-TYPE STORMS WILL
BE POSSIBLE IF STORMS CAN DEVELOP IN AREAS THAT RECEIVE THE GREATEST
HEATING...ESPECIALLY ALONG AND NORTH OF THE I-20 CORRIDOR. /EC/

&&

.PREV DISCUSSION... /ISSUED 902 AM CDT MON SEP 2 2013/

UPDATE...

A COMPLEX OF SHOWERS/THUNDERSTORMS AFFECTING THE HIGHWAY 82
CORRIDOR...ESPECIALLY IN THE DELTA REGION IS BRINGING HIGH COVERAGE
OF RAINFALL AND HAVE INCREASED POPS TO REFLECT THIS. THE EXPECTATION
IS THAT THIS COMPLEX WILL DIMINISH AS IT MOVES SOUTHEAST INTO A MORE
STABLE MID LEVEL ENVIRONMENT LATER THIS MORNING AND EARLY AFTERNOON.
WITH STRONG AFTERNOON HEATING...STORMS COULD ERUPT ALONG ANY
DIFFERENTIAL/OUTFLOW BOUNDARIES PRODUCED BY THIS COMPLEX...HOWEVER
THE HRRR AND ASSORTMENT OF WRF GUIDANCE ARE STINGY WITH ADDITIONAL
CONVECTIVE DEVELOPMENT LATER THIS AFTN. SO CONFIDENCE IN CONVECTIVE
BEHAVIOR/EVOLUTION TODAY IS LOWER THAN USUAL. /EC/

PREV DISCUSSION... /ISSUED 405 AM CDT MON SEP 2 2013/

SHORT TERM...TODAY THROUGH TUESDAY NIGHT...UPPER RIDGING THAT HAS
BEEN PRESENT OVER OUR REGION THIS WEEKEND WILL CONTINUE TO
RETROGRADE TO THE WEST. IN ADDITION...AN UPPER TROUGH WILL BE
SITUATED ACROSS THE OHIO VALLEY/EASTERN THIRD OF THE UNITED STATES.
THIS WILL LEAVE THE ARKLAMISS REGION BETWEEN THESE TWO UPPER LEVEL
FEATURES AND GENERALLY UNDER NORTHWEST FLOW ALOFT. THIS WILL HELP TO
BRING A SHORTWAVE TROUGH INTO OUR REGION TODAY AHEAD OF A FRONTAL
BOUNDARY. THIS TROUGH LOOKS TO BE RESPONSIBLE FOR THE CONVECTION
CONTINUING ACROSS PORTIONS OF THE MID SOUTH EARLY THIS MORNING.
MODELS INDICATE THAT CONVECTION SHOULD CONTINUE TO DEVELOP THROUGH
THE DAY IN ASSOCIATION WITH THIS SHORTWAVE TROUGH...THE APPROACHING
FRONTAL BOUNDARY...AND LEFTOVER MESOSCALE OUTFLOW BOUNDARIES PRESENT
ACROSS THE AREA. GIVEN COOL MIDLEVEL TEMPERATURES AROUND -6 TO -8C
PRESENT ACROSS THE REGION LEADING TO VERTICAL TOTALS AROUND
28-29C...AMPLE MOISTURE...AND SUFFICIENT DAYTIME HEATING...
CONVECTION WILL INCREASE LATER THIS AFTERNOON ITO THE EVENING. SOME
OF THE STORMS COULD BE SEVERE GIVEN THE BETTER LAPSE RATES AND WILL
CONTINUE TO ADVERTISE THIS POTENTIAL...ESPECIALLY GIVEN THE LABOR
DAY HOLIDAY. THE BEST CONDITIONS APPEAR TO BE NORTH OF I-20 AND
ESPECIALLY NORTH OF HIGHWAY 82 CORRIDOR.

WITH THE FRONTAL BOUNDARY LINGERING ACROSS THE REGION...SHOWERS AND
STORMS WILL LINGER THROUGH THE NIGHT AND INTO TUESDAY ALONG AND
SOUTH OF THE FRONT. BEHIND THE FRONT...DRIER AIR WILL BEING TO
FILTER INTO THE REGION ON TUESDAY. THIS...ALONG WITH COOLER LOW
LEVEL TEMPERATURES...WILL HELP TO MAKE FOR A RATHER PLEASANT DAY ON
TUESDAY FOR LOCATIONS ESPECIALLY NORTH OF I-20/HIGHWAY 82. BY 12Z
WEDNESDAY...MODEL PW VALUES SHOW LOCATIONS SOUTH OF I-20 SEEING
VALUES AROUND 1.5 INCHES...WHEREAS LOCATIONS NORTH OF I-20 WILL BE
AROUND 1-1.3 INCHES. GUIDANCE HAS CONTINUOUSLY BEEN SHOWING MUCH
COOLER TEMPERATURES ON TUESDAY WITH ENSEMBLE MEANS AROUND THE UPPER
80S FOR HIGHWAY 82 CORRIDOR. CONTINUED THE TREND OF CUTTING MAV
GUIDANCE BY A DEGREE OR TWO IN ACCORDANCE WITH THIS AIRMASS BEING
BEHIND THE BOUNDARY. THE MORE NOTICEABLE CHANGE WILL COME IN
OVERNIGHT LOWS. LOWS ON TUESDAY NIGHT WILL BE IN THE MID TO LOWER
60S ACROSS THE NORTHERN COUNTIES. /28/

LONG TERM...WEDNESDAY THROUGH SUNDAY...THE CWA WILL BE DIVIDED IN
HALF THROUGH MUCH OF THE LONG TERM WITH A DRIER AIRMASS AND VERY
LITTLE CHANCE FOR RAIN ACROSS THE NORTH WITH DEEP MOISTURE AND
GREATEST RAIN CHANCES CONTINUING ACROSS THE SOUTH.  COME WEDNESDAY
MORNING A LARGE MID LEVEL(595DAM) HIGH WILL BE CENTERED OVER
COLORADO WITH A 1020MB SURFACE RIDGE CENTERED OVER THE TENNESSEE AND
OHIO VALLEYS. A STALLED COLD FRONT IS EXPECTED TO BE DRAPED ACROSS
THE SOUTHERN PORTIONS OF OUR CWA. A DRIER AIRMASS WITH PWS BELOW AN
INCH AND A HALF AND MID 60 SURFACE DEWPOINTS WILL RESIDE NORTH OF
THE FRONT WHILE NEAR TWO INCH PWS AND LOWER 70 DEW POINTS CONTINUE
ACROSS THE SOUTHERN THIRD OF OUR CWA. THIS DRIER AIRMASS WILL LEAD
TO BELOW NORMAL MORNING LOWS ACROSS THE NORTH THROUGH THE END OF THE
WEEK. WARMER THAN NORMAL AFTERNOON HIGHS WILL CONTINUE HOWEVER THE
GFS MOS WAS AMONG THE HIGHEST ENSEMBLE MEMBER AND HAVE LEANED TOWARD
ENSEMBLE MEAN HIGHS THURSDAY THROUGH THE END OF THE WEEK. MAINLY
AFTERNOON AND EARLY EVENING RAIN CHANCES WILL BE CARRIED SOUTH OF
INTERSTATE 20 WEDNESDAY WHILE WL LEAVE OUT MENTION NORTH OF
INTERSTATE 20. VERY LITTLE CHANGE IN SENSIBLE WEATHER IS EXPECTED
OVER OUR AREA THURSDAY BUT A SECOND STRONGER SURFACE HIGH WILL DROP
OUT OF THE NORTHERN PLAINS ACROSS THE GREAT LAKES REGION THURSDAY
NIGHT AND THEN TO THE MID ATLANTIC SEABOARD FRIDAY. THIS WILL
REINFORCE THE DRY NORTH TO NORTHEAST FLOW ACROSS OUR REGION AND
NUDGE THE STALLED FRONTAL BOUNDARY JUST SOUTH OF HIGHWAY 84. DRY
CONDITIONS ARE EXPECTED TO CONTINUE ACROSS THE NORTHERN TWO THIRDS
OF OUR CWA BUT MODEL CONSENSUS SUGGESTS CARRYING LOW POPS ACROSS THE
HIGHWAY 84 CORRIDOR FRIDAY AND SATURDAY. THE LARGE MID LEVEL RIDGE
WILL BREAK DOWN SUNDAY INTO MONDAY WHILE WEAK SURFACE RIDGING
BECOMES ORIENTED ALONG THE GULF COAST. DEEPER MO

&&

.AVIATION...

SHOWERS AND THUNDERSTORMS ARE AFFECTING THE GLH-GWO-CBM/GTR CORRIDOR
THIS MORNING. THIS ACTIVITY WILL DIMINISH BY EARLY AFTERNOON...WITH
ISOLATED AFTERNOON STORMS POSSIBLE NEAR TAF SITES THIS AFTERNOON AND
EVENING. OTHERWISE...MORNING MVFR CATEGORIES WILL BE POSSIBLE AGAIN
EARLY TUESDAY MORNING...ESPECIALLY IN AREAS THAT RECEIVE RAINFALL.

&&

.PRELIMINARY POINT TEMPS/POPS...
JACKSON       96  71  92  68 /  16  36  21  13
MERIDIAN      95  70  92  67 /  20  36  23   8
VICKSBURG     96  69  93  67 /  31  41  22  13
HATTIESBURG   97  73  96  72 /  20  20  32  17
NATCHEZ       96  72  93  71 /  16  25  35  20
GREENVILLE    93  70  92  65 /  64  39  14  11
GREENWOOD     92  69  92  64 /  61  41  13  10

&&

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

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