Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 281623 AAA
AFDJAN

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON MS
1023 AM CST SUN DEC 28 2014

.UPDATE...REMAINDER OF RAIN EVENT IS LOOKING MORE AND MORE STRATIFORM
AS INSTABILITY APPEARS NEGLIGIBLE AND LAPSE RATES RATHER POOR. WILL
STILL HAVE GOOD ISENTROPIC FORCING WITH MAIN MID LEVEL SHORTWAVE AS
IT EJECTS OUT OF TX THIS AFTERNOON INTO TONIGHT. WHILE MOISTURE PLUME
CONTINUES TO BE EVIDENT IN THE BLENDED TOTAL PRECIPITABLE WATER
IMAGERY...MAIN HIGH PW BULLSEYE HAS PUSHED INTO AL AND UPSTREAM PW
VALUES ARE QUITE A BIT LOWER THAN WE WERE DEALING WITH YESTERDAY. WITH
THE EXPECTATIONS OF LOW AND SLOW RAINFALL ACCUMULATIONS...HAVE
DROPPED THE FFA AS ANY FLOODING FROM FUTURE ACCUMULATIONS SHOULD BE
MINOR AT BEST./26/


&&

.AVIATION...WIDESPREAD IFR TO LOW-END MVFR CONDITIONS WILL CONTINUE
DUE PRIMARILY TO CEILINGS AS WE GO THROUGH THE REST OF THE DAY.
WINDS WILL BE MAINLY FROM THE NORTH AT 5 TO 15 MPH. EXPECT
ADDITIONAL WIDESPREAD LIGHT TO MODERATE RAIN TO MOVE BACK INTO SITES
GRADUALLY THROUGH THE REMAINDER OF TODAY AS WELL...FURTHER HAMPERING
FLYING CONDITIONS. WITH CONTINUED WEAK COLD ADVECTION...STRATUS MAY
NOT BE FAST TO MOVE OUT AS WE GO THROUGH TONIGHT...BUT CIGS MAY
CLEAR OUT AT IN THE GLH/GWO AREA LATE TONIGHT INTO MONDAY WITH MOST
OF THE RAIN EXITING BY DAYBREAK MONDAY. ELSEWHERE...EXPECT CIGS TO
RISE TO MVFR CATEGORY MONDAY EVEN IF THEY DO NOT CLEAR OUT. /EC/BB/


&&

.PREV DISCUSSION... /ISSUED 419 AM CST SUN DEC 28 2014/

DISCUSSION...

TODAY THROUGH MONDAY NIGHT...

THE RISK FOR FLASH FLOODING CONTINUES TODAY BUT IT IS DIMINISHED FROM
WHAT IT WAS YESTERDAY INTO LAST NIGHT AS THE FIRST ROUND OF
SHORTWAVE ENERGY SHEARS EASTWARD EARLY THIS MORNING. CURRENT CONVECTION
OVER CENTRAL AND EASTERN MS HAS BEEN DECREASING IN INTENSITY...BUT
THE NEXT SHORTWAVE TROUGH IN THIS CURRENT TROUGH-TO-RIDGE SET-UP IS
APPROACHING AND WILL BRING AN INCREASE IN LARGE SCALE ASCENT AND
MOSTLY ANA-FRONTAL RAINFALL AS THE DAY PROGRESSES.

THE CONSENSUS IS THAT THIS NEXT ROUND OF SIGNIFICANT RAINFALL WILL
BE FOCUSED MORE OVER THE NORTHWEST HALF OF THE AREA THIS AFTERNOON
AND EVENING. OVERALL...RAINFALL TODAY WILL BE LESS CONVECTIVE...AND
IT IS NOT EXPECTED TO CAUSE FLASH FLOODING CONCERNS...BUT HAVE KEPT
MUCH OF THE FLASH FLOOD WATCH GOING TO ACCOUNT FOR HEAVY RAIN THAT
FELL IN THE PAST 24 HOURS AND LITTLE ROOM FOR QPF ERROR. OTHERWISE...
WITH THE SURFACE FRONT PUSHING THROUGH TODAY...MUCH OF THE FOREAST
AREA WILL HAVE RAW/RAINY CONDITIONS MAKING FOR AN UNCOMFORTABLE
OUTDOOR EXPERIENCE.

RAIN WILL DIMINISH TONIGHT WITH THE PASSAGE OF THE NEXT SHORTWAVE
TROUGH AXIS...BUT CONDITIONS WILL BE SLOW TO IMPROVE WITH CONTINUED
COLD ADVECTION AND CONSIDERABLE LOW CLOUDINESS GOING INTO MONDAY.
EXPECT CLEARING SKIES BY MONDAY NIGHT WITH SEASONABLY CHILLY LOW
TEMPERATURES. /EC/

TUESDAY THROUGH SUNDAY...OVERALL ACTIVE WEATHER PATTERN WILL
CONTINUE IN THE LONG TERM. PERIOD STARTS OUT WITH MASSIVE ARCTIC HIGH
CONTINUING TO BUILD TOWARD REGION FROM NORTHERN ROCKIES/PLAINS
STATES. BRUNT OF THIS COLD AIR WILL REMAIN TO OUR NORTH AND WEST AS
HIGH WEAKENS AS IT DROPS SOUTH...AND COLD AIR IS DEFLECTED OFF AS 500
MB PATTERN TRENDS TOWARD SPLIT FLOW AND SUBTROPICAL STREAM BECOMES
INCREASINGLY DOMINANT. STILL...THERE WILL BE A GOOD PUSH OF MUCH
COOLER AIR TO START THIS FORECAST PERIOD WITH SUBFREEZING MINS MOST
AREAS WED/THU...AND MAXES MAINLY IN THE 40S.

DEEP UPPER LOW DROPPING INTO SW CONUS THU/FRI WILL CAUSE MID/UPPER
LEVEL FLOW TO BACK ACROSS OUR AREA...RESULTING IN INCREASING
MOISTURE ALOFT. WITH WEAKENING SURFACE HIGH ACROSS REGION AND RESIDUAL
COOL/DRY LOW LEVEL AIR...WILL LIKELY TAKE SOME TIME FOR
PRECIPITATION TO BREAK OUT...BUT WILL SHOW GRADUALLY INCREASING POPS
THROUGH THIS TIME PERIOD. WHILE TEMPS GENERALLY LOOK TO MODERATE
ENOUGH TO PRECLUDE ANY SERIOUS WINTER WEATHER RISK...CERTAINLY COULD
BE ENOUGH DRY/COOL NEAR SURFACE AIR TO RESULT IN SOME INITIAL
MIXTURE WITH SLEET...PARTICULARLY IF PRECIPITATION BREAKS OUT SOONER
RATHER THAN LATER DUE TO MID LEVEL MOISTENING. WILL NOT INCLUDE THIS
IN GRIDS AT THIS POINT...BUT SOMETHING FOR LATER SHIFTS TO MONITOR.

FORECAST DETAILS BECOMING INCREASINGLY MURKY AS WE GO LATER INTO THE
WEEK. LARGE SPREAD IN OPERATIONAL AND ENSEMBLE MODEL SYSTEMS WITH
REGARD TO STRENGTH/TIMING OF SYSTEM EJECTING OUT OF THE SW CONUS.
GIVEN THE STRONG SUBTROPICAL RIDGE DEVELOPING OVER FL AND SLOWLY
EJECTING SYSTEM FROM THE SW...WOULD CERTAINLY SEEM TO BE ANOTHER
FAVORABLE SETUP FOR HEAVY RAINFALL...AND ALL MODELS DEPICT AN AXIS
OF SEVERAL INCHES OF RAIN OVER/NEAR PARTS OF CWA DEPENDING ON
INDIVIDUAL MODEL HANDLING OF EJECTING SYSTEM. SEVERAL MODEL
SOLUTIONS OVER LAST 24 HOURS HAVE ALSO SUGGESTED SOME RISK OF SEVERE
WEATHER. THIS INCLUDES MOST RECENT ECMWF WHICH HAS A STRONGER SURFACE
LOW PASSING TO OUR NW THAN GFS/GGEM...AS WELL AS FAVORABLE PARAMETER
SPACING/500 MB PATTERN TO SUPPORT SEVERE POTENTIAL. GIVEN LARGE
MODEL SPREAD AND LACK OF RUN TO RUN CONSISTENCY FEEL MOST PRUDENT
COURSE FOR NOW IS TO LEAVE MENTION OF SEVERE/FLOODING OUT OF HWO
UNTIL A CLEARER SOLUTION EMERGES...ESPECIALLY GIVEN THAT ECENS
GENERALLY DOES NOT SEEM TO SUPPORT AS STRONG OF SYSTEM AS THE
OPERATIONAL RUN. HAVE ACCEPTED LIKELY POPS DEPICTED BY MODEL BLENDS
IN FRI/SAT TIME FRAME.                                 /AEG/

&&


.PRELIMINARY POINT TEMPS/POPS...
JACKSON       53  42  52  40 /  93  88  13  14
MERIDIAN      61  44  55  42 /  90  86  13  15
VICKSBURG     50  40  50  38 /  95  79  13  12
HATTIESBURG   66  47  60  46 /  74  66  11  10
NATCHEZ       52  41  53  40 /  91  73  13  12
GREENVILLE    46  37  48  36 /  95  58  10  11
GREENWOOD     49  39  50  37 /  95  73  11  12

&&

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

$$






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