Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 191637
AFDJAN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
1037 AM CST FRI DEC 19 2014

.UPDATE...

THE FORECAST IS GENERALLY ON TRACK FOR TODAY WITH WIDESPREAD LIGHT TO
MODERATE RAINFALL SPREADING EAST-NORTHEAST ACROSS MOST OF THE
ARKLAMISS. THE GREATEST MOISTURE FLUX/ASCENT HAS BEEN FOCUSING A BAND
OF HEAVIER RAIN OVER CENTRAL LA THAT SHOULD AFFECT THE I-20 CORRIDOR
THROUGH MID AFTERNOON. THEREAFTER...CONVECTIVE RAINFALL CURRENTLY
OVER SE TX/SW LA IS FORECAST BY THE HRRR TO ACCELERATE EASTWARD
ALONG THE COAST AND INTERCEPT BETTER MOISTURE FLUX. GUIDANCE
SUGGESTS THIS WILL HELP TO FOCUS BETTER LIFT AND HEAVIER RAINFALL
OVER SOUTHERN PORTIONS OF THE FORECAST AREA AS WE GO INTO THE
EVENING.

OVERALL...RAINFALL AMOUNTS OF 1-2 INCHES ALONG AND SOUTH OF I-20
STILL LOOK LIKE A REASONABLE FORECAST. OTHERWISE WILL BE MAKING SOME
MINOR ADJUSTMENTS TO TEMPERATURES TO ACCOUNT FOR LATEST TRENDS. /EC/

&&

.AVIATION...

DETERIORATING CONDITIONS WILL CONTINUE THROUGH THE AFTERNOON
AS A LOW PRESSURE SYSTEM MOVES ALONG THE GULF COAST AND SENDS
WIDESPREAD RAIN INLAND. MVFR CEILINGS SHOULD BE COMMON TODAY INTO
THIS EVENING WITH SOME MVFR VIS RESTRICTIONS. IN ADDITION THERE WILL
BE SOME OCCASIONAL IFR RESTRICTIONS... PARTICULARLY ALONG AND SOUTH
OF THE HKS/JAN TO MEI CORRIDOR WHERE THE HEAVIER RAINFALL IS
EXPECTED. /28/17/

&&

.PREV DISCUSSION... /ISSUED 345 AM CST FRI DEC 19 2014/

SHORT TERM...TODAY THROUGH SATURDAY NIGHT...AREA RADARS AND
SATELLITE ARE PICKING UP LIGHT TO MODERATE RAIN WITH SOME EMBEDDED
CONVECTION OVER SOUTHEAST TEXAS INTO SOUTHERN LOUISIANA PUSHING
TOWARD THE ARKLAMISS...ASSOCIATED WITH A STRONG SHORTWAVE TROUGH WAS
OBSERVED OVER THE SOUTHERN PLAINS. HIGH RES MODELS SHOW WIDESPREAD
MODERATE RAINS PUSHING INTO THE REGION FOR TODAY THROUGH TONIGHT.
MODEL CROSS SECTIONS AND SOUNDINGS CONTINUE TO SUPPORT SOME EMBEDDED
CONVECTION ACROSS THE SOUTH FOR TODAY. MODELS CONTINUE TO SUPPORT
STRONG ISENTROPIC ASCENT FOR POTENTIALLY HEAVY RAINFALL RATES...BUT
GUIDANCE HAS GENERALLY COME DOWN TO MAINLY ONE TO TWO INCHES SOUTH OF
INTERSTATE 20 WITH LIGHTER AMOUNTS FARTHER NORTH. SO WITH THIS IN
MIND WILL KEEP CURRENT WIDESPREAD POPS FOR TODAY AND LOWER POPS SOME
FOR TONIGHT. THE RAINS WILL MOVE OUT OF THE REGION ON SATURDAY
MORNING. ANOTHER SHORTWAVE WILL COME DOWN INTO THE SOUTHERN PLAINS ON
SUNDAY. IT WILL PUSH MOISTURE TOWARD THE REGION FROM THE SOUTH ON
LATE SUNDAY NIGHT AS CLOUDS INCREASE ACROSS THE REGION./17/

LONG TERM...SUNDAY THROUGH FRIDAY...SUNDAY MORNING A SURFACE RIDGE
AXIS FROM THE NORTHEAST WILL BE ACROSS THE NORTHERN PORTIONS OF OUR
CWA AND LIMIT ANY LOW LEVEL MOISTURE RETURN AHEAD OF THE NEXT UPPER
LEVEL TROUGH THAT WILL BE OVER THE CENTRAL CONUS. A WEAK SURFACE LOW
WILL DEVELOP OVER THE WESTERN GULF IN RESPONSE TO THE APPROACHING
TROUGH AND RESULT IN RAIN CHANCES OVER OUR SOUTHEAST ZONES SUNDAY
AFTERNOON. THIS SURFACE LOW WILL TRACK FARTHER SOUTH THAN THE ONE ON
FRIDAY. MODELS SHOW BY SUNDAY AFTERNOON THE RIGHT REAR QUAD OF A
>120KT JET STREAK OVER OUR SOUTHEAST COUNTIES BUT PWS WILL ONLY BE
ONE INCH OR LESS AND INSTABILITY WILL BE LIMITED SO ONLY LOW POPS OF
LIGHT QPF IS EXPECTED. THIS SYSTEM WILL SHIFT EAST OF OUR CWA BY
MONDAY MORNING BUT A CLOSED LOW WILL DROP OVER THE NORTHERN PLAINS
MONDAY RESULTING IN A DEEPENING OF THE UPPER LEVEL TROUGH OVER THE
CENTRAL CONUS. THIS WILL INDUCE WEAK WAA ADVECTION OVER OUR REGION
DURING THE DAY MONDAY AND RESULT IN A FEW LIGHT SHOWERS. THE
DEEPENING TROUGH WILL SUPPORT A STRONG COLD FRONT THAT IS EXPECTED
TO MOVE ACROSS OUR CWA TUESDAY. THE CHANCE FOR RAIN WILL INCREASE
AFTER MIDNIGHT MONDAY NIGHT AND THE HIGHEST POPS OF THE LONG TERM
WILL BE CARRIED ACROSS THE AREA ALONG AND AHEAD OF THE FRONT
TUESDAY. COOLER AND DRIER AIR WILL FILTER INTO THE REGION TUESDAY
NIGHT SENDING TEMPERATURES BELOW NORMAL BY WEDNESDAY MORNING. THE
GFS IS MUCH FARTHER NORTH THAN THE ECMWF WITH THE CLOSED LOW
WEDNESDAY MORNING AND ENDS THE RAIN FASTER. RAIN WILL LIKELY LINGER
LONGER INTO TUESDAY NIGHT THAN WAS THOUGH LAST NIGHT BUT DRY WEATHER
IS EXPECTED TO RETURN WEDNESDAY. THE CLOSED LOW WILL LIFT UP INTO
CANADA WEDNESDAY NIGHT AND THE UPPER TROUGH WILL SHIFT EAST OF OUR
CWA. THIS WILL LEAVE NEAR ZONAL FLOW ACROSS OUR CWA AND A WEAK
SURFACE LOW OVER THE NORTHERN GULF FOR CHRISTMAS DAY. CHRISTMAS DAY
WILL BE DRY BUT THE GFS AND ECMWF DIFFER SIGNIFICANTLY WITH THE NEXT
UPPER LEVEL TROUGH MOVING OVER THE ROCKIES. THE ECMWF IS MUCH
STRONGER WITH A CLOSED LOW AND ASSOCIATED SURFACE LOW OVER THE
CENTRAL CONUS BY FRIDAY MORNING. EITHER SOLUTION WILL BRING AN
INCREASE IN RAIN CHANCES DURING THE DAY FRIDAY. /22/

&&

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

&&

$$






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