Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 181602
AFDJAN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
1102 AM CDT FRI APR 18 2014

.UPDATE...

MADE A FEW ADJUSTMENTS TO RAIN CHANCES FOR TODAY...THE FORECAST IS
GENERALLY ON TRACK.

AS DISCUSSED PREVIOUSLY...THERE ARE TWO MID LEVEL SHORTWAVE TROUGHS
IN THE PROCESS OF PHASING OVER THE GULF COAST REGION TODAY. ENERGY
ASSOCIATED WITH UPSTREAM WAVE IS TRANSLATING EASTWARD IN THIS PROCESS
AND WILL PROVIDE SOME WEAK LIFT FOR SHOWER REDEVELOPMENT WITH ENOUGH
INSTABILITY FOR DEEP CONVECTION AND THUNDER. COMPLICATING MATTERS IS
THE SUBSIDENCE AROUND THE WESTERN PERIPHERY OF THE RAIN SHIELD OVER
ALABAMA WHICH MAY LIMIT PRECIP OVER MUCH OF EAST CENTRAL MS. THE NEAR
TERM GUIDANCE CONSENSUS SEEMS TO FOCUS RENEWED CONVECTION IN THE
VICINITY OF THE I-55 CORRIDOR THIS AFTERNOON WHERE MOISTURE
CONVERGENCE MAY MAXIMIZE BETWEEN THE SUBSIDENCE RING AND APPROACHING
TROUGH. OTHERWISE...INCREASED POPS SOME IN THE NATCHEZ AREA BASED ON
CURRENT RADAR TRENDS. /EC/

&&

.PREV DISCUSSION... /ISSUED 337 AM CDT FRI APR 18 2014/

SHORT TERM...TODAY THROUGH SATURDAY NIGHT...TWO DISTINCT MID LEVEL
WAVES NOTED THIS MORNING IN WATER VAPOR IMAGERY WILL BE THE MAIN
FOCUS IN THE IMMEDIATE SHORT TERM. FIRST WAVE MOVING ACROSS THE
NORTHERN GULF AT THE MOMENT...WHILE SECONDARY WAVE IS CLOSE BEHIND
OVER NE TX/E OK. WHILE THESE SYSTEMS LOOK TO PHASE TOGETHER OVER THE
NEXT 12 TO 24 HOURS AND DEEPEN OVER AL...IT WILL PRIMARILY BE THE
UPSTREAM WAVE THAT WILL HAVE THE BIGGEST IMPACT ON OUR CWA AS IT
TRAVERSES TODAY.

PRESENTLY...ISENTROPIC RAINS CONTINUE OVER THE FAR SE AREAS
ASSOCIATED WITH THE LIFT FROM THE GULF WAVE. THESE WIDESPREAD RAINS
SHOULD DIMINISH THIS MORNING...BECOMING MORE SHOWERY EVERYWHERE BY
THE AFTERNOON. NARROW BAND OF CONVECTION AT THE MOMENT OVER AR/LA
ASSOCIATED WITH SECONDARY WAVE SHOULD INCREASE IN COVERAGE FURTHER
TO EAST AFTER SUNRISE. THIS WAVE APPEARS TO HAVE THE COLD AIR
ALOFT WITH -18C AT H5. WHILE AREAS IN THE EAST WILL HAVE OVERCAST
AND SOMEWHAT COOL SHOWERY CONDITIONS TODAY...AREAS TO THE WEST LOOK
TO BREAK OUT FROM THE CLOUD COVER AND WARM INTO THE LOWER 70S PRIOR
TO THE COLD AIR COMING IN ALOFT. WITH THE COLD CORE PASSING OVER DURING
THE AFTERNOON...CAPES APPROACHING 1500 J/KG AND 7.5C/KM H7-H5 LAPSE
RATES WILL SET UP WITH VERTICAL TOTALS NEAR 28 AND THUS EXPECT
SCATTERED THUNDERSTORM POTENTIAL IN THESE AREAS. NOT EXPECTING
ANYTHING SEVERE...BUT WOULD NOT BE SURPRISED TO SEE SOME SMALL HAIL
IN SOME OF THE STRONGER AFTERNOON STORMS.

CLOUDS SHOULD CLEAR RATHER RAPIDLY DURING THE EVENING AND COOLEST
MINS SHOULD OCCUR IN THE EAST CLOSEST TO THE EXITING COLD CORE.
SHORTWAVE RIDGING FOR SATURDAY SHOULD PROVIDE A QUITE PLEASANT DAY
WITH MAXES REACHING THE MID 70S./26/

LONG TERM...SUNDAY THROUGH NEXT FRIDAY...THE TAIL END OF EASTER
WEEKEND STILL LOOKS DRY AND WARM BUT RAIN AND GENERAL TSTORM CHANCES
WILL INCREASE MONDAY AFTN AND PEAK TUES MRNG INTO THE TUES AFTN AS A
WEAK BOUNDARY MOVES THROUGH. TEMPERATURES LOOK TO BE NEAR TO JUST
SLIGHTLY ABOVE NORMAL THROUGH THE PERIOD.

OVERALL CONFIDENCE REMAINS ABOVE AVERAGE WITH GOOD MODEL AGREEMENT
IN THE MEDIUM RANGE WHILE SLIGHTLY DECREASING AT THE END OF THE
PERIOD TOWARDS LATE NEXT WEEK WITH DIFFERING PATTERN PROGRESSIVENESS
DEPICTED BETWEEN EC/GFS/GEM. THE ARKLAMISS WILL BE ON THE WESTERN
EDGE OF A LOW AMPLIFIED EASTWARD PROGRESSING OMEGA BLOCK ACROSS THE
SOUTHERN CONUS BY SUNDAY EVENING. H7-H5 TROUGHING WILL APPROACH THE
REGION BY MONDAY MORNING WHILE A WEAK SURFACE TROUGH USHERS A WEAK
BOUNDARY TOWARDS THE REGION. TOP-DOWN MOISTURIZING STILL APPEARS TO
BE SLOW GOING MONDAY AND HAVE SLOWED TIMING JUST A BIT MORE LIKE
YESTERDAY WITH SLIGHTLY LESS SHOWER/TSTORM COVERAGE MON MRNG AND
AFTN. BEST COVERAGE (SCATTERED AT BEST) WILL BE ACROSS NORTHERN AND
SOME CENTRAL AREAS AS PWATS CLIMB TOWARDS 1.3" WITH 500-1000 J/KG
SBCAPE PRESENT. INSTABILITY WILL WANE THROUGH THE EVENING BUT ENOUGH
SURFACE CONVERGENCE FROM THE WEAK BOUNDARY UNDER MODERATE QG LIFT
SHOULD KEEP SHOWER ACTIVITY GOING THROUGH THE OVERNIGHT MAINLY
ACROSS THE HWY 82 CORRIDOR. WEAK BOUNDARY WILL PUSH SOUTH THROUGH
THE DAY TUESDAY AND WITH DIABATIC HEATING EXPECTED AHEAD...SBCAPE
VALUES OF 750-1500 J/KG SHOULD BUILD AND ALLOW FOR REGENERATION OF
GENERAL TSTORMS LATE MRNG TUES INTO THE AFTN. SHEAR AND OVERALL
THERMODYNAMICS WILL LIMIT POTENCY OF SAID TSTORMS TO REMAIN
SUB-STRONG. WIDESPREAD HEAVY RAIN ALSO DOES NOT APPEAR TO BE A RISK
AND THIS WILL ALLOW FOR SWOLLEN RIVERS TO SLOWLY ABATE. WILL KEEP
HWO CLEAR FOR THIS SLIGHTLY MORE ACTIVE PERIOD.

FOR WED-FRI...THE WEAK BOUNDARY THAT SETTLED NEAR THE COAST WILL
RETURN NORTH BY EARLY FRIDAY WHILE A STRONG SURFACE LOW AND PARENT
TROUGH DEVELOP ACROSS THE CENTRAL CONUS. MODELS ARE AT ODDS ON THIS
FEATURE AND THIS WILL BE WATCHED FOR ANY POTENTIAL IMPACT ON THE
ARKLAMISS. THIS TIME FRAME WILL BE WARM WITH HIGHS IN THE UPPER 70S
LOW 80S AND LIMITED RAINFALL POTENTIAL UNTIL POSSIBLY NEXT WEEKEND.
/ALLEN/

&&

.AVIATION...A MIXTURE OF VFR...MVFR AND IFR CONDITIONS ARE OCCURRING
THIS MORNING. RAIN IS MOVING THROUGH THE MS RIVER AREA AND QUICKLY
DISSIPATING. THERE MAY BE SOME REDEVELOPMENT LATER THIS AFTERNOON
BUT CLOUD COVER WILL SLOWLY ERODE THROUGH THE DAY. MOST LOCATIONS
SHOULD BE VFR BY LATE THIS AFTERNOON. /28/

&&

.PRELIMINARY POINT TEMPS/POPS...
JACKSON       70  49  76  52 /  40   6   1   5
MERIDIAN      67  47  76  48 /  30  17   0   3
VICKSBURG     72  50  76  51 /  42   4   2   5
HATTIESBURG   71  47  77  51 /  31  16   3   2
NATCHEZ       72  50  75  53 /  50  11   3   3
GREENVILLE    72  52  76  54 /  34   5   2   6
GREENWOOD     72  51  75  52 /  38   7   2   5

&&

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

$$








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