Area Forecast Discussion
Issued by NWS Jackson, MS

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000
FXUS64 KJAN 051604 AAA
AFDJAN

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE JACKSON MS
1105 AM CDT SAT SEP 5 2015

.UPDATE... A LARGE AND WEAK UPPER LEVEL LOW CURRENTLY CENTERED OVER
THE CAROLINAS WILL BE GRADUALLY BACKDOORING TOWARD OUR REGION
THROUGH THE NEXT 24 HOURS. THE NET RESULT WILL BE A GRADUAL RAMPING
UP IN AFTERNOON AND EVENING SHOWER AND STORM CHANCES OVER THIS
WEEKEND...ESPECIALLY ALONG AND SOUTH OF THE I-20 CORRIDOR. THE 12Z
JAN SOUNDING REVEALS A SLIGHTLY HOTTER...MORE MOIST...AND MORE
UNSTABLE ENVIRONMENT ACROSS THE HEART OF THE ARKLAMISS REGION THAN
WAS THE CASE YESTERDAY. THIS SHOULD DIRECTLY CORRELATE TO SLIGHTLY
WARMER TEMPERATURES TODAY THAN YESTERDAY AS WELL AS A LITTLE MORE
AFTERNOON SHOWERS AND STORMS. CONSIDERING THAT A FEW STORMS COULD
OCCUR WHERE AIR TEMPS ARE AT LEAST IN THE MID 90S IT IS QUITE
POSSIBLE SOME LOCALLY GUSTY WINDS WILL BE POSSIBLE WITH ANY
CONVECTION THIS AFTERNOON. HOWEVER...THE LOCAL MICROBURST CHECKLIST
DID NOT REPRESENT MUCH RISK FOR MICROBURSTS AND WITH THAT IN MIND WE
WILL LEAVE CONVECTIVE THREATS FOR TODAY OUT OF THE HWO. BUT THE HWO
WAS UPDATED TO INCLUDED A LIMITED RISK OF HEAT THREATS DUE TO THE
FACT THAT PEAK HEAT INDICES WILL LIKELY RANGE FROM 99 TO 105 ACROSS
THE REGION THIS AFTERNOON...WHICH IS SOMEWHAT CONCERNING FOR LATE IN
THE SUMMER IN THE MIDST OF THE HOLIDAY WEEKEND. /BB/

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL TODAY. ISOLATED SHOWERS AND
THUNDERSTORMS WILL OCCUR BETWEEN 18 AND 00Z...BUT MOST TAF SITES
WILL REMAIN DRY. ANY SHRA/TSRA THAT DOES OCCUR WILL BRING GUSTY
WINDS AND BRIEF MVFR VIS RESTRICTIONS. SOME MVFR PATCHY BR WILL BE
POSSIBLE LATE TONIGHT. /28/

&&

.PREV DISCUSSION... /ISSUED 341 AM CDT SAT SEP 5 2015/

SHORT TERM...TODAY THROUGH SUNDAY NIGHT...THE EVER PRESENT
MID/UPPER RIDGE... EXTENDING FROM TX INTO THE UPPER MS VALLEY...WILL
CONTINUE TO DOMINATE THE PATTERN IN THE SHORT TERM...HOWEVER...
CYCLONIC SHEAR AXIS WILL WOBBLE BACK INTO THE AREA FROM THE EAST BY
SUNDAY.

LATEST WV IMAGERY SHOWING A SHORTWAVE MOVING THROUGH THE REGION WITH
A 35-40 KNOT H3 JET STREAK EXTENDING FROM CENTRAL AR TO SE MS. AS
RIGHT ENTRANCE REGION OF THIS FEATURE MOVES ACROSS SOUTHERN PORTIONS
TODAY...EXPECT CONVECTIVE COVERAGE TO BE BEEFED UP SOMEWHAT MORE
THAN THE ISOLATED THAT WAS ALREADY EXPECTED. CONVECTION SHOULD BE
RATHER TAME THOUGH AS MID LEVEL LAPSE RATES ARE QUITE FEEBLE...
GENERALLY LESS THAN 6 C/KM.

MODELS IN AGREEMENT THAT CYCLONIC SHEAR AXIS APPROACHING FROM THE
EAST WILL SWING A DECENT SHORTWAVE ACROSS THE AREA FROM THE NE
SUNDAY. COOLER AIR ALOFT WITH THIS FEATURE WILL YIELD 6.5 C/KM LAPSE
RATES AS WELL AS INCREASED WIND FIELDS WITH 25-30 KNOTS OF DEEP
LAYER SHEAR. BEST CONVECTIVE COVERAGE WILL CONTINUE TO BE IN THE
SOUTH IN THE DEEPEST MOISTURE. WITH INCREASED SHEAR/INSTABILITY...
MAY SEE SOME ORGANIZED CLUSTERS PRODUCING STRONG WIND GUSTS DURING
MAX HEATING SUNDAY AFTERNOON. WILL NOT INCLUDE IN THE HWO AT PRESENT
BUT WILL CONTINUE TO MONITOR MODEL TRENDS./26/

LONG TERM...MONDAY THROUGH FRIDAY...ABOVE NORMAL TEMPERATURES AND
LOW RAIN CHANCES LOOK TO CONTINUE THROUGH THE WEEK BUT GREATER RAIN
CHANCES AND COOLER TEMPERATURES ARE INDICATED BY THE WEEKEND. COME
MONDAY OUR CWA WL BE BETWEEN A 593DAM RIDGE CENTERED OVER THE
SOUTHERN PLAINS AND A 585DAM HIGH CENTERED TO OUR SOUTHEAST OVER THE
NORTHERN GULF. A SURFACE RIDGE IS EXPECTED TO BE NOSING BACK ACROSS
OUR CWA FROM THE NORTHEAST...FROM A HIGH CENTERED OVER THE MID
ATLANTIC SEABOARD. THIS WL PRODUCE A LIGHT EAST LOW LEVEL FLOW
ACROSS OUR CWA AND KEEP A SLIGHTLY DRIER AIR MASS OVER THE NORTHERN
HALF OF OUR CWA. DAYTIME HEATING WL LEAD TO ISOLATED COVERAGE OF
MAINLY AFTERNOON AND EARLY EVENING STORMS AND MAINLY OVER OUR
SOUTHEAST WHERE THE LOWER HEIGHTS RESIDE. NORMAL AFTERNOON HIGHS RUN
IN THE UPPER 80S. HIGHS WILL TOP OUT FROM THE LOWER 90S EAST TO THE
UPPER 90S WEST. MAXIMUM HEAT INDEX VALUES IN THE WEST WILL BE IN THE
LOWER 100S. THE LARGE MID LEVEL RIDGE OVER THE SOUTHERN PLAINS AND
THE MID LEVEL LOW OVER THE NORTHERN GULF WILL WEAKEN THROUGH
WEDNESDAY RESULTING IN LOWER AFTERNOON HIGHS EACH DAY. WL STILL
MAINTAIN A RELATIVELY MOIST AIR MASS OVER THE REGION SO DIURNALLY
DRIVEN ISOLATED TO SCATTERED COVERAGE OF CONVECTION CAN BE EXPECTED
OVER MORE OF OUR CWA. BY THURSDAY THE SURFACE RIDGE WILL BECOME
ORIENTED ALONG THE GULF COAST. THIS WILL HELP MAINTAIN GREATER LOW
LEVEL MOISTURE THROUGH THE END OF THE WEEK. MODELS DIFFER ON TIMING
BUT A SERIES OF SHORTWAVES WILL BEGIN DEEPENING AN UPPER LEVEL
TROUGH OVER OUR REGION AS WE GO INTO FRIDAY. THIS WILL HELP INCREASE
RAIN CHANCES AHEAD OF A SIGNIFICANT COLD FRONT THAT MODEL CONSENSUS
MOVES INTO OUR CWA FRIDAY NIGHT. COOLER AND DRIER WEATHER WILL
FOLLOW IN THE WAKE OF THE COLD FRONT SATURDAY. /22/

&&

.PRELIMINARY POINT TEMPS/POPS...
JACKSON       96  72  93  71 /  24  18  30  20
MERIDIAN      95  71  91  70 /  23  24  28  21
VICKSBURG     97  72  94  72 /  25  16  27  18
HATTIESBURG   95  73  92  71 /  34  27  35  21
NATCHEZ       94  73  95  71 /  31  21  31  21
GREENVILLE    97  73  96  73 /  17  10  13  10
GREENWOOD     97  72  94  72 /  15  10  15   9

&&

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

$$

BB/28/26/22



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