Area Forecast Discussion
Issued by NWS Jackson, MS

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FXUS64 KJAN 211545
AFDJAN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
945 AM CST FRI NOV 21 2014

.UPDATE...HIGH PRESSURE ACROSS THE OHIO VALLEY WILL PUSH SLOWLY EAST
TODAY ALLOWING SOUTHERLY FLOW TO CONTINUE. THIS WILL SLOWLY INCREASE
TEMPERATURES AND DEWPOINTS THROUGH THE DAY. HAVE MADE THE USUAL
ADJUSTMENTS TO THE TEMPERATURE AND DEW POINT TRENDS BUT HIGHS LOOK
GOOD. ALSO...TRIMMED BACK SMALL SHOWER CHANCES IN OUR WESTERN AREAS A
FEW HOURS BUT KEPT IN FOR THIS AFTERNOON.

WE WILL CONTINUE TO EVALUATE THE PARAMETERS FOR THE SYSTEM EXPECTED
TO IMPACT THE AREA SATURDAY NIGHT AND SUNDAY MORNING. THERE STILL
APPEARS TO BE A WINDOW OF OPPORTUNITY FOR SEVERE WEATHER BETWEEN
APPROX 3AM AND NOON SUNDAY. ALSO...WILL EVALUATE THE POTENTIAL FOR
SUNDAY TO BE WINDY PARTICULARLY IN THE SOUTHERN PORTIONS OF THE
FORECAST AREA. /SW/

&&

.AVIATION...VFR CONDITIONS WILL PREVAIL THIS TAF PERIOD WITH SOME
MIX OF MID LEVEL CLOUDS ACROSS THE WEST AND THEN SPREADING OVER THE
AREA LATER TONIGHT. AS WE APPROACH MIDDAY SAT...SOME LOW END
POTENTIAL WILL EXIST FOR MVFR CEILINGS...BUT WILL NOT INCLUDE IN THE
NEW SET OF TAFS AT THIS TIME. /CME/

&&

.PREV DISCUSSION... /ISSUED 431 AM CST FRI NOV 21 2014/

SHORT TERM...TODAY THROUGH SUNDAY...THE STORY FOR THE SHORT
TERM CONTINUES TO BE THE POTENTIAL FOR SEVERE STORMS SATURDAY NIGHT.
HIGH PRESSURE WILL CONTINUE TO PREVAIL OVER MUCH OF THE AREA TODAY
AND WITH SOUTHERLY FLOW THE WARMING TEND WILL CONTINUE WITH HIGHS IN
THE MID/UPPER 60S. WITH THE BETTER MOISTURE ALONG AND WEST OF THE
MISSISSIPPI RIVER A FEW SHOWERS WILL BE POSSIBLE THIS AFTERNOON OVER
THOSE AREAS. LITTLE WILL CHANGE TONIGHT WITH A FEW SHOWERS POSSIBLE
IN THE FAR WEST AND SLIGHTLY WARMER OVERNIGHT LOWS IN THE MID/UPPER
40S.

A VERY STRONG PACIFIC JET WILL DIG OUT A DEEP UPPER TROUGH AND DROP
DOWN INTO THE FOUR CORNERS AREA FRIDAY NIGHT INTO SATURDAY.
MOISTURE WILL INCREASE ACROSS THE AREA SATURDAY AFTERNOON INTO THE
EVENING HOURS OUT AHEAD OF THIS SYSTEM WITH PWATS CLIMBING TO
1.7-1.8 INCHES BY LATE EVENING. THE MODELS HAVE BEEN SLOWING THIS
SYSTEM DOWN THE PAST FEW RUNS AND BY SATURDAY AFTERNOON THE
NEGATIVELY TILTED TROUGH WILL EXTEND OVER CENTRAL TEXAS WITH AN
ASSOCIATED SURFACE LOW/FRONTAL BOUNDARY. THE MODELS ARE IN PRETTY
GOOD AGREEMENT ON THE TIMING OF THE SYSTEM ACROSS THE AREA SATURDAY
NIGHT INTO SUNDAY MORNING. THE WIND SHEAR WITH THIS SYSTEM IS
IMPRESSIVE...BUT THE BIG QUESTION CONTINUES TO BE THE AMOUNT OF
INSTABILITY WITH THE SYSTEM AS IT CROSSES THE ARKLAMISS. BOTH THE
GFS/ECMWF ARE SHOWING AROUND 100-300 J/KG OF ML CAPE MAINLY OVER THE
SOUTHERN PORTIONS OF THE AREA. THE H700-H500 LAPSE RATES ARE NOT TO
IMPRESSIVE EITHER RANGING FROM AROUND 5.5-6.0 C/KM. THE LATEST RUN
OF THE CIPS ANALOG INDICATES THE POTENTIAL FOR SEVERE ACROSS MOST OF
THE AREA...SO WILL LEAVE OUR CURRENT RISK AREAS WITH THE GREATEST
POTENTIAL FOR SEVERE ALONG AND SOUTH OF I-20.

THE STORMS WILL SHIFT EAST OF THE AREA BY MID MORNING ON SUNDAY WITH
A FEW REMNANT SHOWERS POSSIBLE IN THE EAST UNTIL EARLY AFTERNOON.
DRIER AIR WILL BUILD IN QUICKLY SUNDAY AFTERNOON WITH PWATS FALLING
BELOW AN INCH BY EARLY EVENING. THE GFS/ECMWF INDICATE H925
TEMPERATURES AROUND 18C ON SUNDAY AND THIS TRANSLATES TO VERY WARM
TEMPS ON SUNDAY WITH HIGHS IN THE MID/UPPER 70S.

LONG TERM...SUNDAY NIGHT THROUGH NEXT FRIDAY...

A DRY AND COOLER PATTERN IS IN STORE FOR THE ARKLAMISS THANKSGIVING
WEEK AS A WESTERN RIDGE AND EASTERN TROUGH PATTERN SETS UP AND
BRINGS DRY NORTHWEST FLOW ALOFT. EXPECT SURFACE TEMPERATURES TO BE
5-10 DEG F BELOW NORMAL FOR THE MOST PART. CIPS SHOWS SUBSTANTIAL
NEGATIVE TEMPERATURE ANOMALIES...BUT THIS POLAR AIRMASS WILL NOT BE
NEARLY AS COLD AS THE RECENT ARCTIC AIR OUTBREAK. IT APPEARS THE
NEXT SIGNIFICANT CHANCE FOR RAINFALL MAY NOT MATERIALIZE UNTIL THE
FIRST WEEK OF DECEMBER. /EC/

&&

.PRELIMINARY POINT TEMPS/POPS...
JACKSON       67  48  68  58 /   7   5  14  96
MERIDIAN      67  44  66  56 /   3   3  12  88
VICKSBURG     68  49  69  58 /  11  10  18  96
HATTIESBURG   68  46  68  59 /   2   3  30  96
NATCHEZ       67  51  70  61 /   7   6  37  96
GREENVILLE    64  49  67  55 /  22  16  14  96
GREENWOOD     66  49  67  56 /  17   9  10  95

&&

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

$$



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