840
FXUS64 KJAN 240829
AFDJAN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
329 AM CDT THU JUL 24 2008
SHORT TERM
SURFACE ANALYSIS THIS MORNING SHOWS THE REMNANTS OF
THE BOUNDARY STRETCHED ACROSS NORTHERN PORTIONS OF THE FORECAST
AREA. WATER VAPOR IMAGERY SHOWS DRIER AIR MOVING INTO THE AREA.
UPPER LEVEL RIDGING EXISTS OVER THE PLAINS STATES WITH THE TROUGH
OVER THE NORTHEASTERN CONUS.
RIDGING IS EXPECTED TO BEGIN TO BUILD OVER THE CWFA OVER THE NEXT
COUPLE OF DAYS. THE REMNANTS OF THE BOUNDARY IS EXPECTED TO WASH OUT
OVER THE NEXT COUPLE OF DAYS AS WELL. SHOWER AND THUNDERSTORM
ACTIVITY TODAY WILL BE HAMPERED BY RISING HEIGHTS AND WARMING MID
LEVEL TEMPERATURES...AS WELL AS THE DRIER AIR MOVING INTO THE
REGION. THE SEA BREEZE WILL CONTRIBUTE A LITTLE MORE SUPPORT FOR
THE SOUTHERN HALF OF THE CWFA. OVERALL DO NOT EXPECT MUCH MORE THAN
ISOLATED CONVECTION THIS AFTERNOON. ANY ACTIVITY THAT DEVELOPS TODAY
WILL STRUGGLE TO DEVELOP UNTIL THE AFTERNOON HOURS...AND SHOULD
QUICKLY DIE OFF AFTER SUNSET. WITH THESE FEATURES ACTING AGAINST
CONVECTION TODAY...STRONG TO SEVERE THUNDERSTORMS WILL BE HARDER TO
COME BY THIS AFTERNOON. HIGH PRESSURE WILL CONTINUE TO BUILD OVER
THE REGION AS WE MOVE INTO FRIDAY. THERE WILL BE A SLIGHT INCREASE
IN MOISTURE OVER THE REGION. WITH MORE MOISTURE THERE MAY BE MORE
CONVECTION ON FRIDAY THAN TODAY. HOWEVER UPPER LEVEL RIDGING WILL
AGAIN HAMPER ACTIVITY FROM BECOMING TOO WIDESPREAD. AS A RESULT
HAVE LOWERED POPS IN A FEW LOCATIONS TO REFLECT MORE ISOLATED
COVERAGE FOR FRIDAY OVER THE FORECAST AREA. ACTIVITY THAT DEVELOPS
FRIDAY WILL AGAIN DIE DOWN QUICKLY AFTER SUNSET.
TEMPERATURES FOR TODAY AND ESPECIALLY ON FRIDAY WILL BEGIN TO BE A
LITTLE WARMER...ESPECIALLY ACROSS THE NORTHWEST. HIGH PRESSURE
BUILDING INTO THE REGION AND WARMING MID AND LOW LEVEL TEMPS WILL
AID IN WARMING TEMPERATURES. HAVE WENT AHEAD AND RAISED
TEMPERATURES FOR TODAY AND FRIDAY FOR A FEW LOCATIONS...ESPECIALLY
ACROSS THE DELTA WHERE RIDGING WILL BE STRONGEST. OVER THESE
LOCATIONS TEMPERATURES SHOULD REACH THE UPPER 90S WITH MIDDLE 90S
EXPERIENCED ELSEWHERE. /14/
LONG TERM
MAIN FOCUS FOR THE EXTENDED WILL BE WITH HIGH TEMPS AND
THE HEAT. THE AREA WILL SEE THE UPPER RIDGE PEAK ON FRI AND THEN SEE
THE CENTER RETROGRADE FOR THE REST OF THE WEEKEND INTO NEXT WEEK.
THIS WILL ALLOW FOR THE LOW LEVEL FLOW TO BECOME OUT OF THE W/NW FOR
AN EXTENDED PERIOD OF TIME AND REALLY PUSH IN EXTREMELY WARM
925/850MB TEMPS. THE AREA SHOULD SEE 925MB TEMPS 27-30C AND 850MB
TEMPS 21-23C FROM SUN THROUGH AT LEAST TUE. USING THESE
VALUES...CLIMO SUGGESTS 98-102 DEGREES EASILY FOR A FEW DAYS.
LOCALIZED EFFECTS WILL LIKELY RESULT IN A FEW LOCATIONS PEAKING
HIGHER...BUT AT THIS POINT...GETTING THE FORECAST IN THE BALLPARK IS
THE BEST COURSE OF ACTION WHILE FORECASTING NEAR RECORD TYPE HEAT.
GUID TEMPS SUPPORT THIS...BUT ARE LIKELY NOT WARM ENOUGH IN MOST
LOCATIONS. I HAVE CONTINUED THE TREND OF RAISING MAX TEMPS ABV GUID.
AS FOR WHAT THE HEAT INDEX WILL BE...THAT'S A TOUGHER QUESTION.
LATEST GUID SUGGESTS THAT SAT-MON...SOLID MIXING WILL OCCUR AND SFC
DEWPTS WILL LIKELY DROP INTO THE 63-68 DEGREE RANGE. IF THIS
OCCURS...THEN HEAT INDEX VALUES WILL BE HELD IN CHECK AND ONLY TOP
OUT BETWEEN 100-105 DEGREES. IF SFC DEWPTS CAN HOLD IN THE UPPER 60S
TO AROUND 70...THEN VALUES >105 WILL BE POSSIBLE. EITHER WAY...IT
WILL BE HOT AND A PORTION...IF NOT ALL...OF THE CWA MAY NEED A HEAT
ADV AT SOME POINT. DETAILS WILL DETERMINE THAT IN THE COMING DAYS.
AS FOR NOW...I WILL CONTINUE TO MENTION THE HEAT IN THE HWO.
AS FOR PRECIP POTENTIAL...THE WAY THINGS LOOK NOW...NO REAL DAY HAS
ANY DECENT SHOT. GUID WANTS TO HOLD ONTO BETTER 850MB MOISTURE ON
SAT...ESPECIALLY ACROSS THE EAST...BUT FEEL THAT IS THE ONLY
POSITIVE FOR SUPPORTING CONVECTION. GUID POPS SEEMED GOOD AND HAVE
FOLLOWED. LOOK FOR 10% IN THE WEST TO 30% IN THE EAST. DRIER LOW
LEVEL AIR IS EXPECTED TO MOVE IN FOR SUN-TUE AND THE HEAT WILL
REALLY BE ON. FOR THIS PERIOD...I HAVE ONLY GONE WITH 10% POPS FOR
THE AFTERNOON AND EARLY EVENING. BY WED...THINGS BEGIN TO CHANGE
SOME AS SLIGHTLY BETTER MOISTURE MOVES IN AS LOW LEVEL FLOW BECOME
MORE OUT OF THE SW/S. ADDITIONALLY...THE POSSIBILITY OF A S/W OR TWO
MAY DROP S/SE OUT OF THE PLAINS AS NW FLOW WILL BE IN PLACE. AS IS
THE CASE WITH THIS TYPE OF PATTERN AND EXTREME TEMPS...ANY
CONVECTION IN THE MON-WED TIMEFRAME WILL HAVE TO BE WATCHED CLOSELY
AS SOLID LAPSE RATES WILL EXIST. /CME/
AVIATION
VFR FLIGHT CATEGORIES WILL PREVAIL THROUGH THE NEXT 24
HOURS. A FEW SITES MAINLY OVER THE EAST WILL EXPERIENCE SOME MVFR TO
IFR PATCHY FOG THIS MORNING DUE TO MOIST GROUNDS. THIS WILL MAINLY BE
BETWEEN 09-14Z AND SHOULD QUICKLY LIFT AFTER SUNRISE. ISOLATED
SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE OVER THE AREA
TODAY...MAINLY FOR AREAS SOUTH OF THE INTERSTATE 20 CORRIDOR. THIS
COULD BRING BRIEF PERIODS OF LOWERED FLIGHT CATEGORIES. ANY ACTIVITY
THAT DEVELOPS THIS AFTERNOON SHOULD QUICKLY DISSIPATE THIS
EVENING...LEAVING A QUIET NIGHT FOR THE ENTIRE REGION. /14/
PRELIMINARY POINT TEMPS/POPS
JACKSON 94 72 95 73 / 16 9 20 11
MERIDIAN 94 70 94 71 / 20 11 20 18
VICKSBURG 96 73 94 73 / 16 10 22 9
HATTIESBURG 95 72 96 72 / 24 15 21 23
NATCHEZ 93 72 93 73 / 24 13 24 16
GREENVILLE 97 72 97 73 / 11 8 23 6
GREENWOOD 94 73 96 74 / 14 8 23 10
JAN WATCHES/WARNINGS/ADVISORIES
MS...NONE.
LA...NONE.
AR...NONE.
14/CME
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