000 
FXUS64 KMEG 051003
AFDMEG

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEMPHIS TN
503 AM CDT SAT SEP 5 2009

.DISCUSSION...

EXCESSIVE RAINFALL/FLASH FLOODING...STRONG THUNDERSTORMS...AND RAIN
CHANCES THIS HOLIDAY WEEKEND ARE THE MAIN CONCERNS.

LATEST MODELS WERE IN FAIR AGREEMENT. USED A BLEND OF MAINLY THE
00Z GFS/ECMWF MODELS.

THE ONLY SIGNIFICANT CHANGE TO THE PREVIOUS FORECAST WAS TO
INCREASE RAIN CHANCES AND ADD HEAVY RAINFALL MENTION TODAY NORTH
OF A HARRISBURG AR TO DYERSBURG TN LINE.

AT 5 AM CDT ACROSS THE MIDSOUTH AND FORECAST AREA...MAINLY RAINFREE
CONDITIONS WERE OCCURRING WITH SURFACE TEMPERATURES IN THE 60S.
NUMEROUS SHOWERS/STORMS WERE NEAR THE AR/MO LINE MOVING EAST.
PATCHY DENSE FOG WAS OCCURRING NEAR THE TN RIVER AND FAR NE MS
WHERE SKIES WERE MOSTLY CLEAR. A MID LEVEL LOW PRESSURE
DISTURBANCE/SHORT WAVE WAS OVER SOUTHERN MO.

TODAY...THE FIRST CONCERN IS EXCESSIVE RAINFALL/FLASH FLOODING
THREAT NORTH OF I-40...PARTICULARLY NORTH OF A HARRISBURG AR TO
DYERSBURG TN LINE. CURRENT BAND OF STORMS NEAR MO/AR LINE WILL
SLOWLY MOVE EAST AND PROBABLY MAINTAIN ITSELF WITH 850 MB JET
15-25 KTS. WITH PW 1.5-1.7 IN...ABOUT 120-140 PERCENT OF
NORMAL...A LOCALIZED FLASH FLOODING THREAT EXISTS OVER NE AR...MO
BOOTHEEL...AND FAR NW TN. AT THIS TIME...DECIDED AGAINST FLASH
FLOOD WATCH FOR THESE AREAS WITH HIGH FLASH FLOOD GUIDANCE
VALUES...3-4 INCHES PER 3 HOURS AND AROUND 4 INCHES PER 6 HOURS.
WILL CONTINUE TO MONITOR. INCREASED RAIN CHANCES...ADDED HEAVY
RAINFALL MENTION TO ZONES...AND MENTIONED FLASH FLOODING/EXCESSIVE
RAINFALL IN HWO. APPEARS TO BE A WET DAY ACROSS THESE LOCATIONS
WITH SOME LOCATIONS GETTING 2 TO 4 INCHES OF RAINFALL WITH LOCALLY
HEAVIER AMOUNTS POSSIBLE.

ACROSS THE REST OF THE AREA TODAY...EXPECT ISOLATED TO SCATTERED
CONVECTION TO DEVELOP THIS AFTERNOON. DEEPER MOISTURE ACROSS
CENTRAL ALABAMA WITH PW 1.6-1.9 INCHES AND SURFACE DEWPOINTS
APPROACHING 70 DEGREES IS FORECAST TO SURGE NORTH/NORTHWEST.
THUS..INCREASED RAIN CHANCES OVER NE MS AS THINK BAND OF
SHOWERS/STORMS MAY MOVE INTO THESE AREAS THIS AFTERNOON. NOT
EXPECTING ALL DAY RAINS ALONG AND SOUTH OF I-40 WITH MANY MORE DRY
HOURS THAN WET ONES. NOT ALL PLACES WILL GET WET. WITH
SHOWERS/STORMS BEING SLOW MOVERS...HEAVY RAINFALL AND LOCALIZED
FLOODING ARE POSSIBLE. A FEW STRONG STORMS ARE POSSIBLE WITH
MODERATE INSTABILITY FORECAST...LIFTED INDICES -3 TO -6...WITH
GUSTY WINDS BEING THE MAIN HAZARD. CANNOT RULE A STRAY SEVERE
STORM...BUT WIDESPREAD ORGANIZED SEVERE STORMS ARE NOT EXPECTED
WITH WEAK SHEAR OVER THE AREA.

AS FOR TEMPERATURES TODAY...WENT BELOW MODEL GUIDANCE NORTH OF
I-40 WITH HIGHS MAINLY IN THE LOWER 80S. OTHERWISE...THINK
TEMPERATURES WILL REACH THE MID TO UPPER 80S. ANY LOCALIZED DENSE
FOG NEAR TN RIVER EARLY THIS MORNING WILL QUICKLY DISSIPATE WITH
DAYTIME HEATING. DO NOT THINK FOG WILL BE DENSE ENOUGH FOR DENSE
FOG ADVISORY.

TONIGHT...KEPT RAIN CHANCES OVER THE ENTIRE WITH MORE CONCERN FOR
HEAVY RAINFALL/FLASH FLOODING NORTH OF I-40. TIERED RAIN CHANCES
FROM 30 PERCENT SOUTH OF I-40 TO 60 PERCENT OVER NE AR AND MO
BOOTHEEL. CONCERNED ABOUT EXCESSIVE RAINFALL ACROSS NORTHERN AREAS
WITH PW VALUES INCREASING ABOVE 1.5 INCHES AND LOW LEVEL JET
INCREASING TO MAINTAIN CONVECTION. WOULD NOT BE SURPRISED IF
ADDITIONAL TRAINING OF SHOWERS/STORMS BRINGS 2 TO 4 OR MORE
ADDITIONAL INCHES OF RAINFALL TO A LOCALIZED AREA. MUGGY
CONDITIONS WITH LOWS IN THE MID TO UPPER 60S CAN BE EXPECTED.

SUNDAY...DEEPER MOISTURE AND BEST RAIN CHANCES ARE FORECAST TO
SHIFT EAST OF THE MS RIVER. INCREASED RAIN CHANCES TO LIKELY IN
THESE AREAS. ADDITIONAL HEAVY RAINFALL...LOCALIZED FLOODING...AND
STRONG STORMS ARE POSSIBLE. NOT EXPECTING ORGANIZED SEVERE STORMS.
MANY DRY HOURS ARE EXPECTED WEST OF I-55. CLOUDS AND RAIN SHOULD
KEEP HIGHS MAINLY IN THE LOWER TO MID 80S. 

SUNDAY NIGHT INTO LABOR DAY...SLIGHT MID LEVEL RIDGING FORECAST
WITH THE LOW PRESSURE DISTURBANCE/SHORT WAVE MOVING NORTHEAST OF
THE AREA MAY ALLOW FOR LOWER COVERAGE OF SHOWERS/STORMS...SO KEPT
LOWER RAIN CHANCES 20 TO 40 PERCENT. APPEARS AREAS NEAR TN RIVER
AND NE MS WILL HAVE THE HIGHEST RAIN CHANCES. A FEW STRONG STORMS
WITH HEAVY RAINFALL REMAIN POSSIBLE. IF STORMS DEVELOP...THE
SEVERE POTENTIAL MAY BE SLIGHTLY HIGHER WITH HIGHER INSTABILITY
AND MORE MID LEVEL DRY AIR TO ENHANCE DOWNDRAFTS...BUT WEAK SHEAR
WILL KEEP CONVECTION PULSY AND UNORGANIZED. MODEL GUIDANCE LOWS IN
THE 60S AND HIGHS MAINLY IN THE MID 80S.

MONDAY NIGHT THROUGH FRIDAY...MID LEVEL RIDGING SHOULD LIMIT 
MOST CONVECTION. 00Z GFS WAS WETTER THAN THE 00Z ECMWF. KEPT 20
PERCENT FOR MAINLY AFTERNOON CONVECTION AS THE AIR WILL REMAIN
WARM...MOIST...AND UNSTABLE. WOULD NOT BE SURPRISED IF SOME DAYS
DURING THIS TIME FRAME WERE COMPLETELY DRY. TEMPERATURES WILL BE
NEAR NORMAL WITH HIGHS IN THE MID TO UPPER 80S AND LOWS IN THE
60S. FOGGY MORNINGS ARE POSSIBLE WITH ABUNDANT LOW LEVEL MOISTURE
AND GOOD NIGHTTIME RADIATIONAL COOLING AS THE NIGHTS GET LONGER.

MBS

&&

.AVIATION...

06Z TAF CYCLE

RAIN IN THE NORTHWEST ZONES AND TAFS...FOG ELSEWHERE.  THUNDERSTORMS 
WILL SLOWLY MOVE THROUGH JONESBORO THIS MORNING.  THESE STORMS 
SHOULD MAKE IT TO MEMPHIS...HOWEVER...CONFIDENCE LOW AS STORMS MAY 
WEAKEN BEFORE GETTING TO MEMPHIS.  LINE SHOULD WEAKEN ENOUGH THAT 
FELT SHOULD LEAVE JACKSON DRY FOR PERIOD.

IFR CONDITIONS AT TIMES IN JACKSON...MOST OTHER PLACES WILL SEE MVFR 
CONDITIONS WITH THE FOG.  MEMPHIS NOT EXPECTED TO HAVE ANY FOG.

SHOWERS AND THUNDERSTORMS WILL DEVELOP AGAIN ON SATURDAY 
AFTERNOON...EXPECT MOST OF SHOWERS TO DEVELOP WEST OF MISSISSIPPI 
RIVER.  SOME SHOWERS WILL MOVE INTO MEMPHIS AREA.  TLSJR

&&

.PRELIMINARY POINT TEMPS/POPS...
MEM  87  69  84  68 /  40  40  50  30 
MKL  85  67  82  65 /  30  40  70  40 
JBR  83  67  83  64 /  70  60  50  30 
TUP  87  68  84  67 /  50  40  70  40 

&&

.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&

$$