Scientific Forecaster Discussion

NWS Discussion
			
				
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
140 AM EDT THU MAY 23 2013


.UPDATE...
QUICK UPDATE TO GRIDS. APPEARS COVERAGE OF TSRA OVER ERN AL AND
WRN GA LOWER THAN MODEL FCSTS. WILL BACK OFF ON POPS. MLCAPE
PRETTY STOUT WITH VALUES 1500-2000 J/KG AND 0-6KM BULK SHEAR
AROUND 20-30KTS. APPARENTLY FORCING AND LOCALIZED LIFT IS LACKING.
WILL CONTINUE TO MONITOR.

SNELSON

&&

.PREV DISCUSSION... /ISSUED 350 PM EDT WED MAY 22 2013/ 

SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/...
AFTERNOON CONVECTION EXPECTED TO INCREASE IN COVERAGE AND PERSIST 
INTO THE EVENING AND OVERNIGHT HOURS AS UPPER LEVEL TROUGH MOVES 
THROUGH THE MISSISSIPPI VALLEY. CONVECTION EXPECTED TO BECOME MORE 
ORGANIZED AS ASSOCIATED SHORT WAVE FOCUSES DEVELOPMENT. MODELS A 
LITTLE INCONSISTENT WITH THE DEVELOPMENT AND/OR PROGRESSION OF THE 
ORGANIZED PRECIPITATION...BUT WITH INCREASING 
INSTABILITIES...DIURNAL HEATING...AND INCREASING SHEAR ACROSS THE 
AREA...FEEL THERE IS ENOUGH TO SUPPORT GOOD CHANCE TO LIKELY 
POPS...ESPECIALLY ACROSS NORTH GEORGIA. HAVE CONTINUED MENTION OF 
POSSIBLE SEVERE STORMS...ACCOMPANIED WITH GUSTY WINDS AND SMALL 
HAIL...IN THE GRIDS THROUGH 02Z TONIGHT ACROSS NORTH 
GEORGIA...GENERALLY NORTH OF THE ATL METRO AREA. HAVE ALSO 
QUICKLY TAPERED OFF EVENING AND OVERNIGHT POPS INTO THURSDAY 
MORNING...WITH GENERALLY SLIGHT CHANCE POPS ACROSS THE AREA THROUGH 
THE DAY THURSDAY AS SHORT WAVE PUSHES INTO THE CAROLINAS.

AS PREVIOUSLY MENTIONED...THE SEVERE THREAT IS PRIMARILY CONFINED TO 
NORTH GEORGIA...THOUGH STRONG STORMS CAN BE EXPECTED ACROSS MUCH OF 
THE CWA. THE PRIMARY CONCERNS IN SEVERE ACTIVITY WILL BE GUSTY WINDS 
TO 60 MPH OR HIGHER...1 INCH HAIL OR HIGHER...FREQUENT LIGHTNING AND 
PERIODS OF HEAVY RAINFALL. GUSTY WINDS AND SMALL HAIL ARE ALSO 
POSSIBLE IN THE STRONGER STORMS.

PRESSURE GRADIENT TIGHTENS THURSDAY AFTERNOON AND INTO FRIDAY...WITH 
WINDS 10 TO 15 MPH WITH GUSTS NEAR 20 MPH...ESPECIALLY ACROSS 
NORTHERN AND EASTERN GEORGIA.

FOR THE TEMPERATURES..HAVE GENERALLY GONE WITH A GUIDANCE BLEND. 
TEMPERATURES THURSDAY MORNING ARE EXPECTED TO BE IN THE 60S...AND 
DEPENDING ON THE TIMING OF THE DIMINISHING CONVECTION AND CLOUDS OUT 
OF THE AREA...THIS COULD IMPACT MORNING LOWS BY A FEW DEGREES. 
TEMPERATURES WILL BE BACK IN THE LOW TO MID 80S THURSDAY AFTERNOON 
BEFORE COOLING BY FRIDAY.

31

LONG TERM /FRIDAY THROUGH WEDNESDAY/...
NO MAJOR CHANGES MADE TO THE EXTENDED PORTION OF THE FORECAST. A MUCH
DRIER AIRMASS MOVES OVER THE AREA FRIDAY WITH DRY NW FLOW ALOFT
AND SURFACE HIGH PRESSURE BUILDING OVER THE OH/TN VALLEYS DURING
THE DAY. GRADIENT WINDS WILL INCREASE GETTING CLOSE TO WIND
ADVISORY CRITERIA(20 MPH SUSTAINED) FOR SOME AREAS. DRY CONDITIONS
SHOULD CONTINUE THROUGH THE WEEKEND EVEN WITH SLIGHT DIFFERENCES
BETWEEN THE GFS AND ECMWF. THE NW FLOW ALOFT N OF THE AREA IS
EXPECTED TO BECOME MORE ACTIVE WITH INCREASED PRECIP CHANCES NORTH
OF THE STATE...BUT IT SHOULD STAY DRY ACROSS GA. LOOKS LIKE THE
BETTER MOISTURE FINALLY MOVES IN ACROSS THE AREA BY THE BEGINNING
OF NEXT WEEK SO WILL SLOWLY INCREASE CHANCES OF POPS MON THROUGH DAY
7. TEMPERATURES GENERALLY RUNNING WITHIN 5 DEGREES OF NORMAL
THROUGH THE PERIOD EXCEPT SATURDAY ND SUNDAY MORNING LOWS ARE
RUNNING 10-15 DEGREES BELOW NORMAL.

01

&&

.AVIATION...
06Z UPDATE...
SHOWERS/THUNDERSTORMS HAVE MOVED PAST ALL TAF SITES EXCEPT ATHENS 
AND MACON. SOME SCT TO BKN040 TO LINGER FOR THE REMAINDER OF THE 
NIGHT. EXPECT VFR AFTER SUNRISE WITH SCT040-050. MVFR AND POSSIBLY 
IFR FOG EXPECTED UNTIL 14Z MAINLY FOR PDK...AHN...MCN. ONLY ISOLATED 
CONVECTION MAINLY NORTH AND EAST OF TAF SITES TODAY. WINDS WILL 
BECOME NORTHWEST 10KT AFTER SUNRISE WITH GUSTS TO 20-25KT POSSIBLE. 

//ATL CONFIDENCE...06Z UPDATE...
MEDIUM CONFIDENCE ON IFR FOG THIS MORNING. 
HIGH CONFIDENCE ON ALL OTHER ELEMENTS.

41

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          65  85  59  79 /  60  20   5   0 
ATLANTA         66  83  59  76 /  70  10   5   0 
BLAIRSVILLE     61  78  54  71 /  70  20  10   0 
CARTERSVILLE    64  83  57  76 /  70  10   5   0 
COLUMBUS        68  89  63  82 /  70  10   5   0 
GAINESVILLE     64  82  57  75 /  70  10   5   0 
MACON           66  89  60  83 /  60  20   5   0 
ROME            64  84  57  77 /  50  10   5   0 
PEACHTREE CITY  64  85  58  77 /  70  10   5   0 
VIDALIA         68  89  65  88 /  40  20   5   0 

&&

.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM...SNELSON
LONG TERM....BAKER
AVIATION...SNELSON