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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS62 KFFC 171951
AFDFFC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
351 PM EDT FRI MAY 17 2013

.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
-- Changed Discussion --
SCATTERED TO BROKEN CLOUD COVER PREVAILED OVER NORTH AND CENTRAL GA
AT THIS TIME WITH A FEW LIGHT SHOWERS. THE UPPER LEVEL TROUGH OVER THE
MS RIVER VALLEY HAS ASSOCIATED SHORT WAVES ROTATING THROUGH NORTH AL
AND CENTRAL TN WITH NUMEROUS SHOWERS AND SCATTERED TSTMS. MOST MODELS
ARE IN AGREEMENT THE TROUGH WILL GRADUALLY MOVE EAST THROUGH
SATURDAY NIGHT. THE UPPER LEVEL DISTURBANCES WILL COMBINE WITH
ADEQUATE GULF MOISTURE...PWS AROUND 1.5 INCHES...TO SPREAD NUMEROUS
SHOWERS AND SCATTERED TSTMS OVER THE NORTH HALF OF GA. WILL LEAN
TOWARD THE NAM...HRRR AND LOCAL WRF MODEL SOLUTIONS WHICH EXPECT THE
SHOWERS AND A FEW TSTMS TO ENTER NORTHWEST GA TONIGHT AND OVER MOST
OF NORTH GA BY MIDNIGHT. THE TSTM POTENTIAL SHOULD DIMINISH TO
ISOLATED LATER TONIGHT AS THE RAIN COOLED AIR STABILIZES THE AIRMASS
OVER THE STATE. DIURNAL HEATING ON SATURDAY WILL TRIGGER ADDITIONAL
TSTMS IN THE AFTERNOON AND EVENING WITH MUCAPES IN THE 1500-2000
J/KG RANGE. A SLIGHT RISK OF SEVERE TSTMS WILL BE POSSIBLE...MAINLY
OVER NORTHWEST GA DUE TO THE CLOSE PROXIMITY OF THE UPPER LEVEL
TROUGH. QPF AMOUNTS OF 1 TO 1.5 INCHES ARE EXPECTED OVER NORTH GA
WITH 0.75 INCH OR LESS OVER CENTRAL GA. TEMPORARY STREET FLOODING WILL
BE POSSIBLE WITH PERIODS OF HEAVY RAIN...HOWEVER CREEK OR RIVER
FLOODING SHOULD BE LIMITED UNLESS MORE QPF DEVELOPS IN A MUCH
SHORTER PERIOD OF TIME. A MET/MAV MOS BLEND WAS USED FOR MIN AND MAX
TEMPS.

16


.LONG TERM /SUNDAY THROUGH FRIDAY/...
SHORTWAVE IS IN THE PROCESS OF SHIFTING EAST OF THE CWA ON
SUNDAY...SO THIS...IN ADDITION TO PLENTY OF MOISTURE ACROSS THE
CWA AND FORECAST MUCAPE AROUND 3000 J/KG WILL ALLOW FOR THE TREND
OF SHOWERS AND THUNDERSTORMS TO CONTINUE INTO SUNDAY. HAVE
EXTENDED LIKELY POPS FURTHER WEST THAN PREVIOUS FORECAST FOR
SUNDAY. WITH UPPER RIDGE BUILDING IN FOR MONDAY AND
TUESDAY...POPS DECREASE...BUT THERE IS ENOUGH MOISTURE AROUND TO
KEEP SLIGHT CHANCE TO CHANCE POPS. GFS AND ECMWF STILL DIFFER
WITH MID-WEEK FRONTAL BOUNDARY WITH THE ECMWF FASTER THAN THE GFS
IN THE 12Z RUN. GIVEN DIFFERENCES...HAVE CONTINUED THE TRENDS
ADVERTISED IN THE PREVIOUS FORECAST. THE PREVIOUS DISCUSSION FOLLOWS.

11

LONG TERM /SATURDAY THROUGH THURSDAY/...
MODELS IN GENERAL AGREEMENT FOR SATURDAY TARGETING THE AREA WITH
SCATTERED TO NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS. THIS
DUE TO THE INFLUENCE OF UPPER LOW PRESSURE MOVING TO THE OH/TN
VALLEY AREAS AND THE MAIN UPPER TROUGH AFFECTING GA. WHILE N GA IS
TARGETED WITH THE HIGHEST POPS...INSTABILITY ACROSS THE AREA WILL
ALLOW FOR SCATTERED SHOWERS/STORMS ACROSS CENTRAL GA AS WELL. EVEN
WITH CLOUDS AND PRECIP CHANCES...A WARM AIRMASS IN PLACE WILL
ALLOW FOR HIGH TEMPERATURES NEAR NORMAL.

UPPER SYSTEM IN THE PROCESS OF PASSING THE AREA FOR SUNDAY BUT STILL
PLENTY OF MOISTURE AND INSTABILITY IN PLACE FOR SCATTERED TO
NUMEROUS SHOWERS AND SCATTERED THUNDERSTORMS. MODELS IN SOME
DISAGREEMENT FOR MONDAY WITH THE GFS WETTER THAN THE EUROPEAN AS THE
EUROPEAN HAS A STRONGER DRIER UPPER RIDGE MOVING OVER THE AREA THAN
THE GFS. GFS CONTINUES TO BE WETTER ON TUESDAY THAN THE EUROPEAN
WITH THE INFLUENCE OF AN UPPER RIDGE OVER THE AREA. STILL PLENTY OF
MOISTURE AND INSTABILITY FOR SOME AFTERNOON/EVENING CONVECTION.
INFLUENCE OF THE UPPER RIDGE DIMINISHES ON WEDNESDAY AS A COLD FRONT
MOVES ACROSS THE MID U.S. THIS WILL ALLOW FOR THE CHANCES OF SHOWERS
AND STORMS ACROSS THE AREA WITH CHANCES A LITTLE HIGHER ACROSS THE
N. GFS/EUROPEAN IN DISAGREEMENT WITH THE FRONT ON THURSDAY WITH THE
GFS MOVING THE FRONT INTO THE AREA AND THE EUROPEAN KEEPING THE
FRONT WELL TO THE NW. MOISTURE AND INSTABILITY WILL AGAIN COMBINE
FOR A CHANCE OF SHOWERS AND STORMS. A WEAK FRONT WILL LIKELY BE IN
THE AREA ON FRIDAY WITH AT LEAST SMALL CHANCES FOR SHOWERS AND
STORMS. TEMPERATURES GENERALLY RUNNING NEAR TO ABOVE NORMAL.

BDL
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&&

.AVIATION...
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18Z UPDATE...
THE UPPER LEVEL TROUGH OVER THE MIDDLE MS RIVER VALLEY CONTINUED
TO PRODUCE SHRA/TSRA OVER AL/TN. THE CONVECTION WILL GRADUALLY
MOVE EAST THROUGH THE NEXT 24 HOURS. EXPECT VFR CONDITIONS TO
PREVAIL AT ATL WITH -SHRA MOVING IN AROUND 03Z AND CONTINUING WITH
A CHANCE OF -TSRA AFTER 16Z. THERE WILL BE THE POSSIBILITY OF A
BRIEF MVFR CIG OF 1200 FT AROUND SUNRISE. SURFACE WINDS OF S-SW 10
KNOTS OR LESS WILL PREVAIL.

//ATL CONFIDENCE...18Z UPDATE...
MEDIUM CONFIDENCE ON ALL ELEMENTS.
-- End Changed Discussion --

&&

.PRELIMINARY POINT TEMPS/POPS...
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ATHENS          64  82  64  82 /  40  60  70  60
ATLANTA         64  81  65  82 /  60  60  70  60
BLAIRSVILLE     59  73  57  78 /  70  80  80  70
CARTERSVILLE    64  80  64  82 /  70  70  80  60
COLUMBUS        66  85  67  86 /  50  50  50  30
GAINESVILLE     63  79  64  80 /  60  70  70  60
MACON           64  84  64  85 /  20  40  40  50
ROME            64  80  64  83 /  80  80  80  60
PEACHTREE CITY  62  80  63  84 /  60  50  60  60
VIDALIA         66  87  67  86 /  30  30  30  50
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&&

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

$$

SHORT TERM...16
LONG TERM....11/BDL
AVIATION...16