Severe Thunderstorm Warning 131, NWS Atlanta, GA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
333 PM EDT THU JUN 7 2007

.SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/...
UPPER RIDGE REMAINS THE MAIN FEATURE ALOFT FOR THE SHORT TERM AND
EXTENDED. GFS FLUCTUATES FROM RUN-TO-RUN ON EXACTLY WHERE THE CENTER
OF THE UPPER RIDGE WILL BE...BUT IN ESSENCE THE RIDGE REMAINS OVER
THE SOUTH CENTRAL AND SOUTHEAST U.S...KEEPING THE MAIN DYNAMICS
ACROSS THE NORTHERN STATES. AS EXPECTED YESTERDAY...DEEP LOW-LEVEL
MOISTURE SURGED NORTHWARD EARLY TODAY. SFC DEWPOINTS HAVE RISEN A
GOOD 10 TO 15 DEGREES IN THE PAST 24 HRS...WITH 65-70 COMMON
ACROSS MUCH OF THE CWA. THIS COMBINED WITH TEMPERATURES AROUND 90
HAVE ALLOWED FOR DEVELOPMENT OF ISOLATED TO SCATTERED
CONVECTION...MAINLY ACROSS WEST CENTRAL AND CENTRAL
GEORGIA...CLOSEST TO THE BEST GULF MOISTURE FEED. HOWEVER...WARMING
ALOFT OF +5C IN THE 600-400MB LAYER HAS REALLY PUT A LID ON TSRA
SO FAR TODAY. THE FREEZING LEVEL IS AROUND 16000 FT AND ECHO TOPS
HAVE GENERALLY BEEN IN THE 15000-20000 FT RANGE...SO MOSTLY JUST
TROPICAL +SHRA SO FAR. THE SEVERE WEATHER THREAT APPEARS MINIMAL
FOR TODAY...BUT LOCALLY HEAVY RAIN CAN BE EXPECTED...WHICH SHOULD
NOT BE A PROBLEM GIVEN THE VERY DRY GROUND IN MOST AREAS. THE
ACTIVITY SHOULD DIMINISH QUICKLY WITH THE LOSS OF DAYTIME HEATING
AND THE RUC MODEL DEPICTS THIS WELL. FOR FRIDAY...THE TAIL END OF
THE FRONT...NOW MOVING THROUGH THE GREAT LAKES AND
NORTHEAST...WILL MOVE TO NEAR THE TN/GA BORDER BY FRI NIGHT AND
THEN WASH OUT SOMEWHERE IN NORTH GA SAT. CURRENT INDICATION IS
THAT THIS WILL COME THROUGH NORTH GA AFTER 06Z SAT...A MINIMAL
DIURNAL CONVECTION TIME. IT IS VERY DIFFICULT TO FIND THE FEATURE
SAT AFTER THAT..BUT THE MODEL WIND FIELDS SUGGEST THAT IT WILL BE
LOCATED SOMEWHERE ACROSS CENTRAL GA AT THAT TIME. AS THE UPPER
RIDGE BACKS OFF TO THE WEST...THIS WOULD SUPPORT MORE SOUTHWARD
MOVEMENT OF THE FRONT. THE GFS IS INSISTENT ON CONSIDERABLY DRYING
OF THE ATMOSPHERE FROM NORTH TO SOUTH OVER THE WEEKEND AND INTO
MONDAY. THE BIG QUESTION IS WILL THE FRONT ENHANCE CONVECTION LATE
FRI-SAT ACROSS THE CWA. THE AIR MASS WILL BE VERY UNSTABLE EACH
AFTERNOON WITH GFS MUCAPE IN EXCESS OF 4000 J/KG AND LIS IN THE -4
TO -6 RANGE. THUS...I AM CONFIDENT THAT THE FRONT WILL PROVIDE
ENOUGH FOCUS FOR SCATTERED DIURNAL CONVECTION...IN THE NORTH
FRIDAY AND AREAWIDE SATURDAY. THERE IS EVEN THE POTENTIAL FOR SOME
ACTIVITY TO LINGER OVERNIGHT FRI NIGHT GIVEN THE WEAK LIFT
PROVIDED BY THE FRONT. HAVE KEPT POPS IN THE CHANCE CATEGORY UNTIL
THERE IS A BETTER INDICATION OF WIDESPREAD CONVECTION...WHICH NONE
OF THE MODELS ARE ADVERTISING AT THIS TIME. MAV/MET/FWC MOS TEMPS
VERY SIMILAR AND GENERALLY ACCEPTED. MINS WILL BE QUITE
MILD...MOSTLY NEAR 70. FOR MAX TEMPS...WENT A LITTLE COOLER THEN MAV MOS
FOR SAT-SUN GIVEN EXPECTED INCREASE CLOUD COVER AND SHRA/TSRA
ACTIVITY. MAV MOS FOR RMG GENERALLY TOO HIGH THROUGH THE PERIOD
AND LOWERED 3-5 DEGREES MOST DAYS.

.LONG TERM /SUNDAY THROUGH THURSDAY/...
GFS COMING INTO LINE BETTER WITH THE ECMWF/UKMET WITH RESPECT TO
THE UPPER RIDGE NEXT WEEK. NOW SHOWING IT NOT MAKING AS MUCH
PROGRESS TO THE WEST AS INDICATED IN MODEL RUNS YESTERDAY. THIS
HINGES ON STRONGER ENERGY INTO THE SW U.S. WHICH WILL MOVE THE
RIDGE BACK FURTHER EAST JUST AS IT IS TRYING TO RETROGRADE WEST.
GIVEN THAT THIS HAS BEEN THE RULE THE PAST COUPLE OF
MONTHS...CANNOT ARGUE WITH THIS AND MODELS GENERALLY IN GOOD
AGREEMENT ON THIS OCCURRING. NORTHERLY FLOW ALOFT STRENGTHENS OVER
THE EASTERN U.S. NEXT WEEK...AS THE UPPER RIDGE AMPLIFIES IN
RESPONSE TO DEEPENING LOW PRESSURE IN THE NORTH ATLANTIC AND A
DEEP TROUGH INTO THE CENTRAL ATLANTIC. NORMALLY THIS WOULD BE A
DRY WEATHER PATTERN FOR THE AREA. HOWEVER...THE GFS CONTINUES TO
SHOW A BACKDOOR FRONT INTO THE AREA TUE-WED AND A DISTURBANCE
RIDING OVER THE HIGH AMPLITUDE RIDGE FROM THE OHIO VALLEY INTO THE
SE U.S. AT THE SAME TIME. THIS PATTERN ALSO SUPPORTS COOLING
ALOFT...WHICH WILL INCREASE THE LAPSE RATES AND HENCE INSTABILITY.
THUS...CONDITIONS APPEAR AMPLE FOR CONTINUED DAILY DIURNAL
CONVECTION. WITH NO REAL CLEAR FOCUS FOR CONVECTION HAVE JUST
OPTED FOR MAINLY DIURNAL LOW CHANCE POPS THROUGH THE EXTENDED.
WITH UPPER RIDGE OVER AREA...MAX TEMPS SHOULD REMAIN NEAR OR ABOVE
NORMAL. 12Z MEX QUITE A BIT WARMER THAN THE 00Z MEX...SO RAISED
MAX TEMPS A FEW DEGREES.

&&

.PRELIMINARY POINT TEMPS/POPS...
ATHENS          69  90  68  89  68 /  20  20  20  30  10
ATLANTA         71  89  71  87  70 /  20  20  20  30  20
BLAIRSVILLE     64  85  64  84  61 /  20  30  20  30  10
CARTERSVILLE    67  89  66  87  64 /  20  30  20  30  10
COLUMBUS        72  93  73  91  72 /  30  20  20  40  20
GAINESVILLE     70  89  69  87  68 /  20  30  20  30  10
MACON           71  93  70  92  71 /  30  20  20  40  20
ROME            69  90  69  87  65 /  20  30  20  30  20
PEACHTREE CITY  66  90  67  89  65 /  20  20  20  30  20
VIDALIA         74  91  70  92  72 /  30  20  20  40  20

&&

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

19/17

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
611 AM EDT THU JUN 7 2007

GAZ001>009-011>016-019>025-027-030>039-041>062-066>076-078>086-
089>098-102>113-081015-
BALDWIN-BANKS-BARROW-BARTOW-BIBB-BLECKLEY-BUTTS-CARROLL-CATOOSA-
CHATTAHOOCHEE-CHATTOOGA-CHEROKEE-CLARKE-CLAYTON-COBB-COWETA-
CRAWFORD-CRISP-DADE-DAWSON-DEKALB-DODGE-DOOLY-DOUGLAS-EMANUEL-
FANNIN-FAYETTE-FLOYD-FORSYTH-GILMER-GLASCOCK-GORDON-GREENE-
GWINNETT-HALL-HANCOCK-HARALSON-HARRIS-HEARD-HENRY-HOUSTON-JACKSON-
JASPER-JEFFERSON-JOHNSON-JONES-LAMAR-LAURENS-LUMPKIN-MACON-
MADISON-MARION-MERIWETHER-MONROE-MONTGOMERY-MORGAN-MURRAY-
MUSCOGEE-NEWTON-NORTH FULTON-OCONEE-OGLETHORPE-PAULDING-PEACH-
PICKENS-PIKE-POLK-PULASKI-PUTNAM-ROCKDALE-SCHLEY-SOUTH FULTON-
SPALDING-STEWART-SUMTER-TALBOT-TALIAFERRO-TAYLOR-TELFAIR-TOOMBS-
TOWNS-TREUTLEN-TROUP-TWIGGS-UNION-UPSON-WALKER-WALTON-WARREN-
WASHINGTON-WEBSTER-WHEELER-WHITE-WHITFIELD-WILCOX-WILKES-
WILKINSON-
611 AM EDT THU JUN 7 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH AND CENTRAL GEORGIA.

.DAY ONE...TODAY AND TONIGHT
ISOLATED THUNDERSTORMS POSSIBLE ACROSS NORTH AND CENTRAL GEORGIA
THIS AFTERNOON AND EVENING.

.SYNOPSIS...
HIGH PRESSURE OVER THE WESTERN ATLANTIC...ALONG WITH A STRONG LOW
OVER THE NORTHER PLAINS HAS RESULTED IN SOUTHERLY LOW LEVEL FLOW
AND THE RETURN OF TROPICAL MOISTURE TO THE AREA.

.PRIMARY HAZARDS...
THE PRIMARY HAZARD FROM THUNDERSTORMS THIS AFTERNOON AND EVENING
WILL BE OCCASIONAL CLOUD-TO-GROUND LIGHTNING.

.DISCUSSION...
THE RETURN OF TROPICAL MOISTURE TO THE REGION WILL RESULT IN
MODERATE INSTABILITY ACROSS MOST OF NORTH AND CENTRAL GEORGIA WITH
DAYTIME HEATING. HOWEVER...UPPER LEVEL RIDGING AND THE LACK OF A
FOCUSING MECHANISM AT THE SURFACE SHOULD KEEP COVERAGE OF
THUNDERSTORMS LIMITED.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY
ISOLATED TO SCATTERED THUNDERSTORMS WILL BE POSSIBLE ACROSS NORTH
AND CENTRAL GEORGIA FRIDAY AND SATURDAY...CENTRAL GEORGIA
SUNDAY...AND NORTH AND CENTRAL GEORGIA MONDAY THROUGH WEDNESDAY.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION IS NOT EXPECTED THROUGH TONIGHT.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
410 PM EDT THU JUN 7 2007

GAZ078-089-072045-
410 PM EDT THU JUN 7 2007

...SIGNIFICANT WEATHER ALERT FOR PEA SIZED HAIL AND 45 MPH WINDS IN
MUSCOGEE AND HARRIS COUNTIES UNTIL 445 PM EDT...

AT 404 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM OVER COLUMBUS...MOVING NORTHEAST AT 25 MPH.

THIS STORM HAS THE POTENTIAL TO PRODUCE PEA SIZED HAIL...FREQUENT
CLOUD TO GROUND LIGHTNING AND WIND GUSTS TO 45 MPH AS IT MOVES ACROSS
MUSCOGEE AND HARRIS COUNTIES THROUGH 445 PM EDT. SOME LOCATIONS IN
THE PATH OF THIS STORM INCLUDE FORTSON...COLUMBUS...MIDLAND...
CATAULA...ELLERSLIE AND WAVERLY HALL. BRIEF HEAVY DOWNPOURS MAY CAUSE
PONDING OF WATER ON ROADWAYS.

SIGNIFICANT WEATHER ALERTS ARE ISSUED WHEN WINDS UP TO 57 MPH ARE
EXPECTED...HAIL IS EXPECTED TO BE LESS THAN THE SIZE OF PENNIES...OR
SIGNIFICANT CLOUD-TO-GROUND LIGHTNING IS EXPECTED.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
435 PM EDT THU JUN 7 2007

GAZ090-102-072100-
435 PM EDT THU JUN 7 2007

...SIGNIFICANT WEATHER ALERT FOR 1/2 INCH DIAMETER HAIL IN STEWART
AND CHATTAHOOCHEE COUNTIES UNTIL 500 PM EDT...

AT 431 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
STRONG THUNDERSTORMS FROM PROVIDENCE CANYON STATE PARK TO FORT
BENNING...MOVING NORTHEAST AT 10 MPH.

LIGHTNING DETECTION SYSTEMS INDICATE NUMEROUS CLOUD-TO-GROUND
LIGHTNING STRIKES ACROSS STEWART AND CHATTAHOOCHEE COUNTIES.
RESIDENTS IN THE AREA SHOULD REMAIN INDOORS UNTIL THE STORM HAS
PASSED. ELECTRICAL APPLIANCES AND TELEPHONES SHOULD NOT BE USED
UNLESS IN AN EMERGENCY.

SIGNIFICANT WEATHER ALERTS ARE ISSUED WHEN WINDS UP TO 57 MPH ARE
EXPECTED...HAIL IS EXPECTED TO BE LESS THAN THE SIZE OF PENNIES...OR
SIGNIFICANT CLOUD-TO-GROUND LIGHTNING IS EXPECTED.

19