Damaging Winds in South Carolina, April 20, 2009

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
943 PM EDT SUN APR 19 2009

.SYNOPSIS...
AS LOW PRESSURE OVER THE OHIO RIVER VALLEY MOVES NORTHEAST...A
TRAILING COLD FRONT WILL MOVE GRADUALLY EAST. THE COLD FRONT WILL
MOVE THROUGH THE AREA ON MONDAY AND OFF THE COAST BY TUESDAY. HIGH
PRESSURE WILL BUILD OVER THE AREA IN THE MIDDLE OF THE WEEK AND THEN
MOVE OVER THE ATLANTIC BY THE END OF THE WEEK.

&&

.NEAR TERM /THROUGH MONDAY/...
WATER VAPOR IMAGERY SHOWS THE STRONG UPPER VORTEX CHURNING THROUGH
WRN TN THIS EVENING. THE 18Z NAM INITIALIZED THIS FEATURE WELL AND
BRINGS THE AXIS OF BEST DVPA INTO THE SRN APPALACHIANS CIRCA
06Z...ALONG WITH IMPROVING UPPER JET DIVERGENCE. SHOWER COVERAGE
SHOULD BE CATEGORICAL ACROSS MUCH OF THE FORECAST AREA OVERNIGHT.
THE BEST PRE/FRONTAL CONVECTION UPSTREAM CONTINUES TO FIRE IN THE
AREA OF HIGHEST 850 MB EQUIVALENT POTENTIAL TEMPERATURE OVER AL.
THIS THETA E RIDGE IS EXPECTED TO PUSH EASTWARD AND CROSS THE SRN
TIER OF THE FORECAST AREA OVERNIGHT. DEWPOINTS HAVE ALREADY RISEN
INTO THE UPPER 50S ACROSS MUCH OF THIS SRN SECTION. FORTUNATELY...IT
APPEARS THAT 850 MB FLOW WILL VEER SLIGHTLY AS THE BETTER
INSTABILITY AXIS MOVES IN LATE. THUS...AGREE WITH THE LATEST SPC
OUTLOOK THAT SEVERE THREAT TO THE WEST MAY DIMINISH AS CONVECTION
MOVES INTO THE FORECAST AREA. SRN MTN PRECIPITATION COULD BE HEAVY
AT TIMES...BUT SHOULD BE BELOW CRITICAL GUIDANCE FOR ANY FLOODING.
THE MAIN CHANGE WILL BE TO INCREASE THE THUNDER COVERAGE INTO THE
CHANCE RANGE OVERNIGHT.

THE COLD FRONT WILL CROSS THE REGION FROM THE WEST MONDAY. A DEEP
DRY SLOT IS INDICATED WRAPPING INTO THE SW PART OF THE FORECAST AREA
DURING FROPA...SO A TONGUE OF LOWER POPS WILL BE FEATURED IN THIS
AREA BY MIDDAY. INSTABILITY SHOULD BE STRONGEST ALONG THE INTERSTATE
77 CORRIDOR MID TO LATE AFTERNOON...AND A FEW SEVERE THUNDERSTORMS
LOOK POSSIBLE GIVEN THE IMPROVING LAPSE RATES ALONG WITH THE ARRIVAL
OF DRY AIR ALOFT IN THE PROFILES. MAX TEMPS WILL BE NEAR OR SLIGHTLY
ABV NORMAL E OF THE MTNS...AND AT OR SLIGHTLY BELOW NORMAL IN THE
MTNS.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
AS OF 200 PM SUNDAY...THE PERIOD BEGINS MONDAY NIGHT WITH A MID AND
UPPER LEVEL LOW CENTERED TO THE NORTHWEST OF THE FA. THIS LOW IS
EXPECTED TO MEANDER NORTHEASTWARD ON TUESDAY BEFORE BECOMING AN OPEN
WAVE TUESDAY NIGHT. A TRAILING SHORTWAVE WILL DIVE DOWN THE WESTERN
SIDE OF THE LOW ON TUESDAY...PUSHING A CHANNELED PIECE OF VORT
ENERGY ACROSS THE WESTERN CAROLINAS. THE TROF AXIS WILL MOVE ACROSS
THE REGION TUESDAY NIGHT...TRANSLATING EAST OF THE AREA ON
WEDNESDAY. AT THE SURFACE...THERE WILL BE PLENTY OF LOW LEVEL
MOISTURE IN PLACE ACROSS THE FA MONDAY NIGHT THROUGH TUESDAY NIGHT
WITH VERY LITTLE LOW LEVEL FORCING. THE MAIN PERIOD FOR SHOWER
ACTIVITY IS EXPECTED TO BE TUESDAY AFTERNOON AS THE UPPER SHORTWAVE
AND ATTENDING VORT MAX MOVE ACROSS. HOWEVER...THE MAJORITY OF THE
SHOWER ACTIVITY SHOULD REMAIN CONFINED TO THE MOUNTAINS AS A DRIER
SUBCLOUD LAYER EXISTS IN THE FOOTHILLS AND PIEDMONT. OVERALL...LOOKS
TO BE A VERY LOW QPF EVENT WITH AT MOST A TENTH OF AN INCH EXPECTED.

A PERIOD OF UPSLOPE FLOW WILL MOVE IN TUESDAY NIGHT IN THE CAA
ALLOWING SNOW LEVELS TO FALL ACROSS THE NC MOUNTAINS. IN
FACT...MODELS SHOW THAT MUCH OF THE FA WILL BE IN SUB FREEZING H85
TEMPS BY 12Z WEDNESDAY. GIVEN THE LIGHT PRECIP AND AT BEST SCATTERED
COVERAGE OF RAIN AND SNOW SHOWERS...EXPECT ONLY A COUPLE TENTHS OF
ACCUMULATION IN ISOLATED HIGHER ELEVATION LOCATIONS. ALSO...COULD BE
SOME LIGHT FREEZE ISSUES AS ELEVATIONS ABOVE 4000 FEET OR SO DROP
BELOW FREEZING. OVERALL...TEMPS WILL RUN 5-6 DEGREES BELOW CLIMO
WITH CLOUD COVER AND CAA TUESDAY NIGHT.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
AS OF 1100 AM SUNDAY...THE OUTLOOK FOR THE MEDIUM RANGE IS TRANQUIL.
THE TROF EXITS THE EASTERN CONUS WEDNESDAY NIGHT AND THURSDAY AND
RIDGING BEGINS TO BUILD IN FOR THE WEEKEND. THE BELT OF WESTERLIES
GETS LIFTED WELL NORTH OF THE REGION LEAVING ONLY LIGHT MID AND
UPPER LEVEL FLOW UNDER THE INFLUENCE OF THE BUILDING RIDGE. AT THE
SURFACE...ANY SYSTEMS AND FRONTS ARE EXPECTED TO PASS BY THE NORTH
WITH HIGH PRESSURE IN CONTROL OVER THE WESTERN ATLANTIC AND EASTERN
SEABOARD. NO POPS ARE CARRIED IN THE FORECAST THROUGH SUNDAY. THE
MAIN STORY WILL BE THE MILD TEMPERATURES. WE SHOULD SEE A GOOD 10-12
DEGREE WARMING TREND FROM THURSDAY THROUGH SUNDAY. HIGHS START OUT
ON THURSDAY AT OR JUST BELOW NORMAL...WARMING TO THE LOW 80S BY
SUNDAY WHICH IS ABOUT 7-8 DEGREES ABOVE CLIMO.

&&

.AVIATION /02Z MONDAY THROUGH FRIDAY/...
AT KCLT...A SLOWER TREND IS INDICATED IN THE DESCENT TOWARD MVFR
CIGS ON THE LATEST MODEL PROFILES AND MOS SOURCES...WITH MVFR NOW
INDICATED AFT 07Z. SHOWER COVERAGE WILL FILL IN...WITH SOUTHERLY
FLOW INCREASING OVERNIGHT AND INSTABILITY SLOWLY IMPROVING WITH
RISING DEWPOINTS. WILL ADVERTISE CB CLOUD TYPE AFTER 07Z...BUT THE
BEST INSTABILITY WILL HOLD OFF UNTIL LATER IN THE PERIOD. CIGS WILL
LIKELY RECOVER TO VFR CIRCA 14Z...THEN STEEP LAPSE RATES WILL
PROVIDE THE BEST CHANCE OF THUNDER AND CB CLOUDS AFTER 18Z. WINDS
SHOULD GUST TO 20 KT OR BETTER ONCE MIXING KICKS IN MONDAY.

ELSEWHERE...MVFR CIGS WILL PERSIST OR DEVELOP FROM KAVL TO KHKY
FIRST THIS EVENING...WITH MVFR BECOMING LIKELY FROM KAND TO KGSP
AFTER MIDNIGHT. SHOWER COVERAGE WILL STEADILY GROW OVERNIGHT...BUT
INSTABILITY APPEARS LACKING FOR A SIGNIFICANT THUNDER THREAT. CB
CLOUD TYPES MAY BE NEEDED ON LATER UPDATES. SOUTHERLY FLOW SHOULD
BACK SLIGHTLY LATER THIS EVENING BEFORE TURNING SW AND BECOMING
GUSTY WITH MIXING MONDAY MORNING. THE MIXING SHOULD ALLOW CIGS TO
RECOVER TO VFR LEVELS. SOUNDINGS LOOK SLIGHTLY CAPPED TO DEEP
CONVECTION WEST OF A KHKY TO KAND LINE...BUT CB CLOUDS ARE WARRANTED
GIVEN THE ENCROACHING STEEPER LAPSE RATES ALOFT. FLOW WILL TURN NW
LATE IN THE PERIOD WITH FROPA AT KAVL.

OUTLOOK...SCATTERED SHOWERS WILL LIKELY PERSIST MONDAY NIGHT THROUGH
TUESDAY...ESPECIALLY NEAR KAVL...WITH A DEEP LOW PRESSURE TROUGH
OVERHEAD. NO SIGNIFICANT RESTRICTIONS ARE EXPECTED...EXCEPT TEMPO
MVFR RESTRICTIONS ARE POSSIBLE AT KAVL IN MOIST NW FLOW. DRIER
WEATHER IS EXPECTED FOR WEDNESDAY AND THURSDAY.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

SYNOPSIS...TJB
NEAR TERM...HG
SHORT TERM...BSH
LONG TERM...BSH
AVIATION...HG

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1250 AM EDT MON APR 20 2009

GAZ017-018-026-028-029-NCZ056-068>071-507>510-SCZ001>014-019-210500-
HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-CATAWBA-CLEVELAND-LINCOLN-
GASTON-MECKLENBURG-RUTHERFORD MOUNTAINS-GREATER RUTHERFORD-
POLK MOUNTAINS-EASTERN POLK-OCONEE MOUNTAINS-PICKENS MOUNTAINS-
GREENVILLE MOUNTAINS-GREATER OCONEE-GREATER PICKENS-
GREATER GREENVILLE-SPARTANBURG-CHEROKEE-YORK-ANDERSON-ABBEVILLE-
LAURENS-UNION SC-CHESTER-GREENWOOD-
1250 AM EDT MON APR 20 2009

...TORNADO WATCH 177 IN EFFECT UNTIL 7 AM EDT THIS MORNING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST GEORGIA...PIEDMONT
NORTH CAROLINA...WESTERN NORTH CAROLINA AND UPSTATE SOUTH CAROLINA.

.DAY ONE...TONIGHT.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   TORNADO WATCH.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTERS ARE REQUESTED TO FORWARD ANY REPORTS OF LARGE
HAIL...DAMAGING WINDS...TORNADOES OR FLASH FLOODING TO OUR OFFICE.

GAZ010-NCZ035>037-057-072-082-501>506-210500-
RABUN-ALEXANDER-IREDELL-DAVIE-ROWAN-CABARRUS-UNION NC-
CALDWELL MOUNTAINS-GREATER CALDWELL-BURKE MOUNTAINS-GREATER BURKE-
MCDOWELL MOUNTAINS-EASTERN MCDOWELL-
1250 AM EDT MON APR 20 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTHEAST GEORGIA...PIEDMONT
NORTH CAROLINA AND WESTERN NORTH CAROLINA.

.DAY ONE...TONIGHT.

ISOLATED THUNDERSTORMS WILL BE POSSIBLE OVERNIGHT AS A COLD FRONT
APPROACHES THE REGION FROM THE WEST. STRONG GUSTY WINDS CAN BE
EXPECTED WITH ANY THUNDERSTORMS THAT DEVELOP.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTERS ARE REQUESTED TO FORWARD ANY REPORTS OF LARGE
HAIL...DAMAGING WINDS...TORNADOES OR FLASH FLOODING TO OUR OFFICE.

NCZ033-048>053-058-059-062>064-210500-
AVERY-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-GRAHAM-
NORTHERN JACKSON-MACON-SOUTHERN JACKSON-TRANSYLVANIA-
1250 AM EDT MON APR 20 2009

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN NORTH CAROLINA.

.DAY ONE...TONIGHT.

ISOLATED THUNDERSTORMS WILL BE POSSIBLE OVERNIGHT AS A COLD FRONT
APPROACHES THE REGION FROM THE WEST. STRONG GUSTY WINDS BE
EXPECTED WITH ANY THUNDERSTORMS THAT DEVELOP.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

TEMPERATURES ARE EXPECTED TO FALL BELOW FREEZING BY WEDNESDAY
MORNING IN THE HIGHER ELEVATIONS ABOVE 4000 FEET. A FREEZE WATCH
MAY BE NEEDED ON MONDAY. AS TEMPERATURES FALL...LIGHT RAIN
SHOWERS WILL CHANGE OVER TO SNOW...PRODUCING VERY LIGHT SNOW
ACCUMULATIONS IN THE HIGHER ELEVATIONS. A DUSTING TO A FEW TENTHS
OF AN INCH OF SNOW IS POSSIBLE BY WEDNESDAY MORNING.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTERS ARE REQUESTED TO FORWARD ANY REPORTS OF LARGE
HAIL...DAMAGING WINDS...TORNADOES OR FLASH FLOODING TO OUR OFFICE.

NCZ065-210500-
HENDERSON-
1250 AM EDT MON APR 20 2009

...TORNADO WATCH 177 IN EFFECT UNTIL 7 AM EDT THIS MORNING...

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN NORTH CAROLINA.

.DAY ONE...TONIGHT.

PLEASE LISTEN TO NOAA WEATHER RADIO OR GO TO WEATHER.GOV ON THE
INTERNET FOR MORE INFORMATION ABOUT THE FOLLOWING HAZARDS.

   TORNADO WATCH.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY.

TEMPERATURES ARE EXPECTED TO FALL BELOW FREEZING BY WEDNESDAY
MORNING IN THE HIGHER ELEVATIONS ABOVE 4000 FEET. A FREEZE WATCH
MAY BE NEEDED ON MONDAY. AS TEMPERATURES FALL...LIGHT RAIN
SHOWERS WILL CHANGE OVER TO SNOW...PRODUCING VERY LIGHT SNOW
ACCUMULATIONS IN THE HIGHER ELEVATIONS. A DUSTING TO A FEW TENTHS
OF AN INCH OF SNOW IS POSSIBLE BY WEDNESDAY MORNING.

.SPOTTER INFORMATION STATEMENT...

SKYWARN SPOTTERS ARE REQUESTED TO FORWARD ANY REPORTS OF LARGE
HAIL...DAMAGING WINDS...TORNADOES OR FLASH FLOODING TO OUR OFFICE.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1211 AM EDT MON APR 20 2009

GAZ018-SCZ001-004-200500-
GREATER OCONEE-OCONEE MOUNTAINS-STEPHENS-
1211 AM EDT MON APR 20 2009

...STRONG THUNDERSTORMS WILL AFFECT OCONEE AND STEPHENS COUNTIES
THROUGH 100 AM EDT...

AT 1209 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
STRONG THUNDERSTORMS ALONG A LINE EXTENDING FROM LAKEMONT TO
TOCCOA...MOVING NORTHEAST AT 50 MPH.

THESE STORMS WILL BE NEAR...
  LAKE HARTWELL BY 1220 AM EDT.
  WESTMINSTER BY 1225 AM EDT.
  WALHALLA BY 1230 AM EDT.
  SENECA BY 1235 AM EDT.
  LAKE KEOWEE BY 1240 AM EDT.

WIND GUSTS OF 30 TO 40 MPH ARE EXPECTED WITH THESE STORMS.

KRENTZ