Damaging Winds in North Carolina, December 10, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
332 AM EST WED DEC 10 2008

.SYNOPSIS...
A COLD FRONT WILL STALL OUT OVER OUR AREA TODAY AS LOW PRESSURE
DEVELOPS OVER THE CENTRAL GULF COAST.  THIS LOW PRESSURE IS EXPECTED
TO CROSS OUR REGION LATE TONIGHT AND THURSDAY.  HIGH PRESSURE WILL
BUILD IN FOR THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AT 330 AM...THE 06Z SURFACE ANALYSIS PLACE A STATIONARY FRONT FROM
KTYS...TO THE UPPER SAVANNAH RIVER VALLEY...AND THEN NORTHEAST FROM
KGRD TO KCLT TO KGSO. A SURFACE WAVE WAS LOCATED OVER CENTRAL
MS...WITH A STRONG COLD FRONT EXTENDING NORTHEAST TO LAKE ERIE...AND
SOUTH INTO THE MS RIVER DELTA. A SLOWLY PROGRESSIVE AND HIGHLY
AMPLIFIED PATTERN WILL RESULT IN AN UPPER LOW CUTTING OFF IN THE
BASE OF A TROUGH OVER LA BY TONIGHT. A TIGHTENING GRADIENT EAST OF
THE SLOWLY APPROACHING COLD FRONT WILL DIRECT ISENTROPIC UPGLIDE AND
UPSLOPE FLOW AGAINST THE BLUE RIDGE TODAY. THE FRONT WILL REACH OUR
AREA AT MIDDAY...STALLING NEAR INTERSTATE 85 TONIGHT. A STRONG
SURFACE WAVE ASSOCIATED WITH THE UPPER LOW IS EXPECTED TO OCCLUDE
OVER THE GULF STATES TONIGHT...WITH ITS DEFORMATION ZONE ORIENTED
ALONG THE BLUE RIDGE...FURTHER ENHANCING RAINFALL. UP TO TWO  INCHES
OF RAINFALL ARE POSSIBLE TODAY..WITH THE MAXIMUMS ON THE BLUE RIDGE
ESCARPMENT SOUTHWEST OF INTERSTATE 26 INTO NORTHEAST GA. A FLASH
FLOOD WATCH WILL BE ISSUED FOR 9 AM TO 6 PM TODAY FOR THE BLUE RIDGE
ESCARPMENT BETWEEN NC AND GA/SC. UPSTREAM REPORTS OF 2 INCHES PER
HOUR...WITH MUCH LESS TERRAIN...HAVE BEEN RECEIVED FOR THE LINE
WORKING ACROSS AL/GA.

INSTABILITY ASSOCIATED WITH THE WARM SECTOR WILL BE MAINLY CONFINED
TO THE AREA SOUTH OF INTERSTATE 85 TODAY AND TONIGHT...WITH THE BEST
CHANCE OF THUNDER IN THE PIEDMONT OF SC. LINEAR CONVECTION IN AL IS
EXPECTED TO REACH THE SOUTHERN PORTION OF OUR AREA BY THIS
AFTERNOON...AND WITH PLENTY OF SPEED SHEAR...DAMAGING WINDS OR AN
ISOLATED TORNADO CANNOT BE RULED OUT. 850 MB WINDS OF 45 KNOTS OR
MORE WILL KEEP WINDS AT ADVISORY CRITERIA AT THE HIGHER ELEVATIONS
OF THE NC MOUNTAINS THIS MORNING...WITH A GRADUAL WEAKENING THIS
AFTERNOON. A LAKE WIND ADVISORY WILL LIKELY BE NEEDED THERE THIS
AFTERNOON...IF THE WIND ADVISORY IS NOT EXTENDED. MAXIMUM
TEMPERATURES TODAY WILL BE CLOSER TO THE COOLER MAV GUIDANCE UNDER
CLOUDS AND PRECIPITATION. MINIMUM TEMPERATURES TONIGHT ARE EXPECTED
TO BE JUST A FEW DEGREES BELOW CLIMATOLOGICAL MAXIMUMS WITH
WARM/MOIST ADVECTION AND CLOUD COVER.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 300 AM WEDNESDAY...CONFIDENCE IN THE SHORT TERM FORECAST
PERIOD IS INCREASING AS OPERATIONAL MODELS CONTINUE TO CONVERGE ON A
MORE CONSENSUS SOLUTION FOR THURSDAY AND THURSDAY NIGHT. I HAVE
PRIMARILY USED A BLEND OF THE NAM AND GFS FOR DETAILS OF THE
FORECAST AND THIS IS FURTHER SUPPORTED BY THE FACT THAT THE 00Z
ECMWF HAS COME IN LINE WITH THIS BLENDED SOLUTION.

ALOFT...THE PERIOD BEGINS WITH A CLOSED MID AND UPPER LEVEL LOW
POSITIONED OVER SE LOUISIANA THAT MOVES EASTWARD ACROSS THE DEEP
SOUTH ON THURSDAY. THE CENTER OF THE UPPER LOW IS EXPECTED TO PASS
ACROSS UPSTATE SC THURSDAY NIGHT BEFORE OPENING UP AND BEING
ABSORBED IN THE THE BROADER LONGWAVE TROUGH BY FRIDAY MORNING.
CHANNELED VORT ENERGY MOVES INTO THE SOUTHERN APPS ON FRIDAY AND
SHIFTS EAST OF THE REGION BY FRIDAY NIGHT. AT THE SURFACE...THE LOW
PRESSURE SYSTEM WILL BE CENTERED ALONG THE GA/AL STATE LINE THURSDAY
MORNING WITH A FRONTAL BOUNDARY DRAPED ACROSS THE FA. THE LOW CENTER
WILL TRACK NORTHEASTWARD DURING THE DAY ROUGHLY JUST SOUTH OF THE
I-85 CORRIDOR...EXITING TO THE NORTHEAST THURSDAY NIGHT. EXPECT
PRECIP TO BE ONGOING THURSDAY MORNING ALONG THE REMNANT FRONTAL
BOUNDARY...WITH THE COVERAGE AND INTENSITY INCREASING THROUGHOUT THE
DAY AS THE SURFACE LOW MAKES ITS APPROACH. THERE WILL BE COPIOUS
FORCING WHICH WILL BE FIRST FOCUSED ALONG THE OLD FRONTAL
BOUNDARY...AND THEN FINALLY WITH UPPER DIVERGENCE SPREADING ACROSS
THE FA AS THE UPPER LOW MOVES INTO THE REGION. EXPECT PRECIP TO
CONTINUE INTO THURSDAY NIGHT...ESPECIALLY ACROSS THE NC
MOUNTAINS...AS THE UPPER LOW MOVES ACROSS WITH A CHANGEOVER TO SNOW.
THINGS DRY OUT RAPIDLY ON FRIDAY AS THE MOISTURE PULLS OUT IN THE
WAKE OF THE SURFACE LOW. COMBINATION OF PLENTIFUL MOISTURE AND
STRONG FORCING PROVIDES A SETUP FOR A STRONG CHANCE OF HEAVY
RAINFALL ACROSS THE AREA. USING A BLEND OF HPC AND SREF QPF I END UP
WITH 1 TO 1.25 INCHES OF RAIN FOR THURSDAY...AND ITS NOT OUT OF THE
QUESTION TO HAVE EMBEDDED 2 INCH AMOUNTS IN AREAS THAT SEE
CONVECTION IN THE AFTERNOON.

CONCERNING THE SVR THREAT...THE CURRENT DAY 2 SPC OUTLOOK PLACES THE
SE HALF OF THE FA IN A SLT RISK. THIS MAKES PERFECT SENSE FOLLOWING
THE NAM/GFS SURFACE LOW TRACK WHICH WOULD HIGHLIGHT AREAS SOUTH OF
I-85 INTO THE CHARLOTTE AREA. PLAN VIEW CAPE FROM THE NAM PAINTS
CAPE VALUES OF 300-500 J/KG ACROSS THIS AREA AT 18Z THURSDAY
ESPECIALLY IN THE NC PIEDMONT AREA IN THE CHARLOTTE VICINITY. THERE
IS PLENTIFUL SHEAR WITH 0-6 KM ON THE ORDER OF 50-70 KTS. ALSO THERE
IS PLENTY OF TURNING IN THE WIND PROFILE AS SOUTHERLY SURFACE WINDS
HAVE A SLIGHT EASTERLY COMPONENT AND A 50+ KT H85 JET MOVES OVERHEAD.
ALSO...FOLLOWING THE NAM/GFS SOLUTION THE WARM FRONT EXTENDING
NORTHEAST OF THE SURFACE LOW WILL BE DRAPED RIGHT ALONG I-85 IN THIS
AREA. THERE ARE SOME LIMITING FACTORS. THE SETUP OF THE WARM FRONT
WILL BE CRUCIAL. THE FURTHER SOUTHEAST THE FRONT IS POSITIONED THE
LESS THE THREAT OF CONVECTION WILL BE. ALSO...CAPE IS STILL EXPECTED
TO BE ON THE MINIMAL SIDE AND IT COULD END UP BEING THAT THE
GREATEST THREAT WILL BE JUST SOUTH AND EAST OF THE CHARLOTTE METRO
AREA. REGARDLESS...WILL INTRODUCE THUNDER SOUTH OF I-85 UP THROUGH
THE CHARLOTTE AREA BETWEEN 18-00Z. ALSO BRING IN A DAMAGING WIND
MENTION OVER TOWARDS THE I-77 AREA AND WILL HIGHLIGHT IN THE HWO.

FINALLY...THE LAST THREAT FOR THIS PERIOD WILL BE THE POTENTIAL FOR
CHANGEOVER TO SNOW IN THE NC MOUNTAINS. SREF PLUMES SUPPORT THIS FOR
AVL THURSDAY NIGHT WITH SOME RELATIVELY LIGHT PRECIP. LIMITING
FACTOR I THINK WILL BE TEMPERATURES WHICH WILL RELEGATE SNOW TO
PRIMARILY THE EARLY MORNING HOURS ON FRIDAY...AS THE COLD AIR CHASES
THE PRECIP OUT. I ENDED UP WITH ABOUT A HALF INCH ACROSS THE
MOUNTAINS...PERHAPS A BIT MORE IN THE HIGHER ELEVATIONS WHERE THE
CHANGEOVER COULD OCCUR EARLIER. AN ADVISORY MAY BE NECESSARY CLOSER
TO THE TIME.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 210 AM WEDNESDAY...THE MEDIUM RANGE MODELS SHOW THE UPPER
TROUGH MOVING OFF THE MID ATLANTIC COAST ON SATURDAY WITH SURFACE
HIGH PRESSURE EXPANDING ALONG THE ENTIRE LENGTH OF THE ATLANTIC
SEABOARD.  THIS SURFACE RIDGE WILL SHIFT OFF THE COAST INTO THE
START OF THE UPCOMING WEEK AS ANOTHER COLD FRONT APPROACHES FROM THE
NORTHWEST.  THIS FRONT WILL BE SLOWING DOWN AS IT GETS CLOSER TOWARD
THE MID WEEK WHILE AN UPPER RIDGE CENTERED GENERALLY OVER THE GULF
STEERS MOST ENERGY NORTH AND AWAY FROM US.  VERY LITTLE HAS CHANGED
IN THE MEDIUM RANGE AS WE MAINTAIN A SLIGHT INCREASE IN POPS FOR THE
NC MOUNTAINS AT THE END OF THE DAY 7 FORECAST.  TEMPERATURES WILL
SLOWLY MODERATE AHEAD OF THE SLOWLY APPROACHING FRONT.

&&

.AVIATION /09Z WEDNESDAY THROUGH SUNDAY/...
KCLT...SOUTHERLY WINDS WILL PERSIS AT AROUND 10 KNOTS...WITH A
DECREASE IN SPEED TO AROUND 5 KNOT THIS EVENING. NAM GUIDANCE WAS
TOO PESSIMISTIC FOR CURRENT CONDITIONS...SO A MORE OPTIMISTIC MODEL
BLEND WAS USED...KEEPING CEILINGS MVFR...WITH HIGH END MVFR THIS
AFTERNOON. SREF GUIDANCE INDICATED MVFR VISIBILITY IS EXPECTED THIS
MORNING.AS RAIN WORKS EAST DURING LOWEST DEW POINT DEPRESSIONS...
OTHERWISE LOW END VFR VISIBILITY IN LIGHT RAIN.

ELSEWHERE...RAIN SPREADING EAST WILL BRING DOWN VISIBILITY TO IFR BY
DAWN...EXCEPT AT KAND WHERE THE SREF INDICATED MVFR. LIFR OR IFR
CEILINGS SHOULD COME UP TO MVFR AS WINDS INCREASE AFTER DAWN...
EXCEPT AT KAND WHERE RAIN WILL BRING CEILINGS DOWN FROM VFR TO MVFR.
BLENDED GUIDANCE LOWERS CEILINGS TO IFR LATE THIS EVENING...WITH
MVFR VISIBILITY AT KGSP/KGMU...AND IFR AT KAVL. THE EXCEPTION IS
KAND...WHERE GUIDANCE INDICATES CEILING IMPROVING TO LOW VFR AS
ISENTROPIC UPGLIDE DECREASES OVER THE UPPER SAVANNAH RIVER VALLEY.

OUTLOOK...CEILING AND VISIBILITY RESTRICTIONS IN RAIN AND FOG
CONTINUE THURSDAY. VFR WEATHER RETURNS FRIDAY AND WILL CONTINUE
SATURDAY AND SUNDAY.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...FLASH FLOOD WATCH FROM 9 AM EST THIS MORNING THROUGH THIS
     AFTERNOON FOR GAZ010-017-018-026.
NC...WIND ADVISORY UNTIL 11 AM EST THIS MORNING FOR NCZ033-048>053-
     058-059-062>065.
     FLASH FLOOD WATCH FROM 9 AM EST THIS MORNING THROUGH THIS
     AFTERNOON FOR NCZ062>065.
SC...FLASH FLOOD WATCH FROM 9 AM EST THIS MORNING THROUGH THIS
     AFTERNOON FOR SCZ001>005.

&&

SYNOPSIS...DEO
NEAR TERM...JAT
SHORT TERM...BSH
LONG TERM...DEO
AVIATION...JAT

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
529 PM EST TUE DEC 9 2008

NCZ033-048>053-058-059-062>065-102230-
AVERY-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-GRAHAM-
NORTHERN JACKSON-MACON-SOUTHERN JACKSON-TRANSYLVANIA-HENDERSON-
529 PM EST TUE DEC 9 2008

...WIND ADVISORY IN EFFECT UNTIL 11 AM EST WEDNESDAY...

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.

   WIND ADVISORY.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

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

   WIND ADVISORY.

.SPOTTER INFORMATION STATEMENT...

NONE.

GAZ010-017-018-026-028-029-NCZ035>037-056-057-068>072-082-501>510-
SCZ001>014-019-102230-
RABUN-HABERSHAM-STEPHENS-FRANKLIN-HART-ELBERT-ALEXANDER-IREDELL-
DAVIE-CATAWBA-ROWAN-CLEVELAND-LINCOLN-GASTON-MECKLENBURG-CABARRUS-
UNION NC-CALDWELL MOUNTAINS-GREATER CALDWELL-BURKE MOUNTAINS-
GREATER BURKE-MCDOWELL MOUNTAINS-EASTERN MCDOWELL-
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-
529 PM EST TUE DEC 9 2008

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

.DAY ONE...TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

NONE.