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000
FXUS62 KGSP 241446
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1046 AM EDT FRI OCT 24 2008
.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL MOVE NORTHEAST FROM THE GULF OF MEXICO
TODAY...THEN MOVE NORTHEAST SATURDAY AS HIGH PRESSURE BUILDS IN FROM
THE WEST THROUGH SUNDAY. A FAST MOVING COLD FRONT WILL MOVE SOUTH
THROUGH THE AREA MONDAY...WITH HIGH PRESSURE REBUILDING THROUGH MID
WEEK.
&&
.NEAR TERM /THROUGH TONIGHT/...
ATMOS FINALLY MOISTENING UP AS RAIN BEGINS MOVING IN FROM THE WEST
AND SOUTH. STILL EXPECT WIDESPREAD RAIN OVER THE AREA BY LATE
AFTERNOON AS MOISTENING CONTINUES AND LIFT INCREASES. TEMPS WILL BE
TRICKY AS WELL WITH SLOWER RAIN ONSET. TEMPS OVER ERN SECTIONS WILL
BE SLIGHTLY WARMER WITH NORMAL DIURNAL CURVE. WRN TEMPS WILL BE
SIMILAR TO CURRENT FORECAST WITH EARLY HIGHS THEN NEAR STEADY TEMPS.
WINDS HAVE INCREASED OVER THE MTNS AND 45 KT H85 JET MOVES IN. BEST
WINDS ARE USUALLY WEST OF THE STATE LINE IN TN IN THESE TYPE OF
SITUATIONS. BUMPED UP RIDGE TOP WINDS AND GUSTS...BUT VALLEY
LOCATIONS DO NOT USUALLY SEE HIGH WINDS. WILL ISSUE LAKE WIND
ADVISORY FOR THESE WINDS. OTHERWISE LITTLE CHANGE FROM PREVIOUS
THINKING FOR TONIGHT.
RAIN WILL THEN INCREASE ACROSS THE AREA BY THIS AFTN AS SW 850 MB
JET MOVES IN WITH GUSTY WINDS TO 35 MPH OVER HIER MTNS. MODELS STILL
IN DECENT AGREEMENT WITH THE DEEPEST MOISTURE AND STRONGEST OMEGA
CROSSING THE AREA 18Z-06Z AS SFC LOW CENTER MOVES SW TO NE...JUST S
OF CWA. WITH CLOUD COVER AND RAIN IN THE COOL WEDGE...MODEL BLEND
YIELDED HIGHS TODAY IN THE LOWER 50S.
BUFKIT SOUNDINGS SHOW VERY STRONG WIND SHEAR LATE THIS AFTN INTO THE
OVERNIGHT PERIOD BUT LITTLE IF ANY INSTABILITY. THIS WILL HAVE TO BE
MONITORED CLOSELY FOR POTENTIAL WIND DAMAGE IF CONVECTIVE LINES OF
SHOWERS DEVELOP...ESP ACROSS THE SE PART OF THE CWA. SYSTEM
CONTINUES MOVG NE OVERNIGHT WITH DRYER AIR TRYING TO WORK IN FROM
THE SW LATE TONIGHT...SO REDUCED POPS FROM THE SW AFTER 06Z. EXPECT
LOWS TO RANGE FROM L50S IN THE SE TO 40S IN THE MTNS.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
AS OF 230 AM FRIDAY...
SATURDAY...UPR LOW GETS ABSORBED INTO THE NRN STREAM FLOW...AS OUR
AREA IS DOMINATED BY DRY SLOT AND LLVL CAA. CLD COVER SHUD CLR FROM
W TO E...AND WLY WNDS SHUD ALLOW TEMPS TO REACH ABT NORMAL FOR MAXES
DESPITE WET GROUND AND LATE START ON INSOLATION. I TWEAKED POPS TO
HAVE THEM TAPER TO SLGT CHC ALONG I-77 CORRIDOR BY AFTN.
SATURDAY NIGHT AND SUNDAY...WEAK SFC HI PRES CONT ACRS SOUTHEAST
STATES...AS A POTENT S/W TROF DIGS ACRS NRN PLAINS. MODELS BEGIN TO
DIVERGE ON STRENGTH/TIMING OF S/W. FOR OUR WX...IT LUKS PLEASANT
WITH MOSTLY CLR SKIES AND TEMPS SLIGHTLY ABV NORMAL.
SUNDAY NIGHT AND MONDAY...UPR S/W CROSSES SPINE OF APPALACHIANS...AS
ANOTHER SURGE OF COLD AIR PUSHES INTO OUR AREA MONDAY MORNING.
GUIDANCE SHOWS ONLY SOME SHALLOW MOISTURE REACHING THE TN/NC BORDER
EARLY MONDAY WITH THE H8 FRONT. I KEPT A SLGT CHC FOR LGT SHWRS
THERE. THE RAIN/SNOW ALGORITHM BASED ON TEMP GRIDS SHOWS THERE
COULD BE A MIX OF SNOW WITH THESE SHWRS (MAINLY ABV ARND 5000 FT).
BY LATE MORNING IT SHUD BE DRY WITH MORE CAA AND DRY LLVL FLOW.
MAX TEMPS WILL BE COOL IN THE MTNS...BUT DOWNSLOPE WNDS MAY ALLOW
TEMPS TO GET CLOSE TO NORMAL ACRS THE PIEDMONT.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
AS OF 245 AM FRIDAY...
MODEL CONSENSUS IS FOR A LRG UPR RDG ENCOMPASSING MOST OF THE
CONUS...WITH DEEP TROF (POSSIBLY CLOSING OFF) INVOF NORTHEAST
STATES/CANADIAN MARITIMES. THIS RESULTS IN OUR AREA STAYING UNDER
DEEP NWLY FLOW AND SFC HI PRES. THE 00Z GFS SHOWS ANOTHER LLVL COLD
SURGE OVR THE MID ATLC/SRN APPLNS WEDNESDAY AFTN/EVE. COOL AND DRY
NLY/NELY LLVL FLOW CONTINUES THRU THURSDAY NGT. THIS IS IN LINE WITH
INHERITED GRIDS...SO I MADE LTL CHG HERE. BELOW NORMAL TEMPS AND DRY
CONDITIONS THRU THE PERIOD.
&&
.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
CIGS WILL CONTINUE TO FALL AS MOISTURE INCREASES FROM THE SW. LOOK
FOR MVFR CLOUDS TO DEVELOP IN UPSLOPE FLOW ALL SITES BY
DAYBREAK...WITH IFR TOWARD MIDDAY AS RAINFALL RATES INCREASE SYSTEM
MOVES IN FROM THE SW. NE FLOW WILL CONTINUE WITH SPEEDS OF 10-12KTS.
WINDS SHOULD REMAIN SE AT KAVL. RAIN WILL BEGIN TO LET UP FROM THE
SW AS THE LOW MOVES OFF TO THE NE BUT WITH ABUNDANT LOW LEVEL
MOISTURE AND LGT WINDS...IFR CIG/VSBY WITH LGT RA/DZ EXPECTED
THROUGH 12Z.
OUTLOOK...COOL WEDGE OF HIGH PRESSURE WILL REMAIN OVER THE REGION
THROUGH SAT MORNING WITH WIDESPREAD MVFR/IFR CIG/VSBY. LOOK FOR
IMPROVEMENT SAT AFTN AS DRIER HIGH PRESSURE BUILDS OVER THE REGION.
A STRONG COLD FRONT WILL BRING COLDER AIR INTO THE REGION MON NIGHT
WITH MVFR CIGS POSSIBLE BEHIND THE FRONT AT KAVL AS WINDS TURN NW.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...LAKE WIND ADVISORY UNTIL 6 PM EDT THIS AFTERNOON FOR NCZ033-
048>052-058-059-062.
SC...NONE.
&&
$$
SYNOPSIS...RB
NEAR TERM...RB/RWH
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...RB