Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 290524
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
124 AM EDT SUN MAR 29 2015

.SYNOPSIS...
COLD AND DRY HIGH PRESSURE WILL SETTLE OVER THE REGION TONIGHT AND
MOVE OFF THE SOUTHEAST COAST LATE SUNDAY. A LOW PRESSURE CLIPPER
SYSTEM AND ASSOCIATED COLD FRONT WILL THEN PASS OVER THE AREA
EARLY MONDAY MORNING. HIGH PRESSURE WILL RETURN FOR MIDWEEK WITH
MOISTURE INCREASING AGAIN LATER IN THE WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 120 AM EDT SUNDAY...ABUNDANT RADIATIONAL COOLING UNDERWAY
ACROSS THE REGION AS WINDS CONTINUE TO DECREASE BENEATH CLEAR
SKIES.  CURRENTLY MOST NORTHEAST GA...UPSTATE SC...AND NC PIEDMONT
LOCATIONS HAVE ALREADY FALLEN INTO THE LOWER/MID 30S WHILE
SUBFREEZING TEMPERATURES ARE OVERSPREADING THE HIGH TERRAIN.
THUS...THINK CURRENT FCST REMAINS ON TRACK WHICH CONTINUES TO YIELD
POSSIBLE RECORD BREAKING LOWS...ESPECIALLY AT CHARLOTTE.  NO SIG
CHANGES MADE.

PREVIOUS DISCUSSION...

AS OF 215 PM...UPPER LEVEL CONFLUENCE IN THE WAKE OF THE TROUGH JUST
OFF THE MID-ATLANTIC COAST WILL ALLOW DEEP HIGH PRESSURE TO SETTLE
OVER THE REGION TONIGHT. THIS HIGH IS SHOWN TO BE MORE OR LESS
CENTERED OVER THE CWFA AT 12Z SUNDAY...FOSTERING MINIMAL RH OVER A
DEEP LAYER...AND GOOD RADIATIVE CONDITIONS IN THE PRESENCE OF AN
ALREADY VERY COLD AIRMASS. PER NWS RAPID CITY RAOB CLIMATOLOGY...
850MB TEMPS TONIGHT WILL BE ON THE ORDER OF 2 STANDARD DEVIATIONS
BELOW NORMAL. ON THE OTHER HAND NAM PROG SOUNDINGS FOR TONIGHT
SUGGEST DECOUPLING WILL BE SLOW TO OCCUR...AS A MODEST PRESSURE
GRADIENT STILL EXISTS MUCH OF THE NIGHT UNTIL THE AIRMASS CENTERS
OVER THE AREA. MIN TEMPS WILL FLIRT WITH RECORDS...BUT I DID NOT
FAVOR THE COLDEST GUIDANCE IN LIGHT OF THE SLOW DECOUPLING.
NONETHELESS A HARD FREEZE IS NEARLY CERTAIN FOR MOST OF THE AREA. A
FREEZE WARNING IS IN EFFECT FOR ALL ZONES WHERE WIDESPREAD PLANT
GROWTH HAS GOTTEN UNDERWAY.

THE SFC HIGH SETS UP OVER THE SOUTHEAST COAST DURING THE DAY SUNDAY
AS A SHORTWAVE RIDGE MOVES OVERHEAD. THIS USHERS IN SWLY WARM
ADVECTION ALOFT...THOUGH THE ASSOCIATED MOISTURE WILL REMAIN OFF TO
OUR WEST. THUS A DRY AND SUNNY DAY IS ANTICIPATED PERHAPS WITH A FEW
ELEVATED CLOUDS FILTERING IN BY LATE AFTN. HOWEVER TEMPS WILL REMAIN
CHILLY...MAXES BEING 10 OR MORE DEGREES BELOW CLIMO. RH WILL STILL
BE QUITE LOW DURING THE AFTERNOON. CRITERIA FOR A FIRE DANGER
STATEMENT WILL BE MET IN OUR NORTHEAST GEORGIA COUNTIES. SEE FIRE WX
SECTION BELOW FOR DETAILS.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...
AS OF 215 PM EDT SATURDAY...A DIGGING LOW PRESSURE SYSTEM OVER THE
GREAT LAKES WILL SEND A SHORTWAVE ACROSS THE WRN CAROLINAS AND NE GA
SUNDAY NIGHT INTO MONDAY. ISENTROPIC LIFT WILL BRIEFLY DEVELOP OVER
THE SRN APPALACHIANS AHEAD OF THE APPROACHING WAVE SUNDAY
EVENING...BUT WITH 850 MB FLOW VEERING QUICKLY WESTERLY OVERNIGHT.
THE DEEPEST MOISTURE WITH THE PASSING CLIPPER AND ASSOCIATED SURFACE
COLD FRONT WILL OCCUR MAINLY LATE SUNDAY NIGHT THROUGH MONDAY
MORNING. TEMPERATURE PROFILES ACROSS THE MTNS APPEAR WARM ENOUGH TO
SUPPORT LIQUID PTYPES THROUGHOUT. DESPITE THE MORNING FROPA...
DOWNSLOPE WARMING AND GOOD INSOLATION WILL ALLOW MAX TEMPS TO RISE
TO WITHIN A CATEGORY OF CLIMO EAST OF THE MOUNTAINS MON AFTN.
MOUNTAIN TEMPERATURES...ON THE OTHER HAND...WILL REMAIN 5 TO 10
DEGREES BELOW CLIMO IN MOST AREAS.

DEEP LAYER NW FLOW WILL THEN SET UP MON NIGHT THROUGH TUE. W TO SW
FLOW AT LOW LEVELS WILL PERMIT A STEADY WARMUP...WITH ABOVE CLIMO
TEMPS THROUGHOUT BY TUE AFTN. A WEAKER SHORTWAVE WILL BRUSH THE NRN
TIER LATE TUE...BUT WITH MORE LIMITED MOISTURE THAN THE SUNDAY
NIGHT/MONDAY SYSTEM.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 145 PM SATURDAY...THE GLOBAL MODELS CONTINUE TO STRUGGLE...OR
AT LEAST OFFER SIGNIFICANT DIFFERENCES IN SOLUTIONS...WITH THE SHORT
WAVE DETAILS WITHIN CHANGING UPPER FLOW PATTERN NEXT WEEK. IN
GENERAL...THE GFS EXHIBITS STRONGER SHORT WAVE ENERGY IN THE
NORTHERN STREAM (AT LEAST EARLY IN THE PERIOD)...WHILE THE ECMWF IS
CONSIDERABLY STRONGER (AND THEREFORE SLOWER) WITH A SOUTHERN STREAM
VORT MAX THAT LIFTS OUT OF THE ARKLATEX WED NIGHT. WHILE THE MORE
AMPLIFIED ECMWF WOULD SUGGEST MORE SUBSTANTIAL PRECIP CHANCES...AND
CERTAINLY THE POTENTIAL FOR A MORE SIGNIFICANT RAIN EVENT THU INTO
THU NIGHT...EVEN THE GFS DEPICTS A LIGHT QPF RESPONSE DURING THIS
TIME...SO WE WILL CONTINUE TO FEATURE SOLID POPS THROUGH THU...
GRADUALLY TAPERING OFF TOWARD FRIDAY MORNING.

MODEL DIFFERENCES ONLY BECOME FURTHER AMPLIFIED TOWARD THE END OF
THE WEEK. AGAIN...THE GFS FEATURES A QUITE AMPLIFIED SHORT WAVE
TROUGH PASSING BETWEEN HUDSONS BAY AND THE GREAT LAKES LATE
THURSDAY. THIS RESULTS IN RATHER WEAK UPSTREAM SHORT WAVE ACTIVITY
ACROSS CENTRAL AND WESTERN N.A. MEANWHILE...THE ECMWF... WHICH IS
MUCH MORE MUTED WITH THE LEAD WAVE...ALLOWS FOR A SUBSTANTIAL
LOWERING OF HEIGHTS ACROSS THE CENTRAL CONUS BY FRIDAY...WITH A
MAJOR CYCLONE DEVELOPING NEAR THE MID-MISS VALLEY...LIFTING INTO THE
GREAT LAKES BY THE END OF THE WEEK. THIS SOLUTION WOULD ALLOW FOR A
LARGE WARM SECTOR TO DEVELOP ACROSS THE EASTERN CONUS...WITH A
RATHER STRONG COLD FRONT MOVING ACROSS THE AREA BY THE END OF THE
PERIOD. THIS WOULD BE A DECENT SEVERE WEATHER PATTERN FOR OUR
AREA...BUT AGAIN CONFIDENCE IS BELOW NORMAL ATTM OWING TO
UNCERTAINTIES REGARDING THE SHORT WAVE DETAILS. (AND INDEED THE
PATTERN INDICATED BY THE LESS AMPLIFIED/WEAKER GFS WOULD BE MUCH
LESS CONDUCIVE TO SIGNIFICANT CONVECTION. NEVERTHELESS...SIGNALS IN
THE MODEL GUIDANCE WARRANT INCREASING POPS ABOVE CLIMO FROM LATE
FRIDAY INTO EARLY SATURDAY. THE PATTERN CHANGE WILL SUPPORT A
WARMING TREND...WITH NEAR NORMAL TEMPS EXPECTED EARLY IN THE
PERIOD...AND ABOVE NORMAL TEMPS EXPECTED BY THE END OF THE WEEK.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AT KCLT AND ELSEWHERE...VFR CONDITIONS WILL PREVAIL THROUGH THE TAF
PERIOD. INTRUDING HIGH PRESSURE WILL ALLOW FOR DECREASING WINDS
OVERNIGHT BENEATH CLEAR SKIES.  AS THE HIGH CENTER SHIFTS OVERHEAD
THROUGH MID MORNING EXPECTING FLOW TO INCREASE OUT OF THE SE BEFORE
VEERING TO THE SW AT AROUND 6-8KTS AT ALL SITES BY LATE MORNING.
EXPECTING SKC TO PREVAIL AT ALL SITES THROUGH THE FIRST HALF OF THE
PERIOD...HOWEVER AS A COLD FRONT SLIDES INTO THE OHIO VALLEY MODELS
INDICATE HIGH LEVEL CIRRUS ADVECTING DOWNSTREAM OVER THE REGION.
THUS...ALL SITES FEATURE FEW HIGH CLOUDS BY EARLY AFTERNOON...WITH
THE ADDITION OF A FEW LOW CLOUDS AT KAVL LATE IN THE PERIOD AS
PREFRONTAL MOISTURE INTRUDES.

OUTLOOK...CIG/VSBY RESTRICTIONS WILL BE POSSIBLE WITH THE NEXT FROPA
ON MONDAY AT ALL SITES...ESPECIALLY FOR MID/LATE MORNING AT KAVL.
BROAD SURFACE HIGH PRESSURE REGAINS CONTROL IN THE MIDDLE OF NEXT
WEEK...AHEAD OF AN APPROACHING WARM FRONT AND RESULTANT MOISTURE
RETURN LATER IN THE WEEK.

CONFIDENCE TABLE...

            05-11Z        11-17Z        17-23Z        23-00Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

.FIRE WEATHER...
THE PRESENCE OF A CONTINENTAL POLAR AIRMASS WILL ALLOW FOR RH TO DIP
TO CRITICAL LEVELS BY MIDDAY SUNDAY...SUGGESTING FIRE DANGER WILL BE
ELEVATED. WINDS WILL BE LIGHT. FUEL MOISTURES IN NORTHEAST GEORGIA
ARE ALREADY NEAR CRITICAL LEVELS IN SOME SPOTS...AND ARE EXPECTED TO
DROP APPRECIABLY THRU TONIGHT AS THE DRIER AIR FILTERS IN. A FIRE
DANGER STATEMENT WILL BE ISSUED FOR SUNDAY AFTERNOON.

&&

.CLIMATE...
RECORD MINIMUM TEMPERATURES FOR MARCH 29TH...

GSP  26  1899
CLT  26  2013
AVL  19  1982

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...FREEZE WARNING UNTIL 11 AM EDT THIS MORNING FOR GAZ010-017-018-
     026-028-029.
     FIRE DANGER STATEMENT FROM NOON EDT TODAY THROUGH THIS EVENING
     FOR GAZ010-017-018-026-028-029.
NC...FREEZE WARNING UNTIL 11 AM EDT THIS MORNING FOR NCZ035>037-048-
     051>053-056>059-062>065-068>072-082-502-504-506>510.
SC...FREEZE WARNING UNTIL 11 AM EDT THIS MORNING FOR SCZ001>014-019.

&&

$$
SYNOPSIS...JPT
NEAR TERM...CDG/JAT/WIMBERLEY
SHORT TERM...HG
LONG TERM...JDL
AVIATION...CDG
FIRE WEATHER...
CLIMATE...


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