Frost Advisory 7, NWS Greenville-Spartanburg, SC

067 
WWUS72 KGSP 210204
NPWGSP

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1004 PM EDT SAT OCT 20 2012

...AREAS OF FROST EXPECTED IN THE NORTH CAROLINA MOUNTAINS
TONIGHT...

.LIGHT WINDS AND CLEAR SKIES ALONG WITH TEMPERATURES IN THE 30S
WILL ALLOW FROST TO FORM OVER MUCH OF THE MOUNTAINS OF WESTERN
NORTH CAROLINA LATE TONIGHT.

NCZ033-048>053-058-059-062>065-501-503-505-211300-
/O.CON.KGSP.FR.Y.0007.121021T0800Z-121021T1300Z/
AVERY-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-GRAHAM-
NORTHERN JACKSON-MACON-SOUTHERN JACKSON-TRANSYLVANIA-HENDERSON-
CALDWELL MOUNTAINS-BURKE MOUNTAINS-MCDOWELL MOUNTAINS-
INCLUDING THE CITIES OF...NEWLAND...SPRUCE PINE...BRYSON CITY...
WAYNESVILLE...ASHEVILLE...SYLVA...FRANKLIN...BREVARD...
HENDERSONVILLE
1004 PM EDT SAT OCT 20 2012

...FROST ADVISORY REMAINS IN EFFECT FROM 4 AM TO 9 AM EDT
SUNDAY...

* LOCATIONS...MOST OF THE NORTH CAROLINA MOUNTAINS.

* TEMPERATURES...LOWS IN THE MID 30S.

* WINDS...NORTH 5 MPH OR LESS.

* IMPACTS...FROST MAY DAMAGE OR KILL SENSITIVE VEGETATION.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FROST ADVISORY MEANS THAT FROST IS POSSIBLE. SENSITIVE OUTDOOR
PLANTS MAY BE KILLED IF LEFT UNCOVERED.

&&

$$

14

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
201 PM EDT SAT OCT 20 2012

.SYNOPSIS...
COOL HIGH PRESSURE CURRENTLY OVER THE SOUTHEAST UNITED STATES WILL REMAIN
ENTRENCHED ACROSS THE AREA THROUGH WEEK. A COLD FRONT IS EXPECTED
TO APPROACH ON THE WEEKEND.

&&

.NEAR TERM /THROUGH SUNDAY/...
AS OF 2 PM EDT...MODEL MOISTURE FIELDS ARE CLOSE TO SATURATION AT
850MB THROUGH THIS AFTERNOON AND EVENING THOUGH TRENDS IN SATELLITE
IMAGERY HAVE SHOWN THAT CLOUDS IN THIS LAYER ARE BEING DIMINISHED BY
DOWNSLOPE FLOW ON THE EASTERN SIDE OF THE MTNS SO THIS MOISTURE BY
ITSELF IS NOT EXPECTED TO PRODUCE CLOUD COVER. HOWEVER...RAPID FLOW
AROUND THE UPPER TROUGH LIFTING UP OUT OF THE OHIO VALLEY WILL ALLOW
A SHORTWAVE PRESENTLY OVER SERN MO/WRN KY TO PASS OVER THE GSP CWFA
BETWEEN 00Z AND 03Z TONIGHT. THIS FEATURE HAS SOME UPPER LEVEL
MOISTURE OF ITS OWN WHILE IT ALSO MAY ENHANCE LIFT ENOUGH TO PRODUCE
A FEW LOWER CLOUDS WITH THE LINGERING MOIST CONDITIONS AT 850MB. WE
COULD SEE PARTIAL SKY COVER IN THE EVENING...BUT I EXPECT SKIES WILL
CLEAR LATER IN THE WAKE OF THE WAVE AND AS MIDLEVELS DRY OUT.

UPPER RIDGING BUILDS IN BEGINNING IN THE WEE HOURS OF THE MORNING
SUNDAY AS SFC HIGH CLOSES OFF OVER THE SRN APPALACHIANS. WEAK
MIDLEVEL COLD ADVECTION BECOMES MOSTLY NEUTRAL. GFS HOLDS ONTO THE
COLD ADVECTION LONGER...AND COOLER GFS MOS LOW TEMPS FOR TONIGHT
REFLECT THAT. A BLEND OF GFS AND NAM MOS LOOKS SUITABLE WHICH PUTS A
LARGE PORTION OF THE MOUNTAINS IN THE MID 30S. WITH THE FAIRLY HIGH
RH VALUES EXPECTED TO GO ALONG WITH THESE TEMPS...FROST IS EXPECTED
OVER MUCH OF THE MOUNTAIN ZONES.

SUNDAY SHOULD BE A VERY QUIET DAY METEOROLOGICALLY AS HIGH PRESSURE
BUILDS AT THE SURFACE. WE WILL SEE DEEP MIXING AS USUAL THOUGH WINDS
IN THE MIXED LAYER ARE UNIFORMLY LIGHT...RESULTING IN MINIMAL GUSTS.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
AS OF 200 PM EDT SATURDAY... RIDGE ALOFT AND SURFACE HIGH PRESSURE
WILL REMAIN OVER THE FORECAST AREA FROM 00Z MONDAY THROUGH TUESDAY.
NONE OF THE NUMERICAL GUIDANCE INDICATES ENOUGH MOISTURE FOR
SIGNIFICANT CLOUDS... SO BOTH MONDAY AND TUESDAY WILL BE MOSTLY
SUNNY AND NIGHTS WILL BE CLEAR WITH THE EXCEPTION OF SOME VALLEY FOG
IN THE MOUNTAINS. PATCHY FROST IS ALSO POSSIBLE IN SOME VALLEYS
MONDAY MORNING. WEAK SURFACE PRESSURE GRADIENT BOTH MONDAY AND
TUESDAY WILL PRODUCE LIGHT WIND. LOWS MONDAY MORNING WILL BE IN
LOWER AND MIDDLE 40S EXCEPT 30S IN THE MOUNTAINS. LOWS TUESDAY WILL
BE MOSTLY IN THE 40 TO 50 RANGE. DAYTIME TEMPERATURES MONDAY AND
TUESDAY WILL RANGE FROM 70 TO 80 WITH A FEW 60S IN THE MOUNTAINS ON
MONDAY.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 200 PM EDT SATURDAY... A LARGE 500 MB RIDGE CONTINUES TO
DOMINATE THE WEATHER OVER THE EASTERN STATES AT 00Z WEDNESDAY. THE
ECMWF AND GFS MOVE A WEAKENING SHORT WAVE TROUGH... WHICH IS
CURRENTLY A CUTOFF LOW OVER THE EASTERN PACIFIC NEAR MEXICO...
THROUGH THE RIDGE AND ACROSS THE AREA BY 00Z THURSDAY. THERE IS NOT
SUFFICIENT MOISTURE AND FORCING TO PRODUCE SIGNIFICANT CLOUDS.
THEREAFTER... THE GFS AND ECMWF GRADUALLY EVOLVE VERY DIFFERENT
PATTERNS BY THE END OF THE WEEK.  IN EITHER CASE... THE 500 MB RIDGE
PROGRESSES TO THE EAST COAST LEADING TO AN INCREASINGLY SOUTHWEST FLOW
ALOFT. THE GEM IS EVEN A LITTLE DIFFERENT IN PLACING A LOWER
AMPLITUDE RIDGE OFFSHORE WITH A MORE ZONAL FLOW ACROSS OUR REGION.
MAJOR HEIGHT DIFFERENCES AMONG THE MODELS BY SATURDAY... ESPECIALLY
OVER WESTERN STATES... ALSO PRODUCE IMPORTANT DOWNSTREAM
DIFFERENCES. WILL OPT TO FOLLOW THE LEAD OF HPC WHICH INDICATES A
COLD FRONT APPROACHING THE APPALACHIANS ON SATURDAY WITH AN
INCREASINGLY MOIST SOUTHERLY FLOW. THIS PATTERN FAVORS THE GFS OVER
THE ECMWF. HPC GUIDANCE POPS INCREASE TO SLIGHT CHANCE AND LOW
CHANCE CATEGORIES ACROSS MUCH OF THE AREA... SO PLAN TO INTRODUCE A
CHANCE OF SHOWERS... WITH HIGHEST POPS IN THE WEST AND NORTH... BY
SATURDAY.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AT KCLT...VFR. SOME VFR CLOUDS MAY SPILL IN FOR THE EVENING HOURS AS
A WEAK SHORTWAVE TROUGH PASSES OVER THE AREA BUT A CIG MAY NOT EVEN
FORM. SKIES SHOULD CLEAR AGAIN BY AROUND 06Z. NO FOG ANTICIPATED
SUNDAY MORNING AS SFC DEWPOINTS WILL BE TOO DRY. WESTERLY WINDS
TODAY SHOULD VEER BACK TOWARD THE NORTH BY LATE AFTERNOON BUT WILL
BE LIGHT AND SOMEWHAT VARIABLE THROUGH THE END OF THE PERIOD AS HIGH
PRESSURE BUILDS OVERHEAD. A FEW OCCASIONAL GUSTS TO 10 KT OR SO MAY
OCCUR THIS AFTERNOON BUT WINDS ALOFT WILL BE TOO WEAK TOMORROW TO
MIX DOWN ANY SIGNIFICANT GUSTS.

ELSEWHERE...SHORTWAVE APPROACHING FROM THE WEST SHOULD PROVIDE
ENOUGH LIFT TO MAKE PARTIAL CLOUDINESS OUT OF MIDLEVEL MOISTURE ONCE
THE WAVE GETS OVER THE MOUNTAINS IN THE EARLY EVENING. THE WAVE WILL
PROGRESS EASTWARD AND WILL SPREAD THE CLOUDS WITH IT...BUT THINGS
SHOULD CLEAR OUT AGAIN BY AROUND 06Z. ANY CIGS ASSOCIATED WITH THE
CLOUDS SHOULD BE VFR. GOOD RADIATIONAL COOLING WILL OCCUR AND
SURFACE RH VALUES WILL BE PRETTY HIGH. MOUNTAIN VALLEYS ARE EXPECTED
TO SEE SOME FOG BUT THE PIEDMONT AND UPSTATE SHOULD STAY FREE OF
FOG. WINDS WILL BE LIGHT AND GENERALLY NORTHERLY WITH HIGH PRESSURE
CENTERED JUST TO THE NORTH OF OUR REGION...THOUGH THE FLOW WILL BE
WEAK AND WINDS MAY GO VARIABLE AT TIMES.

OUTLOOK...VFR THROUGH EARLY NEXT WEEK...EXCEPT FOR EARLY MORNING
MOUNTAIN VALLEY FOG.

AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...

WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM

&&

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

&&

SYNOPSIS...PAT
NEAR TERM...WIMBERLEY
SHORT TERM...LGL
LONG TERM...LGL
AVIATION...WIMBERLEY

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
558 AM EDT SAT OCT 20 2012

NCZ033-048>053-058-059-062>065-211000-
AVERY-MADISON-YANCEY-MITCHELL-SWAIN-HAYWOOD-BUNCOMBE-GRAHAM-
NORTHERN JACKSON-MACON-SOUTHERN JACKSON-TRANSYLVANIA-HENDERSON-
558 AM EDT SAT OCT 20 2012

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN NORTH CAROLINA.

.DAY ONE...TODAY AND TONIGHT.

AREAS OF FROST ARE POSSIBLE LATE TONIGHT IN THE NORTH CAROLINA MOUNTAINS.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

AREAS OF FROST ARE POSSIBLE EARLY SUNDAY MORNING IN THE NORTH CAROLINA
MOUNTAINS...AND AGAIN LATE SUNDAY NIGHT AND EARLY MONDAY MORNING.

.SPOTTER INFORMATION STATEMENT...

NONE.

GAZ010-017-018-026-028-029-NCZ035>037-056-057-068>072-082-501>510-
SCZ001>014-019-211000-
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-
558 AM EDT SAT OCT 20 2012

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

.DAY ONE...TODAY AND TONIGHT.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY.

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

NONE.

07