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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRNK 142002
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
402 PM EDT TUE MAY 14 2013

.SYNOPSIS...
-- Changed Discussion --
HIGH PRESSURE WILL CONTINUE TO SLIDE EAST OFF THE SOUTH CAROLINA
COAST TONIGHT...WHILE A DEEP LOW PRESSURE SYSTEM PASSES ACROSS THE
NORTHERN GREAT LAKES. A WARM FRONT ASSOCIATED WITH THE LOW WILL
PASS JUST NORTH OF OUR AREA...TRIGGERING ISOLATED SHOWERS NORTH
OF THE HIGHWAY 460 CORRIDOR TONIGHT. A FRONTAL BOUNDARY WILL
APPROACH THE AREA ON THURSDAY AND STALL OVER OR NEAR THE REGION
INTO THE START OF THE WEEKEND.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH WEDNESDAY/...
-- Changed Discussion --
AS OF 345 PM EDT TUESDAY...


LOOKING INTO THIS EVENING...WINDS WILL REMAIN A LITTLE ON THE
GUSTY SIDE THROUGH SUNSET AS OUR AREA BECOMES PINCHED BETWEEN HIGH
PRESSURE OFF THE SC COAST...WHILE A DEEP LOW PRESSURE SYSTEM
PASSES ACROSS THE NORTHERN GREAT LAKES. WILL ALSO SEE SCATTERED
MID CLOUDS PUSHING ACROSS THE AREA...BUT WITH DRY AIR IN THE LOW
LEVELS...NOT LOOKING FOR ANYTHING IN THE WAY OF SHOWER ACTIVITY.

OVERNIGHT...A WARM FRONT ASSOCIATED WITH THE LOW WILL PASS JUST
NORTH OF OUR AREA...TRIGGERING ONLY ISOLATED SHOWER ACTIVITY...IF
ANY...ACROSS OUR NORTHERN TIER OF COUNTIES. OTHERWISE WILL BE
LOOKING AT MAINLY JUST INCREASED CLOUD COVER NORTH OF HIGHWAY 460.
WHILE LOW LEVEL WINDS WILL DIMINISH AFTER SUNSET...WINDS ALOFT
WILL INCREASE DURING THE NIGHT...AND MAY SEE A FEW GUSTS IN THE 40
TO 45 MPH RANGE ACROSS THE HIGHEST RIDGES IN THE NORTH CAROLINA
MOUNTAINS INTO EXTREME SOUTHWEST VIRGINIA. AT THIS TIME...DO NOT
THINK ENOUGH OF THE AREA WILL BE AFFECTED TO WARRANT A WIND
ADVISORY. OTHERWISE...WITH UPPER LEVEL RIDGING BUILDING INTO THE
AREA...NO THREAT FOR FROST OR FREEZING TEMPERATURES EXISTS
TONIGHT. EXPECT LOWS TO RANGE FROM THE LOW/MID 50S ACROSS THE
MOUNTAINS...TO THE UPPER 40S TO LOW 50S FURTHER EAST.

THE WARMUP REALLY KICKS IN FOR WEDNESDAY AS THE UPPER RIDGE
SETTLES ACROSS THE AREA AND WE FALL INTO A STRONG WEST TO
SOUTHWESTERLY WIND FLOW. EXPECT A FEW AFTERNOON CLOUDS...WITH
HIGHS APPROACHING THE UPPER 70S TO LOW 80S ACROSS THE
MOUNTAINS...AND REACHING INTO THE UPPER 80S FURTHER EAST.
-- End Changed Discussion --

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
-- Changed Discussion --
AS OF 330 PM EDT TUESDAY...

AIR MASS MODERATES BY THURSDAY WITH MORE TYPICAL MAXIMUM TEMPERATURES.

SOUTHERN STREAM SHORT WAVE REACHES THE TENNESSEE VALLEY THURSDAY
NIGHT THEN WEAKENS AS IT MOVES INTO THE SOUTHERN APPALACHIANS
FRIDAY. FRONT OVER THE MID ATLANTIC REGION DROPS SOUTH THROUGH
VIRGINIA ON THURSDAY NIGHT THEN RETREATS BACK NORTH OF THE
FORECAST AREA ON FRIDAY. COMBINATION OF BOTH THE SHORT WAVE AND
FRONT WILL BRING THE MORE WIDESPREAD SHOWERS AND THUNDERSTORMS
INTO THE AREA THURSDAY NIGHT AND FRIDAY.
-- End Changed Discussion --

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
-- Changed Discussion --
AS OF 330 PM EDT TUESDAY...

SEEING SIGNIFICANT DIFFERENCES BETWEEN THE 00Z/14 ECMWF AND GFS BY
SUNDAY WITH THE LONG WAVE TROF IN THE CENTRAL UNITED STATES. ECMWF
SHOWED A DISTINCT SOUTHERN PIECE OF THE TROF AND WAS MUCH SLOWER
THAN THE GFS.

STARTING OUT FRIDAY NIGHT WITH THE SURFACE FRONT FROM WISCONSIN INTO
NORTHWESTERN VIRGINIA. BY SUNDAY THE FRONT HAS MOVED BACK NORTH.
LEANING TOWARD THE SLOWER ECMWF KEEPS THE FORECAST AREA DEEP IN THE
WARM UNSTABLE AIR THROUGH TUESDAY.

MODELS ALSO ARE TAKING THE UPPER LOW OVER SAN FRANCISCO THIS MORNING
ACROSS THE ROCKIES ...THEN THE TENNESSEE VALLEY...THEN INTO THE
SOUTHERN APPALACHIANS SUNDAY NIGHT. SUSPECT THE DETAILS MAY NOT BE
CORRECT THIS FAR OUT BUT IDEA OF A SHORT WAVE CUTTING INTO THE
EASTERN UPPER RIDGE IS REASONABLE. MAY HAVE ENHANCED PROBABILITY
OF PRECIPITATION WITH ANY FEATURE LIKE THIS SATURDAY THROUGH
TUESDAY.
-- End Changed Discussion --

&&

.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
AS OF 200 PM EDT TUESDAY...

SURFACE OBSERVATIONS INDICATE VFR CONDITIONS AREAWIDE...WITH A
DISTURBANCE CAUGHT IN THE NORTHWESTERLY FLOW ALOFT TRIGGERING MID
LEVEL CLOUD COVER ACROSS THE MOUNTAINS THIS AFTERNOON. HIGH
PRESSURE HAS SHIFTED TO THE SOUTH CAROLINA COAST...ALLOWING
SURFACE WINDS TO BECOME SOUTHWESTERLY. WINDS HAVE BECOME SOMEWHAT
GUSTY THIS AFTERNOON ACROSS THE MOUNTAINS AS THE REGION HAS BECOME
PINCHED BETWEEN HIGH PRESSURE TO THE SOUTH...AND A DEEP LOW
PRESSURE SYSTEM CROSSING THE NORTHERN PLAINS.

FORECAST MODELS STILL PROGGING A WARM FRONT ASSOCIATED WITH LOW TO
PASS ACROSS THE NORTHERN THIRD OF THE AREA TONIGHT. MAY SEE A FEW
SPRINKLES AND CEILINGS IN THE 5KFT TO 8KFT RANGE IN THE VICINITY
OF LWB AND LYH...HOWEVER MORE ORGANIZED SHOWER ACTIVITY IS
EXPECTED TO REMAIN TO THE NORTH...AND HAVE THEREFORE LEFT OUT
MENTION IN THE 14/18Z TAF PACKAGE. A LARGER ISSUE OVERNIGHT WILL
BE THE POSSIBILITY OF WIND SHEAR...AS WINDS NEAR THE SURFACE WILL
DIMINISH THIS EVENING BUT INCREASE ALOFT AS A SURGE OF MUCH WARMER
AIR ARRIVES. LATEST MODELS SHOW A 40KT TO 45KT JET JUST OFF THE
SURFACE AFTER MIDNIGHT...AND HAVE INCLUDED A PERIOD OF LLWS FOR
ALL TAF SITES THROUGH AROUND SUNRISE.

OUR NEXT CHANCE OF ORGANIZED PRECIPITATION AND AREAS OF SUB-VFR
CONDITIONS WILL BE LATE THURSDAY THROUGH SATURDAY WHEN A FRONTAL
SYSTEM MOVES INTO AND THEN STALLS NEAR THE REGION.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.

&&

$$
SYNOPSIS...NF
NEAR TERM...NF
SHORT TERM...AMS
LONG TERM...AMS
AVIATION...JH/NF