000
FXUS61 KRNK 131359
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
959 AM EDT MON MAY 13 2013

.SYNOPSIS...
HIGH PRESSURE ACROSS THE MID MISSISSIPPI RIVER VALLEY WILL DRIFT
SLOWLY EAST REACHING THE THE APPALACHIANS BY TUESDAY MORNING.
WEDNESDAY INTO THURSDAY...THE HIGH WILL SHIFT TO OFF THE ATLANTIC
COAST...AND A WARM FRONT WILL HEAD NORTH THROUGH THE TENNESSEE AND
OHIO VALLEYS. A COLD FRONT WILL APPROACH THE REGION ON
FRIDAY...AND STALL NEAR THE MASON- DIXON LINE OVER THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 950 AM EDT MONDAY...

FREEZE WARNINGS AND FROST ADVISORIES FROM LAST NIGHT ARE NOW
EXPIRED. FREEZE WARNING CONTINUES FOR THE PARTS OF SE WV AND SW VA
NEAR AND ALONG I-64 FOR TONIGHT AND EARLY TUESDAY.

MAIN FEATURE TODAY WILL BE A SHORTWAVE TROUGH MOVING THROUGH THE
MID-ATLANTIC STATES. KFCX RADAR SHOWING SOME WEAK RETURNS OVER
PARTS OF SOUTHEAST WEST VIRGINIA ALREADY. HAVE INCLUDED SOME
SPRINKLES OVER THOSE AREAS CURRENTLY. AS WE HEAD INTO THE
AFTERNOON...THE MID-LEVEL LAPSE RATES WILL INCREASE WHICH WILL
ALLOW BETTER DEVELOPMENT AND INCREASED CLOUD COVER OVER THE
NORTHER THIRD OF THE AREA. HAVE ADJUSTED HOURLY TEMPERATURE...DEW
POINT...AND SKY COVER GRIDS BASED UPON THE LATEST OBSERVATIONS AND
EXPECTED TRENDS INTO THE EARLY AFTERNOON.

AS OF 245 AM EDT MONDAY...

MOUNTAIN STRATO-CU ALONG WITH LIGHT BREEZES CONTINUE TO KEEP TEMPS
UP A BIT THIS MORNING WITH ONLY THE VALLEYS SUPPORTIVE OF
FROST/FREEZE HEADLINES ATTM. HOWEVER SINCE ALREADY UP PLAN TO KEEP
WARNINGS/ADVISORIES ONGOING SINCE COULD STILL SEE SPOTS DIP CLOSER
TO FREEZING DESPITE RATHER HIGH DEWPOINTS IN SPOTS. OTRW ANOTHER
CHILLY DAY FOR MID MAY IN STORE TODAY WITH THE DEEP 5H TROF PIVOTING
ACROSS AND STRONG SHORTWAVE ENERGY NOW OVER THE WESTERN LAKES
DROPPING SE THRU THE REGION BY EARLY THIS EVENING. THIS FEATURE
COMBO WITH COLD AIR ALOFT AND SURFACE HEATING ENOUGH TO CREATE STEEP
LAPSE RATES THIS AFTERNOON WITH PERHAPS JUST ENOUGH MOISTURE TO
PRODUCE A FEW -SHRA BANDS OR SPRINKLES ACROSS THE NW THIRD. THUS
HAVE INCLUDED SOME LOW POPS FROM LATE MORNING ON GNRLY ALONG THE I-
64 CORRIDOR AND ALONG THE SE WVA WESTERN SLOPES WHERE UPSLOPE AIDED.
COULD SEE SOME SPRINKLES DEVELOP OUT EAST OF THE BLUE RIDGE BUT
THINKING MAINLY PC TO MOSTLY CLOUDY PERIODS ELSW EXCEPT MORE SUN
INTO NW NC GIVEN DOWNSLOPE. CHILLY 85H TEMPS AND MORE CLOUDS SHOULD
KEEP HIGH TEMPS UNDER MOS AND WELL BELOW NORMAL AGAIN WITH HIGHER
ELEVATIONS LIKELY STUCK IN THE 40S WITH 50S ELSW MOUNTAINS...WHILE
THE EAST PUNCHES INTO THE LOW/MID 60S.

WAVE PASSES THIS EVENING WITH THE UPPER TROF HEADING EAST AS SURFACE
HIGH PRESSURE BUILDS INTO THE WEST LATE. THINK WILL AGAIN SEE SOME
LIGNERING CLOUDS SE AND OVER THE WEST BEFORE THINGS CLEAR FOR A
WHILE WITH LOSS OF HEATING UNDER WEAK SUBSIDENCE. COLDEST AIR ALOFT
WILL ALSO BE SHIFTING OFF TO THE NE WITH 85H WARMING TAKING SHAPE
LATE ESPCLY WESTERN HIGHER ELEVATIONS. THIS COMBINED WITH SOME
INCREASE IN WARM ADVECTION MID/HIGH CLOUDS LATE MAKES FOR
UNCERTAINTY IN REGARDS TO THE NEXT ROUND OF POSSBILE FROST/FREEZE
CONDITIONS. LATEST COOP MOS REMAINS VERY COLD BUT LOOKS TOO LOW
GIVEN BEST RAD CONDITIONS LIKELY OVER THE NORTH AND NE SECTIONS WITH
MORE OF A VALLEY FROST SCENARIO ELSW OUT WEST. APPEARS SOME OF THE
RIDGES MAY STRUGGLE TO GO MUCH BELOW 40 SO BUMPED UP LOWS IN A FEW
SPOTS. STILL COLD ENOUGH TO GO WITH ANOTHER FREEZE WATCH OVER THE
FAR NW AS EXPECT WILL NEED ADVISORY HEADLINES ELSW NORTH OF HIGHWAY
460 AND IN SPOTS OVER THE SW. HOWEVER WILL HOLD OFF WITH ANY NEW
ADVISORIES AND GIVE THE DAYSHIFT ANOTHER LOOK TO AVOID CONFUSION
SINCE 2ND PERIOD AND ALREADY HAVE THE HEADLINES GOING FOR THIS
MORNING.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
AS OF 315 AM EDT MONDAY...

HIGH PRESSURE OVER THE REGION TUESDAY WILL MOVE EAST INTO THE
ATLANTIC OCEAN BY TUESDAY NIGHT. AFTER A COLD START...HIGH
TEMPERATURES TUESDAY WILL RANGE FROM THE UPPER 50S IN THE MOUNTAINS
TO AROUND 70 IN THE SOUTHEAST.

WARM FRONT CROSSES THROUGH THE OHIO VALLEY WEDNESDAY MORNING WITH
SOME ISENTROPIC LIFT. ENOUGH MOISTURE...LIFT AND WARM AIR ADVECTION
FOR TO INCLUDE A LIGHT POPS IN THE NORTHERN AREAS...SUPPORTED BY
ECMWF AND GFS. IN CONTRAST THE NAM...KEEP POPS AND QPF TO OUR NORTH.
BY LATE WEDNESDAY 850 MB TEMPERATURES RECOVER INTO THE +14 TO +18
RANGE. HIGHS WEDNESDAY WILL BE MUCH WARMER THAN TUESDAY...WITH
READINGS FROM THE LOWER 70S IN THE MOUNTAINS TO THE LOWER 80S IN THE
PIEDMONT. WHILE AN ISOLATED THUNDERSTORM IS POSSIBLE ACROSS THE
HIGHER TERRAIN...THE BEST POTENTIAL FOR CONVECTION REMAIN TO OUR
NORTH INTO WEDNESDAY NIGHT. LOWS WEDNESDAY NIGHT WILL VARY FROM
LOWER 50S IN THE WESTERN MOUNTAINS TO THE LOWER 60S IN THE
SOUTHEAST.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 110 PM EDT SUNDAY...

ZONAL PATTERN ALOFT AND BROAD SOUTHWEST TO WEST SURFACE AND LOW
LEVEL WINDS WILL KEEP STATIONARY FROM PENNSYLVANIA TO MISSOURI
THROUGH THIS PART OF THE FORECAST PERIOD. WITH THE MAIN FOCUS FOR
PRECIPITATION TO THE NORTH OF THE FORECAST AREA...NOT MUCH TO
TRIGGER SHOWERS AND THUNDERSTORMS.

MODELS STILL BRING SHORT WAVE COMING THROUGH THE SOUTHERN STREAM
INTO THE REGION ON FRIDAY. HAVE THIS DAY WITH A SLIGHTLY HIGHER
PROBABILITY OF PRECIPITATION. OTHERWISE JUST EXPECT TYPICAL
OROGRAPHICALLY INDUCED AFTERNOON AND EVENING SHOWERS AND
THUNDERSTORMS.

TEMPERATURES WILL BE NEAR NORMAL TO ABOVE NORMAL THROUGH THE PERIOD.
NO REASON TO STRAY FAR FROM CURRENT GUIDANCE.

&&

.AVIATION /14Z MONDAY THROUGH FRIDAY/...
AS OF 630 AM EDT MONDAY...

STILL EXPECTING OVERALL VFR TO PREVAIL THROUGH TONIGHT. HOWEVER A
WEAK IMPULSE APPROACHING FROM THE NW THIS MORNING WILL ACT TO
KEEP AREAS OF SCTD-BKN STRATO-CU OVER THE MOUNTAINS THIS MORNING
WITH PERHAPS A BAND OF MOUNTAIN WAVE HIGH CLOUDS ABOVE THIS LAYER
EARLY ON. AS THIS WEAK IMPULSE CROSSES DURING THIS AFTERNOON...STEEP
LAPSE RATES ALONG WITH HEATING SHOULD PRODUCE A MORE WIDESPREAD
AREA OF SCTD-BKN 4-6K FT STRATO-CU ESPCLY MOUNTAINS FROM MIDDAY
INTO EARLY THIS EVENING. COULD EVEN SEE A FEW -SHRA OR SPRINKLES
IN ALL LOCATIONS EXCLUDING KDAN BUT WONT INCLUDE MENTION SINCE
IFFY WITH EXPECTED PREVAILING VFR VSBYS. CONTINUED DEEP NW FLOW
ALONG WITH MIXING WILL PUSH GUSTS INTO THE 20-25 KT RANGE WESTERN
SITES THIS AFTERNOON BEFORE SPEEDS QUICKLY DROP OFF EARLY THIS
EVENING.

HIGH PRESSURE WILL STRENGTHEN TUESDAY INTO WEDNESDAY ALLOWING VFR
CONDITIONS TO PREVAIL FOR MID WEEK.

THE NEXT CHANCE FOR SHOWERS AND STORMS AND WIDESPREAD SUB VFR
CONDITIONS IS NOT EXPECTED UNTIL THE END OF THE WEEK...THURSDAY/FRIDAY
TIME FRAME AS FIRST A WARM FRONT LIFTS THROUGH THE REGION...AND
THEN A COLD FRONT APPROACHES FROM THE NORTHWEST BY FRIDAY.

&&

.CLIMATE...
A NEW RECORD LOW WAS ESTABLISHED AT DANVILLE THIS MORNING WITH 37
DEGREES. THE PREVIOUS RECORD WAS 38 DEGREES FROM 1989. ALSO...A
LOW OF 35 DEGREES THIS MORING TIED THE RECORD LOW AT LYNCHBURG.
THE LAST OCCURRENCE WAS IN 1969.

LOW TEMPERATURES TUESDAY MORNING WILL FLIRT WITH RECORD LOW
TEMPERATURES AT ALL CLIMATE LOCATIONS. THE FOLLOWING ARE THE
CURRENT RECORD LOW TEMPERATURES FOR MAY 14 ALONG WITH THE YEAR OF
THAT RECORD.

MAY 14
ROA...37...1996
LYH...33...1997
RNK...31...1996
DAN...38...2007
BLF...33...1996

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...FREEZE WATCH FROM LATE TONIGHT THROUGH TUESDAY MORNING FOR
     VAZ019-020-024.
NC...NONE.
WV...FREEZE WATCH FROM LATE TONIGHT THROUGH TUESDAY MORNING FOR
     WVZ045.

&&

$$
SYNOPSIS...JH
NEAR TERM...DS/JH
SHORT TERM...KK
LONG TERM...AMS
AVIATION...DS/JH/KM
CLIMATE...CF/DS