425 
FXUS61 KRNK 131144
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
643 AM EST SAT MAR 13 2010

.SYNOPSIS...
LOW PRESSURE COVERING THE MID ATLANTIC REGION WILL MOVE SLOWLY
EAST SATURDAY AND SUNDAY AND WILL BE OFF THE NEW JERSEY COAST
SUNDAY NIGHT.

&&

.NEAR TERM /THROUGH TONIGHT/...
LOW PRESSURE WAS CENTERED IN CENTRAL VIRGINIA WITH AN AXIS OF
SURFACE CONVERGENCE FROM THE LOW IN TO SOUTHERN WEST VIRGINIA. A
BAND OF MODERATE TO HEAVY SHOWERS EXTENDED ALONG THE CONVERGENCE
AXIS. WIDESPREAD RAINFALL AMOUNTS REPORTED BY THE IFLOWS NETWORK
RANGED FROM 1.5 TO 2.5 INCHES. PRECIPITATION IS BEING ENHANCED
NORTH OF THE LOW BY UPSLOPE ALONG THE BLUE RIDGE. WILL CONTINUE
THE FLOOD WATCH IN ALL AREAS. MAY BE ABLE TO CANCEL THE COUNTIES
IN NORTHERN NORTH CAROLINA BUT LOCAL GAGES SHOW CREEKS AND STREAMS
STILL RISING IN THAT AREA. 

SREF AND LOCAL WRF LOOK LIKE THEY HAVE A GOOD HANDLE ON THE
NORTHERN DRIFT OF THE BAND OF HEAVY RAIN. HAVE ADJUSTED THE
PROBABILITY OF PRECIPITATION WITH HIGHEST PERCENTAGE IN THE NORTH
TO REFLECT THIS TIMING. EXPECT THAT AFTER 18Z MUCH OF THIS
RAINFALL WILL BE NORTH OF THE FORECAST AREA. ENOUGH LOW LEVEL
WEST WINDS BY THAT TIME TO HAVE A CHANCE FOR SHOWERS IN THE
WESTERN UPSLOPE COUNTIES. MODELS AREA ALSO SHOWING A WEAK SHORT
WAVE ROTATING AROUND THE UPPER LOW WHICH WILL JUST BE MOVING INTO
NORTH CAROLINA BY THE END OF THE DAY. THIS MAY TRIGGER A FEW
SHOWERS ACROSS THE SOUTHERN FORECAST AREA SO HAVE LEFT CHANCE
PROBABILITY IN FOR THIS AFTERNOON. 

AS UPPER LOW APPROACHES TEMPERATURES AT 850 MB START TO DROP.
TOOK A BLEND OF MET/MAV GUIDANCE FOR HIGHS TODAY. LOWS TONIGHT
WILL BE INTO THE 30S IN THE MOUNTAINS SO KEPT THE MIX OF SNOW IN
AT HIGHER ELEVATIONS LATE TONIGHT. STILL SLIGHTLY TOO WARM FOR
ANYTHING BUT MINIMAL ACCUMULATION.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY NIGHT/...
SUNDAY INTO MONDAY...THE AREA REMAINS IN NORTHWEST FLOW BEHIND THE 
EXITING UPPER LOW. PRECIPITATION WILL BE CONFINED TO PRIMARILY THE 
MOUNTAINS...ESPECIALLY THOSE OF SOUTHEAST WEST VIRGINIA. THE 
PRECIPITATION TYPE WILL BE MAINLY RAIN SHOWERS. HOWEVER...WITH 
COLDER AIR BUILDING BEHIND THE DEPARTING LOW...WE CANNOT RULE OUT 
SOME ISOLATED SNOW SHOWERS FOR A FEW HOURS LATE SUNDAY NIGHT...AND 
MONDAY NIGHT AT THE HIGHER ELEVATIONS OF SOUTHEAST WEST VIRGINIA AND 
IN THE NORTHERN MOUNTAINS OF NORTH CAROLINA. ANY ACCUMULATIONS WOULD 
BE UNDER ONE HALF INCH EACH NIGHT. WINDS WILL INCREASE ON MONDAY AS 
THE PRESSURE GRADIENT TIGHTENS BETWEEN THE DEPARTING LOW AND AN 
APPROACHING AREA OF HIGH PRESSURE. THIS HIGH PRESSURE WILL BEGIN TO 
BUILD INTO THE REGION ON TUESDAY BRINGING DECREASING CLOUD COVER AND 
A DRY FORECAST.

&&

.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
THE EXTENDED PERIOD IS CHARACTERIZED BY DRY WEATHER AND NEAR TO 
SLIGHTLY ABOVE NORMAL TEMPERATURES. WE WILL REMAIN IN A MEAN TROUGH 
THROUGH THE PERIOD...WITH 850MB TEMPERATURES STARTING OUT AROUND 1C 
ON TUESDAY AND INCREASING TO 4-5C BY FRIDAY. THIS WILL MEAN WE WILL 
SEE INCREASING TEMPERATURES EACH DAY THROUGH FRIDAY...USED 850MB 
TEMPERATURES AS A STARTING POINT FOR HIGHS AND BLENDED WITH MOSGUIDE.

WITH THE TROUGH OVERHEAD WE WILL HAVE RATHER STEEP LOW LEVEL LAPSE 
RATES TUESDAY THROUGH THURSDAY...WHICH COULD ALLOW ISOLATED 
AFTERNOON SHOWERS TO DEVELOP. THE BEST CHANCE FOR THIS APPEARS TO BE 
ACROSS THE WEST...BUT ANY SHOWERS WILL BE ISOLATED AND THEREFORE 
CURRENTLY JUST GOING WITH A DRY FORECAST. THE NEXT CHANCE FOR MORE 
WIDESPREAD RAIN DOES NOT APPEAR TO BE UNTIL SUNDAY...WHEN MODELS 
SHOW A COLD FRONT MOVING THROUGH.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
BAND OF LIGHT TO MODERATE SHOWERS WILL BE ONGOING AT LWB AT 12Z
WITH BLF AND ROA ON THE SOUTHERN EDGE OF THE BAND. THE
PRECIPITATION WILL CONTINUE TO MOVE NORTH AND IS EXPECTED TO CLEAR
OUT OF LWB AROUND 17Z. CEILINGS AND VISIBILITIES IN THIS AREA WILL
BE MVFR WITH OCCASIONAL IFR CEILINGS WITH THE HEAVIER SHOWERS. 

LOW CONFIDENCE IN REDEVELOPMENT OF SHOWERS LATE THIS MORNING INTO
EARLY THIS AFTERNOON ACROSS THE REST OF THE FORECAST AREA. AS THE
WINDS BECOME MORE WESTERLY UPSLOPE SHOWERS MAY DEVELOP IN THE
MOUNTAINS AND A WEAK SHORT WAVE ROTATING AROUND THE UPPER LOW MAY
SPARK ISOLATED SHOWERS AND THUNDERSTORMS EAST OF THE BLUE RIDGE BY
LATE THIS AFTERNOON. WITH THE UPSLOPE IN THE WEST CEILINGS ARE
EXPECTED TO REMAIN MVFR. IN THE EAST CONDITIONS SHOULD IMPROVE TO
VFR THIS AFTERNOON. CEILINGS MAY DROP TO IFR AT LWB AND BLF AFTER
00Z BUT ONLY MODERATE CONFIDENCE THAT THIS WILL HAPPEN.

SCATTERED SHOWERS ARE LIKELY SATURDAY NIGHT THROUGH SUNDAY...WITH
CEILINGS AND VISIBILITIES FALLING BACK INTO THE MVFR/IFR RANGE
DURING THESE SHOWERS. LOOKS LIKE LOW CLOUDS AND SPOTTY -RA MAY
KEEP AT LEAST MVFR CONDITIONS GOING INTO MONDAY WITH SOME SLOW
IMPROVEMENT TO VFR TUESDAY INTO WEDNESDAY.

&&

.HYDROLOGY...
NO CHANGES TO THE FLOOD WATCH. BLUESTONE DAM AND CLAYTOR LAKE HAVE
INCREASED THEIR RELEASES.  

THE FORECASTS FOR THE NEW...GREENBRIER AND JAMES RIVERS WILL BE
UPDATED BY NOON.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...FLOOD WATCH UNTIL 6 PM EST THIS EVENING FOR VAZ018>020-022>024-
     033>035-043>047-058-059.
     FLOOD WATCH UNTIL NOON EST TODAY FOR VAZ007-009>017-032.
NC...FLOOD WATCH UNTIL 6 PM EST THIS EVENING FOR NCZ005-006.
     FLOOD WATCH UNTIL NOON EST TODAY FOR NCZ001>004-018>020.
WV...FLOOD WATCH UNTIL 6 PM EST THIS EVENING FOR WVZ043>045.
     FLOOD WATCH UNTIL NOON EST TODAY FOR WVZ042.

&&

$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...DS
LONG TERM...MC
AVIATION...AMS/JH
HYDROLOGY...AMS