109 
FXUS61 KRNK 122310
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
610 PM EST FRI MAR 12 2010

.SYNOPSIS...
LOW PRESSURE SITUATED OVER THE OHIO VALLEY WILL SLOWLY MEANDER
ACROSS THIS AREA THROUGH TONIGHT WHILE ANOTHER LOW STRENGTHENS
OVER THE SOUTHEAST. THIS LOW WILL SLIDE NORTH INTO THE MID
ATLANTIC BY SATURDAY NIGHT.

&&

.NEAR TERM /THROUGH SATURDAY/...
WILL KEEP FLOOD WATCH GOING AS IS. MAIN BRUNT OF PRECIP EXPECTED TO 
ARRIVE THIS EVENING IN THE SOUTHWEST...THEN SHIFT NORTHEAST 
OVERNIGHT INTO THE REST OF THE CWA...WITH MAIN BULK OF HEAVIEST 
RAINS OCCURRING ALONG THE BLUE RIDGE THIS EVENING...THEN INTO THE 
NRN/WRN HALF OVERNIGHT AS FLOW BECOMES MORE NORTHEAST WITH THE SFC 
LOW PULLING NORTH ALONG THE COAST.

AS FOR THUNDERSTORMS...BEST INSTABILITY WILL RESIDE OVER THE SWRN 
CWA THIS EVENING AND IT WILL SITUATE FROM NW-SE FROM BLF-MWK OUTSIDE 
OF THE WEAK WEDGE. EVEN THOUGH THE WATCH IS FOR FLOODING...AREAL AND 
RIVERS...ANY THUNDERSTORM HAS THE POTENTIAL TO CREATE A FLASH FLOOD 
THREAT IF THE MOVEMENT IS SLOW.

SLOWLY...THE INSTABILITY EVAPORATES OVERNIGHT WITH SHOWERS 
CONTINUING HEAVY AT TIMES. 

TEMPS SHOULD NOT FALL TOO MUCH TONIGHT SO WENT CLOSE TO MAV GUIDANCE 
AND PREVIOUS FORECAST.

SATURDAY...THE BULK OF THE SHOWERS WILL BE IN THE NRN HALF IN THE 
MORNING INTO EARLY AFTERNOON. AS THE UPPER LOW PIVOTS ACROSS SAT 
AFTERNOON COULD SEE SOME REDEVELOPMENT OF THUNDERSTORMS OUT 
EAST...AND POTENTIAL FOR SMALL HAIL WITH COLD POOL ALOFT.

HIGHS FOR SATURDAY ARE GOING TO BE DEPENDENT ON CLOUD COVER AND 
PRECIP. SUNSHINE THAT MAY POKE OUT WILL BE SELF DESTRUCTIVE WITH THE 
LOW OVERHEAD...SO FOR NOW GOING TO KEEP HIGHS CLOSE TO MAV. FROM 50S 
WEST TO 60S EAST.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
THE CENTER OF THE UPPER LOW WILL MOVE ACROSS THE FORECAST AREA 
SATURDAY NIGHT INTO SUNDAY. THE SURFACE WINDS WILL BACK TO A 
PREVAILING WEST NORTHWEST FLOW ENHANCING PRECIPITATION IN SOUTHEAST 
WEST VIRGINIA...SOUTH THROUGH THE NORTHERN MOUNTAINS OF NORTH 
CAROLINA. THIS UPSLOPE FLOW IS ANTICIPATED TO LAST THROUGH LATE 
MONDAY EVENING. THE UPSLOPE SHOWERS SHOULD BE REDUCED MONDAY NIGHT 
DUE TO THE FLOW TURNING MORE NORTHERLY.

WITH SLIGHTLY COOLER AIR ADVECTING INTO THE AREA THROUGH THE 
WEEKEND...RAIN MAY MIX WITH SOME SNOW MAINLY IN THE HIGHER 
ELEVATIONS...BUT EXPECT IT TO REMAIN PREDOMINANTLY RAIN. 85H 
TEMPERATURES WILL LOWER TO -1C TO -2C ESPECIALLY IN THE WESTERN 
MOUNTAINS. WITH LOW SURFACE TEMPERATURES RIGHT AROUND FREEZING AND 
ONLY A BRIEF PERIOD OF MIXING WITH SNOW...DO NOT THINK ANY 
ACCUMULATION WILL BE A PROBLEM.

MIN TEMPERATURES WILL RANGE FROM THE LOWER 30S WEST TO THE UPPER 30S 
EAST. WHILE MAX TEMPERATURES WILL REACH INTO THE 50S WEST TO NEAR 60 
EAST.

&&

.LONG TERM /TUESDAY 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 /00Z SATURDAY THROUGH WEDNESDAY/...
CONDITIONS CONTINUE TO OSCILLATE BETWEEN MVFR/IFR THIS EVENING AS
BANDS OF LIGHT RAIN/DRIZZLE PUSH WESTWARD THRU THE WEDGE AIDED BY
DEEP SE FLOW. EXPECT THINGS TO ONLY DETEORIATE MORE AS AXIS OF
HEAVIER SHOWERS/ISOLATED TSRA SLOWLY EDGES INTO THE AREA FROM THE SW
AFTER 00Z. THIS MAY CAUSE CIGS TO IMPROVE BRIEFLY TO MVFR DURING
THE HEAVIER RAINFALL WHILE VSBYS DROP TO IFR. THUS EXPECT SOME
FLUCTUATIONS WHEN THE MODERATE TO HEAVY RAIN ARRIVES. WHEN IT IS
NOT RAINING HARD...TYPCIALLY IN THIS SETUP...CIGS FALL DOWN TO IFR
OR LOWER AND VSBYS COULD AS WELL...SO FOR NOW GOING WITH A
PESSIMISTIC OUTLOOK...ESPECIALLY IN LYH/DAN AS THEY WILL SEE A
BETTER INFLUENCE OF MOISTURE FROM THE ATLANTIC.

ONCE THIS BAND OF HEAVER RAINS EXITS...CIGS WILL AGAIN DROP TO IFR
AFTER 12Z SAT...WITH WINDS ADJUSTING FROM NORTHEAST TO WEST
BEHIND THE SFC LOW. HOWEVER POTENTIAL TO SEE SOME IMPROVEMENT IN
FLYING CONDITIONS ESPCLY EAST OF THE MOUNTAINS SAT AFTERNOON AS
THE AREA SLIDES INTO A DRY SLOT IN THE WAKE OF THE DEPARTING
SURFACE LOW. MODELS EVEN TAKE KROA AND POINTS EAST TO VFR FOR A
WHILE BUT GIVEN LOW CONFIDENCE MAY ONLY SHOW THIS TREND FOR LATE
IN THE DAY. OTRW THINK SHOWERS WILL BECOME MORE WIDELY SCATTERED
DURING THE DAY WITH ONLY THE SE WVA SITES HOLDING IN IFR/LOW END
MVFR AS FLOW BECOMES MORE UPSLOPISH DURING THE AFTERNOON.

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. STILL EXPECTING MINOR TO MODERATE
FLOODING ALONG THE GREENBRIER AND PORTIONS OF THE JAMES...AS 1 TO
AS MUCH AS 2 INCHES FALLS OVER THE BASIN THROUGH SATURDAY. 

STILL SEEING POTENTIAL STREAMS AND SMALLER CREEKS TO FLOOD TONIGHT
AS THE BULK OF HEAVIEST RAINS SHIFT ACROSS THE AREA.

THUNDERSTORMS ARE POSSIBLE WHICH COULD POSE A FLASH FLOOD THREAT.

OTHER MAIN STEM RIVERS MAY FLOOD WITH MAIN CONCERN IS GREENBRIER
AND JAMES RIVER.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...FLOOD WATCH THROUGH SATURDAY AFTERNOON FOR VAZ018>020-022>024-
     033>035-043>047-058-059.
     FLOOD WATCH THROUGH SATURDAY MORNING FOR VAZ007-009>017-032.
NC...FLOOD WATCH THROUGH SATURDAY AFTERNOON FOR NCZ005-006.
     FLOOD WATCH THROUGH SATURDAY MORNING FOR NCZ001>004-018>020.
WV...FLOOD WATCH THROUGH SATURDAY AFTERNOON FOR WVZ043>045.
     FLOOD WATCH THROUGH SATURDAY MORNING FOR WVZ042.

&&

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