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000
FXUS61 KRNK 182009
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
409 PM EDT SAT MAY 18 2013

.SYNOPSIS...
A FRONT EXTENDED FROM CENTRAL OHIO INTO NORTHEAST NORTH CAROLINA
THIS AFTERNOON. THIS FRONT WILL LINGER ACROSS THE MID ATLANTIC
REGION THROUGH SUNDAY NIGHT...ACTING AS LOW LEVEL SUPPORT TO
SHOWER AND THUNDERSTORM ACTIVITY AS AN UPPER LEVEL TROUGH PASSES
ACROSS THE AREA THROUGH MONDAY.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
AS OF 345 PM EDT SATURDAY...

RADAR IMAGERY HAS INDICATED THAT WHILE RAINFALL HAS BEEN
WIDESPREAD ACROSS THE FORECAST AREA TODAY...RAINFALL AMOUNTS HAVE
BEEN ON THE LIGHT SIDE FOR THE MOST PART. FORECAST MODELS HAVE
ALSO BACKED OFF ON THE EXPECTED RAINFALL AMOUNTS HEADING INTO THE
OVERNIGHT HOURS AND THEREFORE DO NOT BELIEVE THAT THE FLOODING
THREAT DISCUSSED EARLIER TODAY IS HIGH ENOUGH TO WARRANT A FLOOD
WATCH EAST OF THE BLUE RIDGE AT THIS TIME. THAT STATED...DO NOT
THINK WE ARE ALTOGETHER OUT OF THE WOODS...SO WILL LET THE EVENING
SHIFT MONITOR RADAR AND REASSESS THE SITUATION LATER THIS EVENING.

DESPITE THE OVERALL LIGHT RAIN SO FAR THIS AFTERNOON...THE
INGREDIENT REMAIN FOR THE POSSIBILITY OF HEAVY RAIN TO PASS ACROSS
THE AREA THROUGH LATE SUNDAY EVENING. STILL HAVE A WEAK WEDGE OF
HIGH PRESSURE SITUATED AGAINST THE APPALACHIANS AS INDICATED BY
LIGHT EASTERLY WIND ACROSS OUR AREA...WHILE A LARGE UPPER LEVEL
TROUGH APPROACHES FROM THE WEST. PRECIPITABLE WATER VALUES ARE
APPROACHING 1.5 INCHES EAST OF THE MOUNTAINS...AND ARE EXPECTED TO
REACH AROUND 1.75 INCHES TONIGHT/SUNDAY MORNING...WHICH IS WELL
ABOVE NORMAL. ALSO...UPPER LEVEL WINDS ARE ALSO EXPECTED TO BE
LIGHT...WHICH WILL MAKE FOR SLOW MOVING CELLS. ALL OF THESE
FACTORS MAY LEAD TO VERY EFFICIENT RAIN PRODUCING STORMS THAT WILL
BE MORE PULSE VARIETY COMPARED TO WHAT WAS OBSERVED TODAY.
REGARDLESS...THESE RAIN MAKERS MAY RESULT IN FLASH FLOODING...
ESPECIALLY IF THE CELLS BEGIN TO TRAIN OVER THE SAME LOCATIONS.

AS FOR TEMPERATURES...HIGH DEWPOINTS AND ABUNDANT CLOUD COVER WILL
MAKE FOR A MILD NIGHT...WITH OVERNIGHT LOWS HOLDING IN THE UPPER
50S WEST TO THE LOW/MID 60S EAST. BECAUSE OF THE VERY MOIST
CONDITIONS...WILL ALSO BE IN FOR SOME PATCHY FOG AREAWIDE.

SCATTERED RAINFALL AND WIDESPREAD CLOUD COVER WILL LIMIT HEATING
FOR SUNDAY...ALTHOUGH MID AND HIGH CLOUDS WILL DECREASE SOMEWHAT
AS DRIER AIR WORKS ITS WAY IN ALOFT. AS SUCH...WILL BE LOOKING FOR
HIGHS IN THE LOW TO MID 70S.

&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
AS OF 325 PM EDT SATURDAY...

THE AREA WILL STILL BE INVOLVED WITH SHOWERS AND STORMS ASSOCIATED
WITH THE CURRENT SLOWLY MOVING UPPER LEVEL TROUGH. HOWEVER...MOST OF
THE GUIDANCE OFFER SOLUTIONS THAT PLACES THE AXIS OF THE TROUGH
OVER...OR JUST EAST OF THE AREA BY DAYBREAK MONDAY. THIS WILL BEGIN
A TREND WHERE WE WILL EXPERIENCE LESS PRECIPITATION ACROSS THE
WESTERN PORTION OF THE FORECAST AREA...AND A GREATER AMOUNT OVER THE
EAST. MODEL TIMING OF THE TROUGH IS FAIRLY CONSISTENT THAT IT WILL
BE EAST OF THE AREA BY DAYBREAK TUESDAY. TUESDAY WILL BEGIN A DAY OF
TRANSITION BETWEEN THE DEPARTING TROUGH ON THE EAST COAST...AND OUR
FOCUS TURNING TO ONE THAT WILL BE DEVELOPING ACROSS THE UPPER
MISSISSIPPI VALLEY. IN BETWEEN THE TWO...VERY BRIEF UPPER LEVEL
RIDGING WILL TAKE PLACE ACROSS THE AREA. HOWEVER...ENOUGH LOW LEVEL
MOISTURE WILL REMAIN SO THAT WE CANNOT RULE OUT SOME ISOLATED
SHOWERS OR THUNDERSTORMS ACROSS THE REGION ON TUESDAY. THE INFLUENCE
OF THE UPPER RIDGE SHOULD HELP KEEP THE CONVECTION FROM BECOMING TOO
DEEP.

TEMPERATURES THROUGH THE PERIOD WILL TREND MILDER. BY
TUESDAY...HIGHS IN THE MID TO UPPER 80S ARE EXPECTED ACROSS THE
PIEDMONT WITH A MIX OF 80S IN THE MOUNTAINS. THE HIGHEST ELEVATIONS
WILL BE IN THE UPPER 70S.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
AS OF 1215 PM EDT SATURDAY...

THE AREA ONLY LOOKS TO GET A BRIEF BREAK IN SIGNIFICANT GENEROUS
COVERAGE OF SHOWER ACTIVITY DURING THE TUESDAY NIGHT INTO WEDNESDAY
TIME FRAME. IT WILL BE DURING THIS PERIOD THAT A BRIEF UPPER LEVEL
SHORTWAVE RIDGE BUILDS OVER THE AREA BETWEEN THE PARTING CLOSED LOW
THAT IS CURRENTLY GIVING THE REGION PRECIPITATION...AND THE NEXT
SYSTEM THAT WILL IMPACT OUR REGION LATE WEDNESDAY NIGHT THROUGH THE
START OF THE NEXT WEEKEND. ALTHOUGH...WE CANNOT RULE OUT ISOLATED TO
SCATTERED SHOWERS OR EVEN A FEW STORMS DURING THE TUESDAY NIGHT INTO
WEDNESDAY TIME PERIOD. LOW LEVEL FLOW WILL ALREADY BRINING
ADDITIONAL MOISTURE INTO THE REGION FROM SOUTHWEST IN ADVANCE OF THE
NEXT SYSTEM.

OUR NEXT SYSTEM IS CURRENTLY PROGGED TO BE ASSOCIATED WITH AN UPPER
LEVEL CLOSED LOW THAT WILL PINWHEEL AROUND THE UPPER MISSISSIPPI
VALLEY WEDNESDAY THROUGH AT LEAST FRIDAY. PLENTY OF GULF OF MEXICO
MOISTURE WILL BE ADVECTED NORTHWARD INTO THE REGION IN ADVANCE OF
THIS SYSTEM. ALSO...PERIODIC BITS OF ENERGY WILL SPIRAL EASTWARD
FROM THE MAIN SYSTEM AND COMBINE WITH DAYTIME HEATING TO PROMOTE A
GENEROUS COVERAGE OF SHOWERS AND STORMS OVER THE REGION THROUGH AT
LEAST THE START OF THURSDAY NIGHT. MODEL GUIDANCE VARIES AS TO THE
SPEED OF THE ASSOCIATED SURFACE COLD FRONT. HPC GUIDANCE IS FAVORING
A SLOWER SOLUTION THAT IS MORE IN LINE WITH THE OPERATIONAL 12Z/8AM
GFS THAT DOESN/T HAVE THE FRONT EXITING THE AREA UNTIL FRIDAY
EVENING. HAVE FOLLOW CLOSELY WITH THIS SCENARIO.

TEMPERATURES THROUGH THIS PERIOD OF THE FORECAST WILL TREND
COOLER...WITH HIGHS ON SATURDAY EXPECTED TO BE IN THE LOW TO MID 60S
ACROSS THE MOUNTAINS WITH MID 60S TO NEAR 70 ACROSS THE PIEDMONT.

&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
AS OF 300 PM EDT SATURDAY...

MVFR AND IFR CEILINGS WILL REDEVELOP/LOWER THIS EVENING AS HIGH
PRESSURE WEDGING AGAINST THE APPALACHIANS MAINTAINS A WEAK
EASTERLY FLOW OF VERY MOIST AIR. PERIODS OF HEAVY RAIN AND FOG
OVERNIGHT WILL ALSO LEAD TO INTERMITTENT IFR VISIBILITIES...WHICH
WILL IMPROVE AFTER 19/14Z WITH DAYTIME HEATING. SHOWERS AND
THUNDERSTORMS ALONG WITH MVFR TO IFR FLYING CONDITIONS WILL
PERSIST THROUGH SUNDAY AFTERNOON AS A DEEP UPPER LEVEL TROUGH
PASSES ACROSS THE AREA.

CONDITIONS LOOK TO IMPROVE MONDAY AS THE UPPER TROUGH MOVES
TO THE MID ATLANTIC COAST. EXPECT TUESDAY TO BE THE BEST BET FOR
DECENT FLYING CONDITIONS ALTHOUGH AN ISOLATED AFTERNOON AIRMASS
SHOWER OR THUNDERSTORM IS STILL POSSIBLE. NEXT FRONT APPROACHES
ON WEDNESDAY WITH MORE SHOWERS/STORMS DEVELOPING. THIS FRONT DOES
NOT APPEAR TO BE IN A BIG HURRY AND LOOKS TO BRING MVFR
CONDITIONS...POSSIBLY IFR AT NIGHT...TO TAF SITES FOR THE LATTER
HALF OF THE WEEK.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...FLASH FLOOD WATCH THROUGH SUNDAY MORNING FOR VAZ009-015.
NC...FLASH FLOOD WATCH THROUGH SUNDAY MORNING FOR NCZ001-002-018.
WV...NONE.

&&

$$
SYNOPSIS...NF
NEAR TERM...NF
SHORT TERM...KM
LONG TERM...DS
AVIATION...AMS/PM