Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 031401
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1001 AM EDT TUE MAY 3 2016

.SYNOPSIS...
A COLD FRONT WILL CONTINUE TO SLOWLY MOVE SOUTHWARD THROUGH WEDNESDAY.
MEANWHILE...LOW PRESSURE DEEPENING ACROSS THE GREAT LAKES WILL
DRIFT SOUTHWARD INTO THE SOUTHERN APPALACHIANS BY
THURSDAY...REMAINING OVER THE REGION UNTIL LATE IN THE WEEKEND.
WIDESPREAD RAIN TODAY WILL GIVE WAY TO AN UNSETTLED WEATHER
PATTERN WITH SCATTERED TO NUMEROUS SHOWERS AND UNSEASONABLY COOL
TEMPERATURES DURING THE LATER HALF OF THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1000 AM EDT TUESDAY...

SOME MINOR ADJUSTMENTS TO THE GRIDS THIS MORNING TO ACCOUNT FOR
CURRENT RADAR AND SATELLITE TRENDS. SATELLITE SUPPORTS GUIDANCE
TRENDS FOR THINNING OUT THE CLOUDS AND THIS SHOULD HELP GET SOME
SURFACED BASED INSTABILITY GOING FOR THIS AFTERNOON...LEADING TO
SHOWER/THUNDERSTORM FORMATION. THE MOST LIKELY SCENARIO WILL BE
FOR THE BULK OF ACTIVITY TO FORM THIS AFTERNOON EAST OF THE BLUE
RIDGE WHERE THE POOL OF INSTABILITY WILL BE GREATER...BUT THE BEST
SUPPORT FOR SEVERE WILL BE FURTHER TO THE EAST. WILL STILL HAVE TO
KEEP A VIGILANT EYE ON STORMS THROUGH THE AFTERNOON AS COOL TEMPS
ALOFT WILL STILL SUPPORT HAIL AND PWATS REMAIN HIGH ACROSS THE
PIEDMONT WHERE LOCALLY HEAVY DOWNPOURS ARE POSSIBLE. HIGHS IN THE
MID 70S EAST TO MID/UPPER 60S WEST SHOULD BE GOOD FOR TODAY.

PREVIOUS AFD...

UNSETTLED WEATHER PATTERN TO CONTINUE...BUT SEVERE THREAT AND
FLOODING THREAT GREATLY DIMINISHED.

BIG QUESTION FOR TODAY IS WHETHER OR NOT THERE WILL BE A RESURGENCE
OF CONVECTION ALONG THE FRONT AS A WAVE OF LOW PRESSURE RIDES
ALONG THE FRONT. MODELS TO VARYING DEGREES INCREASE INSTABILITY
ACROSS NORTH CENTRAL NC INTO SOUTHSIDE VA...WHERE SPC HAS
INDICATED A SLIGHT RISK...WITH A MARGINAL RISK AS FAR NORTH AND
WEST AS THE BLUE RIDGE. HOWEVER...SFC LOW PRESSURE IS PROGGED TO
RIDE MAINLY JUST S-E OF THE CWA ALONG THE FRONT AS IT CONTINUES TO
SLOWLY SAG SOUTHEAST. THUS...FEEL SEVERE THREAT IS LIMITED AT BEST
FOR OUR CWA...AND IF SO LIKELY CONFINED TO THE CASWELL/HALIFAX
AREA. ECMWF LEAST IMPRESSIVE ABOUT THUNDER THREAT FOR TODAY...WHILE
GFS/NAM MORE FAVORABLE. OVERALL...SEVERE WEATHER PARAMETERS DO NOT
APPEAR FAVORABLE FOR MUCH SEVERE. HAVE INCLUDED MENTION OF THUNDER
ACROSS SOUTHSIDE INTO NORTH CENTRAL NC...BUT HAVE REFRAINED FROM
MENTIONING ELSEWHERE AND DID NOT MENTION SEVERE AT THIS POINT.
ADDITIONAL RAINFALL SHOULD REMAIN BELOW FLASH FLOOD THRESHOLDS...WITH
THE HEAVIEST RAIN FALLING ACROSS THE AREAS WITH HIGHER FFG VALUES...NAMELY
EAST OF THE BLUE RIDGE. NONETHELESS...LIKELY TO CATEGORICAL POPS
ARE IN ORDER FOR MUCH OF THE CWA THROUGH 00Z...DECREASING TO
CHANCE AFTER MIDNIGHT FROM WEST TO EAST.

MAX TEMPERATURES PROBLEMATIC...BUT THINKING THAT CLOUDS WILL BE
ABUNDANT TODAY AS UPPER HEIGHTS CONTINUE TO LOWER...FRONT REMAINS
QUASI-STATIONARY ACROSS THE S-SE PORTIONS OF THE REGION...AND
LIGHT TO MODERATE RAIN SHOWERS CONTINUE TO MOVE ACROSS THE REGION.
HAVE LEANED TOWARD THE COOLER SIDE OF GUIDANCE AS A RESULT.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
AS OF 400 AM EDT TUESDAY...

THE COLD FRONT SHOULD FINALLY BE OFFSHORE BY WEDNESDAY. HOWEVER...A
DEEP UPPER LEVEL TROUGH FROM HUDSON BAY IN CANADA SHOULD TRACK
OVER THE GREAT LAKES DURING THE DAY. AS IT APPROACHES THE MID
ATLANTIC ON WEDNESDAY NIGHT...WINDS SHOULD SHIFT TO THE NORTHWEST.
A PRETTY STIFF COLD AIR ADVECTION PATTERN TAKES PLACE THROUGH
THURSDAY AND FRIDAY...AS THE UPPER LEVEL TROUGH CUTS OFF FROM THE
FLOW TO BECOME A CLOSED UPPER LEVEL OVERHEAD.

AN OMEGA BLOCK PATTERN WILL RESIDE OVER THE UNITED STATES AS THE
UPPER LEVEL LOW SETTLES OVER THE MID ATLANTIC. THEREFORE...COOL AND
DAMP CONDITIONS ARE EXPECTED FOR THE REMAINDER OF THIS WORK WEEK.
PERIODIC SHOWERS...LOW CLOUDS...AND PATCHY FOG ARE LIKELY. WITH A
DEEP COOL POOL OF AIR ALOFT...TEMPERATURES SHOULD DROP TO NEAR OR
BELOW NORMAL FOR THE FIRST WEEK OF MAY. FOR EXAMPLE...HIGHS ON
THURSDAY SHOULD ONLY REACH THE LOWER 50S TO THE LOWER 60S.
ALSO...LOWS ON FRIDAY DIP INTO THE UPPER 30S TO THE UPPER 40S.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 230 PM EDT MONDAY...

CUTOFF OVER THE AREA FRIDAY WILL WEAKEN AND DRIFT EAST THIS WEEKEND
AS FLOW ALOFT SLOWLY EVOLVES INTO A MORE PROGRESSIVE PATTERN FOR
THE SECOND WEEK OF MAY. THE WEEKEND WILL BE OUR TRANSITION BETWEEN
THE TWO PATTERNS SO LOOK FOR SATURDAY TO BE THE COOLER OF THE TWO
DAYS BUT STILL RESEMBLING SOMETHING CLOSER TO NORMAL WITH RESPECT
TO TEMPERATURE...THEN TRENDING ABOVE NORMAL FOR SUNDAY AND MONDAY.

HIGHEST ELEVATIONS...SUCH AS MOUNT ROGERS...MAY EVEN TOY WITH
TEMPERATURES IN THE 30S. FOR THE WEEKEND...INCREASING SUBSIDENCE
IN THE WAKE OF THE UPPER LOW FAVORS MAINLY DRY CONDITIONS...ALTHOUGH
CAN`T RULE OUT A POP-UP SHOWER IN THE MOUNTAINS. SINCE POPS LESS
THAN 20 PERCENT...REMOVED SHOWER THREAT FOR ALL BUT THE WV
HIGHLANDS. MODELS DO HINT AT ANOTHER FRONTAL ENCROACHMENT MONDAY,
SO MAINTAINED CHANCE THREAT MONDAY.

&&

.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
AS OF 745 AM EDT TUESDAY...

COLD FRONT CONTINUES TO SLOWLY PUSH THROUGH THE MID ATLANTIC
REGION...AND APPEARS TO BE ACROSS THE FAR E-SE PORTION OF THE
CWA...BUT THE ACTUAL FRONT MAY BE SOMEWHAT CONTAMINATED BY
CONVECTIVE OUTFLOW FROM YESTERDAYS THUNDERSTORMS. LIGHT RAIN
CONTINUES TO OVERRUN THE FRONT AS A WAVE OF LOW PRESSURE RIDES
ALONG THE FRONT AND FLOW ALOFT REMAINS SOUTHWEST...AWAITING
REINFORCEMENT FROM A SERIES OF UPSTREAM DISTURBANCES AND A
DEEPENING UPPER LOW SAGGING SOUTHWARD ACROSS THE GREAT LAKES OVER
THE NEXT FEW DAYS.

GENERALLY SEEING IFR CIGS THIS HOUR AT MOST SITES. THIS WILL
LIKELY CONTINUE UNTIL MID-MORNING EAST OF THE BLUE RIDGE...THEN
IMPROVE TO MVFR AND EVENTUALLY VFR AS LOW PRESSURE MOVES EAST OF
THE REGION AND WINDS BECOME W-NW. WEST OF THE BLUE RIDGE...IFR-
MVFR CIGS MAY PERSIST MUCH OF THE DAY...ESPECIALLY KBLF AND KLWB.
OVERNIGHT AS THE UPPER LOW MOVES SOUTHWARD...HEIGHTS LOWER...AND
TEMPS COOL ALOFT...EXPECT REINFORCEMENT OF LOW CLOUDS AND IFR CIGS
WEST OF THE BLUE RIDGE WITH OCCASIONAL -SHRA. SHOWERS SHOULD BE
ENDING EAST OF THE BLUE RIDGE AFT 00Z. VSBYS MOSTLY MVFR OR BETTER
THROUGH THE PERIOD.

WINDS BECOMING W-NW 5-7KTS THROUGH MUCH OF THE PERIOD.

MEDIUM CONFIDENCE IN CIGS AND VSBYS THROUGH THE TAF VALID PERIOD.
MEDIUM TO HIGH CONFIDENCE IN WIND SPD/DIR THROUGH THE TAF VALID
PERIOD.
LOW CONFIDENCE IN ANY TSRA POTENTIAL KDAN TODAY.

EXTENDED AVIATION DISCUSSION...

THE COLD FRONT DEPARTS OFFSHORE ON TUESDAY NIGHT...WHICH WILL
ALLOW ALL TAF SITES TO RETURN TO VFR. HOWEVER...A DEEP UPPER
LEVEL LOW FROM THE HUDSON BAY IN CANADA...SHOULD DIVE SOUTHWARD
TOWARD THE MID ATLANTIC ON WEDNESDAY. THIS UPPER LEVEL LOW SETTLES
OVER THE MID ATLANTIC THROUGH THE REMAINDER OF THIS WEEK. FLYING
CONDITIONS SHOULD REMAIN RATHER POOR DURING THIS TIME DUE TO
PERIODIC SHOWERS...LOW CEILINGS...AND PATCHY FOG.

&&

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

&&

$$
SYNOPSIS...RAB
NEAR TERM...MBS/RAB
SHORT TERM...PW
LONG TERM...PM
AVIATION...PW/RAB


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