Area Forecast Discussion
Issued by NWS Blacksburg, VA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KRNK 272234
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
634 PM EDT WED MAY 27 2015

.SYNOPSIS...
HIGH PRESSURE OFF THE SOUTHEAST COAST WILL MAINTAIN A BROAD
SOUTHERLY FLOW OF MOISTURE INTO THE REGION THROUGH THE REMAINDER
OF THIS WEEK. A WEAK UPPER LEVEL DISTURBANCE AND ASSOCIATED
FRONTAL BOUNDARY WILL SLIDE INTO THE REGION EARLY THURSDAY. THIS
WEATHER FEATURE IN COMBINATION WITH DAYTIME HEATING AND
INSTABILITY WILL RESULT IN PERIODIC ROUNDS OF SHOWERS AND STORMS
OVER THE NEXT FEW DAYS.

&&

.NEAR TERM /THROUGH THURSDAY/...
AS OF 630 PM EDT WEDNESDAY...
MADE SOME ADJUSTMENTS TO POPS FOR THIS EVENING INTO TONIGHT.
USED A BLEND OF HRRR AND RNK WRFARW. DRIER AIR PUSHING IN FROM
THE WEST...WAS HINDERING THUNDERSTORM DEVELOPMENT. GIVEN LIMITED
INSTABILITY EXPECTED CONVECTION TO DIMINISH WITH THE LOSS OF SOLAR
HEATING THIS EVENING. LOW TEMPERATURES WILL BE MILD OVERNIGHT WITH
READINGS FROM AROUND 60 DEGREES IN THE MOUNTAINS TO THE MID 60S
IN THE PIEDMONT.


AS OF 350 PM EDT WEDNESDAY...

CONVECTION STRUGGLING TO GET GOING SO FAR THIS AFTERNOON AND WILL
LIKELY REMAIN ISOLATED THROUGH THIS EVENING...MAINLY IN MTNS AND
FOOTHILLS...GIVEN LIMITED INSTABILITY AND DRIER AIR PUSHING IN FROM
THE WEST BEHIND THE WEAK SHORT WAVE THAT HAS LIFTED NORTHEAST OVER
THE NORTHEAST U.S. ANY WIDELY SCATTERED CONVECTION THAT DOES
MANAGGE TO DEVELOP THE REMAINDER OF THE AFTERNOON SHOULD DIMINISH
QUICKLY WITH LOSS OF HEATING.  WILL NEED KEEP AN EYE ON MORE
ORGANIZED CONVECTION WELL TO THE WEST AS IT MOVES INTO EASTERN KY
AND TN...BUT ALL INDICATIONS ARE THAT THIS WILL DIE QUICKLY WELL
BEFORE IT REACHES WESTERN SLOPES OF APPALACHIANS...WHICH WOULD BE
NEAR MIDNIGHT IF IT DID SURVIVE. KEEPING A SLIGHT CHANCE POP IN THE
WEST FOR THIS SMALL POSSIBILITY... AS WELL AS ALONG BLUE RIDGE
MAINLY IN NW NC GIVEN SOME LINGERING INSTABILITY AND CONVERGENCE
PER THE HRRR...BUT OTHERWISE DROPPING POPS AFTER MIDNIGHT.

SOME SUGGESTION IN THE GUIDANCE THAT PATCHY FOG MAY BE MORE LIKELY
LATE TONIGHT...BUT WITH GENERAL LACK OF RAINFALL EXPECTED REMAINDER
OF THE DAY...AND SOME RESIDUAL MID DECK OVERNIGHT...THINK THIS IS
NOT LIKELY AND HAVE CHOSEN NOT TO INCLUDE IT.

FOR THURSDAY...WE FINALLY HAVE SOME INGREDIENTS COMING TOGETHER TO
SUPPORT MORE WIDESPREAD COVERAGE OF CONVECTION...WITH WEAK UPPER
WAVE MOVING INTO APPALACHIANS EARLY IN THE DAY AND ASSOCIATED WEAK
FRONTAL BOUNDARY...OR REALLY MORE OF A TROUGH AXIS...WHICH WILL ADD
TO SOME WEAK CONVERGENCE ALREADY GEOGRAPHICALLY FAVORED NEAR THE
BLUE RIDGE.  MODELS SUGGEST MODEST INSTABILITY IN PART BECAUSE OF
WARMER AFTERNOON TEMPS EXPECTED...BUT STILL NOTHING SUPER
IMPRESSIVE...AND PERHAPS ENOUGH DRY AIR AT MID LEVELS TO SUPPORT
SOME GUSTY DOWNDRAFTS.  AT THIS POINT THINK SEVERE POTENTIAL IS
LIMITED...BUT MUCH BETTER THAN THE LAST COUPLE OF DAYS. HOWEVER WITH
WEAKER STEERING FLOW AND WELL ABOVE AVERAGE PRECIP WATER VALUES
EXPECTED...LOCALLY HEAVY RAIN WILL BE THE MAIN CONCERN. GIVEN DRY
ANTECEDENT CONDITIONS...NOT ALL THAT CONCERNED ABOUT A FLASH FLOOD
THREAT...BUT STILL SOMETHING TO KEEP AN EYE ON WITH ISOLATED AREAS
IF ANY STORMS BECOME LOCKED ON TERRAIN.  THIS WILL STILL MAINLY BE
OVER THE MOUNTAINS...WITH COVERAGE JUSTIFYING SOME LIKELY POPS...BUT
STORMS MAY DRIFT INTO THE PIEDMONT BY LATE AFTERNOON...SO MID CHANCE
POPS BY LATE IN THE DAY THERE AS WELL.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
AS OF 330 PM EDT WEDNESDAY...

UPPER PATTERN WILL BE IN TRANSITION DURING THE SHORT TERM WITH
FLATTENING OF THE EAST COAST RIDGE AND A TROF DEVELOPING INTO A CLOSED
LOW OVER THE MISSISSIPPI VALLEY. THIS WILL KEEP US IN A WEAKLY FORCED
WARM/MOIST/UNSTABLE ENVIRONMENT WITH A DIURNAL TREND AND MOUNTAIN BIAS
FOR SHOWERS/THUNDERSTORMS. A WEAK COLD FRONT WILL BE APPROACHING FROM
THE NORTHWEST BY THE WEEKEND BUT UNCERTAINTY WILL BE INCREASING AS
GUIDANCE DIFFERS IN HANDLING THE SPEED OF THIS FEATURE. BELIEVE THE
SCENARIO WILL LEAD TO INCREASING CHANCES FOR FOR CONVECTION DURING THE
LATTER PORTION OF THE WEEKEND. BIGGEST CONCERN WILL BE THE POSSIBILITY
OF LOCALLY HEAVY RAIN GIVEN PRECIPITABLE WATER VALUES OF 1.0 TO 1.5
INCHES ACROSS THE REGION. TEMPERATURES WILL REMAIN ABOVE NORMAL WITH
READINGS TRENDING UP A FEW DEGREES THROUGH THE WEEKEND... GENERALLY
LOOKING FOR MID/UPPER 80S EAST OF THE BLUE RIDGE LOWER 80S WEST WITH
THE USUAL COOLER READINGS AT THE HIGHER ELEVATIONS.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
AS OF 330 PM EDT WEDNESDAY...

BY SUNDAY NIGHT THE UPPER PATTERN WILL BE WELL ON ITS WAY TO DEVELOPING
A SPLIT FLOW REGIME ACROSS THE NORTHERN TIER OF STATES AS A CLOSED LOW
DEVELOPS OVER THE MISSISSIPPI VALLEY AND SLOWLY SINKS SOUTHWARD THROUGH
THE MIDDLE OF NEXT WEEK. SOME RIDGING WILL ALSO BE TAKING PLACE OVER
THE MID ATLANTIC REGION AND SET UP A SLUGGISH BLOCKY PATTERN. AT THE
SURFACE HIGH PRESSURE WILL BUILD THROUGH THE NORTHEAST AND WEDGE DOWN
THE EASTERN SEABOARD...BRINGING COOLER/NEAR NORMAL TEMPERATURES TO THE
REGION. HOWEVER...THE PATTERN WILL KEEP US MOIST WITH DEEP SOUTHEASTERLY
FLOW AND EXPECT ENOUGH FORCING BETWEEN OROGRAPHIC UPSLOPE AND DIURNAL
EFFECTS TO KEEP SOME SHOWER ACTIVITY...AND POSSIBLY A THUNDERSTORM...
IN THE FORECAST THROUGH THE PERIOD.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
AS OF 143 PM EDT WEDNESDAY...

MOIST ATMOSPHERE WITH VFR CUMULUS FIELD AND SCATTERED CIRRUS
LAYERS FOR REMAINDER OF AFTERNOON. SCATTERED SHOWERS WITH SOME THUNDER
POSSIBLE VCNTY OF BLUE RIDGE BY 18-20Z...DRIFTING WEST INTO
FOOTHILLS THROUGH ABOUT 00Z. CONFIDENCE FAIRLY HIGH THESE WILL NOT
IMPACT FAR WESTERN AIRPORTS OF KBLF AND KLWB...BUT CANNOT RULE OUT
COMPLETELY. KEPT A VCSH MENTION AT KBCB AND KROA...WITH TEMPO
GROUP FOR A LITTLE LATER AT KLYH...BUT LEFT OUT OF DANVILLE AS
MUCH GUIDANCE STRUGGLES TO GET MUCH THAT FAR EAST BEFORE DYING.
STILL...SOMETHING COULD BE IN VCNTY BY LATE THIS AFTERNOON...BUT
CONFIDENCE TOO LOW AT THIS TIME TO MENTION IN TAF. OTHERWISE VFR
CONDITIONS PREVAIL REST OF TODAY AND EVENING UNLESS A HEAVIER
SHOWER OR STORM PASSES RIGHT OVER AN AIRPORT.

OVERNIGHT ANY SHOWER ACTIVITY EXPECTED TO DIMINISH...WITH ONLY VERY
SMALL CHANCE OF AN ISOLATED SHOWER IN FAR WEST OF FAR EAST. SOME
MID LEVEL RESIDUAL CLOUDS SHOULD PREVENT FOG FROM FORMING...BUT
GUIDANCE IS QUITE LOW NOW FOR PLACES LIKE LWB AND BCB...AND IF ANY
SITE GETS RAINFALL FROM A PASSING SHOWER OR STORM...THEY WOULD SEE
A MUCH HIGHER CHANCE BY MORNING. GENERALLY LEFT THIS OUT...EXCEPT
FOR SOME LIGHT MVFR FOG AT KLWB...KBCB...AND KLYH.

THURSDAY A WEAK UPPER LEVEL DISTURBANCE WILL HELP TO DRAG A WEAK
SURFACE BOUNDARY ACROSS THE REGION...HARD TO CALL IT EVEN A
FRONT...BUT THIS APPEARS LIKELY TO RESULT IN ENOUGH CONVERGENCE TO
HELP DEVELOP MORE WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY BY
MIDDAY IN MTNS. ADDED VCSH FOR WESTERN TAF SITES BY 16 OR
17Z...AND GOOD CHANCE THAT NEXT ISSUANCE OF TAFS WILL ADD TEMPO OR
PREVAILING GROUPS FOR THUNDERSTORMS AT SEVERAL OF THESE LOCATIONS
FOR THE AFTERNOON.

EXTENDED AVIATION DISCUSSION...

FOR THE REMAINDER OF THE PERIOD...A MOIST UNSTABLE AIR MASS
REMAINS ACROSS THE REGION WITH WEAK TRIGGERING MECHANISMS AND
DYNAMICS. A FRONTAL SYSTEM WILL APPROACH FROM THE NORTH BY THE
WEEKEND...BUT WILL LIKELY REMAIN WELL NORTH OF THE CWA THROUGH
SUNDAY. THUS...NO CHANGE IN AIR MASS OR THE OVERALL SYNOPTIC
PATTERN IS EXPECTED THROUGH THE PERIOD.

EARLY MORNING LOW CLOUDS/FOG AND ASSOCIATED IFR-LIFR CIGS/VSBYS BECOME
INCREASINGLY MORE LIKELY THROUGH THE PERIOD...ESPECIALLY FOLLOWING
ANY LATE DAY RAINFALL. OTHERWISE...EXPECT MOSTLY VFR-MVFR CIGS
OUTSIDE HEAVIER SHOWERS/THUNDERSTORMS.

&&

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

&&

$$
SYNOPSIS...PM/SK
NEAR TERM...KK/SK
SHORT TERM...MBS
LONG TERM...MBS
AVIATION...PM/SK



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.