Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000
FXUS61 KRNK 271136
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
736 AM EDT WED AUG 27 2014

.SYNOPSIS...
HIGH PRESSURE WILL BE OVER THE MID ATLANTIC STATES TODAY. A WEAK
COLD FRONT WILL MOVE SOUTH INTO THE REGION TONIGHT AND WILL STALL
ACROSS OUR AREA THROUGH THURSDAY AND FRIDAY...PROVIDING THE FOCUS
FOR OCCASIONAL SHOWERS AND THUNDERSTORMS. THE FRONT WILL LIFT
NORTH AGAIN ON SATURDAY AS A WARM FRONT.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 330 AM EDT WEDNESDAY...

SURFACE HIGH PRESSURE WILL BE OVER THE AREA TODAY. A COLD FRONT THAT
EXTENDED FROM NEW YORK TO MISSOURI EARLY THIS MORNING WILL MOVE
SOUTH TODAY AND WILL REACH THE FORECAST AREA OVERNIGHT. A DRY AIR
MASS IS IS PLACE OVER THE REGION THIS MORNING BUT AS THE FRONT
APPROACHES MOISTURE WILL INCREASE. THE STRONGEST FORCING AND
DYNAMICS WILL STAY TO THE NORTH OF THE COUNTY WARNING AREA. WILL
HAVE A LOW PROBABILITY OF PRECIPITATION IN THE FAR NORTHERN COUNTY
WARNING AREA...MAINLY BETWEEN 22Z/6PM AND 02Z/10PM.

SINCE GUIDANCE HAD BEEN TOO WARM FOR THE PAST COUPLE OF DAYS WITH
MAXIMUM TEMPERATURES...WILL STAY CLOSER TO BIAS CORRECTED MAV
GUIDANCE FOR MAXIMUM TEMPERATURES. WITH DEW POINTS INCREASING AND
SOME CLOUD COVER IN THE EVENING...LOW TEMPERATURES WILL BE NEAR THE
MAV GUIDANCE...SLIGHTLY MILDER THAN THIS MORNING.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
AS OF 245 AM EDT WEDNESDAY...

CHRISTOBAL WILL EXIT THE PICTURE TRACKING AWAY FROM THE US THURSDAY.
A WEAK COOL FRONT WILL THEN HAVE A CHANCE TO MOVE SOUTH OF THE
FORECAST AREA THURSDAY AFTERNOON/NIGHT. THIS BOUNDARY MAY DEVELOP A
SURFACE REFLECTION OVER NORTH CAROLINA WHICH COULD GENERATE ISOLATED
SHOWERS AND THUNDERSTORMS DURING THE AFTERNOON. WITH LIMITED
MOISTURE AND A CAP OVERHEAD...ANY SHOWERS THAN FORM WILL HAVE A
SHORT LIFE SPAN AND FADE WITH SUNSET.

THURSDAY NIGHT...SURFACE HIGH PRESSURE WILL BE CENTERED OVER NEW
ENGLAND AND WEDGE AS FAR SOUTH AS NORTH CAROLINA. THIS SURFACE
RIDGE WILL DRIFT OFF THE NEW ENGLAND AND MID ATLANTIC COAST ON
FRIDAY. MEANWHILE FRIDAY...AN UPPER LEVEL RIDGE WILL BE CENTERED
OVER THE SOUTHEASTERN US STRETCHING NORTH INTO THE OHIO VALLEY AND
MID ATLANTIC REGION. THE FORECAST AREA WILL BE ON THE NORTHERN
PERIPHERY OF THIS RIDGE. WE WILL THEN NEED TO KEEP AN EYE OVER THE
TENNESSEE VALLEY TO SEE IF ANY SHORT WAVES WILL TRACK OVER THE
REGION. FOR NOW...MODELS ARE NOT SHOWING ANY SIGNIFICANT SHORT
WAVES.

AS HIGH PRESSURE DRIFTS OFF SHORE...RETREATING BOUNDARY AND
SOUTHEASTERLY UPSLOPE COMPONENT WILL LIKELY TRIGGER AFTERNOON AND
EVENING CONVECTION FRIDAY AFTERNOON. THE CAP IS EXPECTED TO WEAKEN
OVER THE MOUNTAINS TO INCREASE THE CHANCES FOR CONVECTION TO
DEVELOP. THIS CONVECTION WILL THEN DRIFT EAST TO THE FOOTHILLS AND
PIEDMONT LATE IN THE AFTERNOON AND INTO THE EVENING. IN THIS PULSE
STORM ENVIRONMENT...A FEW STORMS COULD BECOME STRONG TO SEVERE
WITH DAMAGING WINDS THE PRIMARY THREAT.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
AS OF 210 PM EDT TUESDAY...

AIRMASS CHANGE IN STORE AS 5H RIDGE BUILDS ACROSS THE SOUTHEAST THEN
SHIFTS EWD THROUGH NEXT WEEK. THIS IS GOING TO PROVIDE HOTTER TEMPS
FOR LABOR DAY WEEKEND WITH INCREASED HUMIDITY. TROUGH WILL BE
SITUATED OVER THE MIDWEST SAT...SHIFTING EWD INTO THE GREAT LAKES
SUNDAY WHILE SHEARING OUT. FRONTAL BOUNDARY IS GOING TO LAY ACROSS
THE OHIO VALLEY. MOISTURE SURGING NWD FROM THE GULF COAST SHOULD
START TRACKING CLOSER TO OUR AREA. SAT WILL BE THE DRIEST DAY FOR
THE OFFICIAL END TO THE SUMMER SEASON...BUT ISOLATED STORMS ARE
POSSIBLE IN THE MTNS.

SUNDAY IS GOING TO BE A BIT WETTER AS THE FRONT TRACKS CLOSER BUT
STILL IT LOOKS SCATTERED INSTEAD OF WIDESPREAD...BEST COVERAGE OVER
THE MTNS. SO FOR THOSE PLANNING OUTDOOR ACTIVITIES BE AWARE FOR BOTH
STORMS/LIGHTNING AND HOTTER TEMPS.

LABOR DAY ITSELF SHOULD BE STORMY ALTHOUGH FRONT WILL BE NORTH OF
US...BUT UPPER SHORTWAVE MAY PASS ACROSS THE CENTRAL APPALACHIANS
INDUCING BETTER LIFT WITH INCREASED MOISTURE. THE UPPER HEIGHTS
FLATTEN SOMEWHAT AS WELL. HIGHS MONDAY ARE GOING TO STILL BE VERY
WARM WITH LOWER 80S MOUNTAINS TO NEAR 90 SOUTHEAST...THOUGH
INCREASED HUMIDITY AND SW FLOW WILL HINDER A BIG RISE IN TEMPS.

BY TUESDAY...WE ARE STILL SEEING SOMEWHAT FLATTENING OF THE RIDGE
NORTH OF US...WITH NEXT UPSTREAM TROUGH MOVING ACROSS THE UPPER
MISSISSIPPI VALLEY. LOOKS MORE LIKE DIURNALLY DRIVEN CONVECTION
THOUGH 00Z ECMWF SHOWS WEAK IMPULSE MOVING ACROSS THE AREA TUESDAY
AFTN.

&&

.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
AS OF 735 AM EDT WEDNESDAY...

ENHANCED FOG SATELLITE IMAGES CLEARLY SHOWED FOG HAD FILLED IN
THE NEW RIVER AND GREENBRIER RIVER VALLEYS EARLY THIS MORNING.
HIGH CONFIDENCE THAT FOG WILL BURN OFF QUICKLY AFTER 13Z AS
DAYTIME HEATING AND MIXING DEVELOPS. ELSEWHERE...LITTLE OR NO
IMPACT EXPECTED FROM THE RIVER VALLEY FOG WITH VFR CONDITIONS
DOMINATING THROUGH THE 24 HOUR TAF PERIOD.

EXPECTING MORE CLOUD COVER TONIGHT WITH THE APPROACH OF A WEAK
FRONT FROM THE NORTH. THIS MAY LIMIT POTENTIAL FOR FOG AT KLWB
AGAIN OVERNIGHT.

EXTENDED DISCUSSION...
THE COLD FRONT WILL SINK SOUTHWARD FROM THE GREAT LAKES EARLY
THURSDAY TO SETTLE ACROSS THE CENTRAL APPALACHIANS. SPOTTY SHOWERS AND
THUNDERSTORMS WILL BE POSSIBLE INTO THE WEEKEND AS WEAK
DISTURBANCES PASS ALONG THE BOUNDARY. BRIEF PERIODS OF SUB VFR
CONDITIONS ARE EXPECTED WITH THE PRECIPITATION.

&&

.EQUIPMENT...
AS OF 730 AM EDT WEDNESDAY ...

THE VISIBILITY SENSOR AT KDAN...DANVILLE REGIONAL AIRPORT...WAS
OUT OF SERVICE. TECHNICIANS WERE ENROUTE TO DANVILLE TO MAKE
REPAIRS.

&&

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

&&

$$
SYNOPSIS...AMS
NEAR TERM...AMS
SHORT TERM...RCS
LONG TERM...WP
AVIATION...AMS/PM
EQUIPMENT...AMS



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