Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 311754
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
154 PM EDT FRI JUL 31 2015

.SYNOPSIS...
HIGH PRESSURE WILL BUILD EAST INTO THE MID ATLANTIC REGION TONIGHT.
THIS HIGH CENTER WILL STAY OVER MOST OF REGION THIS WEEKEND. A
COUPLE OF UPPER DISTURBANCES MAY BRING A FEW SPOTTY SHOWERS TO THE
MOUNTAINS LATE SATURDAY OR SUNDAY...BUT THE MAJORITY OF OUR AREA
WILL STAY DRY.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 152 PM EDT FRIDAY...

HIGH PRESSURE CENTERED AROUND MISSOURI THIS AFTERNOON WILL
BUILD EASTWARD TONIGHT INTO SATURDAY. SCATTERED AFTERNOON CU WILL
DIMINISH OR DISSIPATE BY SUNSET WITH THE LOSS OF SOLAR HEATING.
TONIGHT...THE FLOW STARTS TO BACK TO THE WEST AS A WEAK UPPER
SHORTWAVE PIVOTS UNDER THE BROAD TROUGH ACROSS THE MID ATLANTIC
REGION. AIRMASS IS TOO DRY TO GENERATE ANYTHING MORE THAN CLOUDS
WITH ANY SHORTWAVE ROTATING AROUND THE UPPER TROUGH. GREAT NIGHT
TO OPEN YOUR WINDOWS. THE COMBINATION OF LIGHT WINDS AND SOME LOW
LEVEL MOISTURE MAY PRODUCE PATCHY FOG IN THE FAVORED VALLEYS.
LEANED TOWARDS THE COOLER MOS COOP GUIDANCE FOR LOW TEMPERATURES
TONIGHT. LOW TEMPERATURES TONIGHT INTO SATURDAY MORNING WILL RANGE
FROM AROUND 50 DEGREES IN THE COLDEST DEEPER VALLEYS TO THE LOWER
60S IN THE PIEDMONT.

HIGH PRESSURE WILL BRING LOWER HUMIDITY AGAIN SATURDAY. ABUNDANT
SUNSHINE AND LIGHT DOWNSLOPE WIND FLOW WILL WARM HIGH TEMPERATURES
SATURDAY INTO THE UPPER 70S IN THE NORTHWEST MOUNTAINS TO THE
LOWER 90S.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 230 AM EDT FRIDAY...

LARGE UPPER LEVEL TROUGHING...CENTERED OVER HUDSON BAY...IS EXPECTED
TO HOLD IN PLACE THROUGH THE PERIOD...KEEPING THE MID ATLANTIC
SITUATED IN WEST NORTHWESTERLY UPPER LEVEL WINDFLOW. COUPLE THAT
WITH DRY HIGH PRESSURE ACROSS THE TENNESSEE VALLEY...AND WE CAN
EXPECT MAINLY DRY CONDITIONS UNDER MOSTLY CLEAR SKIES THROUGH
MONDAY. THE EXCEPTION WILL BE MONDAY EVENING AS FORECAST MODELS
ARE HINTING AT ANOTHER COLD FRONT SINKING SOUTHWARD FROM THE GREAT
LAKES...TRIGGERING AN INCREASE IN SHOWER AND THUNDERSTORM
ACTIVITY. THAT STATED...BEST SUPPORT FOR RAINFALL WILL REMAIN
NORTH OF THE AREA...AND WILL MAINTAIN LOW RAIN CHANCES FOR NOW ON
MONDAY NIGHT.

HIGH PRESSURE WILL BRING WITH IT LOWER HUMIDITY...MAKING FOR MORE
COMFORTABLE AFTERNOONS. ABUNDANT SUNSHINE AND LIGHT DOWNSLOPE
WINDFLOW WILL KEEP AFTERNOON HIGH TEMPERATURES SIMILAR EACH DAY...
RANGING FROM A FEW UPPER 70S TO THE MID 80S ACROSS THE MOUNTAINS...
WHILE THE PIEDMONT WILL CLIMB INTO THE UPPER 80S/LOW 90S.

THE EFFECTS OF THE DRIER AIR WILL BE MORE NOTICEABLE AT NIGHT.
STRONG RADIATIONAL COOLING SATURDAY NIGHT WILL PUSH OVERNIGHT LOWS
INTO THE MID/UPPER 50S MOST SPOTS ACROSS THE MOUNTAINS...AND THE LOW
60S ACROSS THE PIEDMONT. WITH COLD AIR DRAINAGE...WOULD NOT BE
SURPRISED TO SEE A FEW REPORTS OF MID/UPPER 40S COME FROM A FEW OF
THE DEEPER MOUNTAIN VALLEYS. OVERNIGHT TEMPERATURES WILL WARM 2 TO 4
DEGREES EACH SUNDAY AND MONDAY NIGHTS AS THE AIRMASS MODIFIES.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 1230 PM EDT THURSDAY...

MEAN 5H TROUGH TO REMAIN ACROSS THE MID ATLANTIC REGION THROUGH MUCH OF
NEXT WEEK WITH STEADY NW FLOW ALOFT BETWEEN UPPER LEVEL LOW PRESSURE
WELL TO THE NORTH AND STRONG RIDGING OVER THE SW STATES. THIS SHOULD
ALLOW FOR AN OVERALL PERSISTENCE TYPE FORECAST THROUGH THE EXTENDED
WITH TOLERANT HUMIDITY LEVELS ALONG WITH LOWS MOSTLY IN THE 60S AND
HIGHS 80S TO LOWER 90S. COVERAGE OF SHOWERS AND STORMS ALSO LIKELY
LIMITED PENDING PROGRESSION OF THE NEXT POSSIBLE COOL SURGE LATE IN THE
PERIOD. HOWEVER WILL ALSO HAVE TO WATCH LINGERING MOISTURE WITH THE
RESIDUAL FRONT NEAR THE COAST WHICH COULD BE LIFTED BACK NORTH BY
APPROACH OF WEAK IMPULSES ALOFT ESPECIALLY EARLY NEXT WEEK. THIS ALONG
WITH HEATING MAY BE ENOUGH TO SPARK ISOLATED CONVECTION ALONG A
PASSING SHORTWAVE TROUGH AXIS CROSSING FROM THE NW TUESDAY...BUT
LOW POPS AT BEST.

UPPER TROUGH JUST NORTH OF THE LAKES WILL DEEPEN AGAIN BY MIDWEEK AS
MORE SHORTWAVE ENERGY ROTATES THROUGH AND SLIDES AN ASSOCIATED COLD
FRONT SOUTH TOWARD/INTO THE REGION. HOWEVER MODELS DISAGREE ON THE
AMPLITUDE OF THE DIGGING TROUGH WITH THE GFS MOST AGGRESSIVE WHILE
OTHER SOLUTIONS SLOWER/WEAKER WHILE MAINTAINING MORE CONVECTION ALONG
THE BOUNDARY. FOR NOW WILL GO WITH A WEAKER/SLOWER SCENARIO BUT LEAN
TOWARD THE GFS IN DRIVING THE COOL ADVECTION IN BY THE END OF THE
PERIOD SINCE IT HAS BEEN BEST OF LATE.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
AS OF 132 PM EDT FRIDAY...

GREAT FLYING CONDITIONS EXPECTED THIS AFTERNOON INTO THE WEEKEND.
VFR CONDITIONS WILL PREVAIL OVER TAF SITES DURING THIS PERIOD. THE
ONLY EXCEPTION WOULD BE PATCHY MORNING FOG. KLWB AND KBCB HAVE THE
POTENTIAL FOR SOME FOG LATE FRIDAY NIGHT INTO SATURDAY MORNING.
ANY MORNING FOG WILL BURN OFF OR MIX OUT BY 9 AM.

HIGH CONFIDENCE IN CEILINGS...VISIBILITIES AND WINDS DURING THE
TAF PERIOD.

EXTENDED AVIATION FORECAST...

MAINLY VFR THIS WEEKEND WITH HIGH PRESSURE IN PLACE. A FEW UPPER
DISTURBANCES MAY BRING A FEW VFR CIGS TO THE MOUNTAINS LATER
SATURDAY INTO SUNDAY. THE THREAT OF SHOWERS WILL BE LOW THOUGH A
BACKDOOR FRONT MAY ALLOW FOR SOME AGAIN LATER MONDAY OR TUESDAY.
WITH SUSTAINED WINDS STAYING LIGHT TO CALM AT NIGHT AND MAINLY
CLEAR SKIES...THE FOG THREAT WILL EXIST IN THE TYPICAL PREDAWN
HOURS AT KLWB/KBCB BY EARLY NEXT WEEK.

&&

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

&&

$$
SYNOPSIS...KK/WP
NEAR TERM...KK
SHORT TERM...NF
LONG TERM...JH
AVIATION...KK/WP


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