Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000
FXUS61 KRNK 191641
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1241 PM EDT SUN OCT 19 2014

.SYNOPSIS...
A STRONG UPPER LEVEL DISTURBANCE WILL MOVE EAST ACROSS
THE REGION THIS MORNING. HIGH PRESSURE WILL BUILD IN TODAY RESULTING
IN DRIER WEATHER UNDER DIMINISHING WINDS. ON MONDAY AND TUESDAY...
LOW PRESSURE WILL TRACK FROM THE GREAT LAKES TO OFF THE VIRGINIA
COAST.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1240 PM EDT SUNDAY...

CLOUD COVER IN THE WEST IS CONTINUING ITS RAPID DISSIPATION. WE
EXPECT THIS TREND TO CONTINUE THROUGH THE REMAINDER OF THE
AFTERNOON SO THAT BY SUNSET VERY LITTLE IN THE WAY OF CLOUD COVER IS
EXPECTED TO REMAIN. HAVE MADE SOME MINOR ADJUSTMENTS TO FORECAST
HIGH TEMPERATURES FOR THIS AFTERNOON. MOST OF THESE ADJUSTMENTS
HAVE BEEN AN INCREASE IN VALUE BY A DEGREE OR TWO CENTRAL AND
EAST...WITH VALUES ABOUT THE SAME OR A DEGREE OR TWO COOLER IN THE
WEST. NO OTHER SIGNIFICANT CHANGES AT THIS TIME.

AS OF 950 AM EDT SUNDAY...

HAVE MADE NO MAJOR CHANGES TO THE ONGOING FORECAST. THE SAME
GENERAL TREND IS STILL EXPECTED. CLOUD COVER AND ANY LINGERING
LIGHT RAIN SHOWERS IN THE MOUNTAINS WILL GRADUALLY DISSIPATE TODAY
AS THE LOW LEVEL FLOW WEAKENS...AND BACKS MORE WESTERLY. ALSO
ARRIVAL OF DRIER AIR IN THE LOW LEVELS WILL ONLY HELP FACILITATE
THIS TREND. HAVE TWEAKED HOURLY TEMPERATURE...DEW POINT AND CLOUD
COVER TO ADJUST FOR CURRENT CONDITIONS AND EXPECTED TRENDS THROUGH
THE EARLY AFTERNOON.

AS OF 400 AM EDT SUNDAY...

AN UPPER TROUGH AXIS WILL CLEAR OUR AREA THIS MORNING...WITH HIGH
PRESSURE BUILDING IN ITS WAKE FROM THE NORTHWEST. CLOUDS WILL
DECREASE TODAY FROM EAST TO WEST AS HIGH PRESSURE BEGINS TO SETTLE
ACROSS THE AREA. SHAPED HIGH TEMPERATURES THIS AFTERNOON CLOSE TO
THE ADJMAVBC WITH READINGS FROM AROUND 50 DEGREES IN THE NORTHWEST
MOUNTAINS TO THE MID 60S ACROSS THE PIEDMONT WITH PLENTY OF
SUNSHINE.

POSTED FREEZE WARNINGS FOR EASTERN GREENBRIER COUNTY WHERE
TEMPERATURES ARE EXPECTED TO FALL BELOW FREEZING MARK. FROST
ADVISORIES HAD BEEN POSTED FOR PORTIONS OF THE NEW RIVER VALLEY AND
SOUTHERN SHENANDOAH VALLEYS FOR MIDNIGHT TO 9 AM MONDAY MORNING.
SENSITIVE OUTDOOR PLANTS MAY BE KILLED IF LEFT UNCOVERED.

TONIGHT INTO MONDAY...THE CENTER OF THE SURFACE HIGH SHIFTS TO OUR
EAST ALL WHILE SOUTHWEST FLOW INCREASES AT 850 MB AND HIGHER. WE ARE
EXPECTING ONE OF THE COLDEST NIGHTS OF THE SEASON FOR MOST
AREAS...THE COMBINATION OF WINDS AND HIGH CLOUDS MAY MITIGATE THE
EXTENT OF THE COOL DOWN. LOOKS LIKE THE RIDGE TOPS STAY MILDER THAN
THE VALLEYS THANKS TO CONTINUED MIXING OF WINDS AT THE HIGHER
ELEVATIONS...AND THE ELEVATIONS THEMSELVES COULD BE HIGHER THAN THE
TOP OF THE NOCTURNAL INVERSION. EXPANDED THE AREAL COVERAGE OF
PATCHY FROST EASTWARD...ACROSS THE PIEDMONT WHERE LOCATIONS ARE
CLOSEST TO THE CENTER OF THE DEPARTING SURFACE HIGH...AND WINDS
ALOFT WILL BE WEAKER.  FORECAST LOWS TONIGHT WILL RANGE FROM THE
UPPER 20S IN THE DEEPER MOUNTAIN VALLEYS TO NEARLY 40 DEGREES AT THE
RIDGE TOPS.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
AS OF 420 AM EDT SUNDAY...

THE NEXT UPSTREAM TROUGH/ALBERTA CLIPPER WILL BE RAPIDLY
APPROACHING THE REGION FROM THE NORTHWEST MON. COLD SFC HIGH
PRESSURE WILL ALREADY BE CENTERED WELL EAST OF THE REGION AT 12Z
MON ALONG THE NC COAST. SOUTHWEST SFC WINDS WILL ALREADY BE IN
PLACE MON MORNING...QUICKLY ALLEVIATING ANY FURTHER CONCERNS WITH
FREEZING TEMPERATURES OR FROST. ALTHOUGH THE SYSTEM WILL BE
STARVED FOR MOISTURE AND MAINTAINS A TRACK N-NE OF THE REGION
THROUGH THE SHORT TERM...INITIAL STRONG DYNAMICS SHOULD...AS WITH
THE SYSTEM YESTERDAY...SUPPORT SCT SHOWERS INTO THE WESTERN HALF
OF THE REGION...MAINLY WEST OF THE BLUE RIDGE AS EARLY AS MON
AFTERNOON...CONTINUING INTO THE EVENING. AS WITH YESTERDAYS
SYSTEM...THE BEST CHANCE FOR -SHRA WILL BE ACROSS THE NW-W PART OF
THE CWA...MAINLY WEST OF THE ALLEGHANY FRONT...WITH LIKELY LITTLE
MORE THAN -SHRA OR SPRINKLES TO THE EAST...ESPECIALLY EAST OF THE
BLUE RIDGE.

FOR THE REMAINDER OF THE SHORT TERM...THE FORECAST WILL BE
DOMINATED BY YET ANOTHER DEEP UPPER CLOSED LOW. MODELS HAVE COME
INTO CONSENSUS THAT THE UPPER LOW WILL REMAIN N-NE OF THE REGION
THROUGH THE PERIOD...MEANDERING ABOUT THE NORTHERN MID-ATLANTIC
THROUGH THE LATER HALF OF THE WEEK. THIS KEEPS THE BEST MOISTURE
AND DYNAMICS WELL N-NE OF THE CWA. THERE ARE SUBTLE LOBES OF PVA
SLATED TO ROTATE AROUND THE UPPER LOW THAT WILL ENHANCE -SHRA AT
TIMES...AGAIN MAINLY ACROSS THE FAR NORTHERN PARTS OF THE
CWA...AND ESPECIALLY ACROSS THE ALLEGHANYS FROM GREENBRIER DOWN
TOWARD MERCER AND TAZEWELL. WITH THE REGION ON THE COLDER WEST
SIDE OF THE SYSTEM...MODELS HAVE TRENDED DOWNWARD WITH 850MB
TEMPS...SHOWING SOME POTENTIAL FOR POCKETS NEAR 0C ACROSS THE
ALLEGHANYS...BUT MOSTLY AFTER THE BETTER MOISTURE HAS SHIFTED EAST
OF THE REGION. THE LACK OF DYNAMIC COOLING AND MARGINAL 850MB
TEMPS WILL ALLOW ME TO NOT MENTION ANY THREAT OF WINTER PCPN AT
THIS TIME. ON THE OTHER HAND...TEMPERATURES ARE TOO COOL AND THE
AIR MASS ENTIRELY TOO STABLE THROUGH THE PERIOD TO MENTION ANY
THUNDER. MODEL RUN QPF IS MINISCULE THROUGH THE
PERIOD...GENERALLY ON A FEW HUNDREDTHS OF AN INCH EAST OF THE
BLUE RIDGE...AND MOSTLY 1/10 TO 1/4 INCH WEST OF THE BLUE RIDGE.
AGAIN...MODELS CONTINUE TO TREND DOWNWARD WITH QPF AS WELL AS THE
SYSTEM REMAINS MOSTLY NE OF THE REGION.

THE WORK WEEK WILL CERTAINLY BE ON THE COOL SIDE WITH SLIGHTLY
BELOW NORMAL TEMPERATURES EXPECTED THROUGH MUCH OF THE
WEEK...THANKS TO THE PERSISTENT CYCLONIC FLOW...COOL 850MB
TEMPS...NW SFC FLOW...AND COLD CORE ALOFT INDUCED STRATOCUMULUS.
USED A MODEL BLEND FOR MAX/MIN TEMPS. CLOUD COVER...SHOWERS...AND
TURBULENT MIXING WILL PREVENT FREEZING TEMPERATURES THROUGH THE
PERIOD.

&&

.LONG TERM /THURSDAY THROUGH SATURDAY/...
AS OF 445 AM EDT SUNDAY...

BENIGN WEATHER EXPECTED THROUGH THE PERIOD. THE CLOSED NEAR
BAROTROPIC UPPER LOW ACROSS THE NORTHERN MID-ATLANTIC REGION WILL
LIFT OUT OF THE AREA BY FRIDAY...WITH A BROAD UPPER RIDGE
STRETCHING FROM THE SW DESERT STATES INTO THE MIDWEST/MID-ATLANTIC
REGION BY THE WEEKEND. AN ANOMALOUS UPPER LOW IS PROGGED TO
DEVELOP ALONG THE CENTRAL GULF COAST...BUT APPEARS TO BE
ASSOCIATED WITH LITTLE SENSIBLE WEATHER AND AT ANY RATE REMAINS
BLOCKED FROM REACHING AREAS NORTH OF THE IMMEDIATE GULF COAST
THANKS TO THE WEST-EAST ORIENTED RIDGE ACROSS THE MID-LATITUDES.
THUS...MOST OF THE PERIOD SHOULD BE DOMINATED BY WEAK HIGH
PRESSURE AND A DRY WESTERLY FLOW. HAVE REMOVED ALL MENTION OF
-SHRA AFT THU. TEMPERATURES WILL SLOWLY MODERATE THROUGH THE
PERIOD AND MAY ACTUALLY BE SLIGHTLY ABOVE NORMAL BY THE END BY
FRI/SAT. OVERALL...VERY PLEASANT WEATHER EXPECTED THROUGH THE
PERIOD.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
AS OF 730 AM EDT SUNDAY...

EAST OF THE BLUE RIDGE...VFR CONDITIONS EXPECTED THROUGH THE TAF
VALID PERIOD. WEST OF THE BLUE RIDGE...AND ESPECIALLY WEST OF THE
ALLEGHANY FRONT...MVFR CIGS WILL LINGER THROUGH MID TO LATE
MORNING...BEFORE CONDITIONS THERE ALSO IMPROVE TO VFR. STRONG
SHORT WAVE HAS SHIFTED EAST...BUT UPSLOPE NW FLOW CONTINUES ACROSS
THE ALLEGHANYS. CIGS ACROSS EASTERN WV...INCLUDING LWB/BLF
GENERALLY IN THE 010-025 RANGE. BLF HAS BRIEFLY DROPPED TO
009...BUT THIS SHOULD BE SHORT LIVED WITH A LITTLE DAYTIME
HEATING. EAST OF THE BLUE RIDGE...MAY SEE A FEW SC THROUGH
15Z...THEN SKC THROUGH THE REMAINDER OF THE TAF VALID PERIOD. WEST
OF THE BLUE RIDGE...EXPECT CLOUDS TO SCT OUT IN THE 15Z-17Z TIME
FRAME...WITH BLF/LWB LIKELY BEING THE LONGEST TO HOLD ONTO MVFR
CIGS. WINDS NOT AS STRONG AS SAT...BUT GENERALLY WNW 8-12KTS
GUSTING TO 17-22KTS THROUGH MID-AFTERNOON...THEN DIMINISHING
QUICKLY TO NEAR CALM BY 23Z. WINDS WILL QUICKLY BACK TO THE SW
EARLY MON.

HIGH CONFIDENCE IN CIGS THROUGH THE TAF VALID PERIOD.
HIGH CONFIDENCE IN VSBYS THROUGH THE TAF VALID PERIOD.
HIGH CONFIDENCE IN WIND DIR/SPD THROUGH THE TAF VALID PERIOD.

EXTENDED AVIATION DISCUSSION...

ANOTHER UPPER LOW WILL SETTLE INTO THE REGION FROM THE NORTH LATE
MONDAY AND LINGER THROUGH MID-WEEK WITH SCT -SHRA AND MOSTLY MVFR
CEILINGS AND BRIEF PERIODS OF MVFR VISIBILITIES IN -SHRA. LOWER
CIGS AND VSBYS WILL MAINLY IMPACT LWB/BLF/BCB THROUGH THE PERIOD.
IMPROVING CONDITIONS ARE EXPECTED TOWARD THE VERY END OF THE
WEEK WITH MOST VFR CONDITIONS AFTER THU.

&&

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EDT MONDAY FOR
     VAZ010>014-018>020-023-024.
NC...NONE.
WV...FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EDT MONDAY FOR
     WVZ043-044-508.
     FREEZE WARNING FROM MIDNIGHT TONIGHT TO 9 AM EDT MONDAY FOR
     WVZ507.

&&

$$
SYNOPSIS...KK
NEAR TERM...DS/KK
SHORT TERM...RAB
LONG TERM...DS/RAB
AVIATION...KK/RAB


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