Area Forecast Discussion
Issued by NWS Blacksburg, VA

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FXUS61 KRNK 050554
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
154 AM EDT SUN JUL 5 2015

.SYNOPSIS...
LOW PRESSURE MOVING OFF THE MIDDLE ATLANTIC COAST WILL PUSH A COLD
FRONT SOUTHWARD TONIGHT INTO SUNDAY. THIS WILL RESULT IN ROUNDS OF
SHOWERS AND THUNDERSTORMS. THE UNSETTLED WEATHER WILL CONTINUE TO
AFFECT THE REGION FOR THE NEXT SEVERAL DAYS...KEEPING A CHANCE OF
SHOWERS AND THUNDERSTORMS IN THE FORECAST THROUGH THE FIRST PART OF
NEXT WEEK...AS TEMPERATURES BEGIN A GRADUAL WARMING TREND.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 1030 PM EDT SATURDAY...

SEVERAL MODELS SHOWING PRECIPITATION ASSOCIATED WITH CLOSED UPPER
LOW OVER WESTERN TENNESSEE WILL MOVE INTO SOUTHWEST VIRGINIA AND
NORTHWEST NORTH CAROLINA EARLY SUNDAY MORNING. HAVE INCREASED THE
PROBABILITY OF PRECIPITATION IN THAT AREA FROM 2AM THROUGH 8AM
SUNDAY.

A WAVY FRONTAL BOUNDARY REMAIN ACROSS THE REGION ON SUNDAY.
SHORTWAVES CONTINUE TO TRAVEL EAST ALONG THE UPPER TROUGH. SHOWERS
AND THUNDERSTORMS WILL BECOME NUMEROUS BY SUNDAY AFTERNOON.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...
AS OF 330 PM EDT SATURDAY...

MODELS ARE IN AGREEMENT WITH RESPECT TO THE DEVELOPMENT OF A WEAK
CLOSED UPPER LOW ACROSS THE SOUTHEAST STATES AND ITS SUBSEQUENT
NORTHWARD DRIFT INTO THE FIRST PART OF NEXT WEEK.TAIL END OF LONG
STANDING EASTERN U.S. TROUGH WILL BECOME CUTOFF ACROSS NORTHERN
GA/AL/EASTERN TN FROM THE PARENT UPPER TROUGH...WHICH WILL SHEAR
OUT ACROSS NEW ENGLAND AS A SHORT WAVE RIDGE DRIFTS INTO THE OH
VALLEY. THE UPPER LOW WILL THEN DRIFT SLOWLY NORTHEAST INTO
MON...FINALLY LIFTING NORTH OF THE REGION BY TUESDAY AS THE NEXT
UPSTREAM TROUGH DIGS INTO THE GREAT LAKES REGION.

AS THE LOW MOVES NORTH FROM GA IT TAKES ON A NEGATIVE
TILT...WHICH WILL FURTHER ENHANCE OVERALL WEAK DYNAMICS/LIFT AND
CERTAINLY PROLONG THE WET WEATHER PATTERN. ABUNDANT DEEP MOISTURE
WILL REMAIN IN PLACE WITH PWATS IN THE 1.75 TO 2.0 INCH RANGE
ACROSS MUCH OF THE CWA. EXTENSIVE TO NEAR SOLID CLOUD COVER WILL
LIMIT HEATING...SO INSTABILITIES REMAIN MEAGER AND OVERALL
DYNAMICS ARE WEAK.

MODELS ARE IN GOOD AGREEMENT WITH A LARGE SWATH OF DEEP
MOISTURE...ASSOCIATED WITH THE UPPER LOW AND OVERRUNNING EXISTING
SURFACE FRONTAL BOUNDARY...TRACKING FROM GA/SC NORTHWARD INTO THE
RNK CWA BY SUN AFTERNOON...DRIFTING INTO THE NORTHERN PARTS OF THE
CWA MON...THEN FINALLY LIFTING NORTHEAST OF THE CWA BY TUE. THIS
WILL SUPPORT HIGH PROBABILITY OF RAINFALL FROM SUNDAY THROUGH
MONDAY ACROSS MUCH OF THE CWA...WITH A LIMITED DIURNAL SWING
OF TEMPERATURE GIVEN THE UPPER LOW WILL ESSENTIALLY BE DRIFTING
RIGHT ACROSS THE HEART OF THE CWA.

THE PATH OF THE UPPER LOW SHOULD FOCUS THE HEAVIEST RAINFALL
ACROSS THE WESTERN PART OF THE CWA...BLUE RIDGE AND WEST.
WITH 3HR FFG VALUES AVERAGING IN THE 1.5 TO 2.5 INCH RANGE ACROSS
MUCH OF THE CWA AND THE RECENT PROLONGED WET SPELL...WE WILL NEED
TO MONITOR RAINFALL AMOUNTS CAREFULLY...HOWEVER...THE LACK OF ANY
ORGANIZED OR STRONG CONVECTION...GIVEN THE MEAGER LAPSE RATES AND
LACK OF INSTABILITY/DYNAMICS...SHOULD HOLD HOURLY RAINFALL AMOUNTS
IN CHECK. WILL CONTINUE TO HIGHLIGHT THREAT OF POOR DRAINAGE FLOODING
IN THE HWO...BUT POTENTIAL FOR FLASH FLOODING DOES NOT APPEAR TO
BE A CONCERN ATTM.

AS THE UPPER LOW DRIFTS NORTH OF THE AREA TUE...WE SHOULD SEE
ENOUGH SUBSIDENCE AND DRYING TO FINALLY SQUELCH THE SHOWER THREAT
PROVIDING A BREAK BEFORE NEW FRONTAL SYSTEM APPROACHES TUESDAY
NIGHT OR WEDNESDAY.

MAXIMUM TEMPERATURES SHOULD REMAIN BELOW NORMAL THROUGH
MON...TRENDING CLOSER TO NORMAL VALUES TUESDAY WITH GREATER
INSOLATION. MINIMUM TEMPERATURES WILL REMAIN ABOVE NORMAL WITH
HIGH PWATS/DEWPOINTS.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 445 PM EDT SATURDAY...

UNSETTLED WEATHER DESTINED TO CONTINUE. AFTER A VERY BRIEF
RESPITE FROM WIDESPREAD PRECIPITATION TUESDAY...A NEW FRONTAL
SYSTEM WILL DRIFT INTO THE REGION FROM THE WEST BY WEDNESDAY AND
THEN BECOME ELONGATED WEST-EAST ACROSS THE REGION AND STALL FOR
THE LATTER HALF OF THE WEEK. WITH SUBTROPICAL RIDGING TO OUR
SOUTH AND FASTER WESTERLIES TO OUR NORTH...THIS WILL FAVOR ACTIVE
BAROCLINIC ZONE WITH DAILY THREAT FOR SHOWERS/STORMS. PATTERN
SUPPORTS SOME ORGANIZATION OF STORM ACTIVITY AND POTENTIAL FOR
STRONG/SEVERE STORMS PER PRESENCE OF WITH ASSOCIATED UPPER LEVEL
SHORT WAVE ENERGY THAT WILL BE PASSING THROUGH THE FASTER
WESTERLIES TO OUR NORTH.

THE UPPER FLOW ATTEMPTS TO TRANSITION BACK TO NORTHWEST FLOW
TOWARD THE WEEKEND AS UPPER RIDING AMPLIFIES ACROSS THE WEST-
CENTRAL CONUS. THIS COULD REDUCE THE POTENTIAL FOR PROLONGED
CONVECTION/RAINFALL...BUT WILL NONETHELESS SUPPORT AN ACTIVE AND
UNSETTLED WEATHER PATTERN.

WITH ABOVE AVERAGE CLOUD COVER AND MOISTURE LEVELS CONTINUING...EXPECT
NEAR TO SLIGHTLY BELOW NORMAL MAX TEMPERATURES AND WELL ABOVE
NORMAL MINIMUM TEMPERATURES THROUGH THE WEEK.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
AS OF 154 AM EDT SUNDAY...

ONE AREA OF SHOWERS/EMBEDDED THUNDER WAS DIRECTLY UPSTREAM FROM
KDAN SO HAVE GONE PESSIMISTIC THERE FOR THE INITIAL ONE TO TWO
HOUR PERIOD. THIS AREA OF PRECIPITATION IS CURRENTLY WEAKENING SO
WILL AMEND AS NEEDED.

AVIATION CONDITIONS WILL BE QUITE POOR TODAY AS A CLOSED LOW
DEVELOPS ALOFT STAYS JUST TO OUR WEST THROUGH THE PERIOD...WHILE A
SURFACE LOW SLIDES INTO THE WESTERN PORTION OF OUR AREA ALONG THE
OLD LINGERING FRONTAL BOUNDARY THAT HAS BEEN WAVERING ABOUT FOR
THE PAST SEVERAL DAYS. THIS WILL ESTABLISH A DEEP AND PERSISTENT
E/SE WIND FLOW WITH EXCELLENT MOISTURE TRANSPORT INTO THE TAF
SITES. EXPECT MVFR/IFR CONDITIONS TO MOVE IN FROM THE WEST
OVERNIGHT BEFORE BOUNCING BACK UP TO AOA VFR BY LATE MORNING/EARLY
AFTERNOON. PRECIPITATION CHANCES WILL BE INCREASING THROUGHOUT THE
MORNING WITH THE WORST CONDITIONS HOLDING OFF UNTIL THE AFTERNOON
WHEN THERE WILL ALSO BE SOME EMBEDDED THUNDER. THERE ARE
INDICATIONS FOR SPOTTY IMPROVEMENT LATE IN THE PERIOD BUT DO NOT
HAVE ENOUGH CONFIDENCE IN EXACTLY WHERE/WHEN SO WILL STAY
PESSIMISTIC THROUGH THE END OF THE VALID PERIOD.

EXTENDED AVIATION DISCUSSION...

POOR AVIATION CONDITIONS TO CONTINUE INTO NEXT WEEK...BUT WINDOWS
OF OPPORTUNITY FOR VFR CONDITIONS INCREASE TUE. UPPER LOW/TROUGH
WILL MOVE INTO OHIO BY MONDAY. MEANWHILE...A COLD FRONT WILL
APPROACH FROM THE OH VALLEY BY WED. THIS LEAVES A VERY
UNSETTLED/WET PATTERN ACROSS THE REGION THROUGH THE PERIOD.

EXPECT WIDESPREAD LATE NIGHT/EARLY MORNING LOW CLOUDS/FOG WITH
IFR-LIFR CIGS/VSBYS. OVERALL...CONDITIONS SHOULD IMPROVE TO MVFR-
VFR OUTSIDE SHRA/TSRA ACTIVITY DURING THE AFTERNOONS. AT THIS
POINT...TUESDAY APPEARS TO OFFER THE BEST OPPORTUNITY FOR MORE
WIDESPREAD VFR CONDITIONS.

&&

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

&&

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



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