Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000
FXUS61 KRNK 041955
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
355 PM EDT SAT JUL 4 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 SUNDAY/...
AS OF 330 PM EDT SATURDAY...

SEVERAL SHORTWAVES WILL ROTATE THROUGH THE UPPER TROF OVER EAST WITH
SURFACE FRONT WAVERING AROUND THROUGH THE AREA. LOW PRESSURE WILL
PUSH OFF THE MIDDLE ATLANTIC COAST WHICH SWINGS COLD FRONT
SOUTH THIS AFTERNOON INTO TONIGHT. SOLAR HEATING HAS RESULTED IN
ENOUGH INSTABILITY TO GENERATE SCATTERED SHOWERS AND THUNDERSTORMS.
THE MOST UNSTABLE CAPES AND DEEP MOISTURE CONVERGENCE ON SPC HOURLY
MESO ANALYSIS POINTING TO EAST OF THE MOUNTAINS. THE DAY ONE
CONVECTIVE OUTLOOK CLIPS THE SOUTHEAST OF CWA WITH A MARGINAL THREAT
WITH SLIGHT POTENTIAL ACROSS EASTERN NORTH CAROLINA. THE WINDOW FOR
ANY STRONGER STORMS THIS AFTERNOON IS VERY SMALL. STORMS ARE MOVING
THUS NOT ANTICIPATING ANY FLOODING ISSUE.

THE BULK OF THE CONVECTION SHOULD TAPER OFF THIS EVENING INTO
TONIGHT WITH JUST SOME LINGERING ISOLATED SHOWERS FOR THE OVERNIGHT.
IT APPEARS THAT MANY LOCATIONS WILL BE ABLE TO GET OFF FIREWORKS
DISPLAYS. LOWS TEMPERATURES TONIGHT WILL REMAIN MILD WITH READINGS
FROM AROUND 60 IN THE NORTHWEST MOUNTAINS TO THE UPPER 60S IN THE
PIEDMONT.

THE WAVY FRONTAL BOUNDARY REMAIN ACROSS THE REGION ON SUNDAY.
SHORTWAVES CONTINUE TO TRAVEL EAST ALONG THE UPPER TROUGH. SHOWERS
AND THUNDERSTORMS WILL DEVELOP BY SUNDAY LATE MORNING AND BECOME
NUMEROUS BY SUNDAY AFTERNOON. HIGH TEMPERATURES SUNDAY WILL RANGE
FROM THE UPPER UPPER 60S IN THE MOUNTAINS TO THE MID 80S IN THE
PIEDMONTS.

&&

.SHORT TERM /SUNDAY NIGHT 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 /19Z SATURDAY THROUGH THURSDAY/...
AS OF 145 PM EDT SATURDAY...

A COLD FRONT WILL SLOWLY MOVE SOUTH TONIGHT AND SUNDAY. THIS WILL
RESULT IN POOR FLYING CONDITIONS IN CONVECTION AND LOW CLOUDS.
SLOW MOVING UPPER LOW TO THE WEST OF THE REGION WILL SPLIT...WITH
PARENT TROUGH SHEARING OUT TO THE NORTHEAST BY SUNDAY...WHILE A
WEAK CUTOFF DEVELOPS ALONG THE TAIL OF THE UPPER TROUGH ACROSS THE
SOUTHEAST STATES. THIS CUTOFF UPPER LOW WILL DRIFT NORTH INTO THE
AREA SUNDAY INTO MONDAY.

SCT TO BKN MVFR CLOUDS WILL LOWER TO IFR CONDITION IN CONVECTION
THIS AFTERNOON INTO TONIGHT. BAND OF SHOWERS JUST AHEAD OF THE
COLD FRONT IS DIMINISHING AS TRAVELING SOUTH. HOWEVER...SCATTERED
CONVECTION IS FORMING IN THE UNSTABLE AIR. CAPES AND LIS WERE MOST
UNSTABLE EAST OF THE BLUE RIDGE THIS AFTERNOON INTO THIS EVENING.
THE TAF SITE WITH THE BEST CHANCE OF A THUNDERSTORM IS DAN. A
SHOWER MAY CLIP ANY OF THE TAF LOCATIONS THIS AFTERNOON INTO
TONIGHT.

OVERNIGHT...THE AFOREMENTIONED CUTOFF UPPER LOW WILL BEGIN TO
DEVELOP ACROSS THE SOUTHEAST STATES...BUT ASSOCIATED PRECIPITATION
WILL NOT DRIFT BACK INTO THE CWA UNTIL AFT 12 SUN.
HOWEVER...EXPECT WIDESPREAD LOW CLOUDS/CIGS AND FOG TO DEVELOP
OVERNIGHT WITH WIDESPREAD IFR- LIFR CIGS AND VSBYS.

SOUTHWEST WINDS AT 5-7KTS THIS AFTERNOON WILL BECOMING LIGHT TO
CALM OVERNIGHT...HELPING TO PROMOTE WIDESPREAD FOG/LOW CLOUDS WITH
VERY MOIST GROUND IN PLACE.

MVFR/IFR CONDITIONS ARE EXPECTED SUNDAY WITH SHOWERS AND THUNDERSTORMS.
WINDS WILL BECOME SOUTHEAST AT 5-10KTS SUNDAY.

MEDIUM TO HIGH CONFIDENCE IN CEILINGS...VISIBILITIES AND WINDS
DURING THE 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 LINGER WEST OF THE VA/NC COASTAL PLAIN INTO THE SOUTHEAST
STATES THROUGH THE WEEKEND...THEN BEGIN TO DRIFT INTO NORTHERN VA
MON. 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...KK
SHORT TERM...RAB/PM
LONG TERM...PM
AVIATION...KK/MBS/RAB


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