Flood Watch 7, NWS Blacksburg, VA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1122 PM EST SUN DEC 27 2015

.SYNOPSIS...
A COLD FRONT WILL DROP SOUTH INTO THE MID ATLANTIC REGION TONIGHT. A
STRONG LOW PRESSURE SYSTEM THAT WILL TRACK FROM THE PLAINS INTO THE
GREAT LAKES ON MONDAY AND TUESDAY...WHICH WILL BRING ANOTHER COLD
FRONT TO OUR REGION ON THURSDAY.

&&

.NEAR TERM /THROUGH MONDAY/...
AS OF 1114 PM EST SUNDAY...

RAIN SHOWERS FAINT ACROSS SE WV INTO THE SHENANDOAH VALLEY AS
FRONT EXTENDS FROM SE VA INTO NW NC. MODELS ARE SHOWING VERY LIGHT
QPF OVERNIGHT AND HAVE BACKED OFF ON POPS WITH HIGH-RES EVEN MORE
ANEMIC ON COVERAGE. STILL THINK WEDGE SETTING UP SHOULD LEAD TO
PLENTY OF CLOUDS...SOME FOG AND LIGHT RAIN OR DRIZZLE ACROSS THE
BLUE RIDGE AND ADJACENT AREAS INTO THE VA PIEDMONT...AND WEST OVER
THE INTERSTATE 81 CORRIDOR. NO OTHER MAJOR CHANCES PLANNED WITH
THIS UPDATE.

PREVIOUS EARLY EVENING DISCUSSION...

EASED OFF POPS SOME OVER THE NW SECTION OF THE CWA AS SHOWERS ARE
DRYING UP SOME. NOT REALLY SEEING MUCH IN THE WAY OF SHOWER
CHANCES EAST OF THE SE WV MTNS UNTIL MIDNIGHT WHEN THE FRONT FOLDS
OVER AS HIGH PRESSURE MOVES ACROSS THE GREAT LAKES AREA.

PREVIOUS AFTERNOON DISCUSSION...

THE EROSION OF THIS MORNINGS SHALLOW WEDGE COMBINED WITH THE
SOUTHWEST FLOW RESULTING IN RECORD WARMTH THIS AFTERNOON.
TEMPERATURES HAVE CLIMB INTO THE LOWER AND MID 70S IN THE
PIEDMONT. LOOK FOR RER AND PNS ON CLIMATE RECORD. LOW PRESSURE
WILL MOVE EAST OFF THE NEW ENGLAND COAST TONIGHT PUSHING A COLD
FRONT SOUTHWARD INTO OUR AREA OVERNIGHT. THE BACKDOOR COLD FRONT
WILL ADVANCE SOUTH MONDAY...AS A DEEP LOW PRESSURE SYSTEM IN THE
MISSISSIPPI RIVER VALLEY LIFTS NORTHEAST.

MOISTURE WILL INCREASE TONIGHT AS THE WEDGE PUSHES SOUTH ACROSS OUR
AREA. INITIALLY DECREASED OUR POPS FOR RAIN THIS EVENING...THEN
INCREASED CHANCES AS LEADING EDGE OF WEDGE PUSHES SOUTH ACROSS
NORTHERN PORTIONS OF THE FORECAST AREA. USED A BLEND OF THE
RNKWRFARW AND NAM FOR THIS EVENING...THEN WORKED IN THE SUPERBLEND
FOR MONDAY. IN GENERAL...LOW TEMPERATURES TONIGHT WILL RANGE FROM
THE MID 40S ACROSS THE NORTH TO THE MID AND UPPER 50S ACROSS THE
SOUTH.

MONDAY WILL FEATURE PLENTY OF CLOUDS WITH AREAS OF LIGHT
RAIN...DRIZZLE AND FOG. CUT BACK POPS FOR RAIN IN THE NORTHWEST AND
PLAYED THE BEST RAIN CHANCES ALONG THE BLUE RIDGE MOUNTAINS DUE TO
SOUTHEASTERLY UPSLOPE ENHANCEMENT. USED AN NON DIURNAL TEMPERATURE
CURVE AS COOLER MARINE AIR BUILDS IN THROUGH THE DAY. HIGH
TEMPERATURES FOR MONDAY WILL RANGE FROM THE UPPER 40S IN THE NORTH
TO AROUND 60 DEGREES IN THE PIEDMONT. SOUTHEAST WINDS WILL INCREASE
MONDAY AFTERNOON AS THE 850 MB LOW LEVEL JET LIFTS NORTHEAST THROUGH
THE WESTERN MOUNTAINS. WIND GUSTS AS HIGH AS 40 TO 45 MPH ACROSS THE
HIGHER ELEVATIONS BETWEEN MOUNT ROGERS VIRGINIA AND BLUEFIELD WEST
VIRGINIA MONDAY AFTERNOON. THE HEAVIEST RAIN DURING THE DAY ON
MONDAY WILL OCCUR ALONG THE SOUTHERN BLUE RIDGE WHERE UP TO A HALF
INCH MAY FALL. WITH RECENT HEAVY RAINS...THE THREAT FOR FLOODING
WILL INCREASE MONDAY AFTERNOON INTO MONDAY NIGHT.

&&

.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 335 PM EST SUNDAY...

SQUEEZE PLAY BETWEEN HIGH PRESSURE THAT WILL BE CENTERED OVER
NORTHERN NEW ENGLAND EARLY MONDAY NIGHT AND LOW PRESSURE LIFTING
NORTHEAST THROUGH THE MS/OH VALLEYS WILL RESULT IN ANOTHER ROUND OF
WIDESPREAD MODERATE TO LOCALLY HEAVY RAIN AS BROAD UPWARD VERTICAL
MOTION FIELDS THROUGH A NEARLY SATURATED TROPOSPHERE INTENSIFY
OVER THE MID ATLANTIC AND MID APPALACHIAN REGION AS THE RESULT OF
STRONG ISENTROPIC LIFT...WARM MOIST ADVECTION...AND APPROACH OF
RIGHT ENTRANCE REGION OF UPPER JET.

SOUTHEASTERLY LOWER TROPOSPHERIC WINDS EXPECTED TO INCREASE TO PEAK
IN 40-50 KNOT RANGE AT 850 MILLIBAR LEVEL ON MONDAY NIGHT BEFORE
VEERING INTO A MORE SOUTHWESTERLY COMPONENT BY DAYBREAK TUESDAY.
SOME OF THESE WINDS WILL LIKELY RIDE OVER RETREATING COOL WEDGE IN
PLACE OVER THE AREA...BUT STILL MAY BE SUFFICIENT TO TRIP ADVISORY
CRITERIA ACROSS THE HIGHER TERRAIN AND PREFERRED CHANNELING AREAS
FROM AROUND MOUNT ROGERS VA NORTH TOWARD BLUEFIELD WV ON MONDAY
NIGHT. MAY HAVE TO HOIST WIND ADVISORY FOR THIS AREA IN UPCOMING
FORECAST ISSUANCES...BUT FOR NOW...HAVE HIGHLIGHTED MENTION IN
HAZARDOUS WEATHER OUTLOOK. WITH SATURATED GROUND CONDITIONS...ANY
STRONGER WIND GUSTS MAY RESULT IN SOME LOCALLY FELLED TREES AND
POWER OUTAGES.

ANY REPRIEVE FROM WET WEATHER FOLLOWING PASSAGE OF FIRST SYSTEM
AND WEAK COOL FRONT/TROF ON/BY TUESDAY AFTERNOON WILL BE SHORT
LIVED AS YET ANOTHER STRONG SHORT WAVE TROF OVER THE SW PORTION OF
THE NATION IS EXPECTED TO LIFT NORTHEAST THROUGH THE CENTRAL
PLAINS AND INTO THE GREAT LAKE REGION TUESDAY NIGHT INTO
WEDNESDAY. BACKING OF WINDS ALOFT IN ADVANCE OF THIS SYSTEM WILL
SUPPORT ALLOW COOL FRONT/TROF TO BEGIN TO BUCKLE BACK NORTHWARD AS
A WARM FRONT BY DAYBREAK WEDNESDAY.

AT THE PRESENT TIME...THE BULK OF PRECIPITATION ON THE NORTHERN
PERIPHERY OF APPROACHING FRONT EXPECTED TO REMAIN SOUTH OF THE
BLACKSBURG FORECAST AREA ON TUESDAY NIGHT...BUT AREAS ALONG AND
SOUTH OF THE VA/NC BORDER MAY ONCE AGAIN BE IN THE RAIN BY DAYBREAK
WEDNESDAY...WITH AREAS FURTHER TO THE NORTH LIKELY TO EXPERIENCE WET
CONDITIONS SHORTLY THEREAFTER. A REPEAT PERFORMANCE OF WEATHER
EXPECTED ON MONDAY INTO MONDAY NIGHT WILL OCCUR AS SECOND SYSTEM
PASSES THROUGH THE REGION ON WEDNESDAY....PERHAPS INTO WEDNESDAY
NIGHT. GFS MODEL A BIT FASTER IN THE PROGRESSION OF THIS SYSTEM THAN
THE ECMWF...WHICH ENDS THE THREAT FOR PRECIPITATION ACROSS EASTERN
PORTIONS OF THE FORECAST AREA BY LATE WEDNESDAY EVENING...AS OPPOSED
TO ENDING THE THREAT ACROSS THE PIEDMONT COUNTIES BY LATE THURSDAY
AFTERNOON...RESPECTIVELY.

REGARDLESS...WITH GROUND CONDITIONS NEARLY SATURATED...AND WATER
LEVELS IN AREA STREAMS/CREEKS AND RIVERS REMAINING HIGH FROM RECENT
SUCCESSIVE RAINS...THE THREAT FOR ADDITIONAL FLOODING/FLASH FLOODING
WILL AGAIN BE OF CONCERN THROUGH THE ENTIRE SHORT TERM PERIOD.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 335 PM EST SUNDAY...

LONG TERM PERIOD WILL BE CHARACTERIZED BY A DEEPENING UPPER TROF
BECOMING ESTABLISHED OVER THE GREAT LAKES AS A SERIES OF REINFORCING
SHORT WAVES DIVE SE FROM OUT OF CENTRAL CANADA. AS UPPER TROF
STRENGTHENS...UPPER FLOW OVER THE BLACKSBURG FORECAST AREA WILL
SLOWLY VEER FROM A SW TO A NW COMPONENT...INCREASINGLY DEFLECTING
ANY ADDITIONAL COASTAL WAVES OF LOW PRESSURE AND ASSOCIATED
PRECIPITATION TO OUR EAST.

ONGOING COLD ADVECTION WITH A FETCH FROM OFF THE GREAT LAKES
WARRANTS REFLECTION OF UPSLOPING CLOUDS AND A NOMINAL THREAT FOR
SOME LIGHT SNOW SHOWERS/FLURRIES ACROSS THE WESTERN FLANKS OF THE
APPALACHIANS.

TEMPERATURES WILL TREND DOWNWARDS THROUGH THE PERIOD...AND MAY
ACTUALLY GO BELOW SEASONAL NORMALS BY THE WEEKEND...WITH GOOD
INDICATIONS THAT ONCE ESTABLISHED...COULD PERSIST THROUGH MUCH OF
THE FIRST 10 DAYS OF THE NEW YEAR.

&&

.AVIATION /04Z MONDAY THROUGH FRIDAY/...
AS OF 1114 PM EST SUNDAY...

NOT MUCH CHANGE PLANNED IN THE TAFS...AS FRONT MOVES SOUTH WEDGE
SETS UP AND SHOULD SEE LYH/DAN WEST TO LWB/ROA/BCB TANK TO IFR TO
MVFR WITH LOWEST CIGS AT ROA/LYH. FOG FORECAST TRICKY BUT NOT
EXPECTING TO DENSE GIVEN EXTENSIVE HIGH CLOUDS ABOVE AND STRATUS
DECK. ROA/BCB COULD SEE THE LOWER VSBYS. THE NE WIND WILL KICK UP
ACROSS LYH/DAN BEHIND THE FRONT SO THIS SHOULD LIMIT FOG.

WEDGE REMAINS MONDAY RESULTING IN IFR CLOUDS AND FOG FOR MOST OF
THE REGION...THOUGH BLF WILL BE ON THE EDGE SO THEY COULD GO
EITHER WAY WITH LOW CLOUDS VS VFR CIGS. BETTER LIFT ENTERS FROM
THE SOUTH OVERRIDING THE FRONTAL BOUNDARY WHERE RAIN WILL BE
NUMEROUS BY AFTERNOON. WINDS SHIFT MONDAY TO THE EAST TO
SOUTHEAST AROUND 10 MPH WITH GUSTS UP TO 30 MPH POSSIBLE OVER
TOWARD BLF-VJI.

.EXTENDED AVIATION DISCUSSION...

DRIER AIR WILL COME IN BEHIND A COLD FRONT ON TUESDAY. IMPROVEMENT
TO VFR OVER MUCH OF THE REGION IS MORE LIKELY ON THIS DAY...THEN
ANOTHER FRONT AND SFC LOW ARRIVES WEDNESDAY AND WEDNESDAY NIGHT
WITH MORE SUB-VFR CONDITIONS AND RAIN...FOLLOWED BY DRIER AIR
LATER THURSDAY INTO FRIDAY...THOUGH SOME UPSLOPE CLOUDINESS COULD
IMPACT BLF/LWB FRIDAY.

&&

.CLIMATE...
AS OF 632 PM EST SUNDAY...

DO NOT FORESEE RECORD HIGHS MONDAY BUT COULD SEE RECORDS BROKEN
FOR WARMEST LOW TEMPERATURES...EXCEPT BCB.

MONDAY 12/28/2015
SITE  MAXT YEAR  MINT YEAR  LOMAX YEAR  HIMIN YEAR
KBLF    67 1984     4 1977     20 1995     53 1984
KDAN    72 1971    13 1966     28 1950     54 2008
KLYH    76 1984     6 1977     26 1950     51 1959
KROA    75 1984     4 1925     25 1925     51 1984
KRNK    66 1984     6 1977     28 1995     42 1959

&&

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

&&

SYNOPSIS...AMS/KK
NEAR TERM...KK/WP
SHORT TERM...WERT
LONG TERM...WERT
AVIATION...AMS/KK/WP
CLIMATE...AMS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE BLACKSBURG VA
545 PM EST SUN DEC 27 2015

NCZ001>006-018>020-VAZ011>014-016>020-022>024-032>035-043>047-058-
059-WVZ043-044-507-508-282245-
ASHE-ALLEGHANY NC-SURRY-STOKES-ROCKINGHAM-CASWELL-WATAUGA-WILKES-
YADKIN-GILES-WYTHE-PULASKI-MONTGOMERY-CARROLL-FLOYD-CRAIG-
ALLEGHANY VA-BATH-ROANOKE-BOTETOURT-ROCKBRIDGE-PATRICK-FRANKLIN-
BEDFORD-AMHERST-HENRY-PITTSYLVANIA-CAMPBELL-APPOMATTOX-BUCKINGHAM-
HALIFAX-CHARLOTTE-SUMMERS-MONROE-EASTERN GREENBRIER-
WESTERN GREENBRIER-
545 PM EST SUN DEC 27 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR NORTH CENTRAL NORTH
CAROLINA...NORTHWEST NORTH CAROLINA...CENTRAL VIRGINIA...SOUTH
CENTRAL VIRGINIA...SOUTHWEST VIRGINIA...WEST CENTRAL VIRGINIA AND
SOUTHEAST WEST VIRGINIA.

.DAY ONE...TONIGHT.

HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

TWO POTENT WEATHER SYSTEMS ARE EXPECTED DURING THE UPCOMING WEEK
THAT WILL BRING WIDESPREAD MODERATE TO HEAVY RAIN. THE FIRST WILL
OCCUR FROM MAINLY MONDAY AFTERNOON INTO TUESDAY AFTERNOON...AND
THE SECOND SYSTEM WILL IMPACT THE AREA WEDNESDAY INTO WEDNESDAY
NIGHT.

WITH GROUND CONDITIONS ALREADY NEARLY SATURATED...AND WATER
LEVELS IN AREA STREAMS AND RIVERS RUNNING HIGH FROM RECENT
RAINS...THE THREAT FOR FLOODING OR FLASH FLOODING WILL AGAIN
INCREASE MONDAY AFTERNOON...AND CONTINUE UNTIL THE PASSAGE OF THE
SECOND WEATHER SYSTEM LATE WEDNESDAY NIGHT OR ON THURSDAY MORNING.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

VAZ007-009-010-015-WVZ042-282245-
TAZEWELL-SMYTH-BLAND-GRAYSON-MERCER-
545 PM EST SUN DEC 27 2015

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHWEST VIRGINIA AND
SOUTHEAST WEST VIRGINIA.

.DAY ONE...TONIGHT.

HAZARDOUS WEATHER IS NOT EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

TWO POTENT WEATHER SYSTEMS ARE EXPECTED DURING THE UPCOMING WEEK
THAT WILL BRING WIDESPREAD MODERATE TO HEAVY RAIN. THE FIRST WILL
OCCUR FROM MAINLY MONDAY AFTERNOON INTO TUESDAY AFTERNOON...AND
THE SECOND SYSTEM WILL IMPACT THE AREA WEDNESDAY INTO WEDNESDAY
NIGHT.

IN ADDITION...SOUTHEASTERLY WINDS IN ADVANCE OF THE FIRST WEATHER
SYSTEM WILL INCREASE TO 15 TO 25 MPH...WITH SOME GUSTS AS HIGH AS
40 TO 45 MPH ACROSS THE HIGHER ELEVATIONS BETWEEN MOUNT ROGERS VA
AND BLUEFIELD WV MONDAY AFTERNOON INTO MONDAY NIGHT.

WITH GROUND CONDITIONS ALREADY NEARLY SATURATED...AND WATER
LEVELS IN AREA STREAMS AND RIVERS RUNNING HIGH FROM RECENT
RAINS...THE THREAT FOR FLOODING OR FLASH FLOODING WILL AGAIN
INCREASE MONDAY AFTERNOON...AND CONTINUE UNTIL THE PASSAGE OF THE
SECOND WEATHER SYSTEM LATE WEDNESDAY NIGHT OR ON THURSDAY MORNING.
ANY STRONGER WIND GUSTS WILL ALSO HAVE THE POTENTIAL OF TOPPLING
SHALLOW ROOTED TREES DUE TO MOIST GROUND CONDITIONS...RESULTING
IN LOCALIZED POWER OUTAGES.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED AT THIS TIME.

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