Area Forecast Discussion
Issued by NWS Blacksburg, VA

Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS61 KRNK 280523
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
123 AM EDT MON JUL 28 2014

.SYNOPSIS...
UPPER DISTURBANCES WILL CONTINUE TO WORK ACROSS THE AREA THIS
EVENING IN ADVANCE OF A STRONG COLD FRONT THAT WILL BE
ARRIVING FROM THE NORTHWEST AFTER MIDNIGHT. THESE FEATURES MAY
TRIGGER STRONG TO POTENTIALLY SEVERE THUNDERSTORMS INTO EARLY
TONIGHT. THE COLD FRONT WILL MOVE ACROSS THE REGION BY EARLY
MONDAY...RESULTING IN COOLER WEATHER INTO THE MIDDLE OF THE WORK
WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 115 AM EDT MONDAY...

CONVECTION APPROACHING FROM WEST VIRGINIA HAS WEAKENED OVER THE
PAST FEW HOURS...AMOUNTING ONLY TO SHOWER ACTIVITY AT THIS TIME.
SEE NO NEED TO PROLONG THE TORNADO WATCH...AND HAVE THEREFORE
CANCELLED IT EARLY FOR THE MOUNTAIN EMPIRE THROUGH THE SHENANDOAH
VALLEY. ADJUSTED RAIN CHANCES FOR THE NEXT FEW HOURS BASED ON
RADAR TRENDS AND HRRR MODEL DATA WHICH APPEARS TO BE HANDLING THE
CURRENT RAINFALL VERY WELL. EXPECT ONLY SPOTTY UPSLOPE SHOWERS
SHOULD BE ALL THAT REMAIN BY SUNRISE.

LATEST SURFACE OBSERVATIONS INDICATE THE COLD FRONT IS SITUATED
NEAR THE OHIO RIVER...PROGRESSING A LITTLE SLOWER THAN PREVIOUSLY
FORECAST. EXPECT THE FRONT TO ENTER OUR SOUTHEAST WEST VIRGINIA
COUNTIES BY AROUND 5 AM...AND THEN CONTINUE EAST THROUGH THE
MORNING.

AS OF 200 PM EDT SUNDAY...

5H TROF CROSSES EAST OF THE AREA MONDAY ALLOWING HIGH PRESSURE TO
START BUILDING IN FROM THE WEST DURING THE AFTERNOON. HOWEVER
ANOTHER SHORTWAVE ROUNDING DOWN THE BACK OF THE COOL POOL MAY HELP
TO ENHANCE THE SHOWERS AS IT COINCIDES WITH THE COLDEST 85H TEMPS
AND MAX HEATING. THUS BOOSTED POPS WESTERN SLOPES TO A PERIOD OF
LOW LIKELYS MONDAY AFTERNOON WITH A QUICK CUTOFF TO SHRA BLUE
RIDGE AND POINTS EAST WHERE DOWNSLOPING SHOULD ALLOW FOR LESS
CLOUDS. ODOR WILL BE A BREEZY AND COOL DAY FOR LATE JULY OVER THE
MOUNTAINS WHERE MAY STRUGGLE TO GET OUT OF THE 60S WHERE CLOUDS
PERSIST AND ALONG HIGHER ELEVATIONS. SHOULD BE ABLE TO GET WELL
INTO THE 80S UNDER DRY DOWNSLOPE PIEDMONT BUT ONLY 75-82 BLUE
RIDGE.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
AS OF 215 PM EDT SATURDAY...

WEST TO NORTHWEST UPPER FLOW WILL PERSIST OVER THE BLACKSBURG
FORECAST AREA THROUGH THE SHORT TERM PERIOD AS SERIES OF WEAK SHORT
WAVE TROFS EMBEDDED IN UPPER FLOW HELP ANCHOR PIN-WHEELING UPPER
TROF OVER THE GREAT LAKES.

COOLER AIR ALOFT...WEAK FORCING FROM INITIAL SHORT WAVE...AND WEAK
UPSLOPING MAY SUPPORT ISOLATED TO WIDELY SCATTERED SHOWERS ACROSS
THE WESTERN FLANKS OF THE APPALACHIANS ON MONDAY NIGHT...AND PERHAPS
DIURNALLY DRIVEN EVEN INTO TUESDAY.  HOWEVER...DESPITE ADDITIONAL
WEAK STREAM ENERGY...ARRIVAL OF SURFACE RIDGE AND AMPLIFICATION OF
SUBSIDENCE INVERSION SHOULD BE SUFFICIENT TO LIMIT THREAT FOR ANY
ADDITIONAL SHOWER ACTIVITY TUESDAY NIGHT THROUGH WEDNESDAY NIGHT.

UPSLOPING CLOUDS ACROSS THE WEST SHOULD MAINTAIN UNSEASONABLY COOL
TEMPERATURES IN THE MOUNTAINS...WITH DAYTIME HIGHS NOT LIKELY TO
CLIMB OUT OF THE 60S ON EITHER TUESDAY OR WEDNESDAY ACROSS THE
HIGHEST TERRAIN. EAST OF THE BLUE RIDGE...ANY INFLUENCE OF COLD
ADVECTION WILL BE OFFSET BY DOWNSLOPING/COMPRESSIONAL HEATING AND
GOOD INSOLATION SUCH THAT HIGHS REACH INTO THE LOWER TO MID
80S...YET STILL ~5F LOWER THAN CLIMATOLOGICAL AVERAGES.

NIGHTTIME LOWS WILL BE LARGELY GOVERNED BY EXTENT OF MIXING AND
CLOUD COVER. HIGHER ELEVATIONS WHERE/IF CLOUDS CAN CLEAR...AND
ESPECIALLY THE MOUNTAIN VALLEYS WHERE BOUNDARY LAYER DECOUPLING WILL
MORE READILY OCCUR...SHOULD EXPERIENCE AT LEAST SPOTTY READINGS DOWN
INTO THE 40S. READINGS EAST OF THE BLUE RIDGE WILL BE A BIT
MILDER...MAINLY 50S...YET STILL 5-10F BELOW CLIMATOLOGICAL AVERAGES.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
AS OF 1200 PM EDT SUNDAY...

A SURFACE HIGH THURSDAY OVER SOUTHERN MICHIGAN WILL SHIFT EAST
TOWARDS NEW ENGLAND BY FRIDAY AND SATURDAY. AT THE MID LEVELS A
PERSISTENT TROUGH IS SET UP OVER THE EASTERN US WITH A RIDGE OVER
THE WESTERN US. THURSDAY LACKS LOW AND MID LEVEL MOISTURE SO EXPECT
THE DAY TO BE DRY. MOISTURE AND INSTABILITY INCREASE FOR FRIDAY AND
THROUGH THE REST OF THE PERIOD AS SEVERAL DISTURBANCES PIVOT ACROSS
THE REGION AROUND THE BASE OF THE TROUGH. EXPECT SCATTERED SHOWERS
AND THUNDERSTORMS TO DEVELOP EACH AFTERNOON/EVENING AND TAPER OFF TO
JUST SCATTERED SHOWERS DURING THE EVENING. FOCUS OF THE HIGHEST
CHANCE POPS ARE OVER THE MOUNTAINS WHERE THE BEST CONVERGENCE WILL
BE LOCATED...WITH LOWER CHANCE POPS OUT EAST.

THURSDAY WILL BE THE WARMEST DAY OF THE PERIOD WITH 850MB TEMPS
AROUND +16C. THIS WILL CORRESPOND TO SURFACE HIGH TEMPS IN THE MID
80S OUT EAST AND NEAR 80 ACROSS THE MOUNTAINS. AS THE HIGH SHIFTS
EAST ON FRIDAY THE WINDS WILL SHIFT FROM N/NW TO AN EASTERLY
DIRECTION. THIS WILL WEDGE THE AREA IN THROUGH THE REMAINDER OF THE
PERIOD. WITH THE INCREASED LOW/MID LEVEL MOISTURE EXPECT CLOUDY
CONDITIONS. THIS ALONG WITH EXPECTED SCATTERED PRECIP AND 850MB
TEMPS FALLING TO +11-14C...SURFACE HIGH TEMPS WILL BE 5-10 DEGREES
BELOW NORMAL FRIDAY THROUGH SUNDAY.

&&

.AVIATION /05Z MONDAY THROUGH FRIDAY/...
AS OF 745 PM EDT SUNDAY...

STILL AWAITING POTENTIAL ARRIVAL OF MORE SIGNIFICANT CONVECTION
INTO THE CWA AS THE EVENING PROGRESSES WITH STRONG STORMS STILL
POSSIBLE...MAINLY IN AREAS OF BETTER INSTABILITY/HEATING ACROSS
SOUTHSIDE/PIEDMONT. THIS COULD IMPACT ROA/LYH/DAN IN THE 02Z-06Z
TIME FRAME...BUT CONFIDENCE IN THIS OCCURRING IS LOW AS CIRRUS
SHIELD FROM UPSTREAM CONVECTION AND MORNING ACTIVITY HAS
ESSENTIALLY PUT A LID ON CONVECTIVE ACTIVITY TO THIS POINT ACROSS
MOST OF THE CWA THIS AFTERNOON/EVENING. OF GREATER LIKELIHOOD IS
THAT A LINE OF MOST LIKELY SUB SEVERE SHRA/TSRA WILL DEVELOP
ALONG THE FRONT/UPPER TROUGH AS ITS SWINGS RAPIDLY THROUGH THE CWA
IN THE 04Z-08Z TIME FRAME. GIVEN THAT THERE WILL BE A LARGE
UPSLOPE COMPONENT AT THAT TIME...EXPECT THE GREATEST LIKELIHOOD OF
SHRA/TSRA TO BE ACROSS THE WV COUNTIES...BUT ENOUGH DYNAMICS TO
SUPPORT MENTION OF SHRA EASTWARD EVEN INTO THE PIEDMONT. MOST
LIKELY THIS WILL BE ACCOMPANIED BY MVFR CIGS LWB-BLF...TO LOW END
VFR CIGS FURTHER EASTWARD. ALL PCPN SHOULD BE ENDING BY 10Z
MON...BUT EXTENSIVE UPSLOPE SC WILL CONTINUE THROUGHOUT WV MON
WITH A WINTERLIKE SETUP AND STRONG NW FLOW AND STRONG CAA. EXPECT
MVFR CIGS TO PREVAIL ALL DAY LWB-BLF...AND POTENTIALLY EVEN BCB AT
TIMES. FURTHER EAST...CLOUDS SHOULD SCT OUT AND CIGS WILL BE
MOSTLY VFR. VSBYS MOSTLY VFR OUTSIDE ISOLD MVFR IN TIME AND
LOCATION DURING SHRA/TSRA. MAIN CONCERN AFT 06Z AND THROUGH THE
DAY MON WILL BE STRONG NW WINDS AT SPEEDS OF 10-15KTS WITH GUSTS
25-30KTS...ESPECIALLY AFT 14Z MON. WINDS WILL BEGIN TO DIMINISH
TOWARD THE END OF THE TAF VALID PERIOD.

MEDIUM TO HIGH CONFIDENCE IN CIGS THROUGH THE TAF VALID PERIOD.
MEDIUM TO HIGH CONFIDENCE IN VSBYS THROUGH THE TAF VALID PERIOD.
MEDIUM TO HIGH CONFIDENCE IN WIND SPD/HIGH CONFIDENCE IN WIND DIR
THROUGH THE TAF VALID PERIOD.
LOW CONFIDENCE IN TSRA POTENTIAL THROUGH 10Z MON.

EXTENDED AVIATION DISCUSSION...DRIER AIR PUSHING IN FOR TUESDAY-
WEDNESDAY WILL BRING MAINLY VFR CONDITIONS...BUT CANNOT RULE OUT
LATE NIGHT FOG KBCB/KLWB ALTHOUGH THE LOW LEVELS MAY STAY DRY
ENOUGH FOR LESS FOG COVERAGE.

VARIABLE CIGS EXPECTED UNDER ANOMALOUS UPPER LOW THROUGHOUT THE
REST OF THE WEEK. A FEW -SHRA NOT COMPLETELY OUT OF THE QUESTION
ACROSS EASTERN WV...ALONG WITH OCCASIONAL MVFR CIGS. TYPICAL FOG
POTENTIAL LESS THAN NORMAL FOR THIS TIME OF YEAR THROUGHOUT THE
WEEK BECAUSE OF TURBULENT MIXING AND PREVAILING CYCLONIC FLOW.
TOWARD THE END OF THE WEEK...AS THE UPPER LOW RETROGRADES JUST
WEST OF THE REGION...INCREASING POTENTIAL FOR SHRA/TSRA BUT MAINLY
SW OF THE TAF SITES INTO FRIDAY.

&&

.EQUIPMENT...
THE WEATHER RADIO AT HINTON WEST VA TRANSMITTING ON FREQUENCY
162.425 MHZ REMAINS OFF THE AIR LIKELY DUE TO PHONE LINE PROBLEMS.
RESTORATION OF SERVICE IS NOT EXPECTED BEFORE NOON ON MONDAY.

&&

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

&&

$$
SYNOPSIS...JH/NF
NEAR TERM...JH/RAB
SHORT TERM...WERT
LONG TERM...CF
AVIATION...JH/RAB
EQUIPMENT...JH


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.