Area Forecast Discussion
Issued by NWS Blacksburg, VA

Home | 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 301735
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
135 PM EDT SAT MAY 30 2015

.SYNOPSIS...
HIGH PRESSURE OFFSHORE WILL MAINTAIN A VERY WARM AND HUMID AIR
MASS ACROSS THE REGION TODAY INTO SUNDAY. A COLD FRONT WILL
APPROACH FROM THE NORTHWEST LATE IN THE WEEKEND...BEFORE PUSHING
SOUTH OF THE AREA BY MONDAY...RESULTING IN MORE WIDESPREAD SHOWERS
AND THUNDERSTORMS LATER SUNDAY INTO MONDAY AFTERNOON. COOLER
WEATHER UNDER HIGH PRESSURE WILL BUILD IN BY THE MIDDLE OF NEXT
WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1250 PM EDT SATURDAY...

CONVECTIVE INITIATION AND LATEST RADAR TRENDS SHOWED DEVELOPMENT
OF SCATTERED SHOWERS AND THUNDERSTORMS ALONG THE BLUE RIDGE NORTH
OF ROANOKE AND WEST OF A LINE FROM BUENA VISTA TO BLUEFIELD. HAVE
ADJUSTED PROBABILITY OF PRECIPITATION TO HAVE HIGHEST PERCENTAGES
IN THAT AREA. LITTLE CHANGE NEEDED TO TEMPERATURE FORECAST FOR THE
REST OF THE DAY.

THE LATEST NCAR ENSEMBLE AND HRRR BUT STILL
SHOWED NO MORE THAN CHANCE POPS AT BEST. ELSEWHERE CANT TOTALLY
RULE OUT AT LEAST ISOLATED SHRA/TSRA PER HEATING...DECENT
INSTABILITY...AND HIGH 85H THETA-E WITH BEST CHANCES MOUNTAINS
WHERE AIDED BY OROGRAPHICS ESPCLY BLUE RIDGE.

SHOULD BE ONE OF THE WARMEST DAYS SO FAR THIS SEASON GIVEN A WARM START
AND LESS EXPECTED CLOUDS/TSRA THIS AFTERNOON. AGAIN APPEARS MOS A BIT
COOL AS SEEN OVER THE PAST COUPLE OF DAYS AS THICKNESS SUGGESTS HIGHS
CLOSE TO 90 SE...WITH LOW/MID 80S ELSEWHERE OUTSIDE OF THE HIGHEST
ELEVATIONS.

ANY EVENING CONVECTION MAY LINGER ESPCLY MOUNTAINS AN HOUR OR TWO AFTER
SUNSET BEFORE LOSS OF HEATING AND LACK OF FORCING CAUSE SHOWERS TO FADE
SO WILL KEEP SOME LOW POPS GOING THIS EVENING MAINLY FAR WEST. UPSTREAM
PRE-FRONTAL SHRA/TSRA WILL THEN BE THE MAIN CONCERN OVERNIGHT BUT
APPEARS MUCH OF THIS TOO FAR WEST TO REACH THE REGION BY DAYBREAK
SUNDAY. HOWEVER RETURN OF DEEPER MOISTURE AHEAD OF THE TROUGH/FRONT AS
SEEN IN MODEL PWATS LATE SUPPORTS INCLUDING SOME ISOLATED TO LOW CHANCE
POPS MAINLY WESTERN THIRD LATE. OTHERWISE MAINLY PC WITH ADDED PATCHY
FOG BY MORNING. TEMPS TO REMAIN ON THE WARM/MUGGY SIDE WITH MOST SPOTS
ONLY FALLING INTO THE 60-66 RANGE.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
AS OF 245 AM EDT SATURDAY

THE MEDIUM RANGE MODELS ARE ALL IN CONSENSUS THAT A SFC COLD FRONT..
ASSOCIATED WITH AN UPPER TROUGH MOVING THROUGH THE EASTERN GREAT
LAKES INTO NEW ENGLAND...MOVES THROUGH OUR FORECAST AREA MONDAY.
HOWEVER...THE MORE NOTICEABLE DRIER AIR AND COOLER TEMPS ARRIVE
MONDAY NIGHT/EARLY TUESDAY ONCE SOUTHERN STREAM ENERGY AND
ASSOCIATED SFC WAVE LIFT EAST.

THE FORECAST AREA WILL REMAIN FIRMLY ENTRENCHED IN THE WARM SECTOR
SUNDAY. WHILE INSTABILITY WILL INCREASE AS HIGHER PWAT AIR
RETURNS...BEST SHEAR AND UPPER LEVEL DYNAMICS REMAIN NORTH AND WEST
OF THE FORECAST AREA THROUGH SUNDAY. WHILE AN ISOLATED SEVERE STORM
IS POSSIBLE...GREATER CONCERN MAY BE WITH LOCALLY HEAVY DOWNPOURS.
WITH THE SLOWER ARRIVAL OF THE FRONT...PUSHED UP TEMPS A COUPLE OF
DEGREES FOR HIGHS...ESPECIALLY IN THE EAST.

KEPT POPS GOING AFTER SUNDOWN SUNDAY WITH FORCING FROM SFC BOUNDARY
MOVING INTO THE AREA. WENT ABOVE GUIDANCE FOR LOWS SUNDAY NIGHT DUE
TO CLOUDS AND SOME MIXING.

PRECIPITATION MAY BE MORE WIDESPREAD MONDAY...ESPECIALLY IN THE
SOUTHERN HALF OF THE FORECAST AREA...AS SFC BOUNDARY SLOWS SOMEWHERE
IN THE EASTERN PORTION OF THE FORECAST AREA DUE TO A SFC WAVE FROM
SOUTHERN STREAM ENERGY DEVELOPING IN NC. EXPECT MORE CLOUD COVER AND
SLIGHTLY COOLER TEMPS ON MONDAY...AS A RESULT...LOWER INSTABILITY.
THE EXCEPTION WOULD BE IN ADVANCE OF THE FRONT...IN THE FAR EASTERN
PORTION OF THE FORECAST AREA WHERE AN ISOLATED SEVERE STORM CANNOT
BE RULED OUT.

DRIER/COOLER AIR FINALLY SURGES INTO THE FORECAST AREA MONDAY NIGHT
AND TUESDAY. LEANED TOWARD THE COOLER GUIDANCE VALUES DURING THIS
PERIOD. WHILE THE SFC BOUNDARY PUSHES SOUTH OF THE FORECAST AREA BY
TUESDAY...850MB THETA-E AXIS LINGERS IN NC AND SOUTHERN VA AND WEAK
OVERRUNNING WILL KEEP THE THREAT FOR SHOWERS FOR THIS AREA.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
AS OF 245 PM EDT FRIDAY...

THE COLD FRONT WILL WASH OUT OVER OR JUST SOUTH OF THE AREA BY
TUESDAY AFTERNOON. AFTER THIS POINT...THE REGION WILL START TO
TRANSITION BACK A SOUTHERLY FLOW PATTERN AS A LOW/TROUGH DEVELOPS
ACROSS THE LOWER MISSISSIPPI RIVER VALLEY...AND HIGH PRESSURE
BECOMES CENTERED AGAIN OFF THE COAST OF THE CAROLINAS. DAYTIME
HEATING ALONG WITH PIECES OF ENERGY EJECTING OFF THE LOWER
MISSISSIPPI VALLEY LOW WILL HELP YIELD INCREASING CHANCE OF SHOWERS
AND STORMS AGAIN BY THURSDAY INTO FRIDAY. TEMPERATURES WILL ALSO
START TO TREND MILDER THURSDAY INTO FRIDAY.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
AS OF 125 PM EDT SATURDAY...

NWS RADAR SHOWED ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS
WERE DEVELOP AT THE START OF THE 18Z TAF PERIOD WEST OF A LINE
FROM BUENA VISTA VIRGINIA TO ROANOKE TO TAZEWELL VIRGINIA. KLWB
HAS THE HIGHEST PROBABILITY OF HAVE THUNDERSTORMS BEFORE 00Z
TODAY BUT MAY ALSO NEED TO ADD TSRA OR VCTS IN FOR THE KROA AND
KBCB TAFS DEPENDING ON SHORT TERM RADAR TRENDS.

ONCE THE SUN SET THE COVERAGE OF SHOWERS AND THUNDERSTORMS WILL
DIMINISH. EXPECT PATCHY MVFR FOG OVERNIGHT. AIRPORT THAT GET RAIN
THIS AFTERNOON ALSO HAVE A BETTER CHANCE OF HAVING FOG AFTER
MIDNIGHT. SIMILAR TO SATURDAY MORNING FOG WILL BE SHALLOW AND WILL
DISSIPATE BY 14Z/10AM SUNDAY.

COLD FRONT WILL TRAIL ACROSS THE OHIO VALLEY ON SUNDAY. THIS WILL
TURN SURFACE AND LOW LEVEL WINDS TO THE SOUTHEAST. NO OTHER UPPER
SUPPORT FOR SHOWERS AND THUNDERSTORMS SUNDAY. ONCE AGAIN STORMS
WILL DEVELOP BETWEEN 16Z-18Z/NOON-2PM BUT PROBABILITY IS NOT HIGH
ENOUGH IN THAT TIME FRAME TO INCLUDE IN THE TAFS.

EXTENDED DISCUSSION...

THE SLOWLY APPROACHING FRONT WILL RESULT IN DEVELOPMENT OF MORE
WIDESPREAD CONVECTION INITIALLY ALONG THE BLUE RIDGE SUNDAY
AFTERNOON AND ACROSS MUCH OF THE WEST LATE IN THE DAY AS THE FRONT
APPROACHES. SOME OF THE CONVECTION MAY SPREAD EAST OF THE BLUE
RIDGE LATER IN THE AFTERNOON SO POTENTIAL FOR A LITTLE MORE IN THE
WAY OF PERIODIC SUB-VFR SUNDAY AFTERNOON/EVENING ESPCLY OVER THE
MOUNTAIN LOCATIONS.

THIS BOUNDARY SHOULD FINALLY SINK SOUTH INTO THE REGION BY MONDAY
RESULTING IN WIDESPREAD CONVECTION ESPCLY BLUE RIDGE EAST...WITH
ADDITIONAL ROUNDS OF SHRA/TSRA INTO AT LEAST MONDAY NIGHT BEFORE
THE BOUNDARY SINKS TO THE SOUTH. THIS SHOULD MAKE FOR MORE
FREQUENT PERIODS OF SUB-VFR FROM SUNDAY NIGHT INTO TUESDAY WITH
LOWER CIGS/VSBY REDUCTIONS DUE TO SHOWERS/STORMS DURING THE
DAY...AND IN FOG OVERNIGHT INTO THE EARLY MORNING HOURS EACH DAY.
LOWER MVFR/IFR CIGS ARE LIKELY BEHIND THE FRONT INTO THURSDAY WITH
EASTERLY FLOW AND WEDGING IN PLACE RESULTING IN MVFR CEILINGS.

&&

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

&&

$$
SYNOPSIS...AMS/JH
NEAR TERM...JH
SHORT TERM...PH
LONG TERM...DS
AVIATION...AMS/JH/WERT


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