Area Forecast Discussion
Issued by NWS Blacksburg, VA

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000
FXUS61 KRNK 011427
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1027 AM EDT WED APR 1 2015

.SYNOPSIS...
HIGH PRESSURE WILL SHIFT ACROSS THE FORECAST AREA TODAY...
MAINTAINING MOSTLY CLEAR SKIES AND LIGHT WINDS. A WARM FRONT WILL
PUSH NORTH THROUGH THE OHIO VALLEY THURSDAY...SUPPORTING SPOTTY
SHOWER ACTIVITY MAINLY ACROSS THE MOUNTAINS. A COLD FRONT WILL
PASS ACROSS THE AREA ON SATURDAY MORNING...BRINGING WIDESPREAD
RAINFALL TO THE MID ATLANTIC...FOLLOWED BY DRYING DURING THE
AFTERNOON AS HIGH PRESSURE RETURNS FROM THE WEST.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1000 AM EDT WEDNESDAY...

1022 MB SURFACE HIGH PRESSURE WAS CENTERED OVER WEST VIRGINIA.
CLOCKWISE FLOW AROUND THE HIGH WAS RESULTING IN A NORTHEAST BREEZE
ACROSS THE PIEDMONT...AND A LIGHT NORTHWEST BREEZE ACROSS THE
MOUNTAIN RIDGES. AS THE HIGH SETTLES ACROSS THE AREA THIS
AFTERNOON LOOK FOR WINDS TO BECOME LIGHT AND VARIABLE.

EXPECT ABUNDANT SUNSHINE THIS AFTERNOON AS HIGH PRESSURE PASSES
OVERHEAD ON ITS WAY TO THE COAST THIS EVENING. AFTERNOON
HIGHS TEMPERATURES SHOULD EASILY REBOUND INTO THE LOW 60S ACROSS
THE MOUNTAINS...AND THE MID/UPPER 60S EAST OF THE BLUE RIDGE.
DEWPOINTS IN THE 20S/30S WILL PROMOTE HUMIDITY VALUES IN THE
TEENS THIS AFTERNOON.

WINDS WILL BEGIN TO SHIFT SOUTH SOUTHEASTERLY THIS EVENING AS THE
CENTER OF HIGH PRESSURE MOVES OVER THE OUTER BANKS. SKIES WILL
REMAIN MOSTLY CLEAR THROUGH THE NIGHT...ASIDE FROM PASSING HIGH
CLOUDS. HOWEVER...MAY SEE LOW CLOUDS DEVELOP OVER THE NORTH CAROLINA
HIGH COUNTRY TOWARD DAWN THURSDAY WITH MOIST AIR BEGINNING ITS
RETURN NORTHWARD AS SOUTHWESTERLY WINDFLOW OFF THE SURFACE
INCREASES. WEDNESDAY NIGHT WILL BE ONE OF THOSE NIGHTS WHERE
WARMER TEMPERATURES WILL BE FOUND ALONG THE HIGHER RIDGES...AND
OVERNIGHT LOWS WILL OCCUR EARLY IN THE NIGHT...WITH TEMPERATURES
MODESTLY WARMING AGAIN THEREAFTER.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY NIGHT/...
AS OF 400 AM EDT WEDNESDAY...

THE MAJORITY OF THIS PERIOD WILL FOCUS ON A BAROCLINIC ZONE/FRONTAL
BOUNDARY THAT WILL SLOWLY SHIFT SOUTHEASTWARD THROUGH THE REGION
OVER THE THREE DAY PERIOD. A SERIES OF SHORT WAVES EMBEDDED WITHIN A
QUASI-ZONAL FLOW WILL ESSENTIALLY DICTATE THE SOUTHWARD MOVEMENT OF
THE FRONT. DESPITE THE CHAOTIC PATTERN...THE MODELS ARE IN GENERAL
AGREEMENT ON THE PATTERN...BUT DO DIFFER SOMEWHAT ON THE AMOUNTS OF
RAINFALL AND THE PLACEMENT OF THE HEAVIEST RAINFALL.

BEGINNING THURSDAY AN INITIAL SHORT WAVE...ASSOCIATED WITH DEEP LOW
PRESSURE MOVING THROUGH THE GREAT LAKES...WILL TRACK FROM THE
CENTRAL PLAINS INTO THE NORTHERN MID-ATLANTIC REGION AND SHEAR OUT.
THIS WILL ALLOW THE FIRST SOUTHWARD PUSH OF THE FRONT TO NEAR THE
PA/MD/WV BORDER. FURTHER SOUTHWARD MOVEMENT OF THE FRONT WILL AWAIT
THE NEXT IMPULSE EVIDENT ACROSS THE INTERMOUNTAIN WEST AT THIS TIME.
SFC HIGH PRESSURE OFF THE MID-ATLANTIC COAST WILL ALLOW FOR A GOOD
FETCH OF GULF MOISTURE INTO THE REGION. HOWEVER...WITH THE MAIN
DYNAMICS REMOVED TO THE NORTH...FEEL THAT MOST IF NOT ALL MEANINGFUL
RAINFALL WILL REMAIN NORTH-WEST OF THE CWA THU. THUS...HAVE CONFINED
POPS TO AREAS ALONG-WEST OF THE ALLEGHANY FRONT...NAMELY LWB-BLF-TNB
WESTWARD.

FOR FRI...THE AFOREMENTIONED SECONDARY DISTURBANCE WILL TRACK
THROUGH THE BAROCLINIC ZONE INTO WEST VIRGINIA BY FRI AFTERNOON.
MEANWHILE...THE NORTHERN STREAM WILL AMPLIFY ACROSS THE GREAT
LAKES/NORTHEASTERN U.S. IN RESPONSE TO AN UPSTREAM STRONGER SHORT
WAVE. THIS WILL ALLOW THE FRONT TO BEGIN A BETTER PUSH SOUTHWARD AND
EASTWARD LATE FRI/FRI NIGHT. NONETHELESS...THE BEST DYNAMICS
REMAIN NORTH OF THE REGION. WILL CARRY LIKELY TO CATEGORICAL POPS
FROM NW- SE LATE FRI/FRI NIGHT IN ASSOCIATION WITH THE FRONTAL
BOUNDARY.

THE NEXT ISSUE TO ADDRESS IS THE THUNDER POTENTIAL. SPC HAS
OUTLOOKED THE FAR WESTERN PORTION OF THE CWA FOR THUNDER THU
AFTERNOON...AND THE ENTIRE CWA FOR FRI...WITH A MARGINAL RISK FOR
SEVERE MAINLY WEST OF I-77 FRIDAY. INSTABILITY IS MEAGER AND WILL
LARGELY DEPEND ON HEATING FRI...WHICH WILL BE EAST OF THE BLUE RIDGE
WHERE DYNAMICS AR WEAKEST AND THE FRONT ARRIVES DURING THE COOLER
OVERNIGHT HOURS. GFS CAPES PEAK IN THE 400-800 RANGE FRI
AFTERNOON...BUT ARE NOTABLY LESS ON THE OTHER MODELS. THERE IS
HOWEVER A DECENT 850MB LLJ OF 40-50KTS TRACKING ACROSS THE REGION
FRI EVENING WITH NOTABLE LOW-LEVEL SHEAR. THIS MAY SUPPORT SOME
ISOLATED SEVERE...BUT THE THREAT APPEARS MARGINAL AT BEST OTHERWISE.

SIGNIFICANT RAINFALL THAT WOULD RESULT IN ANY HYDROLOGICAL CONCERNS
SHOULD REMAIN WEST OF THE CWA WHERE THE FRONT/BAROCLINIC ZONE WILL
BE HUNG UP THU-EARLY FRI. STILL SHOWING ONLY 1 INCH OR LESS IN THE
WESTERN COUNTIES OF THE CWA TO LESS THAN 1/2 INCH EAST OF THE BLUE
RIDGE. HOWEVER...LOCALIZED THUNDERSTORMS MAY RESULT IN HEAVIER
TOTALS AT ANY GIVEN LOCATION. COULD SEE A SITUATION FRI EVENING
SIMILAR TO WHAT WE SAW AT THE LAST MINUTE ON MARCH 26TH.

FOR SATURDAY...MUCH COOLER TEMPERATURES ARE IN ORDER FOR THE REGION
AS 850MB TEMPS FALL FROM +12C READINGS FRI TO AROUND -4C EARLY SAT.
THE COMBINATION OF LINGERING POST FRONTAL PRECIPITATION AND 850MB
TEMPS DROPPING BELOW 0C ACROSS THE ALLEGHANYS COULD BRING SOME
-SHSN TO THAT REGION BEFORE THE PRECIPITATION SHIELD EXITS THE
AREA SATURDAY MORNING. WINDS WILL ALSO BE AN ISSUE SATURDAY
BEHIND THE FRONT. THE COOLER TEMPERATURES BEHIND THE FRONT WILL BE
BRIEF AND NOT NEARLY AS IMPRESSIVE AS WHAT WE SAW LAST WEEKEND
WITH THE POST SFC HIGH BUILDING EASTWARD FROM THE PLAINS INSTEAD
OF SOUTHEASTWARD FROM CENTRAL CANADA.

&&

.LONG TERM /SUNDAY THROUGH TUESDAY/...
AS OF 430 AM EDT WEDNESDAY...

HIGH PRESSURE WILL BUILD EASTWARD FROM THE CENTRAL U.S. FOR SUN. A
NORTHERN STREAM SHORT WAVE WILL PASS BY TO THE NORTH SUNDAY
AFTERNOON...BUT IT APPEARS ANY ASSOCIATED PRECIPITATION WILL
REMAIN NORTH OF THE CWA...AND EVEN THAT WILL BE MINIMAL AT BEST
BECAUSE OF LIMITED MOISTURE. THE UPPER FLOW REMAINS HIGH
PROGRESSIVE...HOWEVER. IN ADDITION...THERE WILL BE A TENDENCY
THROUGH THE PERIOD FOR EASTERN U.S. RIDGING AND WESTERN U.S.
TROUGHING THAT WILL KEEP A STEADY STREAM OF SHORT WAVES TRACKING
THROUGH THE FLOW ACROSS THE U.S. MON-WED APPEARS UNSETTLED AND WET...
FIRST FROM RETURNING WARM FRONTAL MOISTURE...A SERIES OF UPPER
SHORT WAVES...AND EVENTUALLY A COLD FRONT SLATED TO MOVE SOUTHWARD
THROUGH THE REGION LATE WEDNESDAY.

IT WILL START OFF ON THE COOL SIDE SUNDAY WITH A LIGHT FREEZE
POSSIBLE IN SOME AREAS. AGAIN...NOTHING LIKE WE SAW LAST WEEKEND
AS THIS AIR MASS DOES NOT HAVE ROOTS IN CANADA OR THE ARCTIC.
THEREAFTER...ESPECIALLY WITH A TENDENCY TOWARD RIDGING IN THE
EASTERN U.S...EXPECT SLIGHTLY ABOVE NORMAL TEMPERATURES UNTIL
FRONTAL PASSAGE WEDNESDAY.

&&

.AVIATION /14Z WEDNESDAY THROUGH SUNDAY/...
AS OF 730 AM EDT WEDNESDAY...

VFR CONDITIONS EXPECTED THROUGH THE TAF VALID PERIOD AS HIGH
PRESSURE DRIFTS ACROSS THE REGION. THE AIR MASS REMAINS BONE DRY
THROUGHOUT ALL LEVELS OF THE ATMOSPHERE AT THIS TIME...THUS SKC
AND UNLIMITED VISIBILITY EXPECTED THROUGH 00Z THU.
OVERNIGHT...HIGH-LEVEL MOISTURE WILL BEGIN TO SPREAD TOWARD THE
REGION FROM THE W/SW AS A GENERAL WARM ADVECTION PATTERN BEGINS IN
ADVANCE OF A SLOW MOVING FRONTAL BOUNDARY AND A SERIES OF UPPER
SHORT WAVES THAT WILL BRING WET WEATHER TO THE REGION IN THE WEST
LATE THU...AND ALL AREAS FRI/FRI NIGHT. WINDS WILL BE MUCH LIGHTER
TODAY AS HIGH PRESSURE SETTLES ACROSS THE REGION...STARTING OUT NW
WEST OF THE BLUE RIDGE AND NE EAST OF THE BLUE RIDGE AT SPEEDS OF
4-7KTS...BECOMING SE MOST AREAS DURING THE AFTERNOON...STILL ONLY
SPEEDS OF 4-7KTS...CONTINUING OVERNIGHT AT THESE SPEEDS OR LESS.

HIGH CONFIDENCE IN VFR CEILINGS/VISIBILITIES THROUGHOUT THE TAF
VALID PERIOD.
LOW TO MEDIUM CONFIDENCE IN WIND DIRECTION THROUGH THE TAF VALID
PERIOD.
HIGH CONFIDENCE IN WIND SPEED THROUGH THE TAF VALID PERIOD.

EXTENDED AVIATION FORECAST...
A SLOW MOVING COLD FRONT WILL MOVE ACROSS THE MIDWEST REGION ON
THURSDAY. THE FRONT WILL DRIFT THROUGH THE FORECAST AREA FRI-SAT...
SUPPORTING AN EXTENDED PERIOD OF SHOWERS AND EVEN A FEW
THUNDERSTORMS...ALONG WITH ASSOCIATED MVFR-IFR CIGS/VSBYS AT
TIMES. THE SUB-VFR CONDITIONS WILL IMPACT WESTERN AREAS LONGER
THAN EAST OF THE BLUE RIDGE. IMPROVING CONDITIONS APPEAR LIKELY
SATURDAY AS A STRONG COLD FRONT MOVES ACROSS THE AREA...FOLLOWED
BY HIGH PRESSURE THAT WILL BRING DRIER AIR IN FROM THE WEST ON
GUSTY NW WINDS SATURDAY AFTERNOON. HIGH PRESSURE IS EXPECTED OVER
THE AREA SUNDAY...SUPPORTING VFR CONDITIONS.

&&

.FIRE WEATHER...
...HUMIDITY MINIMUMS IN THE TEENS THIS AFTERNOON BUT ASSOCIATED
WITH MUCH LIGHTER WIND SPEEDS COMPARED TO YESTERDAY...

WIND SPEEDS WILL CONTINUE TO DECREASE TODAY AS HIGH PRESSURE
OVER OHIO PASSES OVERHEAD DURING THE AFTERNOON. AS HIGH PRESSURE
MOVES IN...NORTHERLY FLOW WILL GIVE WAY TO LIGHT AND VARIABLE WINDS
DURING THE AFTERNOON AND EARLY EVENING...FOLLOWED BY SOUTHEASTERLY
WINDFLOW DEVELOPING AFTER SUNSET. HIGH PRESSURE WILL ALSO MAINTAIN
DRY CONDITIONS AND ABUNDANT SUNSHINE...BOTH OF WHICH WILL ACT TO
DRIVE AFTERNOON RH VALUES BELOW 20 PERCENT MOST LOCATIONS...DESPITE
COOLER HIGH TEMPERATURES.

TODAY APPEARS TO BE THE BEST DAY FOR THE REMAINDER OF THE WEEK FOR
PRESCRIBED BURNING. SOUTHERLY WIND SPEEDS AND CLOUD COVER
WILL INCREASE AGAIN ON THURSDAY AS A COLD FRONT MOVES ACROSS THE
MIDWEST STATES. A STRONG COLD FRONT WILL BRING WETTING SHOWERS TO
THE AREA FRIDAY AND FRIDAY NIGHT...FOLLOWED BY GUSTY NORTHWEST
WINDS SATURDAY INTO SUNDAY MORNING.

&&

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

&&

$$
SYNOPSIS...NF
NEAR TERM...NF/PM
SHORT TERM...RAB
LONG TERM...PM/RAB
AVIATION...NF/RAB
FIRE WEATHER...PM



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