Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 020539
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
139 AM EDT WED SEP 2 2015

.SYNOPSIS...
HIGH PRESSURE IN CONTROL THIS WEEK. DIURNAL HEATING COULD PRODUCE
ISOLATED AFTERNOON SHOWERS OR STORMS THROUGH THE WEEK. SOUTHEAST
FLOW MAY INCREASE FRIDAY NIGHT INTO SATURDAY.

&&

.NEAR TERM /THROUGH TODAY/...
PREVIOUS FORECAST ON TRACK. NO CHANGES NECESSARY.

PREVIOUS DISCUSSION BELOW...
715 PM UPDATE...TWEAKED SKY GRIDS BASED ON CURRENT TRENDS.
OTHERWISE...NO CHANGES WERE NECESSARY.

PREVIOUS DISCUSSION FOLLOWS...
DIURNAL HEATING SHOWERS AND STORMS TO REMAIN CONCENTRATED IN
SOUTHERN OHIO AND IN THE HIGHER ELEVATIONS TO THE EAST. THESE WILL
BE SLOW MOVING...BUT GENERALLY SMALL IN TERMS OF SURFACE AREA AND
HAVE TRENDED TOWARDS A SOUTHWARD DRIFT.

UPPER LEVEL LOW CURRENTLY OVER INDIANA WILL DRIFT INTO THE CENTRAL
APPALACHIANS TONIGHT...WITH LITTLE MOISTURE TO WORK WITH. THIS
MAKES THE CLOUD COVER FORECAST TRICKY...AND SUBSEQUENT VALLEY FOG
FORMATION. AT THE SURFACE...HIGH PRESSURE REMAINS IN CONTROL.

WEAK DISTURBANCES ALOFT KEEP THE LOW CHANCES FOR SHOWERS AND
THUNDERSTORMS GOING THROUGH WEDNESDAY.

GROUND HAS HAD SOME TIME TO DRY OUT...WHICH KEEPS THE POTENTIAL
FOR 90 DEGREE TEMPERATURES GOING FOR THE LOWLANDS. WILL KEEP IT IN
THE UPPER 80S RANGE GIVEN THE EXPECTED CLOUD COVER...FIGURING
INSOLATION IS A NECESSITY GIVEN THE TIME OF YEAR AS WE HEAD
TOWARDS THE EQUINOX.

&&

.SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/...
THE WEAKLY FORCED PATTERN IS RELUCTANT TO CHANGE...BUT THERE ARE
SIGNS OF AN INCREASING SOUTHEAST LOW LEVEL FLOW DEVELOPING FRIDAY
NIGHT AND CONTINUING INTO SATURDAY.

THE WEAK MID LEVEL...500 MB...VORT MAX THAT WAS IN INDIANA TUESDAY
AFTERNOON...SHOULD BE EXITING TO THE EAST OF THE MOUNTAINS AT THE
START OF THIS SHORT TERM.  ALL 12Z MODEL RUNS SHOW ANOTHER 500 MB
VORT MAX IN THE WESTERN GREAT LAKES NEAR WISCONSIN AT THAT
TIME/00Z THURSDAY. IN SUCH A WEAK FLOW...WITH 500 MB HEIGHTS
BUILDING OVER THE MID ATLANTIC...HARD TO DETERMINE IF THAT WESTERN
GREAT LAKE VORT MAX WILL ACTUALLY REACH OUR VICINITY THURSDAY NIGHT
OR FRIDAY.

EVEN THE 12Z GFS SHOWING AFTERNOON HEATING RESULTS IN AN EQUILIBRIUM
LEVEL BETWEEN 35 AND 40 THSD...SO WILL BE MORE LIBERAL WITH THE 20
AND 30 POPS USING AREAL COVERAGE WITH THE SLOW MOVING CONVECTION.

WITH THAT PREVIOUSLY MENTIONED SE FLOW...WILL LEAVE POPS THROUGH
FRIDAY NIGHT ALONG OUR MOUNTAIN UPSLOPE AREAS...WITH MORE CLOUDS.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
12Z GFS SOLUTION WAS FASTER THAN THE 12Z ECMWF WITH A SHORT WAVE
AND ASSOCIATED SURFACE FRONT TRYING TO DENT THE RIDGE BY
DAY 7/TUESDAY. AT THIS DISTANCE IN TIME...WILL NOT JUMP ON THE
FASTER SOLUTION BUT STILL HAVE CHANCE POPS IN SE OHIO AND
NORTHERN WV TUESDAY AFTERNOON AND EVENING.

TRIED TO HOLD MAXIMUM TEMPERATURE DOWN A BIT FOR DAY 4/SATURDAY
IN THE SOUTHEAST UPSLOPE AREAS...OTHERWISE NO MAJOR CHANGES.

&&

.AVIATION /05Z WEDNESDAY THROUGH SUNDAY/...
SFC HIGH PRESSURE REMAINS IN CONTROL WITH DRY WEATHER. UPPER
CLOUDS ASSOCIATED WITH AN UPPER LOW/TROUGH WILL MOVE EAST OVER
THE AREA SPREADING CLEAR SKIES FROM WEST TO EAST OVERNIGHT.
CLEARING WILL CREATE RADIATIONAL COOLING. TOGETHER WITH WARM RIVER
WATERS...DENSE RIVER VALLEY FOG IS EXPECTED OVERNIGHT. HTS ALREADY
EXPERIENCING MVFR VISIBILITIES. EXPECT MOST SITES TO DETERIORATE
FROM MVFR TO IFR/LIFR DURING THE 09-12Z PERIOD. ANY FOG WILL
QUICKLY DISSIPATE BY 12-13Z FOR WIDESPREAD VFR CONDITIONS ON
WEDNESDAY.

DIURNAL HEATING...WITH A LITTLE INFLUENCE FROM THE UPPER LOW WILL
PROMOTE THE FORMATIONS OF AFTERNOON SHOWERS AND STORMS MAINLY OVER
THE HIGHER ELEVATIONS. EXPECT BRIEF PERIODS OF MVFR/IFR ALONG THE
STRONGER STORMS. DIFFICULT TO PREDICT IF RAINFALL WILL HIT AN
AIRPORT...SO DID NOT INCLUDE PCPN ON TAFS.

EXPECT IFR RIVER VALLEY DENSE FOG ONCE AGAIN OVERNIGHT WEDNESDAY
TOWARDS THURSDAY MORNING.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z THURSDAY...

FORECAST CONFIDENCE: HIGH.

ALTERNATE SCENARIOS: TIMING AND DEPTH OF FOG TONIGHT MAY VARY FROM
FORECAST.

EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH:   TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW:    TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.

DATE                                             WED 09/02/15
UTC 1HRLY       03   04   05   06   07   08   09   10   11   12   13   14
EDT 1HRLY       23   00   01   02   03   04   05   06   07   08   09   10
CRW CONSISTENCY  H    H    H    M    M    L    L    L    L    M    H    H
HTS CONSISTENCY  H    H    H    M    M    L    L    L    L    M    H    H
BKW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
EKN CONSISTENCY  H    H    H    M    M    L    L    L    L    M    H    H
PKB CONSISTENCY  H    H    H    M    M    M    M    L    L    M    H    H
CKB CONSISTENCY  H    H    H    M    M    L    L    L    L    M    H    H

AFTER 06Z THURSDAY...
IFR POSSIBLE IN DENSE RIVER VALLEY FOG DURING EARLY MORNINGS.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.

&&

$$
SYNOPSIS...FB/ARJ/30/26
NEAR TERM...ARJ/SL/26
SHORT TERM...KTB/JW
LONG TERM...FB/KTB
AVIATION...ARJ



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