Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 280008
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
808 PM EDT THU AUG 27 2015

.SYNOPSIS...
HIGH PRESSURE IN VICINITY OVERNIGHT. WARMING TREND FRIDAY INTO
SATURDAY. MORE HUMID SUNDAY INTO EARLY NEXT WEEK...WITH THE
POSSIBILITY OF SHOWERS RETURNING...ESPECIALLY ON SUNDAY.

&&

.NEAR TERM /THROUGH FRIDAY/...
800 PM UPDATE...
STRATOCU MORE OF A DIURNAL NATURE COMPARED WITH LAST EVENING...AND
THUS LESS TENACIOUS. WITH THE CLOUDS DISSIPATING...THE FCST IS ON
TRACK.

PREV DISCN...
AT 18Z...STRATOCUMULUS AROUND 4 TO 5 THSD FT AGL...UNDER THE
SUBSIDENCE INVERSION LOCATED AT 6 TO 10 THSD FT AGL. STRATOCU IS
MOST WIDESPREAD FROM PA SW...INTO OHIO...LEAST IN SOUTHERN WV AND
SOUTHWEST VIRGINIA. CLOUDS SHOULD CONTINUE TO THIN AND FLATTEN
DURING THE 18Z THU TO 00Z FRIDAY TIME FRAME.

NO REASON TO CHANGE THE RIVER VALLEY FOG FORMING LATE...AFTER 06Z.
FIRST IN THE COOLER MOUNTAIN VALLEYS AROUND EKN ON DOWN INTO THE
UPPER GUYANDOTTE... UPPER TUG AND UPPER BIG SANDY...THEN LATER IN
THE LOWER KANAWHA VALLEY AND OHIO VALLEY.

THERE IS THE DILEMMA OVERNIGHT...ENOUGH MOISTURE LINGERS AROUND 5
THSD FT AGL...YOU CAN NOT RULE OUT SOME PATCHES OF DEAD
STRATOCUMULUS LINGERING OR REFORMING. THAT WOULD DISRUPT THE VALLEY
FOG FORMATION. ALSO SOME SE FLOW STIRS OVERNIGHT ON MOUNTAIN RIDGES
AND SOUTHERN PLATEAU AROUND BKW.

FOR CONSISTENCY...WILL LEAVE THE 15 TO 20 POP NEAR SNOWSHOE LATE
FRIDAY AFTERNOON...FOR A MOUNTAIN THERMAL IN WEAK FLOW...BUT COLUMN
APPEARS RELATIVELY DRY.

850 TEMPS WARM ABOUT 4 C BETWEEN THIS AFTERNOON TO FRIDAY AFTERNOON.
NO MAJOR CHANGES TO MAXIMUM TEMPERATURE FORECAST FOR FRIDAY.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
UPPER RIDGE AND GENERAL SUBSIDENCE HOLDS OVER THE AREA. MOST
AREAS WILL REMAIN RAIN FREE DESPITE INCREASING HEAT AND HUMIDITY.
THE TARGET AREA FOR ANY AFTERNOON SHOWER WILL BE THE ELEVATED HEAT
SOURCE IN THE MOUNTAINS. TEMPERATURES WILL APPROACH 90 DEGREES
SATURDAY.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
THE MAIN CHANGE TO THIS PERIOD WILL BE A STRONGER UPPER
DISTURBANCE FROM THE LOWER MISSISSIPPI VALLEY LIFTING NORTHEAST
ACROSS THE AREA SUNDAY AND SUNDAY NIGHT...ENHANCING THE POTENTIAL
FOR SHOWERS AREA WIDE IN THE VERY WARM AND HUMID AIRMASS IN PLACE.

THIS PERIOD STILL SHOWS A BERMUDA HIGH OVER THE WESTERN ATLANTIC
EXPANDING WESTWARD. THIS EVOLVES INTO A WELL DEFINED UPPER RIDGE
HOLDING OVER THE WESTERN U.S. AND A BUILDING UPPER RIDGE OVER THE
WESTERN ATLANTIC...LEAVING A WEAK UPPER TROUGH BETWEEN THESE UPPER
RIDGES OVER THE EASTERN U.S.. WITH THE SURFACE HIGH CENTER ALSO
BUILDING OFF THE SOUTHEAST COAST...MOISTURE AND HEAT WILL CONTINUE
TO INCREASE ON A SOUTHERLY FLOW REGIME THIS WEEKEND INTO EARLY
NEXT WEEK. THIS WILL GIVE RISE TO A CHANCE OF MAINLY A DIURNAL
SHOWER OR THUNDERSTORM...ESPECIALLY IN THE MOUNTAINS...AND
ESPECIALLY SUNDAY AS A VERY WEAK UPPER DISTURBANCE LIFTS NORTHEAST
FROM THE GULF STATES. TEMPERATURES WILL GENERALLY APPROACH 90
DEGREES EACH DAY WITH RATHER HUMID CONDITIONS.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
STRATOCU MORE OF A DIURNAL NATURE COMPARED WITH LAST EVENING...AND
THUS LESS TENACIOUS. WITH THE CLOUDS DISSIPATING...THERE IS NO
REASON TO CHANGE THE RIVER VALLEY FOG FCST...OTHER THAN HASTENING
THE TIMING BACK TO AROUND 06Z. THE FOG WILL FORM FIRST IN THE
COOLER MOUNTAIN VALLEYS AROUND EKN ON DOWN INTO THE UPPER
GUYANDOTTE... UPPER TUG AND UPPER BIG SANDY...THEN LATER IN THE
LOWER KANAWHA AND MIDDLE OHIO VALLEYS...INCLUDING CRW...PKB...AND
HTS.

STILL CANNOT RULE OUT MOISTURE LINGERING AROUND 5 THSD FT
AGL...RESULTING IN PATCHES OF DEAD STRATOCU OVER THE MOUNTAINS.
THAT...ALONG WITH A LIGHT S FLOW STIRRING ON MOUNTAIN RIDGES AND
SOUTHERN PLATEAU AROUND BKW...COULD DISRUPT THE VALLEY FOG
FORMATION. A REPEAT OF THE DENSE FOG AT BKW LAST NT IS NOT
EXPECTED OVERNIGHT TONIGHT.

LIGHT AND VARIABLE SFC FLOW...NEARLY CALM OVERNIGHT...WILL TREND
FROM NE TO SE ON FRI. LIGHT E FLOW ALOFT WILL SHIFT TO S
OVERNIGHT AND BE LIGHT S TO SW ON FRI.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SATURDAY...

FORECAST CONFIDENCE: MEDIUM TO HIGH.

ALTERNATE SCENARIOS: TIMING OF DENSE RIVER VALLEY FOG 06Z TO 13Z
FRI COULD VARY.

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                                                            FRI 08/28/15
UTC 1HRLY       00   01   02   03   04   05   06   07   08   09   10   11
EDT 1HRLY       20   21   22   23   00   01   02   03   04   05   06   07
CRW CONSISTENCY  H    H    H    H    H    M    M    M    L    L    L    L
HTS CONSISTENCY  H    H    H    H    H    M    L    L    L    L    L    L
BKW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
EKN CONSISTENCY  H    H    H    H    H    H    M    M    L    L    L    L
PKB CONSISTENCY  H    H    H    H    H    H    H    H    M    L    L    L
CKB CONSISTENCY  H    H    H    H    H    H    H    H    M    L    H    H

AFTER 00Z SATURDAY...
IFR IN VALLEY FOG POSSIBLE 06Z TO 13Z SATURDAY. LESS LIKELY
SUNDAY MORNING.

&&

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

&&

$$
SYNOPSIS...KTB/TRM/JMV
NEAR TERM...KTB/TRM
SHORT TERM...JMV
LONG TERM...JMV
AVIATION...KTB/TRM



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