Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 171833
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
233 PM EDT WED SEP 17 2014

.SYNOPSIS...
HIGH PRESSURE THROUGH THE WEEKEND. COLD FRONT POSSIBLY TOWARD THE
END OF THE WEEKEND.

&&

.NEAR TERM /THROUGH THURSDAY/...
LAST OF THE STRATUS OVER THE CENTRAL WEST VIRGINIA LOWLANDS HAS NOW
ERODED WITH JUST ENOUGH TIME LEFT FOR A LITTLE DIURNAL CUMULUS IN
THIS AREA. LOOKING AT A CLEAR EVENING FOR THE MOST PART...WITH THE
EXCEPTION OF THE EASTERN SLOPES OF THE MOUNTAINS.

NAM AND GFS HAVE A WEAKLY DISCERNIBLE TROUGH AXIS IN THE NORTHWEST
FLOW ALOFT THAT SHOULD BRING PASSING CLOUD COVER IN A MID LEVEL DECK
TONIGHT. IN AN OTHERWISE SOLID SET UP FOR RIVER VALLEY FOG
AGAIN...THIS MAY HAVE AN EFFECT ON THAT FORMATION AS WE GO DEEPER
INTO THE OVERNIGHT. THINK RIGHT NOW THE COVERAGE WILL BE OF A
SCATTERED TO BROKEN NATURE...AND WITH ALL THINGS BEING EQUAL...STILL
THINK FOG IS A GOOD BET. ANYTHING THICKER/BETTER COVERAGE THAN THIS
FORECAST WILL LIKELY THWART THE VALLEY FOG TO SOME EXTENT.

OPTED OUT OF THE DRIZZLE ON THOSE EASTERN SLOPES MENTIONED ABOVE FOR
THE REST OF TODAY AND TONIGHT DESPITE THE LOW STRATUS IN PLACE
THERE.

FOR THURSDAY...EXPECTING PRESSURE RISES AS SURFACE HIGH PRESSURE
BUILDS IN OVER THE NORTHERN GREAT LAKES/NORTHERN ONTARIO.

OVERNIGHT...TRENDED THE TEMPERATURES UPWARDS JUST A TOUCH FROM THE
PREVIOUS NIGHT...AND SHOULD ALSO SEE LOW 70S FOR THE LOWLANDS ON
THURSDAY.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
VERY QUIET PATTERN WITH SURFACE RIDGE CENTERED OVER QUEBEC THURSDAY
NIGHT AND VERY BROAD UPPER LEVEL TROUGHING ACROSS THE EASTERN HALF
OF NORTH AMERICA.  ON FRIDAY THE SURFACE RIDGE WILL SHIFT EAST TO BE
CENTERED JUST OFFSHORE OF MAINE WHILE AN UPPER LEVEL LOW FORMS OVER
THE SOUTHEASTERN US.  MODELS ARE SHOWING MOISTURE FROM THIS UPPER
LEVEL LOW CREEPING NORTH UP THE APPALACHIANS SO HAVE INCLUDED SLIGHT
CHANCE POPS IN THE MOUNTAINS. DRY WEATHER WILL PREVAIL FRIDAY NIGHT
AND SATURDAY AS UPPER LEVEL TO THE SOUTH GETS PUSHED EAST AND
OFFSHORE.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
USED WPC THINKING WITH SOME MINOR TWEAKS. COLD FRONT WILL PUSH
SOUTHEAST ON SUNDAY WITH HIGH PRESSURE TAKING CONTROL BY MONDAY.
THE HIGH SHOULD REMAIN IN CONTROL THROUGH THE REMAINDER OF THE
PERIOD.

WPC TEMPS LOOKED GOOD AND WERE GENERALLY USED.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
WEAK TROUGH AXIS ALOFT WILL GENERATE ENOUGH LIFT FOR SOME MID
LEVEL CLOUD FORMATION TONIGHT...WHICH SHOULD BE ENOUGH TO PLAY
HAVOC WITH THE AVIATION/FOG FORECAST. CLOUDS WILL INCREASE AFTER
03Z...BUT GUIDANCE NUMBERS DO NOT SEE ENOUGH THERE TO KEEP LIFR
CONDITIONS FROM FORMING. WITH NEARLY IDEAL CONDITIONS FOR RIVER
VALLEY FOG FORMATION OTHERWISE...A TUG OF WAR WILL ENSUE.

GIVEN THE QUICKNESS AND THICKNESS OF THE VALLEY FOG EARLIER THIS
MORNING UNDER SIMILAR CONDITIONS LESS THE AFOREMENTIONED PASSING
CLOUDS...WILL KEEP THE LIFR IN THE FORECAST FOR TONIGHT. THE RH
SIGNATURE IS NOT STRONG PER SE...AND IS BETTER SEEN ON THE NAM
BUFR SOUNDINGS ABOVE 7KFT. HOWEVER...THIS WEAK TROUGH AXIS IS
EVIDENT ON BOTH THE NAM AND THE GFS.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z THURSDAY...

FORECAST CONFIDENCE: MEDIUM.

ALTERNATE SCENARIOS: GOING WITH MEDIUM CONFIDENCE GIVEN THE
THICKNESS AND COVERAGE OF THE MID LEVEL DECK TONIGHT.

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.

UTC 1HRLY       18   19   20   21   22   23   00   01   02   03   04   05
EDT 1HRLY       14   15   16   17   18   19   20   21   22   23   00   01
CRW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    L    L
HTS CONSISTENCY  H    H    H    H    H    H    H    H    H    H    M    M
BKW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
EKN CONSISTENCY  H    H    H    H    H    H    H    H    H    M    L    L
PKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    M    L
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    M    M

AFTER 18Z THURSDAY...
IFR RIVER VALLEY FOG EXPECTED DURING THE PREDAWN HOURS FRIDAY.

&&

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

&&

$$
SYNOPSIS...26/JR
NEAR TERM...26
SHORT TERM...JR
LONG TERM...JSH
AVIATION...26







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