Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 221027
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
627 AM EDT TUE APR 22 2014

.SYNOPSIS...
COLD FRONT CROSSES TODAY WITH SHOWERS. HIGH PRESSURE AND COOLER
WEDNESDAY. DRY WARM FRONT THURSDAY. ANOTHER WEAK COLD FRONT CROSSES
FRIDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
615 AM UPDATE...
SCT SHRA MOVING ALONG AND E OF OH RIVER AS OF 10Z WITH FRONT STILL
HANGING BACK INTO W OH. ADJUSTED HOURLY POPS TO REFLECT CURRENT
RADAR TRENDS FOR THIS MORNING. ONCE THIS PREFRONTAL ACTION PUSHES
E...WILL LOOK FOR SCT DEVELOPMENT ALONG SURFACE FRONT AS IT
CROSSES TODAY.

PREVIOUS DISCUSSION BELOW...
FORECAST THINKING REMAINS ON TRACK...BY AND LARGE. -SHRA BREAKING
OUT ACROSS KY AND E OH AND THIS TREND WILL CONTINUE INTO EARLY
MORNING HOURS. MUCH OF THIS WILL REMAIN ON THE LIGHT SIDE AS IT
SLIDES E INTO CWA AS S/W TROF CROSSES. SURFACE FRONT STILL WELL
BACK TO THE W...WILL MARCH THRU TODAY WITH BAND OF SHRA AND
POSSIBLE THUNDER...WITH TIMING GENERALLY ON TRACK FROM PREVIOUS
FORECASTS. EXODUS OF POST FRONTAL LOW LEVEL MOISTURE WILL LAG A
FEW HOURS BEHIND SURFACE FRONT. NAM MUCH MORE BULLISH ON KEEPING
CLOUDS BEHIND...ESSENTIALLY TRAPPED BENEATH DEVELOPING SUBSIDENCE
INVERSION AS CAA BEGINS. NOT SURE HOW MUCH OF THIS TO BUY WITH
REMAINDER OF MODELS CLEARING THINGS OUT NICELY LATE THIS AFTERNOON
AND EVENING.

CAA WILL COMMENCE IN EARNEST TONIGHT WITH SOME STRATUS FIGURED IN
THE THE N MOUNTAINS PERHAPS EXTENDING W INTO N WV LOWLANDS. H85
TEMPS WILL BOTTOM OUT NEAR -2C BY 12Z WEDNESDAY ON STIFF NW WINDS
JUST OFF THE DECK. AS SUCH...KEEP A GOOD PUFF GOING OVERNIGHT
ACROSS THE N WITH GUSTS 15 TO 20 KTS AND UP TO 40 KTS ON THE
HIGHEST RIDGES IN THE N MOUNTAINS. FURTHER SW ACROSS S WV/TRI
STATE/NE KY...GRADIENT TRIES TO RELAX LATE FOR A FROST THREAT IN
THE SHELTERED VALLEYS AND HOLLOWS. ELECTED TO KEEP FROST OUT OF
THE WX GRIDS ATTM THOUGH...DUE TO SOME UNCERTAINTY ON MAGNITUDE
OF BL AND SURFACE WINDS ACROSS THOSE LOCATIONS.

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
HIGH PRESSURE WILL BE IN CONTROL OF THE WEATHER ON WEDNESDAY. BASED
ON 850 MB TEMPERATURES AND A NORTHERLY WIND FLOW...WENT A BIT BELOW
MOS GUIDANCE FOR HIGH TEMPERATURES.

GOOD RADIATION CONDITIONS FOR PART OF WEDNESDAY NIGHT...BUT THEN
SOME CLOUDS FROM THE WARM FRONT ARRIVE...MAINLY IN THE SOUTHWEST.
WILL GO ON THE LOWER SIDE OF MOS GUIDANCE IN THE NORTH WHERE MODEL
DEW POINTS AND GOOD RADIATION SHOULD ALLOW TEMPERATURES TO GET NEAR
OR BELOW FREEZING. MAY NEED TO HOIST A FREEZE WATCH EVENTUALLY...BUT
WITH WARM FRONT CLOUDS APPROACHING...A BIT IFFY RIGHT NOW. IN THE
SOUTHWEST WHERE WARM FRONTAL CLOUDS ARE MOST LIKELY...WILL GO TOWARD
THE WARMER SIDE OF MOS.

THE WARM FRONT PUSHES THROUGH ON THURSDAY...BUT MODELS INDICATING
THAT DRY LOWER LEVELS SHOULD PREVENT PRECIPITATION. WILL CONTINUE
DRY FOR NOW...BUT MAY EVENTUALLY NEED TO ADD SOME SPRINKLES.

ECMWF AND GFS ARE VERY SIMILAR ON COLD FRONT LATE THURSDAY NIGHT
INTO FRIDAY...WITH NAM HAVING JUST SLIGHTLY DIFFERENT TIMING. WITH
FAIRLY GOOD AGREEMENT BETWEEN MODELS...WILL TIGHTEN POP GRADIENT
CONSIDERABLY...AND REMOVE POPS BEHIND THE FRONT FRIDAY AFTERNOON AND
FRIDAY NIGHT.

&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
A QUICK WARM UP THURSDAY NIGHT AND FRIDAY AHEAD OF AN APPROACHING
COLD FRONT.

MODELS...ECMWF/GFS CONTINUE IN GOOD AGREEMENT WITH THE TIMING AND
STRENGTH MAINTAINING CONSISTENCY DURING THE PAST FEW
DAYS. BOTH MODELS HAVE SOME CONVECTION AHEAD OF THE FRONT REACHING
SOUTHEAST OH BY 09Z FRIDAY. SHOWERS OR STORMS WILL SPREAD EAST
INTO FRIDAY NIGHT. INTRODUCED LIKELY POPS WITH FRIDAYS COLD FRONT.

MODELS SUGGEST A SECONDARY FRONT SWEEPING ACROSS MAINLY THE NORTHERN
SECTIONS FRIDAY NIGHT INTO EARLY SATURDAY.

THIS TIMING IS NOT DURING THE PEAK DIURNAL HEATING UNDER CUTTING
THUNDERSTORM PROBABILITY. MODELS CONTINUE TO SHOW HIGH DEEP
LAYERED SHEAR AS WITH MOST COLD FRONTS. BUT TOO FAR OUT TO TRUST
THERMODYNAMIC PARAMETERS. KEPT HPC DEWPOINTS AND TEMPERATURES
THROUGH THE PERIOD.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
12Z TUESDAY THROUGH 12Z WEDNESDAY...

-SHRA ACROSS WV WILL SLIDE E INTO MOUNTAINS AROUND 12Z BEFORE
EXITING SHORTLY AFTER. GENERALLY VFR CONDITIONS BUT SOME MVFR VSBY
RESTRICTIONS IN THE MORE ROBUST SHRA.

SHRA BECOME MORE ISOLATED IN NATURE AFTER 15Z BEFORE PICKING BACK
UP AGAIN ALONG A DEVELOPING FRONTAL BAND OF SHRA AND PERHAPS A
RUMBLE OF THUNDER. HAVE SOME LOW END VFR CIGS AND 5 TO 6SM VSBY ALONG
THIS AS IT CROSSES TODAY. SOME QUESTION ON HOW FAST CLEARING
OCCURS POST FRONTAL THOUGH. NONETHELESS...CAA THIS EVE SHOULD
ALLOW SOME MVFR STRATUS TO DEVELOP ACROSS THE N MOUNTAINS TO
INCLUDE KEKN. WINDS WILL REMAIN GUSTY BEHIND THE FRONT OUT OF
NW...ON THE ORDER OF 15 TO 20 KTS WITH HIGHER GUSTS ON THE HIGHER
RIDGES IN THE N MOUNTAINS. THIS THEME WILL CONTINUE TONIGHT ACROSS
THE N WV LOWLANDS AND THE N MOUNTAINS AS WINDS TRY TO SLACKEN LATE
ACROSS NE KY/S WV.

FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 12Z WEDNESDAY...

FORECAST CONFIDENCE: MEDIUM.

ALTERNATE SCENARIOS: MINOR TIMING DIFFERENCES MAY SHOW UP WITH
FRONT AND ASSOCIATED SHRA. EXTENT OF POST FRONTAL STRATUS IN
QUESTION 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       11   12   13   14   15   16   17   18   19   20   21   22
EDT 1HRLY       07   08   09   10   11   12   13   14   15   16   17   18
CRW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
HTS CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
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    H    H    H
PKB CONSISTENCY  H    M    H    H    H    H    H    H    H    H    H    H
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H

AFTER 12Z WEDNESDAY...
NO IFR CONDITIONS EXPECTED.

&&

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

&&

$$
SYNOPSIS...ARJ/RPY/30
NEAR TERM...30
SHORT TERM...RPY
LONG TERM...ARJ
AVIATION...30








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