Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 300852
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
452 AM EDT THU OCT 30 2014

.SYNOPSIS...
HIGH PRESSURE TODAY. LOW PRESSURE WITH RAIN FRIDAY EVENING. COLDER
AIR AND THE LOW SHOULD RESULT IN ACCUMULATING SNOW IN THE MOUNTAIN
COUNTIES OVERNIGHT FRIDAY NIGHT INTO SATURDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
HIGH PRESSURE...CURRENTLY CENTERED OVER THE MIDDLE MISSISSIPPI
VALLEY...WILL BUILD NORTHEAST INTO THE AREA BY LATE TODAY...AND
THEN TO OUR EAST BY LATE TONIGHT. EXPECT AN AREA OF LOW PRESSURE
WILL BE LOCATED OVER THE GREAT LAKES REGION BY LATE TONIGHT...WITH
A COLD FRONT EXTENDING SOUTHWEST ACROSS CENTRAL KY INTO SOUTH
TEXAS.

AS EXPECTED...CLOUDS WERE DEVELOPING...MAINLY ACROSS NORTHERN
PORTIONS OF THE AREA. SOME CLOUDS SHOULD CONTINUE TODAY...WITH
SOUTHERN PORTIONS OF THE REGION SEEING MORE SUNSHINE THAN THE
NORTH.

AS THE LOW AND ASSOCIATED COLD FRONT APPROACH FROM THE WEST...
EXPECT CLOUDS WILL BEGIN TO THICKEN AND LOWER...WITH MOSTLY CLOUDY
SKIES EXPECTED BY LATE TONIGHT. POPS SHOULD BEGIN TO INCREASE FROM
THE WEST LATE AS WELL.

FORECASTED HIGHS TODAY LOOKED GOOD AND HAVE ONLY MADE SOME TWEAKS
TO REFLECT LATEST TRENDS IN GUIDANCE.

FOR TONIGHT...LATEST GUIDANCE IS COOLER THAN THE PREVIOUSLY
FORECASTED VALUES. WITH LIGHT WINDS AND DRY AIR...THIS TREND IS
BELIEVABLE. HOWEVER...FEEL INCREASING CLOUDS SHOULD ACT TO LIMIT
OF RADIATIONAL COOLING THAT MAY OCCUR. HAVE LOWERED OVERNIGHT
LOWS...HOWEVER...NOT AS MUCH AS SUGGESTED BY THE LATEST GUIDANCE.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
...FIRST MEANINGFUL SNOW OF THE SEASON ANTICIPATED FOR THE WV AND VA
MOUNTAINOUS COUNTIES...AND PERHAPS HILLTOPS IN THE SOUTHERN WV COAL
FIELDS...OVERNIGHT FRIDAY NIGHT AND SATURDAY MORNING...

WHATEVER THE WINTER OF 2014/15 WILL BRING...IT BEGINS EARLY AND
LOUDLY...AS MAJOR E COAST L/W TROUGH AMPLIFICATION TAKES PLACE EARLY
THIS PERIOD.

A NRN UPPER LEVEL LOW DROPS ALMOST DUE S...DOWN THE BACKSIDE OF THE
AMPLIFYING L/W AND INTO THE BASE...OR FROM THE GREAT LAKES TO THE
SMOKIES...12Z FRI-12Z SAT.  A LEAD SRN STREAM S/W TROUGH ALREADY IN
THE BASE OF THE L/W OVER THE SERN STATES AS OF 12Z FRI...MOVES UP
THE E SIDE OF THE L/W...ALONG THE E COAST...GENERATING AN INITIAL
SFC WAVE ALONG AN OFFSHORE BAROCLINIC ZONE.

FRI FINDS THE FCST AREA ALREADY IN IN RELATIVELY DRY...CHILLY AIR
NEARLY CAPABLE OF SUPPORTING SNOW WITH KEY VALUES NEAR
THRESHOLDS...LIKE 0C AT H8.5 AND 540 KM BETWEEN H5 AND H10...ALONG
WITH PROGGED PW VALUES OF ONLY TWO THIRDS OF AN INCH.  AS SUCH...THE
NRN STREAM UPPER LEVEL LOW WILL NOT HAVE MUCH MOISTURE OR
BAROCLINICITY TO WORK WITH AS IT DIGS THROUGH OR JUST W OF THE FCST
AREA...WITH ASSOCIATED FRONTOGENETIC FORCING NOT REALLY CRANKING UP
UNTIL THE LOW APPROACHES THE SE COAST.

SHOWERS WILL BREAK OUT FRI AS THE SFC COLD FRONT ASSOCIATED WITH THE
NRN STREAM FEATURE...APPROACHES AND THEN MOVES THROUGH FROM THE W.
PRECIPITATION WILL LIKELY BECOME MORE WIDESPREAD FRI NT INTO
SAT...AS THE NEGATIVE TILT FEATURE DIGGING S OF THE AREA PLACES THE
AREA IN STRONG FORCING INCLUDING Q VECTOR CONVERGENCE.  THE
AFOREMENTIONED FACTORS WILL KEEP QPF VALUES MAINLY BELOW A HALF AN
INCH / 6 HRS.

THE COLD CORE SLIDES SEWD ACROSS SW PORTIONS OF THE FCST AREA FRI NT
INTO SAT...WHILE THE WARMER AIR GETS HUNG UP OVER NERN PORTIONS OF
THE FCST AREA FRI INTO FRI NT...UNTIL THE PRIMARY SFC LOW JUST TO
THE N FILLS BY SAT MORNING.  THE WARM BOUNDARY LAYER AIR DOES NOT
GET COMPLETELY ERADICATED...KEEPING ACCUMULATING SNOW LEVELS ABOVE
2500 OR EVEN 3000 FT...WITH LEVELS PERHAPS GETTING BELOW 2500 FT
OVER SW PORTIONS OF THE FCST AREA...CLOSER TO THE UPPER LOW TRACK.

ALL OF THIS SORT OF BALANCES SNOW AMTS IN THE MOUNTAINS THE COLDEST
AIR OVER THE SMALLER SRN MOUNTAINS.  GENERALLY LOOKING AT COUNTY
AVERAGES IN THE ADVISORY RANGE AT BEST...WITH PEAK AMOUNTS NEAR 4
INCHES FOR THE SRN MOUNTAINS AND AS HIGH AS 6 INCHES AT SNOWSHOE.
WILL THUS MAINTAIN HWO MENTION FOR THE MOUNTAINOUS COUNTIES.

AS THE L/W SHIFTS E...THE SYSTEM SCOOTS UP THE E
COAST...OFFSHORE...IT MAKE TAKE UNTIL SUN MORNING FOR THE UPSLOPE
SNOWS SHOWERS TO WANE AND THE CLOUDS TO BREAK UP.  HIGH PRESSURE
SAILS ACROSS SUN NT...PROVING IDEAL RADIATIVE COOLING MOST OF THE NT,

HAVE TEMPERATURES NEARER LOWER SIDE OF GUIDANCE WITH BIAS CORRECTED
GUIDANCE NOT A GOOD FIT IN THIS HIGHLY ANOMALOUS PATTERN.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
MODELS RAPIDLY LIFT THE UPPER LOW OFF THE ATLANTIC COAST SATURDAY
NIGHT...WHICH WILL END THE LINGERING MOUNTAIN SNOW SHOWERS...WITH
ONLY ADDITIONAL MINOR HIGH ELEVATION ACCUMULATIONS BEFORE DAWN
SUNDAY. STRONG DRY CANADIAN HIGH PRESSURE WILL THEN BE THE DOMINANT
FEATURE THROUGH MONDAY. THE HIGH PRESSURE CENTER WILL SETTLE OVER
THE AREA SUNDAY NIGHT...THEN SHIFT OFF THE ATLANTIC COAST EARLY NEXT
WEEK. THIS WILL BRING A DRAMATIC TURNAROUND IN TEMPERATURES THIS
PERIOD. WELL BELOW NORMAL TEMPERATURES THIS WEEKEND WITH WIDESPREAD
SUB FREEZING TEMPERATURES SUNDAY NIGHT UNDER THE CENTER OF HIGH
PRESSURE...WILL WARM UP TO NEAR NORMAL VALUES BY TUESDAY AS THE HIGH
SHIFTS OFF THE ATLANTIC COAST.

WHILE ALL THIS ABOVE IS HAPPENING...MODELS SHOW ANOTHER UPPER TROUGH
DIGGING INTO THE MISSISSIPPI VALLEY AND DRIVING IT EAST TO AFFECT
OUR AREA LATER TUESDAY AND WEDNESDAY. BY THIS TIME...TEMPERATURES
WILL BE WELL ABOVE FREEZING FOR A RAIN EVENT.

&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
LATEST SURFACE OBSERVATIONS AND FOG CHANNEL SATELLITE IMAGERY
SHOWS CLOUDS AT OR ABOVE 3500 FT WHERE DEVELOPING ACROSS PORTIONS
OF THE AREA. STILL NOT REAL CONFIDENT THAT MUCH IN THE WAY OF
MIST/FOG WILL DEVELOP BETWEEN 07Z AND 12Z...ESPECIALLY WITH THE
DEVELOPMENT OF THESE CLOUDS. HAVE CONTINUED MENTION OF MVFR
CONDITIONS WHERE THE CLOUDS ARE MOST LIKELY TO IMPACT...SUCH AS
CRW AND EKN...WITH IFR CONDITIONS POSSIBLE ACROSS THE VALLEYS OF
THE SOUTHERN COAL FIELDS.

EXPECT ANY IFR/MVFR CONDITIONS THAT MAY DEVELOP WILL IMPROVE BY
14Z...WITH VFR CONDITIONS EXPECTED THROUGH THE REMAINDER OF THE
AREA.

WINDS SHOULD BE LIGHT THROUGH THE PERIOD.

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

FORECAST CONFIDENCE: MEDIUM.

ALTERNATE SCENARIOS: TIMING AND DENSITY OF MORNING FOG.

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                              THU 10/30/14
UTC 1HRLY       06   07   08   09   10   11   12   13   14   15   16   17
EDT 1HRLY       02   03   04   05   06   07   08   09   10   11   12   13
CRW CONSISTENCY  H    H    H    M    M    M    M    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    M    M    M    M    M    M    M    H    H    H    H
PKB CONSISTENCY  H    H    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 06Z FRIDAY...
IFR DEVELOPING FRIDAY EVENING IN RAIN...CHANGING TO MOSTLY SNOW OVER
SOUTHERN MOUNTAIN COUNTIES INCLUDING BKW 06Z TO 12Z SATURDAY...WITH
A RAIN AND SNOW MIXTURE IN THE LOWLANDS SATURDAY.

&&

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

&&

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






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