Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 010014
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
713 PM EST SAT JAN 31 2015

.SYNOPSIS...
WARM ADVECTION PRECIPITATION EARLY SUNDAY.  LOW PRESSURE SYSTEM
PASSES NORTH OF THE AREA LATE SUNDAY NIGHT.  MUCH COLDER AIR BLOWS
IN ON MONDAY.  HIGH PRESSURE BUILDS IN MONDAY NIGHT INTO TUESDAY.

&&

.NEAR TERM /THROUGH SUNDAY/...
700 PM UPDATE...
FINE-TUNED POPS BASED ON SREF AND LOCALLY RUN WRFARW AND WRFNMM.
THIS TIGHTENS UP THE GRADIENT A BIT AND REFLECTS A BIT OF A DAGGER
SE INTO WV EARLY MON MORNING...AHEAD OF THE WARM FRONT ASSOCIATED
WITH THE UPCOMING SYSTEM.  STILL LOOKING AT A MINIMAL FZRA POTENTIAL
OVER A SMALL PORTION OF THE MIDDLE OHIO VALLEY ON THE ORDER OF A FEW
HUNDREDTHS OF AN INCH ICE ACCRETION.

PREV DISCN...
MODELS CONTINUE TO STAY WITH THE CURRENT WARM WEDGE SOLUTION OVER
MUCH OF CWA. GENERALLY USED A BLEND OF SREF AND GFS FOR POPS. ONLY
REAL SIGNIFICANT CHANGE WAS TO INCLUDE A DRY SLOT ACROSS MUCH OF THE
CWA FOR SUNDAY.

HAVE WARM ADVECTION PRECIP MOVING IN PRE-DAWN SUNDAY MORNING.
TEMPS...AND THUS PRECIP TYPE FOR THIS TIME ARE A LITTLE TRICKY...AND
HINGE ON HOW QUICKLY THE CLOUDS THICKEN UP AND STOP A RADIATIVE
COOLING TONIGHT. ON TOP OF THAT...DRY AIR MAY WET BULB SOME. ENDED
UP WITH A FAIRLY BRIEF PERIOD OF WINTRY MIX ACROSS SOUTHWESTERN AND
WESTERN ZONES...WITH SNOW FARTHER NORTH. WILL MENTION POTENTIAL OF
VERY LIGHT ICING IN HWO. THIS IS NOT REALLY A SITUATION LIKE LAST
FREEZING RAIN EVENT EARLIER THIS WEEK WHERE TEMPS SURGED INTO THE
UPPER 30S WITH ROADS STILL BELOW FREEZING. ROAD SURFACES TODAY
SHOULD BE RELATIVELY WARM DUE TO SUNSHINE...AND SHOULD NOT GET AS
COLD OVERNIGHT AS CLOUDS MOVE IN. STILL...CAN ENVISION SOME PATCHY
SLICK SPOTS EARLY SUNDAY MORNING. FARTHER NORTH...IT SHOULD BE
MAINLY SNOW POSSIBLY MIXED WITH SOME SLEET THROUGH MID MORNING.
850MB TEMPS CONTINUE TO WARM SUNDAY...AND HAVE RAIN ACROSS ENTIRE
FORECAST AREA BY MID AFTERNOON...EXCEPT FOR JUST A COUPLE OF THE
HIGHEST SPOTS IN THE NORTHERN MOUNTAINS. WITH THE DRY SLOT...AND
SOME DOWNSLOPE COMPONENT TO THE WIND...REDUCED CLOUD COVER IN
EASTERN LOWLANDS...AND BOOSTED AFTERNOON HIGHS ROUGHLY 5 DEGREES
OVER PREVIOUS FORECAST FOR THIS SAME AREA.

IN COORDINATION WITH SHORT TERM FORECASTER...GOING WITH A WINTER
WEATHER ADVISORY FOR PERRY AND MORGAN COUNTIES IN OHIO WITH 1-3
INCHES OF SNOW SUNDAY MORNING AND THEN ALSO COVERING THE SNOW THAT
FALLS SUNDAY NIGHT INTO MONDAY. WILL ALSO CONTINUE THE BUFFER ZONE
AROUND THE ADVISORY CURRENTLY IN THE HWO...ALLOWING FOR SOME SHIFT
IN LOW TRACK AND INHERENT THERMAL PROFILE CHANGES.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
LOW PRESSURE STARTING TO MOVE THROUGH OHIO VALLEY REGION AT THE
START OF THE SHORT TERM PERIOD. BASED ON THE NORTHERN PATH OF THE
LOW...WILL SEE A WARM SURGE OF AIR ACROSS THE AREA...WITH THE BULK
OF PRECIPITATION STARTING OUT AS RAIN ACROSS THE AREA. THE LOW WILL
GRADUALLY MOVE OFF TO THE NORTH AND EAST OF THE AREA LATE SUNDAY
NIGHT/EARLY MONDAY...WITH MUCH COLDER AIR RUSHING INTO THE AREA
BEHIND THE LOW...WITH A GRADUAL CHANGE OVER FROM RAIN...TO SNOW.
SOUTHEAST OHIO WILL SEE A CHANGE OVER FIRST...WITH CHANGE OVER FROM
RAIN TO SNOW GENERALLY AFTER 2 AM. MUCH OF THE WEST VIRGINIA
LOWLANDS WONT START TO SEE A CHANGE OVER TO SNOW UNTIL AFTER DAWN ON
MONDAY. AS THE COLDER AIR IS FINALLY ABLE TO WORK ITS WAY IN ENOUGH
FOR A CHANGE OVER TO SNOW...THE BULK OF MOISTURE WILL GRADUALLY EXIT
WITH THE EXIT OF THE LOW TO THE EAST. AS A RESULT...FIGURING ONLY
LIGHT ACCUMULATIONS FOR MUCH OF THE AREA...WITH GENERALLY 2 TO 4
INCHES POSSIBLE ACROSS PERRY COUNTY....WITH 1 TO 3 IN MORGAN
COUNTY...AND AROUND AN INCH FOR THE REMAINDER OF SOUTHEAST OHIO.
EXPECT MUCH OF THE WEST VIRGINIA LOWLANDS TO RECEIVE AROUND AN INCH
OR LESS...EXCEPT NORTHERN WEST VIRGINIA LOWLAND COUNTIES SUCH AS
CLARKSBURG AREA...WHERE A GOOD INCH OR TWO IS POSSIBLE. MOUNTAINOUS
COUNTIES COULD EASILY GET 2 TO 4 INCHES...WITH ADDITIONAL
ACCUMULATIONS POSSIBLE ON NW FACING SLOPES. THE SNOW WILL TRANSITION
FROM A HEAVY WET SNOW...TO A LIGHTER FLUFFIER SNOW AS THE DAY
PROGRESSES ON MONDAY AS 850MB -16C AIR RUSHES INTO THE REGION. THIS
SHOULD ALLOW FOR ACCUMULATIONS IN THE HIGHER TERRAIN COUNTIES IN
LINGERING UPSLOPE FLOW.

WE WILL ISSUE A WINTER WEATHER ADVISORY FOR PERRY AND MORGAN
COUNTIES THROUGH MONDAY MORNING. WILL KEEP AN EYE ON THE POTENTIAL
FOR MOUNTAINOUS COUNTIES.

HIGH PRESSURE WILL BUILD IN FOR TUESDAY...WITH DRY CONDITIONS...AND
MODERATING TEMPERATURES.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
BROAD EASTERN MID/UPPER LEVEL TROF WITH FAST FLOW...AND FEW
OPPORTUNITIES TO ACCESS THE GULF OF MEXICO MOISTURE.

WEAK WARM AIR ADVECTION ONGOING TUESDAY NIGHT...WILL TRY TO BRING
SOME 20/30 POPS A BIT FASTER SOUTH BY DAWN WEDNESDAY INTO OUR
NORTHERN COUNTIES.

12Z GFS A BIT MORE AGGRESSIVE WITH THE MOISTURE  MOVING UP THE OHIO
VALLEY WEDNESDAY ALONG THAT FRONTAL BOUNDARY. ECMWF CERTAINLY NOT AS
MOIST. FOR NOW...WILL KEEP POPS IN CHANCE CATEGORY WITH FRONT
WEDNESDAY INTO WEDNESDAY NIGHT.

HAVE COLDER AIR BLOWING SOUTH AGAIN OVERNIGHT WEDNESDAY NIGHT INTO
THURSDAY.  WENT COLDER THAN OUR PREVIOUS FORECAST.

DRYING AGAIN THURSDAY NIGHT THRU FRIDAY NIGHT.

IN THE FAST FLOW...NEXT SYSTEM COULD ARRIVE BY LATE DAY 7.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
VFR START...BUT HIGH PRESSURE DEPARTS IN FAVOR OF A LOW PRESSURE
SYSTEM APPROACHING FROM THE W THAT WILL REACH THE LOWER OHIO VALLEY
BY THE END OF THE TAF PERIOD...00Z MON.  ITS WARM FRONT WILL BRING A
ROUND OF MVFR TO IFR CONDITIONS IN MIXED WINTRY PRECIPITATION MAINLY
ACROSS THE MIDDLE OHIO VALLEY AND NRN WV...BEFORE LIFTING N OF THE
AREA BY 00Z MON.

WITH THE CHANCE FOR FREEZING RAIN MINIMAL BASED ON THERMAL
PROFILES...HAVE GENERALLY A SNOW TO SLEET TO RAIN TRANSITION SUN
MORNING.  FOR PKB...THIS SNOW / TRANSITION IS CODED FOR 09-16Z SUN
WITH MVFR VSBY AND CIGS.  VSBY BECOMES VFR AS THE RAIN DIMINISHES
SUN AFTERNOON...AND CIGS MAY ALSO CLIMB ABOVE 3 KFT FOR A MAINLY
VFR AFTERNOON.  FOR CKB...THE TIMING IF 12-16Z BUT WITH SNOW
POSSIBLY BRINGING A BRIEF PERIOD OF IFR.  FOR EKN...THE SNOW /
TRANSITION TIME IS 14-17Z WITH MAINLY MVFR CONDITIONS.  CKB AND EKN
WILL ALSO SEE IMPROVEMENT SUN AFTERNOON AS THE RAIN DIMINISHES.

SOUTHERN SITES HTS...CRW AND BKW WILL HAVE VFR THROUGH THE PERIOD
WITH ALTOCU...ALTHOUGH AN MVFR STRATOCU DECK COULD BRIEFLY SNEAK AS
FAR SE AS CRW BEFORE DAWN SUN MORNING.

THE CHANCE FOR RAIN STARTS TO INCREASE QUICKLY FROM W TO E LATE
SUN...AS THE COLD FRONT ASSOCIATED WITH THIS SYSTEM APPROACHES FROM
THE W.

LIGHT AND VARIABLE SFC FLOW OVERNIGHT WILL BECOME S ON SUN AND
FRESHEN TO NEAR 10 KTS...AND BECOME A BIT GUSTY ON THE MOUNTAIN
RIDGES...SUN AFTERNOON.  UP N FROM PKB TO CKB...SFC FLOW WILL REMAIN
LIGHT AND EVEN BACK TO SE AGAIN LATE IN THE DAY.  MODERATE NW FLOW
ALOFT OVERNIGHT BECOMES LIGHT TO MODERATE W SUN MORNING...AND THEN
LIGHT TO MODERATE SW SUN AFTERNOON.

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

FORECAST CONFIDENCE: HIGH EARLY ON...DESCENDING TO MEDIUM.

ALTERNATE SCENARIO: TIMING OF DROPS IN FLIGHT CONDITIONS AND DEGREE
AND DURATION OF WORST CONDITIONS MAY VARY.  TIMING OF PRECIP TYPE
TRANSITIONS MAY ALSO VARY AND...WHILE NOT EXPLICITLY CODED UP...FZRA
IS A POSSIBILITY PKB...CKB...EKN...AND EVEN A SLIGHT CHANCE FREEZING
RAIN EARLY SUN MORNING HTS AND CRW.

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                                                                 SUN
UTC 1HRLY       00   01   02   03   04   05   06   07   08   09   10   11
EST 1HRLY       19   20   21   22   23   00   01   02   03   04   05   06
CRW CONSISTENCY  H    H    H    H    H    H    H    H    H    M    M    M
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    M
PKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    M
CKB CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H

AFTER 00Z MONDAY...
IFR CONDITIONS POSSIBLE IN SNOW LATE OVERNIGHT SUNDAY NIGHT OVER THE
MIDDLE OHIO VALLEY...AND THE HIGHER WV MOUNTAINOUS
TERRAIN....LINGERING IN AND NEAR THE WV MOUNTAINS INTO MONDAY.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...WINTER WEATHER ADVISORY FROM 1 AM SUNDAY TO 10 AM EST MONDAY
     FOR OHZ066-067.
KY...NONE.
VA...NONE.

&&

$$
SYNOPSIS...MZ/SL
NEAR TERM...TRM/MZ
SHORT TERM...SL
LONG TERM...KTB
AVIATION...TRM





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