998
FXUS61 KRLX 200901
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
401 AM EST THU FEB 20 2020
SYNOPSIS
LOW PRESSURE PASSES SOUTH OF THE AREA TODAY. STRONG HIGH
PRESSURE DOMINATES FRIDAY THROUGH THE WEEKEND, WHICH STARTS COLD
AND THEN MODERATES. LOW PRESSURE MONDAY AND AGAIN MIDWEEK.
NEAR TERM /THROUGH TONIGHT/
AS OF 145 AM THURSDAY...
SLIGHT NORTHWARD PUSH TO THE PRECIPITATION SHIELD AS SEE IN THE
MIDLEVEL DEFORMATION ZONE AROUND THE 18Z TIME FRAME, AND HAVE
ADJUSTED THOSE POPS ACCORDINGLY. STILL LARGELY ON THE NORTHERN
FRINGE OF THIS BROAD PRECIPITATION SHIELD THAT WILL AFFECT CWAS
FURTHER SOUTH MORE THAN OURS. TEMPERATURES MARGINAL, WITH MID
30S IN THE FORECAST AROUND PRECIPITATION ARRIVAL TIME AND FOR
DAYTIME MAX VALUES, SO POCKETS SOUTH OF THE AFOREMENTIONED
DEFORMATION ZONE MAY FIND THEMSELVES IN RAIN OR A RAIN/SNOW MIX.
THINK THE BULK OF THE MOS GUIDANCE IS TOO WARM GIVEN THE
NORTHERLY WIND FLOW AD THE COLD HIGH PRESSURE IN PLACE SO THE
VALUES IN THE FORECAST ARE HUGGING THE LOWER SIDE OF GUIDANCE.
THE BEST CHANCES FOR ACCUMULATING SNOW IS GOING TO BE THE ON THE
SOUTHERN EDGES OF OUR TWO VA COUNTIES. COULD SEE A TOUCH OVER
AN INCH IN THESE AREAS, WHILE ANYWHERE ELSE IN THE SHIELD OF
POPS WILL BE LESS THAN AN INCH. THE DURATION OF THIS
PRECIPITATION IS FAIRLY LIMITED, FROM 15Z TO AROUND 22Z BEFORE
THE POPS COME BACK BELOW 15. NO ADVISORY PLANNED AS SNOW DOES
NOT MEET 12 HOUR ADVISORY CRITERIA. CLEARING EXPECTED OVERNIGHT
WILL CHILLY READINGS EXPECTED, BUT NOT UN-FEBRUARY LIKE BY ANY
MEANS.
SHORT TERM /FRIDAY THROUGH SUNDAY/
AS OF 345 AM THURSDAY...
..DRY WEEKEND ON TAP
A LARGE HIGH PRESSURE SYSTEM SLOWLY WEAKENS AS IT CROSSES THE
AREA THIS PERIOD. THE HIGH REPRESENTS A MODIFYING ARCTIC AIR
MASS THAT CONSERVES ITS LOW DEW POINTS MUCH MORE THAN THE
TEMPERATURES. TEMPERATURES START OUT BELOW NORMAL, AND THEN RISE
SEVERAL DEGREES PER DAY, GETTING ABOVE NORMAL FOR SUNDAY
AFTERNOON. ADJUSTED CENTRAL GUIDANCE LOWS DOWN IN THE VALLEYS
GIVEN CLEAR, CALM CONDITIONS. THERE MAY BE STRATOCU IN AND NEAR
THE MOUNTAINS FIRST THING FRIDAY MORNING BUT, WITH VERY DRY AIR
ARRIVING, THESE CLOUDS SHOULD MIX OUT QUICKLY, AND THEN THERE
SHOULD BE NARY A CLOUD UNTIL SOME CIRRUS ARRIVES ON SUNDAY, AS
UPPER LEVEL RIDGING FLATTENS.
AFTERNOON RH VALUES WILL DROP INTO THE 20S AND 30S, WITH
SATURDAY BEING THE DRIEST, WITH WIDESPREAD 20S, EVEN TEENS IN
THE MOUNTAINS. THE COOL WEATHER AND LIGHT FLOW SHOULD KEEP THE
FIRE DANGER MINIMAL, THOUGH. RH VALUES AT LEAST THIS LOW IN
THIS TYPE OF PATTERN THIS TIME OF YEAR IS A HIGH CONFIDENCE
FORECAST, AND ACTUAL VALUES MAY TURN OUT TO BE EVEN LOWER.
LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/
AS OF 345 AM THURSDAY...
..FOLLOWED BY ANOTHER ACTIVE WEEK
A SOUTHERN STREAM TROUGH AND LOW PRESSURE SYSTEM APPROACH
SUNDAY NIGHT, AND THEN THE SURFACE LOW TRACKS NORTH OF THE AREA
MONDAY THROUGH MONDAY NIGHT. CLOUDS WILL BE ON THE INCREASE
SUNDAY NIGHT, AND RAIN WILL OVERSPREAD THE AREA QUICKLY MONDAY
MORNING, MAKING FOR ANOTHER WET START TO THE WORK WEEK, IN THE
WARM ADVECTION AHEAD OF THE SYSTEM. THE COLUMN MAY WET-BULB COOL
ENOUGH FOR WET SNOW TO BE IN THE MIX OVERNIGHT SUNDAY NIGHT
ACROSS THE NORTH, BUT THIS WILL BE PRIMARILY A RAIN EVENT. THE
WET WEATHER CONTINUES MONDAY NIGHT, AHEAD OF THE COLD FRONT
THAT EVENTUALLY CROSSES, AND OF THE APPROACHING SHORT WAVE.
MODELS DIFFER ON HOW QUICKLY THE SYSTEM PULLS OUT ON TUESDAY,
BUT A SECOND SOUTHERN STREAM TROUGH DROPS DOWN AS THE FIRST
LIFTS OUT, AND THEN A NORTHERN STREAM SHORT WAVE TROUGH DROPS
IN, AS AN AMPLIFYING LONG WAVE TROUGH SETS UP SHOP OVER THE
EASTERN U.S. MID TO LATE WEEK.
THE SECOND SOUTHERN STREAM SHORT WAVE BRINGS A GOOD CHANCE FOR
RAIN WEDNESDAY. PRECIPITATION SHOULD TRANSITION TO SNOW OR SNOW
SHOWERS SOMETIME WEDNESDAY NIGHT, BUT THE TIMING, AND COVERAGE,
WILL DEPEND UPON WHERE LOW PRESSURE FORMS AND TRACKS, AND HOW
QUICKLY IT INTENSIFIES. NEXT THURSDAY SHOULD, AT THE LEAST,
BRING NORTHWEST LOW LEVEL FLOW GIVEN LOW PRESSURE EAST OR
NORTHEAST OF THE AREA BY THEN, BENEATH DEEP TROUGHING ALOFT.
THIS WOULD SPELL NUMEROUS SNOW SHOWERS, BUT DAYTIME TEMPERATURES
MAY STILL LIMIT ACCUMULATIONS ACROSS THE LOWLANDS.
NO CHANGES WERE MADE TO CENTRAL GUIDANCE TEMPERATURES, WHICH
DROP BACK BELOW NORMAL AT THE END.
AVIATION /09Z THURSDAY THROUGH MONDAY/
AS OF 1225 AM THURSDAY...
CRW, HTS, PKB, CKB, AND EKN ALL VFR AND PRECIPITATION FREE
THROUGH THE PERIOD. EACH SITE WILL SEE A VARYING DEGREE OF
CEILING LOWERING FROM A SOUTHERN STREAM LOW PRESSURE SYSTEM.
BKW IS ANOTHER STORY, AND WILL GET INTO A BRIEF PERIOD OF SNOW.
WILL UTILIZE A FEW HOURS OF 2SM -SN AND CEILINGS TOUCHING MVFR,
BUT THE BULK OF THE PRECIPITATION FROM THIS SYSTEM WILL BE TO
THE SOUTH OF AREA. THE BKW TERMINAL LIES ON THE NORTHERN FRINGE
OF THE MOISTURE THAT IS DEEP ENOUGH FOR PRECIPITATION, AND SOME
LIGHT ACCUMULATION IS NOT OUT OF THE QUESTION.
WINDS LESS THAN 12KTS ACROSS THE BOARD.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z FRIDAY...
FORECAST CONFIDENCE: HIGH.
ALTERNATE SCENARIOS: SOME TIMING ADJUSTMENTS FOR SNOW AT BKW MAY
BE NEEDED.
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 02/20/20
UTC 1HRLY 09 10 11 12 13 14 15 16 17 18 19 20
EST 1HRLY 04 05 06 07 08 09 10 11 12 13 14 15
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 L H M
EKN CONSISTENCY H H H H H H H H 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...
NO WIDESPREAD IFR CONDITIONS EXPECTED AT THIS TIME.
RLX WATCHES/WARNINGS/ADVISORIES
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
SYNOPSIS...26/TRM
NEAR TERM...26
SHORT TERM...TRM
LONG TERM...TRM
AVIATION...26
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