702
FXUS61 KRLX 222358
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
658 PM EST FRI FEB 22 2019
SYNOPSIS
OCCASIONAL RAIN CONTINUES ACROSS THE SOUTH OVERNIGHT. A SECOND
UPPER LEVEL WAVE BRINGS HEAVY RAIN ACROSS PARTS OF THE AREA
SATURDAY, THEN A COLD FRONT BLOWS THROUGH EARLY SUNDAY.
NEAR TERM /THROUGH SATURDAY/
AS OF 745 PM FRIDAY...
FORECAST REMAINS ON TRACK. ONLY MADE MINOR ADJUSTMENTS TO
TEMPERATURES TO MATCH CURRENT OBSERVATIONS AND TRENDS. ALSO,
ADDED SOME POPS TO THE SOUTHERN AREA AND INCREASED CLOUD
COVERAGE.
AS OF 240 PM FRIDAY...
THIS AFTERNOON, WE SIT BETWEEN CENTRAL GREAT LAKES HIGH PRESSURE AND
DEVELOPING LOW PRESSURE ACROSS THE MISSISSIPPI VALLEY. THE BOUNDARY
BETWEEN, AIDED BY A FLAT WAVE AND JET ALOFT, STILL PRODUCES
SHOWERS ACROSS SOUTHERN WV AND SOUTHWEST VA. SHOWERS WILL
CONTINUE AS SUBTLE, WEAK WAVES MOVE ACROSS THIS BOUNDARY THROUGH
TONIGHT. MEANWHILE, A TROUGH EJECTS FROM THE ROCKIES THIS
AFTERNOON, TILTING NEGATIVELY AS IT DOES SO, AND CYCLOGENESIS
COMMENCES IN THE LEE OF THE ROCKIES, TRACKING NORTHEAST WITH THE
PARENT TROUGH.
IN THIS REGION, STRONG WARM ADVECTION RENEWS PRECIPITATION
ACTIVITY ALONG THE REMNANT FRONTAL BOUNDARY AND TRACKS THE
BOUNDARY NORTHWARD AS A WARM FRONT SATURDAY. A BRIEF PERIOD OF
FREEZING RAIN IS POSSIBLE UPON PRECIPITATION ONSET IN THE WV
MOUNTAINS INTO THE HEADWATERS OF THE GREENBRIER BEFORE NEAR-
SURFACE TEMPERATURES WARM ABOVE FREEZING, HOWEVER, MARGINAL
TEMPERATURES AND MARGINAL PRECIPITATION CHANCES COINCIDING WITH
FREEZING TEMPERATURES LED ME TO HOLD OFF ON THE ISSUANCE OF
HEADLINES FOR THIS.
WARM, MOIST 850 MB FLOW IS PROGGED TO SURGE TO AT LEAST 50KTS, WITH
POCKETS OF 70 KTS POSSIBLE, IN RESPONSE TO A STRENGTHENING LOW
AND SE-DIGGING TROUGH. THIS IN TURN KICKS MOISTURE TRANSPORT
AND CONVERGENCE INTO HIGH GEAR ACROSS THE APPALACHIAN REGION.
DEFORMATION FORCING ANALYSIS BRINGS INITIAL BANDS OF STRATIFORM
RAIN IN FROM THE SOUTHWEST DURING THE PRE- TO NEAR-DAWN HOURS
OF SATURDAY, SAILING NORTHEASTWARD THROUGH THE DAY. MOISTURE
AVAILABILITY WILL NEAR 1.2" PWAT WITH THE INITIAL BATCH, HOWEVER
CONVECTION TO THE SOUTH MAY ROB SOME OF THIS MOISTURE, AS
SUGGESTED BY A FEW HI- RES MODELS COMING INTO VIEW. LOOKING AT
POTENTIAL FOR 0.75-1.5" OF RAIN THROUGH SATURDAY WITH HIGHEST
AMOUNTS LIKELY ALONG AND SOUTH OF THE I-64 CORRIDOR ACROSS THE
TUG FORK VALLEY AND SOUTHERN ZONES. CONVECTION TO THE SOUTH OF
THE AREA INTO NORTHEAST TENNESSEE WILL HAVE TO BE CLOSELY
MONITORED - MUCH LOWER QPF IS POSSIBLE WITH MORE CONVECTION TO
OUR SOUTH, HIGHER QPF AS MUCH AS 2-3" LOCALLY IS POSSIBLE
SHOULD CONVECTION TO OUR SOUTH BE LIMITED.
ANOTHER CONFLATING VARIABLE IN ADDITION TO SOUTHERN CONVECTION IS
THE POSSIBILITY OF DOWNSLOPING FLOW FROM THE SOUTHEAST. MODEL
ANALYSIS DOES YIELD A STRONG PRESSURE GRADIENT ACROSS THE
APPALACHIAN SPINE, SUGGESTING SE/DOWNSLOPING FLOW, BUT IT APPEARS TO
BE CHIEFLY TIED TO THE SURFACE. CURRENT THINKING IS THAT ROBUST
SOUTHERLY/SOUTHWESTERLY FLOW AND MOISTURE TRANSPORT IN L/M LEVELS
WILL OVERCOME THIS OBSTACLE THAT OFTEN FOILS HEAVY RAIN CHANCES IN
SOUTH/CENTRAL PORTIONS OF WV. DOWNSLOPING MAY BECOME MORE OF A
LIMITING FACTOR SHOULD CONVECTION STIFLE MOISTURE AVAILABILITY,
HOWEVER.
NO CHANGES WERE MADE TO THE EXISTING FLOOD WATCH WHICH
PRESENTLY COVERS SOUTHERN WV, SOUTHWEST VA, EASTERN KY, AND
PORTIONS OF SOUTHERN OHIO.
SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/
AS OF 225 PM FRIDAY...
VERY ACTIVE WEATHER WILL START OFF THE SHORT TERM PERIOD AS
MOISTURE TRANSPORT CONTINUES TO MIGRATE IN FROM THE SOUTHWEST,
RAMPING UP RAIN ACROSS THE OHIO RIVER VALLEY LATE SATURDAY NIGHT
INTO SUNDAY MORNING. MODEL GUIDANCE IS IN FAIRLY DECENT
AGREEMENT THAT THE SOUTHERN HALF OF THE CWA, ALREADY STRICKEN
WITH VERY SATURATED SOILS, WILL LIKELY RECEIVE AN ADDITIONAL
1-2 INCHES WITH THIS SYSTEM. THIS WILL POSE A CONCERN FOR THE
SECOND HALF OF THE WEEKEND, BEGINNING WITH POTENTIAL FOR THUNDER
LATE SATURDAY NIGHT. WHILE THE INSTABILITY STILL REMAINS LIMITED
TO SUPPORT STRONG WINDS WITH ANY STORMS THAT DEVELOP, DOWNED
TREES AND POWER LINES WILL STILL BE EASILY CAPABLE OF OCCURRING
DUE TO THE WATERLOGGED SOILS. THIS THREAT CONTINUES INTO SUNDAY
AFTER A COLD FRONTAL PASSAGE, WITH A STRONG GRADIENT MOVING
INTO THE REGION IN ITS WAKE. WHILE FORECAST SOUNDINGS SLIGHTLY
DEVIATE FROM ONE ANOTHER IN GUST POTENTIAL, GUSTS UP TO 30-40
KTS ARE POSSIBLE ACROSS THE LOWLANDS WHILE THE MOUNTAINS ARE
STILL SLATED TO SEE ANYWHERE UP TO 50-55 KTS IN GUSTS. WILL
STILL HOLD OFF ON EXPANDING THE CURRENT HIGH WIND WATCH DOWN
INTO THE LOWLANDS, BUT WILL PASS ALONG TO THE NEXT SHIFT TO
MONITOR UPCOMING MODEL TRENDS. WIND GUSTS AND ANY RESIDUAL
SHOWERS ALONG THE MOUNTAINS WILL TAPER OFF BY MONDAY MORNING AS
HIGH PRESSURE BUILDS IN FOR THE FIRST HALF OF THE WORK WEEK.
LONG TERM /TUESDAY THROUGH FRIDAY/
AS OF 220 PM FRIDAY...
STARTING OFF THE LONG TERM UNDER MOSTLY ZONAL FLOW AND CLOSE TO
SEASONABLE TEMPERATURES. HIGH CIRRUS BUILDS BACK INTO THE REGION
AHEAD OF A WEAK COLD FRONT APPROACHING THE REGION TOWARDS
MIDWEEK. PRECIPITABLE WATER VALUES REMAIN FAIRLY LOW WITH THIS
SYSTEM, SO ONLY HAVE A SLIGHT CHANCE FOR SOME WINTRY WEATHER
EARLY WEDNESDAY MORNING BEFORE CHANGING OVER TO RAIN FOR AREAS
OUTSIDE OF THE MOUNTAINS SHORTLY AFTER DAYBREAK.
AVIATION /00Z SATURDAY THROUGH WEDNESDAY/
AS OF 730 PM FRIDAY...
THE BAND OF RAIN ASSOCIATED WITH THE FRONT TO THE SOUTH EDGES
INTO THE AREA, HOWEVER IT MEANDERS FOR MOST OF THIS FORECAST
PERIOD KEEPING RAINFALL CONFINED TO THE EXTREME SOUTHERN HALF OF
THE STATE. A LOW PRESSURE SYSTEM WILL FORM ALONG THE BOUNDARY
AND RIDE UP TOWARDS THIS AREA LATE SATURDAY MORNING BRINGING
WIDESPREAD RAIN AND LOWER CEILINGS THROUGHOUT THE AREA. WITH THE
EXCEPTION OF BKW ALL TERMINALS BY THEN WILL GO FROM VFR TO
MVFR, WITH POSSIBLE IFR LATER IN THE DAY. BKW WILL BE IN AND OUT
OF IFR CONDITIONS FROM NOW THROUGH SATURDAY. HTS/BKW WILL
EXPERIENCE IFR CONDITIONS IN THE AFTERNOON, HOWEVER THE REST OF
THE TERMINALS, WITH THE HELP OF SOUTHEASTERLY DOWNSLOPING
LIFTING CEILINGS, WILL STAY IN MVFR. WIND OVERNIGHT IS OUT OF
THE NORTHEAST GENERALLY AROUND 5KT. WINDS PICK UP OUT OF THE
SOUTHEAST 5-10KT+ BY LATE MORNING. LOOK FOR GUSTS ON RUNWAYS IN
THE UPPER TEENS IN LOW ELEVATIONS AND 20'S IN THE HIGHER
ELEVATIONS.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SUNDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: VISIBILITY MAY VARY IN A HEAVIER RAIN
SHOWER. LLWS MAY BECOME AN ISSUE AT THE BKW TERMINAL DURING
SATURDAY AFTERNOON.
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 SAT
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 H H M
HTS CONSISTENCY H H H H H H H H H H H M
BKW CONSISTENCY L L L L L M H H H H H H
EKN CONSISTENCY H H H H H H H H H H M M
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 00Z SUNDAY...
IFR POSSIBLE IN RAIN CONTINUING THROUGH EARLY SUNDAY. STRONG,
POSSIBLY DAMAGING, WINDS WILL IMPACT ALL SITES SUNDAY.
RLX WATCHES/WARNINGS/ADVISORIES
WV...HIGH WIND WATCH FROM SUNDAY MORNING THROUGH MONDAY MORNING FOR
WVZ030>032-039-040-521>523-525-526.
FLOOD WATCH THROUGH SUNDAY MORNING FOR WVZ005>007-013>015-
024>027-033-034-515>520.
OH...FLOOD WATCH THROUGH SUNDAY MORNING FOR OHZ083-086-087.
KY...FLOOD WATCH THROUGH SUNDAY MORNING FOR KYZ101>103-105.
VA...FLOOD WATCH THROUGH SUNDAY MORNING FOR VAZ003-004.
SYNOPSIS...MC/JZ/MEK
NEAR TERM...MC/JZ
SHORT TERM...MEK
LONG TERM...MEK
AVIATION...JZ
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page