Area Forecast Discussion
Issued by NWS Charleston, WV

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000
FXUS61 KRLX 261032
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
610 AM EDT SAT JUL 26 2014

.SYNOPSIS...
UPPER LEVEL LOW WITH DISTURBANCES IN THE FLOW THROUGH TONIGHT.
COLD FRONT WITH STRONG STORMS SUNDAY. LINGERING CONVECTION IN THE
UPPER LEVEL LOW THROUGH MONDAY. COOLER AIRMASS SETTLES IN PLACE
THROUGH MID WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
6 AM UPDATE...NO SIGNIFICANT CHANGE.

PREVIOUS DISCUSSION...
MODELS ARE IN GOOD AGREEMENT ON A VIGOROUS SHORT WAVE APPROACHING
FROM THE WEST TONIGHT...WITH A WELL DEFINED WARM FRONT FOR THIS TIME
OF YEAR LIFTING NORTH AND EAST TOWARD OUR AREA. GIVEN THE STRENGTH
OF THE DYNAMICS AND A MODERATE 850 MB SOUTHWESTERLY JET FEEDING WARM
AND QUITE MOIST AIR NORTHWARD...THE MODELS TARGET THE BEST
COMBINATION OF THESE PARAMETERS RIGHT ACROSS OUR AREA...MAINLY
LATER TONIGHT IN THE FORM OF AN MCS. WITH HPC AND SPC ALSO TARGETING
OUR AREA WITH A RISK FOR BOTH SEVERE STORMS AND EXCESSIVE
RAINFALL...HAVE TO GO WITH THIS SCENARIO. THIS BRINGS CAT POPS FROM
THE WEST AND NORTHWEST ACROSS OUR AREA TONIGHT...AGAIN MAINLY AFTER
MIDNIGHT. HOWEVER...OF SOME CONCERN IS THE EFFECTS OF A STILL
NORTHWESTERLY COMPONENT OF THE 1000-5000 MB THICKNESS FIELDS...WHICH
MAY PULL THE ANTICIPATED COMPLEX FORMING WELL UPSTREAM LATER TODAY
MORE SOUTHEASTWARD INTO KENTUCKY. AT THIS POINT THOUGH...FROM ALL
THAT IS MENTIONED ABOVE...CONFIDENCE IS NOT HIGH ENOUGH TO DEVIATE
FROM GUIDANCE. WILL MENTION THESE CONCERNS IN THE HAZARDOUS WEATHER
PRODUCT FOR NOW...UNTIL WE GET MORE CONFIDENCE IN THE EVOLUTION OF
THINGS TODAY BEFORE ANY WATCHES ARE CONSIDERED.

OH YES...ABOUT TODAY. TODAY WILL BE THE TRANSITION TO THE SETUP FOR
TONIGHT. SURFACE HIGH PRESSURE SHIFTING FARTHER OFF TO THE EAST WILL
ALLOW STRONG WARM AND MOIST ADVECTION ON INCREASING SOUTHWESTERLY
FLOW. EARLY MORNING UPPER DISTURBANCE WITH THE WIDESPREAD MID CLOUDS
WILL LIFT OUT BY MID MORNING...BEING REPLACED BY A SCATTERED CU
FIELD THIS AFTERNOON WITH LACK OF UPPER DISTURBANCES. THUS...KEEPING
THINGS DRY BUT MUCH WARMER AND MORE HUMID TODAY UNDER A GOOD DEAL OF
SUNSHINE. GOING ON THE WARMER SIDE OF GUIDANCE WITH HIGHS
APPROACHING 90 DEGREES.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
BEST PLACE TO START WITH THIS FORECAST IS THE MODERATE RISK FROM SPC
IN THE MIDDLE OHIO VALLEY AND CENTRAL APPALACHIANS FOR SUNDAY INTO
SUNDAY NIGHT. ALSO HAVE THE POTENTIAL FOR EXCESSIVE RAINFALL.

UPPER LEVEL LOW WILL DIVE INTO TH GREAT LAKES FROM THE NORTHERN
PLAINS LATE THIS WEEKEND WITH YET ANOTHER DYNAMIC SYSTEM. WILL
LIKELY BE DEALING WITH A LATE NIGHT MCS  TOWARDS THE BEGINNING OF
THE SHORT TERM FORECAST BRINGING A WIND THREAT. THIS COULD WORK TO
DESTABILIZE THE ATMOSPHERE LATER IN THE DAY WITH COOLING TO THE MID
LEVELS AS THE SURFACE RECOVERS UNDER SOLAR INSOLATION...THUS
INCREASING THE LOW AND MID LEVEL LAPSE RATES INTO THE LATE AFTERNOON
AND EVENING SUNDAY. STORMS WILL FORM ALONG THE STRONG COLD FRONT AND
PROPAGATE RAPIDLY WITH AN OBVIOUS WIND THREAT AS WELL AS LARGE HAIL.
AS THE SPEED SHEAR INCREASES WITH THE APPROACHING OF THE UPPER LEVEL
LOW...SO DOES THE DIRECTIONAL SHEAR OVER THE LOW LEVELS...AND WILL
SEE SOME VEERING WITH HEIGHT.

RAPID DRYING ALOFT ABOVE 700MB OCCURS AFTER 00Z MONDAY...BUT AS THE
UPPER LOW ROTATES INTO LAKE ERIE...ANOTHER AXIS OF MOISTURE WILL
DROP IN FROM THE NORTH. THIS KEEPS THE POPS GOING AFTER A SHORT
REPRIEVE INTO THE MONDAY TIME FRAME.

IN THE END...THIS COLD FRONTAL PASSAGE WILL BRING YET ANOTHER
SIGNIFICANT CHANGE IN AIRMASS...IN A JULY THAT HAS SEEN A STEADY
DOSE OF THESE COLD FRONTS THAT HAVE USHERED IN INFLUENCES FROM
CANADIAN HIGH PRESSURE. MAX TEMPERATURES WILL BE BACK DOWN AROUND 10
TO 15 DEGREES BELOW NORMAL.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
HIGH PRESSURE BEHIND THE COLD FRONT TAKES CONTROL LATER MONDAY NIGHT
THROUGH THE MIDDLE OF NEXT WEEK WITH NEAR NORMAL TEMPERATURES.

BLENDED HPC WITH PREVIOUS FORECAST NUMBERS AS THEY LOOK
REPRESENTATIVE UNDER HIGH PRESSURE AND SLIGHTLY COOLER NORTHERLY
FLOW.

&&

.AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
12Z SATURDAY THRU 12Z SUNDAY...
OCCASIONAL MVFR RIVER AND VALLEY FOG TIL 13Z...EXCEPT LOCALLY IFR AT
EKN. OTHERWISE...SCT-BKN CLOUDS AOA 8000 FEET AGL THRU 15Z
ASSOCIATED WITH WEAK UPPER DISTURBANCE. AFTER 15Z...GENERALLY
SCATTERED DIURNAL CU.

A THUNDERSTORM COMPLEX WILL BEGIN TO AFFECT AREA AFTER 03Z FROM THE
WEST AND NORTHWEST...WHICH MAY REACH OHIO RIVER BY 06Z...AND
OVER MOST OF THE AREA BY 12Z SUNDAY. GREAT UNCERTAINTY ABOUT THE
DEVELOPMENT AND TRACK OF ORGANIZED THUNDERSTORMS...LEADS TO A TAF
FORECAST THAT BRINGS GENERAL MVFR CONDITIONS WITH SHOWERS AND
SCATTERED STORMS FROM WEST TO EAST TONIGHT...ESPECIALLY AFTER
MIDNIGHT.

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

FORECAST CONFIDENCE: HIGH TODAY...LOW TONIGHT.

ALTERNATE SCENARIOS: TIMING AND COVERAGE OF EARLY MORNING FOG WILL
VARY DEPENDING ON CLOUD COVER. THUNDERSTORM COMPLEX OVER AREA
SATURDAY NIGHT IS UNCERTAIN.

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    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 12Z SUNDAY...
IFR POSSIBLE IN ROUNDS OF CONVECTION SUNDAY AND SUNDAY NIGHT.

&&

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

&&

$$
SYNOPSIS...JMV/26
NEAR TERM...JMV
SHORT TERM...26
LONG TERM...ARJ
AVIATION...JMV









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