Area Forecast Discussion
Issued by NWS Charleston, WV

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FXUS61 KRLX 210812
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
412 AM EDT THU AUG 21 2014

.SYNOPSIS...
ABUNDANT MOISTURE REMAINS IN PLACE WITH A FRONT REMAINING NEARLY
STATIONARY TO THE WEST THROUGH THE WEEKEND.  HIGH PRESSURE WILL TRY
TO NOSE IN FROM THE NORTHEAST EARLY NEXT WEEK AS UPPER RIDGE BUILDS.

&&

.NEAR TERM /THROUGH TODAY/...
FORECAST FACTORS THIS PERIOD INCLUDE WHERE WARM FRONT SETTING UP W
OF THE AREA WILL BE...WHERE CONVECTIVE COMPLEXES FORMING ALONG AND
ON COOL SIDE OF THE FRONT WILL TRACK...AND THE TIMING OF THESE
COMPLEXES.

ONE SUCH COMPLEX ALONG THE FRONT AND 310K PRESSURE GRADIENT SHOULD
TRACK MAINLY S OF THE CWA THIS MORNING AS LONG AS IT CONTINUES
TURNING RIGHT.  SECOND AREA OF RAINFALL FORMING FARTHER N AND MORE
STRATIFORM IN NARROW STRIP THROUGH CHICAGO ALONG A SECOND PRESSURE
GRADIENT ON THE 300K AND 305K SURFACES ALSO MOVING SEWD AND SHOULD
ARRIVE IN FCST AREA AFTER DAYBREAK THIS MORNING AND TRAVERSE THROUGH
THE MIDDAY HOURS AND INTO THIS AFTERNOON.  THIS IS NOT THE MOST
FAVORED TIME OF DAY FOR WARM ADVECTION PRECIPITATION / CONVECTION SO
TOUGH TO FIGURE WHAT THE COVERAGE WILL BE.

ANOTHER COMPLEX WAS STARTING TO GO OFF UPSTREAM OF THAT...EITHER
REMNANTS OF IT OR LATE DAY CONVECTION FIRING IN THE WAKE OF THE
AFTERNOON PRECIPITATION GIVEN ANY BREAKS OF SUNSHINE...WARRANT
HOLDING THE HIGH CHANCE TO LIKELY POPS GOING INTO THE EVENING BEFORE
TRAILING OFF NW TO SE.  TIMING OF PRECIPITATION ALONG A WARM FRONT
GETS DICEY QUICKLY WITH TIME EVEN BY THE END OF THE NEAR TERM...BUT
MODEL DATA SUGGESTS ANOTHER COMPLEX APPROACHING FROM THE NW AS DAWN
FRI APPROACHES.  AREAS OF POST RAIN LOW CLOUDS AND FOG ARE LIKELY IN
THE INTERIM OVERNIGHT TONIGHT.

MET REFLECTS RAINY DAY TODAY IN ITS LOW TEMPERATURE GUIDANCE.  OPTED
TO STAY CLOSE TO PREVIOUS PACKAGE...WHICH IS BETWEEN IT AND THE
HIGHER MAV.  PRECIPITATION IS LIKELY TO ALLOW FOR BREAKS OF SUNSHINE
THIS AFTERNOON ALTHOUGH IT WILL NOT FALL APART AS QUICKLY AS IT DID
WED MORNING.  LOWS TONIGHT LOOKED GOOD IN LIGHT OF LATEST BIAS
CORRECTED GUIDANCE.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...
UNSETTLED WEATHER CONTINUES IN THE SHORT TERM PERIOD...WITH SEVERAL
UPPER WAVES MOVING THROUGH THE AREA IN THE NORTH/NORTHWESTERLY FLOW
ALOFT. ONE SUCH WAVE EXPECTED FRIDAY THROUGH FRIDAY NIGHT...FOLLOWED
BY ADDITIONAL WAVES OVER THE WEEKEND. HEAVY RAIN IS EXPECTED ACROSS
THE AREA FRIDAY AND FRIDAY NIGHT...PARTICULARLY ACROSS THE
NORTH...WITH PLENTY OF UPPER AIR SUPPORT IN PLACE DURING THE PERIOD.
PW VALUES FRIDAY...PROGGED TO BE AROUND 1.8 INCHES...AND WPC HAS
PLACED THE ENTIRE CWA IN A SLIGHT RISK FOR EXCESSIVE RAINFALL FRIDAY
NIGHT AND SATURDAY. WITH PLENTY OF TIME LEFT TO ISSUE ANY WATER
HEADLINES...WILL CONTINUE TO HIGHLIGHT THE ISSUE IN THE HWO.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
WILL SLOWLY TRANSITION TO A DRIER REGIME AS THE UPPER HEIGHTS
SLOWLY BUILD OVER THE AREA COURTESY OF THE STOUT RIDGE AMPLIFYING
OVER MS VALLEY. THE OPPRESSIVE HEAT SHOULD STAY W OF THE AREA BUT
WILL STILL BE CONTENDING WITH THE MUGGIES WITH TEMPS RUNNING 3 TO
5 DEGREES ABOVE NORMAL DAY AND NIGHT.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
SOME DENSE VALLEY FOG OVERNIGHT INTO THU MORNING...BUT PATCHY IFR
AND MVFR CLOUD WILL RAISE/KEEP VSBY MVFR OR BETTER AT TIMES.  ALTOCU
WILL ALSO HAVE MITIGATING AFFECT ON FOG...ESPECIALLY SOUTHERN TAF
SITES.  AS A RESULT...HAVE HIT THE DENSE FOG HARDEST IN THE CODE FOR
THE NRN SITES.

CLUSTERS OF SHOWERS AND THUNDERSTORMS WILL RIDE E TO SEWD ALONG A
WARM FRONT SET UP ACROSS THE LOWER OHIO VALLEY THIS TAF PERIOD.  ONE
CLUSTER WILL CROSS DURING THE DAY THU.  SINCE THE DAYTIME HOURS ARE
NOT A FAVORABLE TIME FOR CONVECTION ASSOCIATED WITH WARM FRONT...IT
IS DIFFICULT TO DETERMINE HOW MUCH AREA COVERAGE THERE WILL BE...BUT
THERE SHOULD BE A DECREASE IN COVERAGE THU NT.  THE NEXT COMPLEX
SHOULD ARRIVE FRI MORNING...BEYOND THE CURRENT 24 HR TAF PERIOD.
POST RAIN LOW CLOUD AND FOG MAY FORM IN THE INTERIM.

SFC FLOW WILL BE LIGHT AND VARIABLE...MAINLY W...WHILE LIGHT TO
MODERATE W FLOW ALOFT BECOMES NW THU.

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

FORECAST CONFIDENCE: LOW TO MEDIUM.

ALTERNATE SCENARIOS: TIMING AND INTENSITY OF FOG WILL VARY IN
RESPONSE TO CHANGING CIGS INCLUDING MVFR TO IFR CIGS.  IFR IS
POSSIBLE BUT DIFFICULT TO TIME IN SHOWERS AND THUNDERSTORMS THU.
AREAS OF POST RAIN FOG AND LOW CLOUD MAY FORM THU NT.

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 08/21/14
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  M    M    M    H    L    L    L    L    M    H    L    M
HTS CONSISTENCY  H    H    M    M    M    H    H    M    M    M    M    M
BKW CONSISTENCY  H    H    M    M    M    H    H    M    M    M    M    M
EKN CONSISTENCY  L    L    L    L    L    L    L    L    L    H    H    H
PKB CONSISTENCY  L    L    L    L    L    L    L    L    M    H    H    H
CKB CONSISTENCY  L    L    L    L    L    L    L    M    H    M    M    M

AFTER 06Z FRIDAY...
IFR CONDITIONS POSSIBLE IN ANY ROUND OF CONVECTION FRI THROUGH FRI
NT.  LATE NIGHT AND EARLY MORNING POST RAIN FOG AND STRATUS ALSO
POSSIBLE EARLY FRI MORNING AND SAT MORNING.

&&

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

&&

$$
SYNOPSIS...JS/ARJ/30
NEAR TERM...JS/ARJ/TRM
SHORT TERM...30
LONG TERM...30
AVIATION...TRM





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