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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KRLX 211518
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
1118 AM EDT TUE MAY 21 2013

.SYNOPSIS...
AFTERNOON CONVECTION TUESDAY AND WEDNESDAY. COLD FRONT APPROACHES
WEDNESDAY AND MOVES ACROSS THURSDAY. COOLER HIGH PRESSURE FRIDAY AND
THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
1100 AM MESOSCALE UPDATE...

TRICKY FCST FOR THIS AFTN REGARDING CONVECTION POTENTIAL. AS OF
15Z...TRACKING OUTFLOW BOUNDARY FROM LAST NIGHT CONVECTION THAT HAS
RACED E INTO W ZONES...CLOCKED ARND 50KTS. NOT SEEING MUCH IN THE
WAY OF DEVELOPMENT ALONG THIS LLVL CONVERGENCE ZONE CURRENTLY...WITH
MOST OF CU ACROSS SE KY AND SOME ACROSS S COAL FIELDS. MDL SOUNDINGS
SHOW AREA STILL CAPPED EXCEPT WEAKLY CAPPED ACROSS MTNS. WILL BRING
IN LOW POPS NEXT FEW HRS TO ACCOUNT FOR POSSIBLE DEVELOPMENT ALONG
THIS BOUNDARY AS CAP ERODES WITH HEATING. WILL ALLOW FOR ADDITIONAL
DEVELOPMENT IN N MTNS ON RIDGES WHERE DEVELOPING S TO SE LLVL FLOW
THIS AFTN SHOULD ALLOW FOR SOME AFTN DEVELOPMENT.

OF BIGGER CONCERN IS CONVECTIVE LINE GETTING GOING ACROSS W KY
WITH SUBTLE S/W TROF. NAM...RUC...AND HI RES WRF MDLS ARE PICKING
UP ON THIS AND ALLOWING FOR IT TO GET INTO CWA LATER THIS AFTN.
WILL ALLOW FOR LKLY POPS TO ENCROACH USING CONSENSUS SFC MOISTURE
CONVERGENCE AND MID LVL OMEGA FIELDS FOR GENERAL TIMING. HAVE THIS
ENTERING W ZONES BY 20Z IF NOT A LITTLE SOONER...INTO CENTRAL
ZONES BY 22Z...AND EXITING MTNS SHORTLY AFTER BY 01Z. MDL
SOUNDINGS SHOW MEAGER AMNTS OF MOISTURE WHICH IS REALLY THE ONLY
LIMITING FACTOR. MDLS GENERATE 2 TO 3K SFC CAPE THIS AFTN WITH
RELATIVELY LOW FRZ LVLS AMID STEEP LAPSE RATES. SO THERE IS A HAIL
CONCERN. GENERAL FLOW ALOFT IS RATHER WEAK...HOWEVER THERE IS
SOMEWHAT GREATER OF A CONCERN FOR DOWNBURSTS GIVEN SFC TO H7 THETA
DIFF AND AMNT OF DOWNDRAFT CAPE PROGGED. MDL SOUNDINGS SHOW A
DECENT LLVL DRY LYR TO CONTRIBUTE TO THIS. CODED UP SMALL HAIL AND
GUSTY WIND WORDING IN GRIDS. SPC DOES NOT HAVE AREA HIGHLIGHTED
WITH ANYTHING ATTM THOUGH.
-- End Changed Discussion --

&&

.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
SHORT TERM PERIOD STARTS OUT WITH THE CWA IN THE WARM SECTOR OF LOW
PRESSURE SYSTEM THAT WILL PUSH EAST ACROSS THE GREAT LAKES REGION
EARLY IN THE PERIOD. CONDITIONS WILL CONTINUE TO BE WARM AND HUMID
ON WEDNESDAY IN THE SOUTHERLY FLOW OUT AHEAD OF THE APPROACHING COLD
FRONT AND UPPER TROUGH. TEMPERATURES ON WEDNESDAY ARE NOT EXPECTED TO
BE AS HIGH AS ON TUESDAY...DUE TO EXPECTED CLOUD COVER...AND
PRECIPITATION.

WEDNESDAY WILL SEE INCREASED SHOWER AND THUNDERSTORM ACTIVITY AS THE
COLD FRONT AND UPPER TROUGH PUSHES CLOSER TO THE AREA. SEVERAL
EMBEDDED SHORTWAVES WILL ROUND THE BASE OF THE TROUGH...AND MOVE
NORTHEAST THROUGH THE AREA. STILL LOOKING LIKE THERE COULD BE SEVERE
WEATHER ON WEDNESDAY...PARTICULARLY IN SOUTHEAST OHIO...EASTERN
KY...AND WV COUNTIES NEAR TO THE OHIO RIVER AS GOOD UPPER
DYNAMICS...INSTABILITY...AND 0-6KM BULK SHEAR OF 30+ KTS WILL EXIST.
STRONG/DAMAGING WINDS...AND HAIL WILL BE PRIMARY THREATS...WITH
FZLVS PROGGED TO BE AROUND 11K FEET. COLD FRONT WILL END UP
SOMEWHERE ALONG/NEAR SOUTHEAST OHIO ZONES BY 12Z THURSDAY.

UPPER TROUGH WILL PUSH THROUGH THE AREA THURSDAY AND
FRIDAY...KEEPING A MENTION OF SHOWERS AND THUNDERSTORMS IN THE
FORECAST THROUGH AT LEAST THURSDAY NIGHT. MUCH COOLER AND DRIER AIR
IS EXPECTED TO WORK ITS WAY INTO THE CWA FOR THE WEEKEND AS HIGH
PRESSURE ACROSS THE NORTH BUILDS IN.

&&

.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
HAVE GENERALLY FOLLOWED WPC THINKING FOR THIS PORTION OF THE
FORECAST.

HIGH PRESSURE WILL BE IN CONTROL OF THE WEATHER ACROSS THE AREA INTO
SUNDAY NIGHT.  HOWEVER...MODELS SUGGEST A FEW WEAK MID-LEVEL
SHORTWAVE MAY MOVE SOUTHEAST.  BELIEVE AREA SHOULD REMAIN DRY...WITH
A FEW MORE CLOUDS BEGINNING SATURDAY NIGHT

A WARM FRONT WILL THEN DEVELOP AND APPROACH THE REGION ON MONDAY. AS
A RESULT...THERE WILL BE A CHANCE OF SHOWERS AND STORMS MONDAY AND
TUESDAY...MAINLY DURING THE AFTERNOON AND EVENING HOURS.

TEMPERATURES ON SATURDAY SHOULD BE NEAR NORMAL WITH DAYTIME HIGHS IN
THE 70S ACROSS THE LOWLANDS...WITH 60S ACROSS THE HIGHER
ELEVATIONS.  AS THE HIGH PUSHES EAST ON SUNDAY...EXPECT TEMPERATURES
TO WARM TO SLIGHTLY ABOVE NORMAL VALUES MONDAY AND TUESDAY.

&&

.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
-- Changed Discussion --
PATCHY DENSE FOG WILL BURN OFF BY MID MORNING. CUMULUS CAN THEN BE
EXPECTED TODAY...WITH AFTERNOON AND EVENING THUNDERSTORMS POSSIBLE.
PATCHY DENSE FOG CAN BE EXPECTED AGAIN TONIGHT IN VALLEYS IN THE
MOUNTAINS AND JUST WEST OF THE MOUNTAINS...ESPECIALLY IN AREAS THAT
RECEIVE SHOWERS TODAY. FURTHER WEST AND ON HILLTOPS...WINDS SHOULD
PREVENT THE DENSE FOG.

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

FORECAST CONFIDENCE...HIGH.

ALTERNATE SCENARIOS: TIMING OF FOG DISSIPATION COULD VARY. TIMING OF
SHOWERS AND THUNDERSTORMS THIS AFTERNOON COULD VARY.

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       14   15   16   17   18   19   20   21   22   23   00   01
EDT 1HRLY       10   11   12   13   14   15   16   17   18   19   20   21
CRW CONSISTENCY  H    H    H    H    H    H    H    H    H    H    H    H
HTS CONSISTENCY  H    M    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 WEDNESDAY...
IFR CONDITIONS POSSIBLE WEDNESDAY WITH SHOWERS AND THUNDERSTORMS.
-- End Changed Discussion --

&&

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

&&

$$
SYNOPSIS...RPY/SL
NEAR TERM...RPY/30
SHORT TERM...SL
LONG TERM...JSH
AVIATION...RPY