901
FXUS61 KRLX 130714
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
314 AM EDT TUE AUG 13 2013
.SYNOPSIS...
COLD FRONT PASSES TUESDAY. COOLER AND DRIER...FRESHER AIR
WEDNESDAY AND THURSDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
SURFACE LOW CURRENTLY OVER NORTHEAST OHIO WITH COLD FRONT STRETCHING
SOUTHWESTWARD THROUGH CINCINNATI TO THE CONFLUENCE OF THE OHIO AND
MISSISSIPPI RIVERS. CONVECTION ONGOING AS FRONTOGENETIC FORCING IS
ON THE INCREASE...AND WILL SEE COVERAGE OF THE CONVECTION INCREASE
CONCURRENTLY. MODELS HAVE THE COLD FRONT MOVING QUICKLY THROUGH THE
CWA TODAY...AND SHOULD BE CLEAR OF THE MOUNTAINS LATER THIS
AFTERNOON. A LINGERING STRATUS DECK MY BE ON THE SLOWER TO ERODE
BEHIND THE FRONT.
NORTHERN SECTIONS OF THE CWA HAVE RECEIVED TRAINING THUNDERSTORMS
OVER THE LAST FEW HOURS...AND WILL CONTINUE TO BE SENSITIVE TO
ADDITIONAL RAINFALL THROUGH THE MORNING. WPC CURRENTLY HAS THE AREA
IN SLIGHT RISK FOR EXCESSIVE RAINFALL. SEVERE THUNDERSTORMS NOT
EXPECTED. ALTHOUGH WIND GUST OR TWO IS POSSIBLE.
POST FRONTAL CONDITIONS COULD SUPPORT AN ISOLATED SHOWER OR
TWO...AND KEEP THE SLIGHT CHANCE POPS GOING INTO THIS EVENING FOR
PORTIONS OF THE LOWLANDS AND INTO THE MOUNTAINS. OTHERWISE...THIS
WILL BE A CLEAN SWEEP OF THE EXISTING TROPICAL AIRMASS IN FAVOR OF
COOLER AND DRIER CONDITIONS. DEWPOINTS WILL DROP INTO THE 50S
TODAY...AND SHOULD BE ABLE TO RADIATE TONIGHT ACROSS THE LOWLANDS.
AS A RESULT...WIDESPREAD 50S LIKELY. HIGH PRESSURE WILL BUILD IN
FROM THE WESTERN GREAT LAKES.
TRICKY CLOUD FORECAST FOR THE MOUNTAINS TONIGHT WITH THE
AFOREMENTIONED STRATUS DECK TRYING TO HOLD IN PLACE. LOWLAND AREAS
SHOULD BEGIN TO FOG IN THE RIVER VALLEYS LATER TONIGHT...BUT COULD
TAKE SOME TIME TO DO SO IN THE MOUNTAIN VALLEYS.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY/...
IT HAS BEEN A VERY WET SUMMER SO FAR...BUT THIS PERIOD FROM
WEDNESDAY THROUGH FRIDAY WILL BE DRY AS CANADIAN HIGH PRESSURE
RIDGES SOUTHEASTWARD ON THE BACK SIDE OF THE STRONG EASTERN CANADIAN
UPPER LOW. THE AIR WILL BE QUITE COOL INITIALLY FOR THIS TIME OF
YEAR ON WEDNESDAY AND WEDNESDAY NIGHT...WITH TEMPERATURES WELL BELOW
NORMAL. HOWEVER...MODEL GUIDANCE DOES NOT INDICATE ANY RECORD
BREAKING LOW TEMPERATURES WITH THIS COOL OUTBREAK. TEMPERATURES WILL
SLOWLY MODERATE THURSDAY AND FRIDAY AS THE UPPER LOW BEGINS TO LIFT
OUT AND SUNSHINE WORKS ON THE AIRMASS.
THERE IS EXCELLENT AGREEMENT AMONG THE MODELS IN THE MASS FIELDS...
...WHICH HAS HIGH PRESSURE DOMINATING. WHILE ALL THE MODELS ARE
TRENDING TO AN UPPER LOW DEVELOPING OVER THE OHIO VALLEY BY
SATURDAY...THE GFS LOOKS TO BRING MOISTURE BACK TOO FAST ON FRIDAY. IT
WILL LIKELY TAKE UNTIL FRIDAY NIGHT FOR ENOUGH MOISTURE TO WORK BACK
IN OVER THIS STRONG HIGH PRESSURE FOR RAIN.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
FOLLOWED WPC THINKING WITH SOME TWEAKS. SURFACE HIGH PRESSURE
WILL PUSH EAST ACROSS OUR NORTHERN COUNTIES THURSDAY NIGHT INTO
FRIDAY. HOWEVER...MODEL CONSENSUS SUGGESTS A FEW MID-LEVEL
SHORTWAVES MAY TRACK EAST ACROSS THE AREA DURING THIS PERIOD.
AN UPPER LEVEL LOW/TROF IS THEN EXPECTED TO DEVELOP TO OUR WEST ON
FRIDAY AND MOVE EAST LATE IN THE PERIOD.
EXPECT MAINLY DIURNAL PRECIP CHANCES WILL GIVE WAY TO BETTER CHANCES
STARTING SATURDAY...EXTENDING INTO MONDAY.
&&
.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
ONGOING CONVECTION ACROSS THE AREA EXPECTED TO INCREASE IN
COVERAGE THROUGH DAWN AS THE COLD FRONT MOVES INTO SOUTHEAST OHIO.
LOTS OF TEMPO GROUPS REQUIRED FOR CURRENT CONVECTION TRENDS ACROSS
THE AREA. PKB AND CKB UNDER THE GUN CURRENTLY AND WILL BOUNCE
BETWEEN LIFR AND MVFR THROUGH DAWN.
EXPECT THE OTHER SITES TO GET INTO THE ACTION SOON. SAME SITUATION
EXPECTED WITH BOUNCING OBSERVATIONS IN AND OUT OF CONVECTION.
FIGURE CEILINGS SHOULD DROP WITH THE WIDESPREAD RAIN THROUGH THE
DAY...AND CARRY PREVAILING MVFR CONDITIONS FROM THAT STAND POINT.
WESTERN TERMINALS TO SCATTER OUT OF MVFR IN THE LATER AFTERNOON
AFTER 18Z OR SO...WITH CRW FOLLOWING. MOUNTAIN TERMINALS EXPECTED
WORSEN TO IFR/LIFR CEILINGS BEYOND 00Z WEDNESDAY IN WEAK LOW LEVEL
UPSLOPE WITH FORECAST SOUNDING SHOWING SATURATION IN THE LOWEST
100MB.
LOWLAND AREAS TO CLEAR OUT...AND MAY SEE THE START OF FOG TOWARDS
06Z WITH LOWER TEMPERATURES EXPECTED.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z WEDNESDAY...
FORECAST CONFIDENCE: LOW TO MEDIUM.
ALTERNATE SCENARIOS: CONVECTION TIMING TO VARY. TIMING OF MVFR
DECK FORMATION TO VARY. IFR/LIFR DECK IN QUESTION IN THE MOUNTAINS
THIS EVENING.
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 TUE 08/13/13
UTC 1HRLY 08 09 10 11 12 13 14 15 16 17 18 19
EDT 1HRLY 04 05 06 07 08 09 10 11 12 13 14 15
CRW CONSISTENCY H H H H M M L H H H H M
HTS CONSISTENCY M M M H M L M M M M M M
BKW CONSISTENCY M M M M M H H M H H M M
EKN CONSISTENCY M M L M M L M M M M H H
PKB CONSISTENCY M M M M M H M H H M M H
CKB CONSISTENCY M H H H H H M H H H H H
AFTER 06Z WEDNESDAY...
LIFR FOG POSSIBLE WEDNESDAY NIGHT.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...FLASH FLOOD WATCH UNTIL 11 AM EDT THIS MORNING FOR WVZ005>011-
013>020-024>040-046-047.
OH...FLASH FLOOD WATCH UNTIL 11 AM EDT THIS MORNING FOR OHZ066-067-
075-076-083>087.
KY...FLASH FLOOD WATCH UNTIL 11 AM EDT THIS MORNING FOR KYZ101>103-
105.
VA...FLASH FLOOD WATCH UNTIL 11 AM EDT THIS MORNING FOR VAZ003-004.
&&
$$
SYNOPSIS...JMV/26
NEAR TERM...26
SHORT TERM...JMV
LONG TERM...JSH
AVIATION...26