084
FXUS63 KPAH 131125
AFDPAH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
625 AM CDT THU AUG 13 2020
UPDATE
ISSUED AT 625 AM CDT THU AUG 13 2020
UPDATED FOR AVIATION FORECAST DISCUSSION.
SHORT TERM
(TODAY THROUGH SATURDAY NIGHT)
ISSUED AT 349 AM CDT THU AUG 13 2020
STILL DEALING WITH A NEARLY STAGNANT UPPER LEVEL TROUGH/LOW SYSTEM
OVER THE REGION WHICH WILL MOVE VERY LITTLE IN THE NEXT 24-36 HOURS.
VERY DEEP MOISTURE PRESENT IN THE ATMOSPHERE WITH PWS 2.00+ INCHES.
EXPECTING THE COVERAGE OF SHOWERS AND THUNDERSTORMS TO INCREASE
RAPIDLY THROUGH THE MORNING AND INTO THE AFTERNOON HOURS ACROSS THE
AREA. THERE WILL LIKELY BE A SHARP GRADIENT TO THE RAIN CHANCES
ESPECIALLY ON OUR WESTERN BORDER. WE WILL GO WITH SCATTERED WORDING
FOR THE POPS, ESPECIALLY IN THE LATE MORNING INTO THE AFTERNOON.
THIS MORNING, HIGHER POPS WILL BE PLACED ACROSS THE WESTERN TWO
THIRDS OF THE AREA IN ALIGNMENT WITH THE STRONGEST AREA OF LIFT
ASSOCIATED WITH ENERGY ROTATING AROUND THE UPPER LEVEL SYSTEM.
DUE TO THE MOISTURE CONTENT IN THE ATMOSPHERE ALONG WITH VERY WEAK
FLOW ALOFT, WHERE ACTIVITY OCCURS, WE WILL SEE TORRENTIAL DOWNPOURS
WITH HIGH RAINFALL RATES, WHICH MAY LEAD TO LOCALIZED FLOODING
ISSUES. THIS LINES UP WITH WPCS EXCESSIVE RAINFALL OUTLOOK, WHICH
HAS NEARLY OUR ENTIRE AREA IN A MARGINAL RISK. LOCATION OF THE BEST
POPS WILL BE DIFFICULT ESPECIALLY LATER ON THIS AFTERNOON, AS
PLACEMENT OF THE ACTIVITY WILL BE TIED TO OUTFLOW BOUNDARY
INTERACTIONS OF THE INITIAL CONVECTION.
IN ADDITION, SIMILAR TO YESTERDAY, WOULD NOT BE SURPRISED TO SEE
MORE REPORTS OF FUNNEL CLOUDS GIVEN THE UNCHANGED ENVIRONMENT. AS
WAS MENTIONED, THESE FUNNELS RARELY TOUCH DOWN, BUT IF THEY DO,
THEIR LIFE SPAN IS RATHER SHORT AND PRODUCE LITTLE IF ANY DAMAGE.
THE ACTIVITY IS FORECAST TO WEAKEN/DECREASE IN COVERAGE DURING THE
EVENING HOURS. HOWEVER, AFTER MIDNIGHT, WE WILL LIKELY SEE SOME
RENEWED CONVECTION DEVELOP ESPECIALLY EAST OF THE MISSISSIPPI RIVER
AND THE HIGHEST POPS WILL BE ACROSS PARTS OF WEST KY.
ON FRIDAY, OUR FAR WEST/NORTHWEST COUNTIES WILL BEGIN TO DRY OUT A
BIT, AS THE SYSTEM TRIES TO SLIDE A BIT FURTHER EAST. ACROSS THE
REST OF THE AREA, IT WILL BE MUCH OF THE SAME FORECAST, SLOW MOVING
SCATTERED SHOWERS AND STORMS, SOME WITH HEAVY RAINFALL WHICH MAY
CAUSE SOME LOCALIZED FLOODING ISSUES, AS NOT MUCH WILL CHANGE IN THE
ENVIRONMENT. HOWEVER, BY FRIDAY AFTERNOON AND INTO FRIDAY NIGHT, WE
WILL SEE DRIER AIR FILTER IN FROM WEST TO EAST, AS THIS SYSTEM
STARTS MOVING EASTWARD, AS AN AMPLIFIED UPPER RIDGE BUILDS SOUTHEAST
TOWARD THE AREA. THEREFORE, HIGHEST POPS BY FRIDAY AFTERNOON WILL BE
ACROSS SOUTHEAST IL, SOUTHWEST IN AND WESTERN KY. BY FRIDAY NIGHT,
ANY LINGERING RAIN CHANCES WILL BE IN OUR FAR EASTERN COUNTIES.
ON SATURDAY, BELIEVE MOST OF THE AREA SHOULD BE DRY AS A WEAKENING
UPPER LEVEL RIDGE BUILDS SOUTHEAST INTO THE AREA. THE NBM SEEMS TO
HAVE A LOT OF THE 12Z ECMWF INFLUENCE, SO WILL TREND INHERITED POPS
(FAR EAST) DOWN AS MUCH AS POSSIBLE, AS THE 00Z ECMWF IS TRENDING
DRIER LIKE THE OTHER GUIDANCE. BY SATURDAY NIGHT, WE WILL BE IN
NORTHWEST FLOW ALOFT AND WILL HAVE TO WATCH FOR ANY SUBTLE
DISTURBANCES/WEAK SFC FRONT MOVING DOWN INTO THE AREA. HOWEVER, WITH
DEEP MOISTURE LACKING, ANYTHING THAT DEVELOPS SHOULD BE LIMITED IN
COVERAGE, SO LEFT POPS BELOW MENTIONABLE.
LONG TERM
(SUNDAY THROUGH WEDNESDAY)
ISSUED AT 349 AM CDT THU AUG 13 2020
A LARGE MID/UPPER RIDGE WILL PERSIST IN THE WESTERN CONUS IN THE
EXTENDED FORECAST PERIOD, AND AS A MID LEVEL LONGWAVE TROF PERSISTS
OVER EASTERN CANADA, THE PAH FORECAST AREA WILL REMAIN UNDER
NORTHWESTERLY FLOW ALOFT OVERALL. THIS PATTERN IS EXPECTED TO
EVENTUALLY RESULT IN COOLER, DRIER CONDITIONS FOR OUR REGION UNDER
HIGHER SURFACE PRESSURES.
FIRST, SUN WILL BE ONE LAST DAY WITH MAINLY AFTERNOON SCATTERED
SHOWER AND TSTM ACTIVITY BEFORE THE DEEPER MOISTURE IS WEDGED OUT OF
OUR REGION BY A DRIER AIRMASS. STARTING SUN NIGHT, MOISTURE THROUGH
THE COLUMN WILL BE MUCH LOWER THAN IT HAS BEEN, RESULTING IN HIGHS
IN THE MIDDLE 80S AND LOWS MAINLY IN THE 60S. TUE AFTERNOON, A MID
LEVEL SHORTWAVE WILL BE IN THE AREA, BUT WITH MUCH LOWER
PRECIPITABLE WATER, THERE COULD BE SOME CLOUDINESS, BUT NOTHING
MEASURABLE AS FAR AS PCPN IS EXPECTED, WHICH IS WHAT THE NATIONAL
BLEND INDICATED. A REINFORCING SHOT OF DRIER, COOLER AIR IS FORECAST
IN THE WAKE OF THE SHORTWAVE, YIELDING HIGHS AROUND 80 AND LOWS
AROUND 60 (SOME MID/UPPER 50S) BY DAY 7 (WED), WITH DEWPOINTS
COINCIDENT WITH THE LOWS.
AVIATION
ISSUED AT 625 AM CDT THU AUG 13 2020
AFTER THE MORNING FOG BURNS OFF, WE ARE EXPECTING MORE SCATTERED
CONVECTION. IT WILL LIKELY BEGIN BY MID TO LATE MORNING IN THE
WEST AND THEN SPREAD NORTH AND EAST THROUGH THE AFTERNOON. HANDLED
THIS WITH A VCTS AT ALL SITES. CONVECTION WILL LESSEN IN COVERAGE
AND/OR DISSIPATE THIS EVENING. THERE ARE SIGNALS MORE CONVECTION
COULD REDEVELOP DURING THE OVERNIGHT HOURS/TOWARD SUNRISE ON
FRIDAY ESPECIALLY IN OUR EASTERN TERMINALS (KEVV/KOWB).
PAH WATCHES/WARNINGS/ADVISORIES
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
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