132
FXUS63 KLMK 200125
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
925 PM EDT FRI AUG 19 2022
FORECAST UPDATE
ISSUED AT 925 PM EDT FRI AUG 19 2022
EARLIER CONVECTION OVER SOUTH-CENTRAL KENTUCKY FADED AWAY NICELY
AROUND SUNSET AS HEATING WAS LOST. PREVIOUS FORECAST OF A QUIET
OVERNIGHT REMAINS WELL ON TRACK, SO THIS UPDATE WILL BE LIMITED TO
TWEAKING HOURLY TRENDS FOR THE HI-RES PRODUCTS.
SHORT TERM
(THIS EVENING THROUGH SATURDAY)
ISSUED AT 325 PM EDT FRI AUG 19 2022
A SHORTWAVE WORKING FROM THE TENNESSEE VALLEY NORTHEAST TOWARDS NEW
ENGLAND IS CUTTING THROUGH CENTRAL KENTUCKY. THIS IS HELPING TO FIRE
CONVECTION SOUTH OF THE KENTUCKY PARKWAYS. NOT EXPECTING ANYTHING
SEVERE, BUT SOME EMBEDDED THUNDER WILL BE POSSIBLE IN THESE ISOLATED
TO SCATTERED SHOWERS WHICH WILL BEGIN TO FADE WITH THE SETTING SUN.
TONIGHT, A STACKED LOW PRESSURE SYSTEM, WHICH IS EMBEDDED IN A LARGE
UPPER TROUGH, WILL CONTINUE TO THE SOUTHEAST FROM ITS CURRENT
LOCATION NEAR THE MINNESOTA/IOWA BORDER, BUT BEFORE ITS INFLUENCE IS
FELT IN THE LOWER OHIO VALLEY, NEAR SURFACE PRESSURE GRADIENTS WILL
BE WEAK, KEEPING WINDS LIGHT TO CALM OVERNIGHT. TEMPERATURES WILL
COOL INTO THE MID 60S IN MOST PLACE WHILE REMAINING SLIGHTLY WARMER
IN LOUISVILLE.
TOMORROW, THE UPPER LOW WILL BEGIN TO OPEN AS THE COLD FRONT BECOMES
MORE DISORGANIZED WITH MULTIPLE IMPULSES RADIATING FROM THE SYSTEM.
AROUND MID-DAY, ONE OF THESE SHORTWAVES WILL TAKE ADVANTAGE OF THE
MOISTURE AVAILABLE WITH SOUTHERN GULF MOISTURE MEETING WITH MOISTURE
TRAILING THE LOW PRESSURE SYSTEM OVER THE CWA. EXPECTING PWATS TO
INCREASE TO AROUND 1.5 INCHES. THE EVENING HOURS WILL LIKELY SEE
VALUES CLIMB TO NEAR 1.6 TO 1.7 INCHES. SHEAR REMAINS WEAK AND
MLCAPE VALUES REACH NEAR 1,500 K/KG, BUT MANY SOUNDING PLACE A WARM
LAYER NEAR 700MB. THIS WILL LIMIT STORM GROWTH, SO ISOLATED TO
SCATTERED SHOWERS WITH A MIX OF GARDEN VARIETY THUNDERSTORMS ARE
EXPECTED. THE NAM, AS IT OFTEN DOES, WAS RUNNING BULLISH WITH
INSTABILITY, BUT THIS WAS DUE TO THE NAM KEEPING THE REGION FAIRLY
SUNNY TOMORROW. BELIEVE CUMULUS WILL BEGIN BUILDING DURING THE LATE
AFTERNOON, SO BELIEVE IT'S THE OUTLIER. 5 TO 10 MPH SOUTHERN WINDS
SHOULD HELP LIFT TEMPERATURES TO THE MID TO UPPER 80S.
LONG TERM
(SATURDAY NIGHT THROUGH FRIDAY)
ISSUED AT 300 PM EDT FRI AUG 19 2022
=====================================
SYNOPTIC OVERVIEW
=====================================
CLOSED UPPER LOW OVER MINNESOTA IS FORECAST TO TRANSITION INTO AN
OPEN WAVE EARLY IN THE PERIOD. THIS FEATURE WILL SLOWLY MOVE
THROUGH GREAT LAKES THIS WEEKEND AND THEN INTO THE NORTHEASTERN US
BY NEXT WEEK. OUR REGION WILL BE ON THE SOUTHERN EDGE OF THIS WAVE,
WITH DEEP MOISTURE POOLING OUT AHEAD OF IT RESULTING IN UNSETTLED
WEATHER IN THE SUNDAY/MONDAY TIME FRAME. ASSOCIATED SURFACE COLD
FRONT IS FORECAST TO PUSH THROUGH ON MONDAY WITH DRIER CONDITIONS
SHOWING UP BY TUESDAY. FOR THE MID-LATE WEEK PERIOD, AN UPPER LEVEL
TROUGH AXIS IS LIKELY TO REMAIN ANCHORED OVER THE EASTERN US WITH
THE OHIO VALLEY REMAINING IN A NORTHWESTERLY FLOW ALOFT. MAIN BELT
OF WESTERLIES WILL REMAIN WELL NORTH OF THE OHIO VALLEY WHILE A
STALLED OUT COLD FRONT AND POOLING MOISTURE WILL BE FOUND ACROSS
MUCH OF THE SOUTHEASTERN US.
=====================================
METEOROLOGICAL DISCUSSION
=====================================
SATURDAY NIGHT - MONDAY NIGHT:
AFOREMENTIONED CLOSED UPPER LOW OVER MN CURRENTLY IS FORECAST TO
TRANSITION INTO AN UPPER LEVEL WAVE. THE LATEST 19/12Z SUITE OF
GUIDANCE CONTINUES TO AGREE WITH THIS WAVE BEING PROGRESSIVE IN
NATURE, BUT WILL LIKELY BE SLOW TO MOVE THROUGH THE GREAT LAKES THIS
WEEKEND. AHEAD OF THE SYSTEM, BROAD/DEEP SOUTHWESTERLY FLOW WILL
ADVECT DEEPER MOISTURE INTO THE REGION. PWATS LOOK TO INCREASE ABOVE
1.5 INCHES BY SATURDAY NIGHT AND MAY APPROACH 1.75 INCHES BY SUNDAY
AFTERNOON.
SOUTHERN EDGE OF THE UPPER TROUGH AXIS WILL APPROACH THE REGION ON
SUNDAY. MODEL CROSS SECTIONS SUGGEST PARTLY/MOSTLY CLOUDY SKIES
WHICH WILL HAVE AN EFFECT ON INSTABILITY. ENOUGH SUNSHINE SHOULD
RESULT IN MLCAPE VALUES PUSHING INTO THE 1500-2000 J/KG RANGE BY THE
AFTERNOON. OVERALL SHEAR PROFILES REMAIN RATHER MARGINAL, BUT
SHOULD BE ENOUGH TO SUPPORT SOMEWHAT ORGANIZED MULTI-CELLULAR
CONVECTION. BASED ON THE SHEAR/INSTABILITY PARAMETERS, ISOLATED
DAMAGING WIND GUSTS WOULD BE THE PRIMARY THREAT. HEAVY RAINFALL IS
LIKELY AS WELL GIVEN THE HIGH PWATS. HOWEVER, ENVIRONMENTAL
STEERING FLOW LOOKS TO REMAIN PROGRESSIVE ENOUGH TO KEEP THE
RESIDENCE TIME OF STORMS IN ANY ONE LOCATION FAIRLY LOW.
NONETHELESS, SOME ISOLATED HYDRO ISSUES COULD CROP UP, ESPECIALLY IN
AREAS THAT SEE REPEATED RAINFALL. TEMPERATURES HERE WILL BE
DIFFICULT TO FORECAST BASED ON CLOUDS/PRECIP. HOWEVER, ENSEMBLE
GUIDANCE HERE SUGGESTS LOW-MID 80S FOR HIGHS WITH OVERNIGHT LOWS IN
THE MID-UPPER 60S.
AS THE UPPER TROUGH AXIS SHIFTS EAST ON MONDAY, ASSOCIATED SURFACE
COLD FRONT WILL SWING THROUGH THE REGION AND BRING AN END TO THE
SHOWERS/STORMS FROM NW TO SE. HIGHS WILL GENERALLY BE IN THE LOWER
80S, THOUGH SOME UPPER 70S WILL BE POSSIBLE IN OUR NORTHERN SECTIONS
OF THE BLUEGRASS REGION. LOWS MONDAY NIGHT SHOULD DROP INTO THE
UPPER 50S TO THE LOWER 60S.
TUESDAY - FRIDAY:
BEHIND THE FRONT, NORTHWEST FLOW WILL DOMINATE OUR WEATHER PATTERN
FOR MUCH OF THE REMAINDER OF THE WEEK. OVERALL, THE GUIDANCE
CONTINUES TO TREND SLIGHTLY DRIER WITH EACH RUN. GIVEN THESE
TRENDS, HAVE BACKED OFF THE NBM POPS FOR WEDNESDAY. WILL KEEP
ISOLATED POPS IN FOR THURSDAY, BUT I HAVE A FEELING WE'LL BE ABLE TO
BACK OFF THOSE AS WELL IN SUBSEQUENT FORECASTS GIVEN THAT FORCING
ACROSS THE REGION WILL BE VERY WEAK. WE MAY BE ABLE TO GET BACK
INTO SOME SORT OF DIURNALLY DRIVEN CONVECTION BY FRIDAY AFTERNOON.
HOWEVER, OVERALL CONFIDENCE IS RATHER LOW.
HIGHS DURING THE PERIOD WILL GENERALLY BE IN THE 83-88 DEGREE RANGE
FOR HIGHS WITH OVERNIGHT LOWS 63-68 DEGREE RANGE.
=====================================
WEATHER IMPACTS/RISKS
=====================================
IN TERMS OF HAZARDOUS WEATHER, SCATTERED TO NUMEROUS THUNDERSTORMS
ARE EXPECTED ON SUNDAY. THE STRONGEST STORMS WILL BE IN THE
AFTERNOON/EVENING WITH THE THREAT OF ISOLATED DAMAGING WINDS. IF A
STRONGER CORE IN A STORM WERE TO DEVELOP, SOME MARGINALLY SEVERE
HAIL WOULD BE POSSIBLE. ANY STORM WILL BE CAPABLE OF PRODUCING
LOCALLY HEAVY RAINFALL. HOWEVER, STORM MOTIONS SHOULD BE FAST
ENOUGH TO LIMIT THE RESIDENCE TIME OVER ANY ONE AREA TO PRECLUDE
FLOODING. HOWEVER, IN AREAS THAT MAY SEE REPEATED RAINFALL, AN
ISOLATED RISK OF HYDROLOGICAL ISSUES IS POSSIBLE.
=====================================
FORECAST CONFIDENCE
=====================================
OVERALL FORECAST CONFIDENCE FOR THE SATURDAY NIGHT - MONDAY NIGHT
TIME FRAME IS MEDIUM-HIGH. CONFIDENCE IN THE TUESDAY THROUGH
FRIDAY PERIOD REMAINS AT THE UPPER END OF THE MEDIUM RANGE.
AVIATION
(00Z TAF ISSUANCE)
ISSUED AT 715 PM EDT FRI AUG 19 2022
TRANSITIONING BACK INTO MORE OF A SUMMER REGIME TONIGHT, WITH LIGHT
WINDS AND MAINLY MID-LEVEL CLOUDS EXPECTED ACROSS THE BOARD.
DEWPOINTS HAVEN'T YET COME UP TO BE CONCERNED ABOUT FOG, SO WE'LL
STAY VFR. WINDS PICK UP OUT OF THE S-SW LATE SAT MORNING, WITH
ENOUGH MID-LEVEL CLOUDS FOR A CEILING UNDER CONTINUED WARM
ADVECTION. COULD SEE A FEW SHOWERS OR T-STORMS BREAK OUT AROUND MID-
AFTERNOON, BUT CONFIDENCE IS NOT HIGH AND IMPACTS WILL BE BRIEF. FOR
NOW WILL HANDLE THAT WITH A WINDOW OF PROB30 FOR ALL BUT HNB.
LMK WATCHES/WARNINGS/ADVISORIES
IN...NONE.
KY...NONE.
UPDATE...RAS
SHORT TERM...KDW
LONG TERM...MJ
AVIATION...RAS
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