240
FXUS63 KLMK 021528
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
1128 AM EDT THU JUL 2 2020
FORECAST UPDATE
ISSUED AT 1120 AM EDT THU JUL 2 2020
DEWPOINTS HAVE BEEN SLOW TO FALL THIS MORNING AS MOISTURE CONTINUES
TO POOL NEAR A COUPLE DIFFERENT SFC BOUNDARIES. MID-LEVEL WARMING IS
EXPECTED, BUT NOT IN TIME TO COMPLETELY SHUT DOWN CONVECTIVE
POTENTIAL, WHICH WILL MOST LIKELY BE FOCUSED BY DIFFERENTIAL HEATING
ALONG THE EDGE OF THE DISSIPATING STRATUS SHIELD EXTENDING FROM THE
PENNYRILE INTO SOUTH CENTRAL KENTUCKY. DECIDED TO GO AHEAD AND
INCLUDE A 20 POP FOR ISOLATED POP-UPS FROM THE HOOSIER NATIONAL
FOREST DOWN TOWARD BOWLING GREEN. DEEPER MOISTURE IS LIMITED AND
WARMING ALOFT SHOULD SHUT THIS DOWN BEFORE SUNSET.
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 259 AM EDT THU JUL 2 2020
UPPER LEVEL RIDGING OVER THE CENTRAL US WILL BUILD EASTWARD OVER THE
OHIO VALLEY BRINGING SOME WELL NEEDED DRY WEATHER TO THE REGION.
LATEST SURFACE ANALYSIS SHOWS A SUBTLE BOUNDARY STRETCHED W-E ACROSS
SOUTHERN INDIANA AND CENTRAL KY, WHICH WILL SLOWLY SLIP SOUTHWARD
THROUGHOUT THE DAY. COULD BE A FOGGY START TO THE DAY FOR THOSE
LOCATED VALLEYS AND LOW LYING AREAS, BUT ANY FOG WILL BURN OFF
SHORTLY AFTER SUNRISE GIVING WAY TO MOSTLY SUNNY SKIES WITH LIGHT NE
WINDS. CAMS ARE SUGGESTING A FEW ISOLATED POP UP SHOWERS POSSIBLE
THIS AFTERNOON DURING PEAK HEATING, MAINLY SOUTH OF THE WKY PKWY.
BUT MODEL SOUNDINGS ARE SHOWING A SUBSIDENCE INVERSION FORMING
BETWEEN 800MB TO 700MB, WHICH SHOULD KEEP CONVECTION RATHER SHALLOW.
WITH THIS IN MIND AND THE DECREASE IN OVERALL ATMOSPHERIC MOISTURE
CONTENT, HAVE KEPT ALMOST ALL AREAS DRY TODAY. THICKNESS VALUES
SUGGEST HIGHS TODAY WILL REACH INTO THE UPPER 80S TO LOWER 90S WITH
FRIDAY MORNING MINS DIPPING INTO THE MID TO UPPER 60S.
ALSO, AN AIR QUALITY ALERT HAS BEEN ISSUED TODAY FOR PORTIONS OF
SOUTHERN INDIANA AND A FEW COUNTIES IN NORTH CENTRAL KY INCLUDING
THE LOUISVILLE METRO VALID UNTIL MIDNIGHT TONIGHT. OZONE IS FORECAST
TO BE UNHEALTHY FOR SENSITIVE GROUPS INCLUDING SENIORS, CHILDREN,
AND PEOPLE WITH BREATHING AILMENTS.
LONG TERM
(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 304 AM EDT THU JUL 2 2020
FRIDAY THROUGH SUNDAY NIGHT...
OVERALL, NOT MUCH CHANGE IN THE FORECAST THINKING FOR THIS PART OF
THE FORECAST PERIOD. GLOBAL MODELS REMAIN IN AGREEMENT WITH AN
UPPER LEVEL RIDGE EXTENDING FROM THE SOUTHWESTERN US THROUGH THE
PLAINS AND INTO THE WESTERN GREAT LAKES. MODEL SOUNDINGS SHOW A
VERY STRONG CAP IN PLACE WHICH LOOKS TO KEEP THE AREA DRY ON FRIDAY
AND SATURDAY. AFTERNOON HIGHS IN THE UPPER 80S TO THE LOWER 90S
WILL BE SEEN WITH OVERNIGHT LOWS IN THE UPPER 60S TO THE LOWER 70S.
DEWPOINTS LOOK TO REMAIN IN THE MID-UPPER 60S THROUGH THE PERIOD
WHICH WILL LIKELY PRODUCE HEAT INDEX READINGS EACH AFTERNOON IN THE
LOW-MID 90S.
BY THE LATE WEEKEND, THE RIDGE AXIS IS LIKELY TO RETROGRADE A BIT TO
THE WEST AS A SURFACE AND UPPER LEVEL TROUGH AXIS SETS UP DOWN ALONG
THE NORTHERN GULF COAST STATES. WE MAY START TO SEE SOME DIURNALLY
DRIVEN CONVECTION BY SUNDAY AFTERNOON, THOUGH THE BEST CHANCE OF
THAT LOOKS TO BE ACROSS SOUTHERN KY. GFS IS A BIT MORE ROBUST WITH
POP CHANCES HERE THAN THE EURO WHICH RESULTS IN THE BLENDED POPS
REMAIN A BIT TOO HIGH HERE. IF EURO SOLUTIONS TRENDS HOLD, CAN
EASILY SEE REDUCING POPS CHANCES ESPECIALLY ACROSS SOUTHERN IN AND
THE NORTHERN HALF OF KY SUNDAY AFTERNOON IN FUTURE FORECASTS. HIGHS
ON SUNDAY WILL BE HOT WITH HIGHS IN THE UPPER 80S TO THE LOWER 90S
AGAIN. DEWPOINTS ON SUNDAY MAY BE A BIT HIGHER HERE WITH READINGS IN
THE UPPER 60S TO NEAR 70. THAT COMBINATION WOULD RESULT IN HEAT
INDEX READINGS TOPPING OUT IN THE MID 90S.
MONDAY THROUGH WEDNESDAY...
FOR NEXT WEEK, THE MAIN BELT OF WESTERLIES WILL REMAIN WELL TO OUR
NORTH. THE OVERALL FLOW IN THE FORECASTS HAS BEEN TRENDING TO A
MUCH LESS AMPLIFIED SOLUTION WITH QUASI ZONAL FLOW EXPECTED ACROSS
NORTH AMERICA. WITHIN THIS FLOW, SEVERAL PERTURBATIONS WILL LIKELY
SWING THROUGH WITHIN THE MEAN FLOW. SENSIBLE WEATHER HERE IN THE
OHIO VALLEY WILL BE TYPICAL OF MID-SUMMER WITH WARM TEMPERATURES AND
A CHANCE OF AFTERNOON/EVE SHOWERS AND STORMS. OVERALL SHEAR PROFILE
LOOKS TO REMAIN RATHER WEAK, SO CHANCES OF WELL ORGANIZED CONVECTION
LOOKS TO BE LOW. FOR NOW, CURRENT FORECAST OF 20-40% POPS EACH
AFTERNOON LOOKS GOOD. TEMPERATURES THROUGH THE PERIOD LOOK TO BE
SLIGHTLY ABOVE AVERAGE WITH HIGHS MAINLY IN THE 88-93 DEGREE RANGE.
THURSDAY INTO LATE WEEK...
LATEST GUIDANCE SUGGESTS THAT THE UPPER LEVEL PATTERN OVER THE CONUS
WILL BECOME A BIT MORE AMPLIFIED LATE NEXT WEEK. THE DATA SUGGESTS
THAT ANOTHER RIDGE WEST/TROUGH EAST PATTERN IS LIKELY TO SET UP
ACROSS THE CONUS. THIS WOULD PLACE THE OHIO VALLEY WITHIN A
NORTHWESTERLY FLOW ALOFT. IN SUCH A PATTERN, NUMEROUS PERTURBATIONS
WILL LIKELY BE FLOWING THROUGH THE MEAN FLOW BRINGING PERIODS OF
UNSETTLED WEATHER TO THE REGION. THE EXPECTED CONFIGURATION OF THE
UPPER PATTERN WOULD FAVOR A COOLER/WETTER PATTERN FOR US, POSSIBLY
LINGERING INTO THE MIDDLE OF JULY. THIS IS NOT OVERLY SURPRISING
GIVEN THAT THIS FLOW PATTERN HAS BEEN RATHER DOMINANT FROM THE
SPRING INTO THIS SUMMER.
AVIATION
(12Z TAF ISSUANCE)
ISSUED AT 638 AM EDT THU JUL 2 2020
CLEARING SKIES AND BUILDING HIGH PRESSURE HAVE RESULTED IN EXTENSIVE
VALLEY FOG ACROSS THE EASTERN HALF OF KY AND A MIX OF LOW STRATUS
AND FOG ACROSS THE WESTERN HALF AND SOUTHERN INDIANA. HNB IS
CURRENTLY LIFR IN FG WHILE BWG IS IFR IN LOW STRATUS. EXPECT BOTH
LOCATIONS TO IMPROVE WITHIN AN HOUR OR TWO OF TAF ISSUANCE.
OTHERWISE, VFR CONDITIONS ARE EXPECTED TO PREVAIL UNDER MOSTLY SUNNY
SKIES AND LIGHT NE WINDS.
LMK WATCHES/WARNINGS/ADVISORIES
IN...NONE.
KY...NONE.
UPDATE...RAS
SHORT TERM...CG
LONG TERM...MJ
AVIATION...CG
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