Area Forecast Discussion
Issued by NWS Louisville, KY
Issued by NWS Louisville, KY
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049 FXUS63 KLMK 100700 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 300 AM EDT Mon Jun 10 2024 .KEY MESSAGES... * Below normal temperatures and humidity Monday and Tuesday. * A warming trend with hot and dry conditions likely for late this week into next weekend. && .SHORT TERM /THROUGH TONIGHT/... Issued at 258 AM EDT Mon Jun 10 2024 Latest fog product view on satellite is showing an area along and south of the KY Parkway system with some fog development where recent rainfall occurred Sunday. A special weather statement has been issued for locally dense fog and rapidly changing visibilities this morning for travelers. Dry frontal passage today and associated upper level trough of low pressure will keep conditions on the cool side of normal with highs in the mid to upper 70s, which is between 5 and 10 degrees below normal for mid June. Some afternoon clouds may pop up in the afternoon, but mainly sunny skies will prevail with lots of dry air in place (PWs based on sounding climo between 10th and 25th percentile today and tonight). Outside of a few clouds, the only other sensible weather will be an occasional NNW wind gust up to 15 mph. Some patchy valley fog is possible overnight into the early morning hours Tuesday, but any impact will be minor and limited to low lying areas. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Issued at 258 AM EDT Mon Jun 10 2024 The extended forecast period from Tuesday through next weekend is expected to feature a lot of dry weather and a big increase in temperatures as a dome of hot temperatures gradually builds across the central and eastern portions of the CONUS. At the beginning of the period on Tuesday, mid and upper-level troughing will still be located over the east coast while broad ridging will abound along and west of the Rockies. At the surface, high pressure is expected to be located near the confluence of the MS/OH River, with the air mass overhead being somewhat cooler and considerably drier than normals for mid June. Both the NAEFS and EPS Ensemble Mean PW values, ranging from 0.4" to 0.6" across the area, are below their respective model climatology`s 5th percentile. For reference, the 10th percentile PW value in observed soundings on June 11th is 0.57" at ILN and 0.76" at BNA. This dry air mass will stick around into the middle and latter portions of the week with modest moisture return expected, allowing for large diurnal temperatures ranges even with an overall warming trend. Wednesday into Thursday, the synoptic pattern will transition to flat, broad ridging with the primary baroclinic zone being shoved into the northern U.S. and southern Canada as the heat dome spreads eastward. Low-amplitude troughs will ride along the top of the building ridge, with associated moisture and precipitation chances remaining well north of the Ohio Valley. Increases in 850 mb temperatures from Tuesday (9-10 deg C) to Thursday (16-18 deg C) will be a good proxy for rises in daytime highs given continued dry air through the column. This would translate to a roughly 15 deg F increase in expected temperatures, which would take us from readings in the mid-upper 70s on Tuesday to a few degrees either side of 90 by Thursday. Fortunately, dew points should remain low enough to keep heat indices in check. By Friday, a more substantial shortwave will try to cut into the northeastern flank of the upper ridge, bringing a cold front with it as it moves across the Great Lakes and into the northeastern U.S. By the time the front reaches our vicinity, it will have lost much of its upper level support as the aforementioned trough progresses quickly eastward. While there will be an area of increasing moisture ahead of the front and some lift associated with FROPA, the dilapidated state of the boundary should limit shower/storm chances. For what it`s worth, the GEFS does depict a more robust trough/front, which would favor more widespread precipitation chances, while the EPS and GEPS families have a weaker front and less in the way of precipitation. At this time, think most areas will experience little more than a few extra clouds and a wind shift Friday into Friday night. If the front makes it through the region Friday night, slightly cooler temperatures would be expected within a low-level NE flow regime on Saturday. However, this should be short-lived as the upper ridge builds quickly back to the east Saturday night into Sunday. At this time, Sunday into early next week has the potential to be rather hot, although increasing moisture from the Gulf of Mexico early next week may limit diurnal temperature ranges and increase cloud cover/precipitation chances. && .AVIATION /00Z TAFS THROUGH 06Z TUESDAY/... Issued at 1238 AM EDT Mon Jun 10 2024 VFR conditions are expected for the next 24 to 30 hours. Mostly clear skies tonight will be replaced with cumulus during the day tomorrow. Winds will ease tonight before increasing out of the north- northwest tomorrow. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ SHORT TERM...MK LONG TERM...CSG AVIATION...MK