Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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427 FXUS63 KDTX 012000 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 400 PM EDT Mon Jul 1 2024 .KEY MESSAGES... - Pleasant conditions today with mostly sunny skies and lower humidity, with temperatures slightly below average. - Seasonable conditions Tuesday as clouds thicken through the day. - Potential for showers to develop Tuesday night, with isolated thunderstorms. Chance of showers and thunderstorms will continue into Wednesday as conditions turn more humid. && .DISCUSSION... Lower column anticyclone well-established over the Great Lakes this afternoon ensures a subsident airmass through the rest of today while cooler Canadian air filters in from the northeast. Mainly clear skies prevail, as expected, given the uncharacteristically dry 01.12Z KDTX RAOB (PWAT of 0.36 inches) which revealed a 40C dewpoint depression at 6 kft AGL (800 mb) and mean mid-level lapse rates of only 5 C/km. Synoptically, the mid-/upper-level ridge axis still remains west of The Mississippi, but will begin to dislodge eastward late this evening and overnight as a longwave trough deepens over the Mountain West. Cloud fraction aloft will increase accordingly as high cirrus/anvil debris eventually spill downstream of on-going convection. Light surface winds veer southeasterly as the surface high pressure center exits toward The Northeast, ushering in more seasonable air. Clouds thicken Tuesday as a warm front lifts into Lower Michigan marked by a jump in H8 temps into the mid-upper teens (Celsius) amidst strengthening return flow. Dewpoints also respond, steadily rising into the mid 50s to near 60F by dusk while mean low-level moisture profiles play catch-up to stronger ThetaE advection aloft. Temperatures peak near 80F (+/- 3F). Chance of showers and thunderstorms increases Tuesday night as a cold front approaches from the west. The longwave state features a parent trough residing over the Canadian Prairies and Montana while a speed max transits the interface between the aforementioned trough and the controlling ridge over ArkLaTex. Poleward confluent flow intensifies across central CONUS as the flanking front migrates east, but uncertainty exists regarding the rate of saturation and how long it takes for the anticyclonic gyre to dislodge, locally. Latest PoP adjustments are generally in-line with inherited values which reserves broader coverage of shower/storm activity until Wednesday. Bulk of upstream/inbound convective activity Wednesday morning will more likely be located over western Lower as the front slowly works through the area and degrades. Main window for CVA expected around the 12-18Z timeframe while surface dewpoints break into the 70s. Best shear remains over the north half of the CWA while the better instability should stay over the south. Lapse rates are rather poor per the GFS and only marginally better per the humidity-biased NAM. Low confidence exists with the coverage and intensity of afternoon convection. Active westerlies in-place just south of the MI/OH line Thursday should keep conditions mainly dry. Still warm and a bit humid through the rest of the work week. Next shortwave digs across the Dakotas Thursday evening sparking cyclogenesis over the Midwest. Additional showers and storms are possible Friday. && .MARINE... A strong high pressure center is now centered over the Great Lakes which will continue to promote dry weather and light winds. High pressure will continue to move east through the day, centering over New England by Tuesday afternoon. This will veer wind direction to the southeast by late tonight. Wind speeds and gust potential will increase slightly on Tuesday with the departure of high pressure, with gust potential of around 20 to 25 knots across Lake Huron. A cold front is then expected to move over the Great Lakes on Wednesday, which will further back wind direction to the southwest as well as bring shower and thunderstorm potential. The southwest fetch across the Saginaw Bay will bring a window to see gusts around 25 knots Wednesday afternoon and evening. Small Craft Advisories may be needed. A weak area of high pressure will build in Thursday, returning lighter winds to the Great Lakes. && .PREV DISCUSSION... Issued at 121 PM EDT Mon Jul 1 2024 AVIATION... High pressure remains in place today maintaining clear skies. Winds below 10 knots will veer from northerly to easterly this evening as the high pressure center moves across the area to the east. Scattered to broken high clouds will move in near the end of the TAF period ahead of the next low pressure system. For DTW/D21 Convection...Thunderstorms are not expected during the upcoming forecast. DTW THRESHOLD PROBABILITIES... * None. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ DISCUSSION...KGK MARINE.......AM AVIATION.....BC You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.