Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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469 FXUS63 KDTX 010604 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 204 AM EDT Wed May 1 2024 .KEY MESSAGES... - Well above normal temperatures remain through the week. - Likely a dry frontal passage today with the next chance of precipitation arriving early Friday morning. && .AVIATION... VFR conditions will prevail through this TAF period as mid to high clouds spread over the region this morning. South-southwest flow will be increasing this morning in the wake of a warm front. Gusts are expected to increase into the 25-30 knot range. The mid to high clouds will sweep through in the morning with an influx of lower level moisture behind the warm front. Showers moving into western Michigan are expected to decrease in coverage as they reach southeast Michigan. Will leave out any VFR shower mention in the TAFS, but cannot completely rule out a stray shower. Better near surface moisture should support some a diurnal lower VFR cumulus field during the afternoon. Gusts and the lower cu field will diminish this evening with sustained westerly winds of 5 to 10 knots during the evening and overnight. For DTW/D21 Convection...Thunderstorms are not expected through the TAF period. There will be minor concern for crosswind thresholds being met at DTW if daytime gusts come in closer to 30 knots. Low confidence at this time in gusts achieving these thresholds. DTW THRESHOLD PROBABILITIES... * Low for crosswinds late this afternoon. * Low for ceilings at or below 5kft midday. && .PREV DISCUSSION... Issued at 352 PM EDT Tue Apr 30 2024 DISCUSSION... The dense stratocumulus cloud line this afternoon is generally west to east along or just south of the M 46 corridor. There could be some slight additional development along the southern edge, but current observation trends suggest a persistence forecast throughout the remainder of the afternoon for the majority of the area. Did try to hand edit some temperature grids to account for temperatures that are cooler under the opaque overcast. Favorable radiative cooling conditions tonight and low dewpoint airmass will support lows down into the 40s, a few colder spots in the outlying low drainage areas. Strong synoptic support for ascent and a reasonably dynamic low pressure system is forecasted to push across northern Wisconsin/U.P. and Lake Superior early Wednesday. The main narrative will be dry conditions for Southeast Michigan as a large amount of static stability will hold between 3.0 and 12.0 kft agl. A notable disconnect in moisture between the mid to low levels with surface moisture will be well lagged and late in the day. From a sensible weather perspective on the ground, warmer and more humid conditions are expected during the afternoon. Surface dewpoints are expected to rise from 40s early Wednesday to the middle 50s between 18-21Z. A rare, dry warm advection/cold front system for Southeast Michigan Longer wavelength ridging is forecasted to develop over the central Great Lakes Thursday before amplifying over the eastern United States on Friday. Strong static stability is expected to hold while lowering on Thursday leading to very comfortable weather. The exception will be areas adjacent to Lake Huron on Thursday with highs in the 50s to lower 60s. The next chance for precipitation will come Friday as a deamplifying shortwave is forecasted to lift out of the Mississippi River Valley. Large scale forcing for ascent will be well to the northwest of Lower Michigan with the forecast area solidly in anticyclonic flow trajectories. There is some potential for elevated showers/rumble of thunder late Thursday night with nocturnal moisture transport/LLJ forcing but higher chance should reside north of Saginaw Bay. Model consensus brings the best potential along and ahead of the surface cold Front Friday afternoon. Surface temperatures are forecasted to warm in the upper 70s with surface dewpoints making a run at 60 degrees. From this vantage point, quality of lower tropospheric moisture is expected to remain compromised as background large scale forcing favors ridging which will try to perpetuate a veered wind profile. Model differences to exist and some adjustment to forecasted thunderstorm expectations are still anticipated. Differential cold/dry air advection with rising geopotential heights will result in building high pressure for next weekend. Comfortable conditions are expected with conditions some 10 degrees above normal. MARINE... Surface ridge in place this evening will provide light and variable winds tonight before south-southwest winds increase tomorrow, ahead of the next low pressure system which will track through Lake Superior. Wind gusts Wednesday afternoon do look to reach 20-25 knots over the nearshore waters, especially over Saginaw Bay and along the shoreline areas. However, banking on the warm air (925 mb temps up to 17 C) ahead of the cold front to provide just enough stability to keep gusts under 25 knots (outside of perhaps a brief stray one). Winds veering to the west over Saginaw Bay by early evening will also help to keep wind speeds in check, vs the more favorable southwest wind. Steady stream of cold advection behind the front Wednesday night into Thursday, and outside of the north half of Lake Huron, expecting wind speeds look to remain light, under 20 knots. Even over northern Lake Huron, wind speeds look to peak at 25 knots to perhaps up to 30 knots, centered around midnight per local probabilistic guidance. A return to light and variable winds for Thursday as surface high builds over Lake Huron. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...Small Craft Advisory from noon today to 9 PM EDT this evening for LHZ421-422-441. Lake St Clair...None. Michigan waters of Lake Erie...None. && $$ AVIATION.....AA DISCUSSION...CB MARINE.......SF You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.