Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI

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000 FXUS63 KDTX 021722 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 1222 PM EST Tue Mar 2 2021 .AVIATION...
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High pressure off to the southeast will continue to be in control resulting in VFR conditions through this afternoon and into the overnight hours. A low pressure system moving across Ontario will assist in increasing the pressure gradient as the areas resides between this low and the high pressure. Southwest winds are now beginning to increase across the area with wind gusts up to 20-25 knots possible this afternoon. The approaching low will also bring in some mid to high level clouds. VFR conditions this afternoon will continue through tonight as the low to the north pushes east. This low will bring a front across the area on Wednesday with increasing mid to high clouds. .DTW THRESHOLD PROBABILITIES... * None.
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&& .PREV DISCUSSION... Issued at 329 AM EST Tue Mar 2 2021 DISCUSSION... Surface high pressure now extends across the Ohio Valley and srn Lower Mi within the mid level confluence that developed last night in the wake of the departing mid level low trekking across ern Canada. A northern stream short wave impulse now over srn Saskatchewan will quickly advance to nrn Ontario and Lake Superior by evening. This will force the sfc high to the south of the forecast area today, allowing a strengthening southwest gradient to take hold across Lower Mi. As a result, there will be good warming in the 800 to 700mb layer today. This will suppress diurnal mixing to a degree (3-4k feet per RAP). There will also be some transient mid/high clouds today, especially in the north, within the mid level warm air advection pattern. Nonetheless, sub 900mb winds increasing to 20 to 30 knots this afternoon and a very dry boundary layer will still support a respectable daytime warming trend with highs reaching 40 by late afternoon over much of the area. The aforementioned short wave will race east toward quebec tonight. A trailing cold front will then be forced south across the Great Lakes, aided by strengthening sfc high pressure across Hudson Bay and northern Ontario. The front will largely remain north of Se Mi tonight. An increase in the wind fields atop the nocturnal inversion tonight will allow low level warming to persist across Se Mi. This will limit nighttime boundary layer cooling despite clear skies, supporting min temp just down around 30. The NAM is much faster than other model solutions in driving the cold front south across the forecast area on Wednesday and is also more aggressive with post frontal stratus. The ARW and HRRR seem to offer a more reasonable solution which also fits how these back door fronts typically behave this time of year. They drive the front into the thumb region early in the day on Wednesday, which keeps the areas near Lake Huron cool and allows inland locations to warm through diabatic heating. These solutions then drive the front inland during the latter half of the day. Based on these solutions, forecast highs Wed will be well into the 40s inland (with some low 50s in the south) and much cooler near Lake Huron. Some retrogression of an upper low over ern Canada Wed and Thurs will drive some colder air into the eastern Great Lakes during the latter half of the week. This will keep temps on the cool side of early March norms. The medium range model suite than show a shift in the long wave pattern over the weekend and into next week that will feature ridging expanding across the eastern US and will offer a warming trend across the Great Lakes. Overall, dry air and some semblance of sfc high pressure in the vicinity will maintain a forecast that is void of any meaningful precip chances through the weekend. MARINE... A brief lull in wind strength occurs this morning as the center of high pressure slides through the Ohio Valley. However, another low pressure system will be quick to drop into the northern Lakes and the resultant gradient will bring an uptick in southwest winds across central Lake Huron this afternoon and evening. SW flow is usually warm and stable heading into early March however the departing air mass is cold and well mixed over central Lake Huron which adds confidence in frequent gusts reaching 35 to 40 knots. A new round of Gale Warnings and Small Craft Advisories are now in effect from noon until 10 PM Tuesday night. The associated cold front moves through by Wednesday morning and will be much weaker than the past Sunday evening and Monday cold fronts. It will open the door for an extended period of NW to N winds for the mid to late week that look to remain below headline criteria. && .DTX WATCHES/WARNINGS/ADVISORIES...
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MI...NONE. Lake Huron...Gale Warning until 10 PM EST this evening for LHZ362-363-462. Small Craft Advisory until 10 PM EST this evening for LHZ421-441. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE.
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&& $$ AVIATION.....SS DISCUSSION...SC MARINE.......TF/BT You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.

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