Area Forecast Discussion
Issued by NWS Detroit/Pontiac, MI
Issued by NWS Detroit/Pontiac, MI
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868 FXUS63 KDTX 091750 AFDDTX Area Forecast Discussion National Weather Service Detroit/Pontiac MI 150 PM EDT Thu May 9 2024 .KEY MESSAGES... - Cooler temperatures (50s to low 60s) hold through Saturday before returning to at or above normal Sunday. - Next chance of showers and thunderstorms comes Saturday with the passage of a compact low pressure system. Severe weather is not expected. - Another chance of showers and thunderstorms comes Monday as a cold front drops through the area. && .AVIATION... Low pressure is moving across the Ohio Valley this afternoon with an area of rainfall on the north end now moving across Lower Michigan. Rainfall will mainly impact PTK and the metro terminals. Northeasterly wind to around 10 knots is present across Michigan with a high pressure to the north helping pump in some drier lower level air. This should keep hold predominately VFR conditions through today with occasional MVFR conditions via lower CIGS or brief reduction VSBY under any heavier shower. Will maintain VFR in TAFs and amened if a better more prolonged MVFR signal develops. Rain clears out this evening with any lower cloud largely clearing out tonight. Winds turn more northerly for tonight with a return of lower VFR clouds by tomorrow morning/afternoon supported by a cooler airmass settling over the state. For DTW/D21 Convection... Instability holds south of the state with no observation of lightning thus far in southeast Michigan. Thunderstorms remain unexpected through this afternoon and early evening. DTW THRESHOLD PROBABILITIES... * Moderate in ceilings aob 5000 feet this afternoon and evening. && .PREV DISCUSSION... Issued at 305 AM EDT Thu May 9 2024 DISCUSSION... Cold advection through the day today. The 00z APX raob indicated a 6 C temperature at 850 MB with a northeast wind. Low level northeast winds will only increase and deepen (reaching 700 MB) through the day, as 850 MB temps progged to reach 3-4 C over southeast Michigan, which is still supportive of lower 60s. However, the cooler marine layer off Lake Huron and thicker clouds and rain showers (south) should lead to slightly cooler temps. The farther south trend continued with the 00z NAM/regional GEM/RAP with the upper level wave coming out of the Midwest. The corresponding 850 MB frontal boundary now progged to reside over Central Indiana/Ohio with the 700 MB FGEN/shear axis not getting much past the southern Michigan border. Will be going dry for M-46 northward, with pops then increasing as one heads toward the southern Michigan border. Positive tilted 500 MB trough axis to clear the State 9-12z Friday, with short lived ridging building in during the daytime hours. Still, the airmass starts out rather chilly (mins 40-45), 850 MB temps around 1 C, and would not be shocked if isolated light showers developed with the steepening diurnal low level lapse rates and some modest cape (<100 J/kg) centered around freezing level. Ultimately, will carry the silent 14 pop. The next upper level wave is progged to move through far southern Lower Michigan Saturday morning. This system is compact but robust with the 500 MB low closing off at 547 DAM as the strong upper level PV wraps around, and forcing looks to be maximized along and south of M-59, as the 850-700 MB Theta-e ridge axis pivots and then sinks south. Showers appear just about a done deal for southern two thirds of the CWA, barring the system diving even farther south than currently indicated. With the strong lift advertised over southern areas and the showalter nearing zero, a slight chance of thunderstorms also appears warranted. Conservative forecast for now would indicated rainfall amounts near half an inch. Good warm advection pattern kicks in for the end of the weekend, but will have to be leery of the warm front activating and generating showers and possible thunderstorms, best chance north of M-46. 850 MB temps reaching 10-12 C will allow for a warm Monday (70s), with the timing and strength of a cold front being watched for potential convection generation. MARINE... Low pressure tracks across the Ohio Valley today, with rain showers flaring up along an elevated warm front through the morning. Shower activity generally holds south of Harbor Beach. Easterly winds today remain light which keeps wave heights aob 4 feet despite the onshore component. Winds then veer to the northwest by early Friday morning as high pressure attempts to build in from the north, leading to drier conditions on Friday. This will be short-lived as the next low pressure system traverses the broader troughing pattern aloft to bring another round of rain chances for Saturday followed by high pressure on Sunday. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...None. Lake Huron...None. Lake St Clair...None. Michigan waters of Lake Erie...Small Craft Advisory until 10 PM EDT this evening for LEZ444. && $$ AVIATION.....AA DISCUSSION...SF MARINE.......MV You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.