Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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157 FXUS63 KGRR 060252 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 1052 PM EDT Sun May 5 2024 .KEY MESSAGES... - Cool tonight, high clouds through Monday night - Risk for Thunderstorms Tuesday - Unsettled and cooling down for the end of the week && .UPDATE... Issued at 1052 PM EDT Sun May 5 2024 High pressure will remain in control of the area weather tonight which will provide dry conditions. Clear to partly cloudy skies are expected with high clouds streaming in from the south associated with an upper shortwave moving into the Ohio Valley. There are some stratocumulus clouds over Southeast Lower Michigan as well at 1030pm and these clouds will likely move across portions of the I-94 corridor through the night. Adrian for example is reporting a ceiling of 2400 feet. No precipitation expected, but sky cover will be somewhat variable given the aforementioned clouds. Lows will range from near 50 in the south to the upper 30s across Central Lower Michigan in spots. An east wind of 5 to 10 knots is expected tonight. && .DISCUSSION... Issued at 202 PM EDT Sun May 5 2024 - Cool tonight, high clouds through Monday night Latest visible loop shows stratus south of I-96 continuing to erode from north to south as drier air moves south from Canada. Concurrently, some high clouds from the lower MS Valley are starting to move north toward Lower MI, but they are thin and won`t do much to block the sun for the remainder of the day. High pressure will settle over Lower MI tonight generating some light winds and helping temperatures fall into the upper 30s across the northern cwa to upper 40s over the southern cwa. There may be a very isolated frost potential in low lying areas of the northern cwa tonight, but not wide spread enough for headlines. Monday looks like a mostly sunny day as upper ridging follows the surface high across the state. High clouds will likely move in from the southwest during the day and more so Monday night as a warm front develops over the MO Valley and begins to move in this direction. HREF sky cover progs point toward increasing clouds throughout the night as the warm front approaches; any precipitation associated with the front will hold off until Tuesday. - Risk for Thunderstorms Tuesday Models continue to show a deeper trough pivoting in from the southwest during the day on Tuesday. We will have to monitor the trends as a stronger mid level jet will be near or just south of Southern Lower MI during the Tuesday aftn/eve hours. This feature will support favorable deep layer shear in that region. An upper level jet will provide diffluence over Lower MI during the afternoon/eve as well. Models vary on the projected SB instability with the NAM showing very little while the GEM and GFS are suggesting we may top 1000 J/kg in southern parts of the CWA, around Kalamazoo, Battle Creek and Jackson. - Unsettled and cooling down for the end of the week A series of mid level troughs dig their way down through the Great Lakes region for the end of the week drawing down cooler air from Canada. One surface wave tracks through the MI/IN border region Wednesday night into early Thursday providing some rain. A secondary surface wave arrives Saturday leading to another round of rain. By Friday and continuing into Saturday, 850 mb temps are shown to make a run at 0 deg C for northern parts of the CWA. This would keep max temps below normal. Those projected 850 mb temps would be cold enough to lead to lake enhanced moisture so its likely to be rather cloudy as well. With precipitation forecasted, we could easily end up stuck in the 50`s Friday and possibly into the weekend. Ensemble temperature forecasts have overall been trending lower as well, adding confidence for cooler than normal temperatures. We will therefore lower the temperatures accordingly in the forecasts. && .AVIATION /00Z TAFS THROUGH 00Z MONDAY/... Issued at 703 PM EDT Sun May 5 2024 Few to scattered high clouds are preventing completely clear skies, regardless VFR is expected this evening. The thing to watch will be during 03z-09z as a couple hours of southeast flow could bring enough moisture off Lake Erie to lead to patchy fog or MVFR cigs. Confidence in development of patchy fog or low clouds is 20-30 percent at JXN and even lower for all other TAF sites so will leave VFR conditions at all sites with this TAF package. A disturbance passing south of lower Michigan will lead to widespread BKN cirrus overnight before clearing from north to south Monday. Mostly sunny skies are expected in the wake of the departing cirrus shield. Generally west to west-northwest winds become light easterly winds overnight before southeasterly winds of 5-10 knots are expected Monday. && .MARINE... Issued at 202 PM EDT Sun May 5 2024 No marine issues for the next 36 hrs as high pressure at the surface and aloft move over the lake. Thunderstorms will pose a marine hazard Tuesday. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ UPDATE...Duke DISCUSSION...MJS/04 AVIATION...Thomas MARINE...04