Area Forecast Discussion
Issued by NWS Grand Rapids, MI
Issued by NWS Grand Rapids, MI
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731 FXUS63 KGRR 011105 AFDGRR Area Forecast Discussion National Weather Service Grand Rapids MI 705 AM EDT Mon Jul 1 2024 .KEY MESSAGES... - Sunny, Dry, Relatively Cool Today - Shower/Thunderstorm Chances Tuesday into Wednesday - Another Round of Storms Friday && .DISCUSSION... Issued at 323 AM EDT Mon Jul 1 2024 - Sunny, Dry, Relatively Cool Today Center of surface high pressure will be over Lower Michigan during the middle of today. Temperatures start off rather cool, about 10-15 degrees below normal, but should warm up into the mid 70s (still a little below normal) with abundant sunshine. Dew points will be on the dry side for summer, around or even below 50 degrees. - Shower/Thunderstorm Chances Tuesday into Wednesday As high pressure moves east of the region, southerly low-level winds bring returning warm air on Tuesday. Cirrus and altostratus clouds will stream in within the southwesterly upper-level flow in advance of the next shortwave trough. There is a chance of rain showers during the day, particularly north of Grand Rapids toward Ludington, though initially any precip from the midlevels will have to overcome dry low-level air on the way down. MUCAPE appears meager but perhaps just enough for a slight chance thunderstorm mention during the day. Rain showers become more likely Tuesday night, especially north of GR toward Ludington, where there may some repeating thunderstorms and narrow swaths of rain totals over an inch. A weakening cold front enters the CWA from the northwest and dissipates over the area early on Wednesday. The main low level jet pivots through the region during this time with the axis of instability and highest PWATs pushing through as well. Ensemble QPF plots capture this weakening trend to the system as it arrives by showing lowering 24 hr value from Ludington to Jackson along with decreasing number of members having measurable values. This will be reflected in the POP forecasts for this period. - Another Round of Storms Friday A southwesterly upper level jet streak arrives in the Great Lakes Region during this period. In the mid levels an associated deepening wave tracks in during the day. From the ECMWF, the combination of deep layer shear and instability would support some organized convection during the day. The surface wave reflects a warm front in the CWA, so that will need to be monitored. Modeled ensemble QPF values show a lot of spread in the various models so some uncertainty exists with this system. Overall though enough confidence exists to feature a risk for thunderstorms associated with this wave that moves in. && .AVIATION /12Z TAFS THROUGH 12Z TUESDAY/... Issued at 702 AM EDT Mon Jul 1 2024 High pressure continues to control our weather. This system will provide mainly clear skies and relatively light winds. An onshore wind will likely develop around KMKG this afternoon. && .MARINE... Issued at 323 AM EDT Mon Jul 1 2024 Sunday`s north winds upwelled colder water along much of West Michigan`s shoreline. The buoys a few miles offshore of Port Sheldon and South Haven recorded a water temperature drop from the mid-upper 60s to around 50. With a high pressure system passing through today, light winds from the east this morning should become light from the west this afternoon as the lake breeze circulation sets up. Increasing south-southeast winds Tuesday and southwest winds on Wednesday may make parts of the shore hazardous for small craft and swimming due to waves and currents. These south winds should help the water temperatures gradually recover this week. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. MARINE...None. && $$ DISCUSSION...MJS/CAS AVIATION...MJS MARINE...CAS