Sunrise 6:13 AM   Sunset 9:08 PM Moonrise 6:32 PM   Moonset 3:59 AM

  Print   HELP   Reset   Save   Recall  New

LMZ845 South Haven To Holland Mi- 405 Pm Edt Tue May 21 2024
.small craft advisory in effect from 10 pm edt this evening through Wednesday evening - .
Through early evening - South winds 10 to 15 knots. Mostly Sunny. Waves 1 foot or less. Tonight - South winds to 30 knots veering southwest toward daybreak. Partly cloudy with a chance of showers and Thunderstorms. Waves 2 to 3 feet building to 4 to 6 feet after midnight. Wednesday - Southwest winds 15 to 25 knots. Mostly Sunny. Waves 4 to 6 feet subsiding to 2 to 4 feet late in the day. Wednesday night - Southwest winds 10 to 15 knots. Clear. Waves 1 to 2 feet. Thursday - Southwest winds 5 to 15 knots. Sunny. Waves around 1 foot. Thursday night - Southeast winds 5 to 10 knots. Mostly clear. Waves 1 foot or less. Friday - South winds 10 to 15 knots. Mostly Sunny with a chance of showers and Thunderstorms. Waves 1 foot or less. Saturday - West winds 10 to 20 knots. Mostly Sunny. Waves 2 to 4 feet.Sunday - Southeast winds 10 to 15 knots backing northeast late in the day. Mostly Sunny with a chance of rain showers. Waves around 1 foot.

LMZ800
No data

FXUS63 KGRR 211950 AFDGRR

Area Forecast Discussion National Weather Service Grand Rapids MI 350 PM EDT Tue May 21 2024

KEY MESSAGES

- Severe Weather Potential Tonight

- Dry for Wednesday and Thursday; Rain Chances Return Friday

- Rain Chances Linger Through the Holiday Weekend

DISCUSSION
Issued at 350 PM EDT Tue May 21 2024

- Severe Weather Potential Tonight

Not expecting more than scattered showers and thunderstorms through this evening before a squall line moves across Lake Michigan from Wisconsin and reaches the western zones around midnight.

Flat shortwave ridging at mid-levels is apparently suppressing afternoon convection today, but heights will begin to fall as a negatively-tilted shortwave trough closes off over Minnesota accompanied by sfc cyclone tracking into Canada with a cold front advancing into Lower Michigan overnight.

An analysis of model soundings and other model-generated severe weather probability guidance suggests the greatest chance for severe weather tonight will be across the western forecast area near the Lake Michigan shore. A line of storms in western Iowa at 330 PM EDT is progged to expand and move east, crossing Lake Michigan. Main threat for our nearshore waters and western forecast area is for downburst winds but transient QLCS mesocyclone circulations cannot be ruled out, resulting in enhanced swaths of higher winds and even a quick tornado.

Model soundings suggest instability decreases as the storms move east and some of the model guidance show a corresponding weakening of the line of storms before they reach Grand Rapids.

The front becomes more parallel to the environmental winds on Wednesday slowing and stalling near or south of the forecast area with lingering showers possible near JXN during Wednesday.

- Dry for Wednesday and Thursday; Rain Chances Return Friday

Good forecast certainty remains for a dry Wednesday and Thursday and this will be accompanied by much more seasonal highs in the 70s.
Humidity will be substantially less oppressive too with dewpoints dropping into the 50s and then 40s by Thursday.

GOES satellite water vapor channels show an upper PV maximum currently diving southward into the Pacific Northwest region. This feature will eventually emerge as a cyclonically breaking upper wave over the Upper Mississippi valley region Friday afternoon/evening.
Strong upper divergence with this feature will support a solid coverage of showers and storms pushing eastward into our forecast area Friday night, although the best QG forcing should remain well northwest of our area. This combined with nocturnal stabilization should limit the threat for severe thunderstorms.

- Rain Chances Linger Through the Holiday Weekend

Unfortunately, forecast details for Memorial Day weekend remain quite uncertain. A brief lull in precipitation for at least part of Saturday seems probable, but that's about as definitive as I want to get right now. Starting Saturday afternoon, PoPs for the rest of the holiday weekend look to be in the neighborhood of 20 percent, which is right around climatology. High temperatures will be quite close to climatology as well in the neighborhood of low 70s.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
Issued at 156 PM EDT Tue May 21 2024

VFR conditions should predominate except for a brief period of MVFR/IFR conditions with the passage of thunderstorms tonight.

We continue to expect a north-south oriented line of strong to severe storms coming onshore at MKG around midnight tonight and then moving east. The storms should weaken quite a bit as they move onshore followed by gradual additional weakening over Lower MI as the line moves east. Wind gusts in excess of 40 kts seem like a good bet at MKG and over 50 kt is not out of the question; farther inland, gusts may end up being considerably weaker. In any case, any given terminal can expect less than an hour of thunderstorms. The storms will be preceded and also followed by a period of LLWS that will peel off to the east and exit the area before 12Z.

MARINE
Issued at 350 PM EDT Tue May 21 2024

No changes to the Small Craft Advisory. In addition to strong southwest winds from the tightening pressure gradient, there could be gusts over 50 knots tonight as a squall line moves across Lake Michigan, arriving in the nearshore area around midnight.

GRR WATCHES/WARNINGS/ADVISORIES
MI...None.
MARINE...Small Craft Advisory from 10 PM this evening to 8 PM EDT Wednesday for LMZ844>849.

toggle option: (graph/table)

Full Color Weather Map

Link to Loop


Other links: GEOS-West     Contential US     Full GOES-East

Grand Rapids/Muskegon, MI,