Sunrise 6:22 AM   Sunset 8:59 PM Moonrise 8:55 AM   Moonset 12:22 AM

  Print   HELP   Reset   Save   Recall  New

LMZ845 South Haven To Holland Mi- 405 Am Edt Sun May 12 2024
Early this morning - South winds 5 to 10 knots. Mostly clear. Waves around 1 foot. Today - South winds 10 to 20 knots. Sunny. Waves 1 to 3 feet. Tonight - Southwest winds 15 to 25 knots. Partly cloudy with a chance of rain showers and isolated Thunderstorms. Waves 2 to 4 feet.Monday - Southwest winds 10 to 20 knots veering northwest late in the day. Partly Sunny with a slight chance of showers and Thunderstorms. Waves 2 to 3 feet. Monday night - Northeast winds 5 to 15 knots. Rain showers likely and a slight chance of Thunderstorms. Waves around 1 foot. Tuesday - Northeast winds 15 to 20 knots. Partly Sunny. Waves 1 to 3 feet building to 3 to 5 feet late in the day. Wednesday - North winds around 15 knots. Sunny. Waves 1 to 3 feet. Thursday - Southeast winds 10 to 15 knots veering southwest. Mostly Sunny with a chance of rain showers. Waves 1 foot or less.

LMZ800
No data

FXUS63 KGRR 120659 AFDGRR

Area Forecast Discussion National Weather Service Grand Rapids MI 259 AM EDT Sun May 12 2024

KEY MESSAGES

- Warmer Today, Chance of Storms this Evening and Tonight

- Showers With a Slight Chance for Storms Monday Night/Tuesday

- Dry Midweek, Then Rain Chances Return Late

DISCUSSION
Issued at 254 AM EDT Sun May 12 2024

- Warmer Today, Chance of Storms this Evening and Tonight

Warmer day in store today as high pressure and abundant sunshine build over lower Michigan. Temperatures should climb into the 70s today before a cold front works into lower Michigan this evening.
A low level jet and heating of the day should help to provide some moisture and instability to aid in the possibility of some thunderstorms this evening and tonight. The greatest risk appears to be up north where hail and gusty winds will be possible in any more organized storm activity. Severe potential continues to be limited, though considering the cold temperatures aloft a couple reports of severe hail cannot be ruled out. Cold front stalls out over the lower peninsula where it will aid in the potential for showers and storms late Monday.

- Showers With a Slight Chance for Storms Monday Night/Tuesday

Model guidance continues to favor showers and perhaps a few storms Monday night into approximately midday Tuesday. Upper divergence is shown to move over southern Lower Michigan by the 00z GFS and 03z RAP, and to a lesser extent the 00z ECMWF. LLJ convergence is also indicated by the GFS and RAP near and south of I-96. PWAT values are forecast to be 1.25"-1.50". A surface cold front will be sagging south through the region as this occurs. Thus, an elevated risk for showers and a few storms is indicated with POPs around 80% along and south of I-96. Rain amounts look variable, with general areal averages in the 0.25"-0.50" for most of the region (mainly less than 0.25" north of M-20), though the NAM 3km and GFS both indicate potential for pockets of an inch or so especially near and south of I-96. The ECMWF favors the highest amounts near and south of I-94. I think it just depends on how far north the LLJ gets, as weak as it may be. Nevertheless, showers are likely and with a small amount of elevated instability (maybe a couple hundred J/kg) there could be a few storms, but those will likely be the exception to the rule.
Expect the precipitation to slowly erode from N to S during the day Tuesday, with areas along and south of I-94 the last to dry out.

- Dry Midweek, Then Rain Chances Return Late

Good model agreement exists in giving us a dry midweek period (as early as Tuesday for central Lower MI, but for all areas Wednesday).
This occurs given N/NE low to mid level flow and a dry airmass in place. Seasonable temps are expected Wednesday with highs around 70F for most. The latest ECE mean 500 mb height pattern is starting to reverse course and trend toward the GEFS mean, which favors upper troughing moving into the upper Midwest by Thursday into Friday.
Ensemble mean PWATs are climbing a bit higher with the 00z guidance for Thursday night into Friday, and ECMWF/GFS deterministic guidance suggests upper jet divergence may move into the region with some lower level jet reflection potentially as well. As a result, rain chances are warranted especially later Thursday into Friday. NBM POPs are not especially high yet with 40-50% chance, which seems reasonable this far out, though POPs could certainly trend higher if ensemble agreement increases further.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/
Issued at 118 AM EDT Sun May 12 2024

Fairly quiet conditions at the terminals for most of this period, but two main items to watch will be a risk for some showers and a thunderstorm after 00z, along with an introduction of low level wind shear. A front sinking south late tonight may bring some showers into MKG and GRR primarily closer to 06z, but that is far from certain. There is potential for a thunderstorm to form, but gusty winds may not quite be able to make it to the surface as any storms will likely be elevated. Low level wind shear could reach 40 kts from the surface up to 2000 ft in the 00z-06z window as a low level jet increases overhead.

MARINE
Issued at 254 AM EDT Sun May 12 2024

Some potential late in the day for small craft conditions on Lake Michigan, especially near and north of Muskegon. However, winds will have a hard time mixing to the surface outside of any storms that develop late in the day. Will continue to hold off on headline at this time.

GRR WATCHES/WARNINGS/ADVISORIES
MI...None.
MARINE...None.

toggle option: (graph/table)

Full Color Weather Map

Link to Loop


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

Grand Rapids/Muskegon, MI,