Sunrise 6:14 AM   Sunset 8:54 PM Moonrise 11:03 AM   Moonset 1:33 AM

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LCZ423 320 Am Edt Fri Apr 19 2024
.strong Thunderstorms approaching the waters - .
the areas affected include - . Detroit river - . Michigan waters of lake erie from detroit river to north cape mi - .
at 320 am edt, doppler radar indicated strong Thunderstorms, capable of producing winds up to 30 knots. These Thunderstorms were located along a line extending from 6 nm northwest of bolles harbor of refuge to 9 nm south of north cape, moving northeast at 40 knots.
strong Thunderstorms will be near - . Monroe harbor, bolles harbor of refuge, north cape, luna pier, and detroit beach around 325 am edt. Stony point and woodland beach around 330 am edt. Estral beach and gibraltar around 340 am edt. Lake erie metropark harbor and detroit river light around 345 am edt. Elizabeth park marina around 350 am edt.
other locations impacted by strong Thunderstorms include woodland beach, stony point, gibraltar, estral beach, and detroit beach.
precautionary/preparedness actions - .
mariners can expect gusty winds up to 30 knots, locally higher waves, and lightning strikes. Boaters should seek safe harbor immediately until these storms pass.
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lat - .lon 4173 8345 4173 8350 4180 8350 4195 8337 4197 8328 4217 8321 4219 8319 4218 8313 4212 8312 4203 8315 4196 8311 4180 8333 4172 8341 4172 8347

LCZ400
No data

FXUS63 KGRR 141552 AFDGRR

Area Forecast Discussion National Weather Service Grand Rapids MI 1152 AM EDT Tue May 14 2024

KEY MESSAGES

- Scattered showers/isolated thunder today, then dry

- Showers with a Few Storms Thursday Night into Friday

- Occasional Storminess Possible Sunday into Early Next Week

UPDATE
Issued at 1152 AM EDT Tue May 14 2024

Elongated moist confluent zone in the mid levels from southeast Iowa to southern Lk Huron continues to generate scattered to numerous showers, currently favoring the central portions of the GRR CWFA.

General trend later today should be for a gradual southward shift of this zone, with showers eventually favoring the I-94 corridor by this evening. There's been some sunshine across far srn Lwr mi with about 500 J/KG of SB Cape now present, so a few tstms are certainly possible across that area roughly 4PM-10PM.

Coolest high temps this afternoon, only around 60, are expected to be in a corridor from near GRR to the Thumb/Saginaw Bay area due to persistent clouds and showers. Meanwhile clearing/partial sunshine on either side of that area will yield highs around 70.

DISCUSSION
Issued at 324 AM EDT Tue May 14 2024

- Scattered showers/isolated thunder today, then dry

Radar continues to show very light rain showers/drizzle over the the northern cwa north of the frontal boundary that stretches east/west along I-96. These showers are closer to the h8 front. On the surface, temperatures north of the front are in the mid 50s with dewpoints in the 40s, compared to lower 60s/mid 50s south of the front.

GFS/Nam3km show a weak wave on the front this morning that moves south during the early afternoon. This should help to drag the frontal boundary through the cwa during the afternoon. Instability is pretty meager today, highest along the southern row of the cwa where MUCAPE around 200 j/kg were noted in the models. An isolated thunderstorm isn't out of the question today, but most of the precipitation will be just showers.

Aloft, a trough is moving across the Ohio Valley and once it moves to the east late afternoon/early evening, we'll see rain chances end. High pressure will nose into the region from Ontario tonight and help to clear out the sky and set the stage for sunshine Wednesday.

Highs will range from the mid 60s to around 70 today and in the 70s Wednesday.

- Showers with a Few Storms Thursday Night into Friday

A 500 mb shortwave trough will move into the Great Lakes late Thursday into Friday, but will be weakening as it does. LLJ orientation and strength is more impressive on the 00z GFS and GEM compared to the ECMWF, and not surprisingly there is greater coverage of showers from both of those models. Given the weakening trough in the upper levels, there is very little surface reflection or change in pressure/temps/dew point as this feature moves through, other than a slight dip in MSLP and a veering of winds from easterly to southerly. Some modest instability is present, mainly elevated, so a few thunderstorms may occur. Total rainfall amounts look varied, but generally 0.25"-0.50" is forecast. The 00z GFS is likely overamplifying the base of the trough Friday into Saturday and creating a surface wave riding along the front. This is not supported by the ECMWF and GEM, nor the GEFS mean 500 mb heights. As such, the prolonging of showers on the GFS well into Saturday is not favored at this time. Drying conditions are more likely to occur than rain on Saturday.

- Occasional Storminess Possible Sunday into Early Next Week

Less than desirable model consensus exists regarding the synoptic pattern beginning Sunday, and poor agreement is in place not only between different model systems but even model run consistency within an individual system (ie. ECMWF). The GEFS mean 500 mb heights and wind speeds show upper ridging working in Sunday into Monday with increasing mid level jet speeds closer to next Tuesday, and 24 hr QPF (50th percentile) favors mainly dry conditions Sunday into Monday. The ECE 50th percentile QPF supports some rain over the region Sunday into Monday. This far out, low POPs seem the best way to go.

There are hints that low and mid level jet cores could be strengthening over the central U.S. early next week, helping draw up low level moisture flow into the Upper Midwest and potentially the Great Lakes as well. The difficulty is anticipating which days have a greater risk for showers/storms than others. The 00z ECMWF would present probably the worst case scenario with multiple rounds of showers and thunderstorms beginning late Sunday and lasting into midweek. Given some of the run to run issues with the ECMWF as of late, that may be overdone. Still, early next week will be an interesting period to watch if stronger synoptic support for storms materializes.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/
Issued at 743 AM EDT Tue May 14 2024

A batch of lower ceilings has indeed materialized in and around LAN as of this writing, and IFR has occurred. Whether this will be a predominant condition into the morning is questionable, so have opted to include as a TEMPO group and will continue monitoring.
These low ceilings at or below 700 feet are patchy across the mid Michigan area. Have included SCT mention at GRR as well as JXN as low level flow is easterly, and could bring a risk for IFR at those sites as well if conditions worsen more than expected.
Scattered showers will be traversing the region into the afternoon hours, and brief reductions to 2sm-3sm are possible in any showers that develop.

MARINE
Issued at 324 AM EDT Tue May 14 2024

Northeast winds behind the frontal boundary may lead to a brief period of higher waves west of the Points today; have opted not to include a headlines due to the limited nature of the threat.

A weak pressure gradient will preclude higher wind/waves in the nearshore waters for the next few days.

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

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