Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 150238
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1038 PM EDT Thu Mar 14 2024

.KEY MESSAGES...

- Risk for Strong/Severe storms through early evening

- Chance for Rain Saturday

- Colder with Chance for Snow Early Next Week

&&

.UPDATE...
Issued at 1038 PM EDT Thu Mar 14 2024

Low pressure traversed the MI/IN-OH state line region this
evening (moving from west to east) and is now off to the east
over Western Lake Erie. Rain north of the low and surface front
has essentially come to an end with dry conditions expected the
remainder of the night. We may see a couple sprinkles or pockets
of drizzle for a few more hours, but we should be mainly dry. In
fact, a clearing line in the low clouds has already progressed
into northern portions of the forecast area across Central Lower
Michigan. We should see a general decrease in clouds the remainder
of the night even with regard to mid and high level clouds. Most
locations by daybreak will be mostly clear to partly cloudy. A
drying northerly wind is expected all night. Lows will be in the
30s in all areas.

&&

.DISCUSSION...
Issued at 254 PM EDT Thu Mar 14 2024

- Risk for Strong/Severe storms through early evening

The marginal risk for severe thunderstorms continues for the region
south of a Grand Rapids to Lansing line during this timeframe.  The
surface warm front remains situated near the I 94 corridor and the
cloud cover was thinning in this region. With a few hours of
heating, there will likely be surface based instability building
along this zone. Models are showing ML CAPE values peaking
roughly 500 to 1000 J/kg 21z to 23z near the warm front. Steady
surface pressure falls were occurring along the frontal zone. Deep
layer shear in the 0 to 6 km layer was over 60 knots just south
of the warm front. So any convection that does form near this zone
will have a potential to organize quickly. In general, the high
res models show only limited coverage of storms, so some
uncertainty exists as to whether we will see much development. The
925 mb low level jet lifts up to the MI/IN border 18z to 00z
which should act for focus the newer storm development near and
south of the warm front through this evening. Storm motion vectors
suggest any storms will be tracking quickly east.

- Chance for Rain Saturday

An upper trough will descend into the Great Lakes Region Saturday
with an associated cold front expected to bring chances for light
precipitation. Lack of moisture along the front will limit the
extent of precipitation, but a few pockets of light rain look
possible with overcast skies. Temps in the 50s should keep
precipitation type as mainly rain, though we could see some snow
develop north of US-10 Saturday evening after temps fall below
freezing.

- Colder with Chance for Snow Early Next Week

The cold front sweeps through the rest of the CWA through Saturday
night. 850mb temps fall quickly dropping to -9C by Sunday morning
and even as low as -10C to -13C by Monday afternoon. Over lake
instability increases with this burst of cold air generating light
lake effect snow for lakeshore areas. Best chances for any snow
accumulation from lake effect will be Sunday evening into Monday
afternoon. High temps stay in the 30s Sunday and Monday, then temps
warm just a touch into the 40s near mid-week.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 814 PM EDT Thu Mar 14 2024

Though threat of storms is over, continued showers with low
ceilings will continue. Showers will linger until the back edge of
the front moves through between now and 06Z. IFR cigs will
continue with MVFR vsbys during this time. IFR cigs due to low
level moisture will continue overnight with TAF sites slowly
improving out of IFR to MVFR between 09Z to 14Z Friday.

&&

.MARINE...
Issued at 254 PM EDT Thu Mar 14 2024

Gusty offshore winds this evening are expected for the marine
zones as the low pulls away from the area. Wave heights will be
limited as a result with the highest values closer to 5 nm
offshore. Gusty conditions and a southwest flow on Saturday will
likely support the need for marine headlines.

&&

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

&&

$$

UPDATE...Duke
DISCUSSION...MJS/Thielke
AVIATION...Ceru
MARINE...MJS


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