367
FXUS63 KGRR 080750
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
350 AM EDT Wed May 8 2024

.KEY MESSAGES...

- Dry and mostly sunny today

- Rain and chance thunderstorm tonight through Thursday

- Showers on Saturday

&&

.DISCUSSION...
Issued at 350 AM EDT Wed May 8 2024

- Dry and mostly sunny today

The upper-level shortwave trough and surface low associated with
yesterday`s thunderstorms is scooting east toward New England today,
while its former parent low over the Dakotas begins to fill and
shear out. There will be a narrow zone of ridging with 500 mb height
rises over our area along with drier air moving through, keeping us
mostly sunny until clouds increase late in the evening. There should
be only a moderate breeze from the west becoming northwest.

- Rain and chance thunderstorm tonight through Thursday

Remnants of the Dakota low phasing with a southward-moving
positively tilted trough from northern Ontario are expected to
develop a surface low across Illinois-Indiana-Ohio tonight. To its
north will be a period of likely rain for much of the day Thursday
across southern to central Lower Michigan. Some MUCAPE may be
present in southern Michigan which could be enough for some rumbles
of thunder. Some questions remain as to the northward extent of a
soaking rainfall, and also rainfall totals. HREF member model mean
rain totals suggest 0.5 to 1.0 inch rain totals are most likely
(though much less near/north of US-10), however, 1.5 inch totals are
possible in some spots.

- Showers on Saturday

Shortwave ridging should bring fair weather for Friday into Friday
night but clouds will be moving in after midnight as a shortwave
trough approaches, with rain moving back in for Saturday. This
trough is less amplified than previous runs but some diurnal
enhancement of the showers Saturday afternoon is still possible
given the steep lapse rates. Isolated thunderstorms are possible and
even some small hail with any deeper updrafts.

Cool air in northerly flow on the back side of the sfc low results
in low temperatures in the upper 30s to lower 40s Saturday night
with scattered frost potential in the colder outlying areas.

The trough moves east on Sunday but there is low confidence with
forecast details next week, although there is model agreement on a
longwave trough forming across the central/eastern CONUS by late in
the week.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 132 AM EDT Wed May 8 2024

VFR conditions will prevail through Wednesday afternoon with winds
turning northwest around 10 knots.

&&

.MARINE...
Issued at 350 AM EDT Wed May 8 2024

West winds becoming north later today are not expected to pose a
hazard on Lake Michigan. East-northeast winds Thursday morning may
gust over 20 knots Thursday morning. As winds become north later on
Thursday, some larger waves may peel toward the shore from the
stronger midlake wind field. Essentially, could be marginally
hazardous for small craft on Thursday, not to mention the chance of
lightning.

&&

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

&&

$$

DISCUSSION...CAS/Ostuno
AVIATION...Ostuno
MARINE...CAS