185
FXUS63 KGRR 290743
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
343 AM EDT Mon Apr 29 2024

.KEY MESSAGES...

- More Showers and Storms Today

- Main chance for rain in the Wed-Sun time frame is Thurs Night-Fri

- Temperatures remain on the warm side of normal this week

&&

.DISCUSSION...
Issued at 343 AM EDT Mon Apr 29 2024

- More Showers and Storms Today

Surface analysis as of 2am shows a surface low centered over eastern
IA with a warm front draped across southern WI into the I-96
corridor in southern MI. A few warm frontal rain showers have
initiated just north of the surface boundary, but otherwise most
areas across the CWA remain dry this morning. Surface based
instability diminished shortly after sunset yesterday evening, so
mainly rain is expected with any showers.

As the low slides northeastward into eastern MN / western WI, the
warm front will lift northwards and a steadier batch of showers
currently moving through central IL will enter southern MI. More
widespread showers can be expected during the mid to late morning
hours. A few storms will be possible across the eastern CWA during
the afternoon as a cold front moves through, but there`s still a
question on storm strength. Instability looks limited with MLCAPE
under 1000 J/kg, but bulk shear will be supportive (40 to 50
knots) alongside an elevated 850mb jet to 30 to 40 knots.
Currently thinking non-severe given the expected afternoon cloud
cover, but if any breaks occur we could see some decently strong
storms develop across the eastern CWA.

The front works its way east by this evening with dry weather to
start Tuesday. Surface ridging moves in place Tuesday leading to the
return of dry weather. Sunny skies are expected with highs in the
60s.

- Main chance for rain in the Wed-Sun time frame is Thurs Night-Fri

The main chance for showers and storms will come late in the work
week from Thursday night into Friday. A strong shortwave will eject
out of a Plains trough and move through the Great Lakes region
during this time frame. A cold front will sweep through Thursday
night and provide the main focus for showers and storms. Most
unstable CAPE values are forecast to reach the 1000-2000 j/kg range
so there will be solid chances for convection.

Otherwise, there is a weak front that approaches and washes out over
the area Tuesday night into Wednesday. The chance for precipitation
is generally low given the weakening front.

- Temperatures remain on the warm side of normal this week

Temperatures through the forecast period are expected to remain near
to above normal. Highs will generally be in the middle 60s to lower
70s. Normal highs are in the lower to middle 60s for this time of
year. Given fruit trees and flowers are in or moving too full bloom
it is good we are not looking at cold weather in the short term.

&&

.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 241 AM EDT Mon Apr 29 2024

TAF sites are situated with a warm front along Interstate 96 and a
cold front upstream over Iowa. The I-96 TAF sites are located
right near the warm front and as such have been going in and out
of IFR conditions. The warm front will move a bit north and VFR
conditions develop and it drops south and 400 foot ceilings
develop. Model forecasts show the front pushing north this morning
so the IFR potential may just be for a few hours early this
morning 06Z to 10Z or so.

We will see some rain spread in from the southwest towards or
around 09Z to 10Z. Several hours of rain are expected at any one
TAF site, ending towards 16Z. VFR Weather should dominate after
that with the cold front sweeping through mainly dry this evening.

Winds will become southwest at 15 to 25 knots today after the
morning rain.

&&

.MARINE...
Issued at 343 AM EDT Mon Apr 29 2024

Winds and waves increase slightly this afternoon, though conditions
should stay below Small Craft Advisory thresholds. Waves to 2 to 3
feet are expected this afternoon with southerly winds at around 15
knots gusting to 20 knots. Dewpoints will still be elevated enough
for some fog formation, but winds should be high enough to prevent
any dense fog from developing.

&&

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

&&

$$

DISCUSSION...Duke/Thielke
AVIATION...Duke
MARINE...Thielke