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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS63 KGRR 231725
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
125 PM EDT Tue Apr 23 2024

.KEY MESSAGES...

- Showers Early this Morning; Marginal Severe Risk Expanded

- Frost/Freeze Risk Wednesday Night/Thursday Morning

- Warmer and unsettled weather moves in for the weekend

&&

.DISCUSSION...
Issued at 357 AM EDT Tue Apr 23 2024

- Showers Early this Morning; Marginal Severe Risk Expanded

 Showers out ahead of the incoming short wave will continue to
spread over the region early this morning. The dry air at the
surface delayed the onset of precipitation, however scattered
showers continue to spread over the region and will continue
through the first half of the morning. Coinciding with this short
wave will be a strong low level jet. Winds upwards of 35 mph will
be possible through the early morning hours. The 925 mb winds
should become more amplified with more directional shear from the
850 and 700 mb layers. Looking at BUFKIT soundings CAMS have a
weak capping inversion from 2,500 to 4KFT this afternoon. If this
is breached, the steep low to mid level lapse rates of 7 to 9 C/KM
should greatly aid in convection.

Couple those lapse rates, the strong shear from the LLJ and the
cold air aloft and there is a decent chance for severe hail.
Latest mesoscale analysis has decent DCAPE moving into the region.
Given that, SPC has expanded the marginal risk for severe storms
for across the region this afternoon. Timing wise, latest CAMS
brings the best opportunity for strongest convection will be late
in the day associated with the cold front, around 00Z. A secondary
LLJ is associated with that boundary as well, though it is weaker
then the one moving through this morning.

- Frost/Freeze Risk Wednesday Night/Thursday Morning

Clearing skies under surface high pressure and very dry air at the
lower levels will create favorable conditions for radiational
cooling Wednesday night into Thursday morning. Temperatures will
likely drop into the upper 20s across a wide swath of southern Lower
Michigan. The coldest temperatures will probably in the northeast
counties where mid 20s can`t be ruled out. The good news is that the
trend of a slightly warmer airmass at 850 mb continues with recent
model runs.

- Warmer and unsettled weather moves in for the weekend

As this final blast of cold air departs the area, a reorientation of
the longwave pattern will move into the central CONUS, setting
Michigan up initially on the "sunny" side of a building upper ridge,
but by Friday afternoon the ridge axis will have passed us and we`ll
fall into several days of deep southwesterly flow.

This pattern will allow much warmer and more humid air to stream
into our state, along with fairly plentiful cloudiness. At least 2
major disturbances/shortwaves will move through this southwest flow,
and bring rounds of rain and possibly storms beginning Friday night
and continuing all weekend. It`s unlikely the whole weekend will be
a washout, but the exact timing and placement of these shortwaves
are still pretty uncertain at this time, so some of the more
pertinent forecast details remain elusive. Instability and the risk
of possible severe weather will be monitored over the coming days,
as breaks of sunshine during the day followed by one of these
shortwaves coming through near peak heating could easily result in a
severe threat.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
-- Changed Discussion --
Issued at 124 PM EDT Tue Apr 23 2024

VFR conditions will continue this afternoon then an increasing
chances of showers and some scattered thunderstorms will bring
areas of MVFR around 00Z. THe thunderstorms could have localized
hail and high winds but the threat is low and coverage is
isolated. Ceilings around 1500 to 200 feet AGL is expected
overnight with some slow clearing in Wednesday morning.

Southwest wilds will gust to near 30 knots at times this
afternoon. Winds will go northwest tonight and north by Wednesday
morning with some gusts over 20 knots.
-- End Changed Discussion --

&&

.MARINE...
Issued at 403 AM EDT Tue Apr 23 2024

An active/hazardous period on Lake Michigan will continue through
Wednesday. Gusty winds will continue with southerly flow this
morning. Winds will briefly slacken over the lake this afternoon.
However winds will shift to the north to 30 kts behind the front
tonight into Wednesday. Though the small craft remains, there is
still a chance for brief periods of gales. Hazardous winds and
waves should subside Wednesday night into Thursday as a sfc
ridge builds overhead.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Small Craft Advisory until 8 PM EDT Wednesday for LMZ844>849.

&&

$$

DISCUSSION...Ceru/AMD
AVIATION...Ostuno/AMD
MARINE...Ceru