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000
FXUS63 KGRR 281402
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1002 AM EDT Sun Apr 28 2024

.KEY MESSAGES...

- Showers and Storms Continue into Sunday and Monday

- Multiple chances for rain exist from Monday night and beyond

- Near to above normal temperatures continue this week

&&

.UPDATE...
Issued at 1001 AM EDT Sun Apr 28 2024

The POPs/Weather grids have been updated per the latest radar
trends and HRRR forecast. Steadier rain will lift north this
morning but the wavering surface front will remain across the
central forecast area as it has been reinforced by outflow from
this mornings showers. Partial clearing this afternoon across the
southern half of the forecast area could create enough sfc-based
instability to pop some storms, as indicated by the HRRR during
the late afternoon. This would most likely occur along the
residual outflow boundary/sfc front across the central forecast
area in the general vicinity of GRR to LAN.

&&

.DISCUSSION...
Issued at 356 AM EDT Sun Apr 28 2024

- Showers and Storms Continue into Sunday and Monday

A surface low ejecting out of the southern plains will carry a warm
frontal boundary into lower Michigan today. This front will stall
over central lower this afternoon keeping showers mainly north of I-
96. Though the bulk of the instability will be mainly south of the
frontal boundary and convection, storms will be possible. Severe
weather does not look likely. HREF probability matched mean
values continue to advertise local patches of 1 to 1.5 inches of
rain from now to Monday morning, suggesting some training of
storms may be possible.

The upper trough associated with the surface low to our west moves
into Ontario providing better upper support for an approaching cold
front. Widespread showers encompass the CWA Sunday night and Monday.
Storms will be possible as modest instability ahead of the front
builds with bulk shear values up to 35 to 45 knots. Showers exit
east late Monday leading to a dry Tuesday.

- Multiple chances for rain exist from Monday night and beyond

The upper system responsible for our chances for rain this weekend
exits the Great Lakes into Canada Monday night. The rain will end
Monday evening and we will be dry the remainder of the night and
through Tuesday. A vort lobe pivots through the Great Lakes Tuesday
night into Wednesday morning with another chance for rain. This
chance for rain appears to be quite light as the upper system is
located well west of the area.

Another active weather period looks to be Thursday into Saturday as
an upper trough moves into and through the area. Showers and
thunderstorms are both in the forecast during this time frame as
surface dew points surge into the 60s F. Most unstable CAPE values
reach the 1000-2000 j/kg range on Thursday which could be the most
active weather day of the upcoming work week. Bottom line the 7 day
forecast remains active and wet with WPC QPF values through next
Sunday morning on the order of 1.00 to 2.00 inches.

- Near to above normal temperatures continue this week

Normal highs are in the lower 60s this time of year and we are
forecast to be above that through the the 7 day forecast. The
warmest day of the period will be Thursday where we could hit 80
along I-94.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 750 AM EDT Sun Apr 28 2024

A warm front will be situated across the area today. Lower clouds
(MVFR) will be in place much of the next 24 hours at the I-96 TAF
sites closer to the front. Some IFR will even occur this morning.
The I-94 TAF sites will improve as we head into the afternoon to
VFR. Periods of showers and storms will occur over the next 24
hours with the most confident batch of showers/storms being this
morning. Another round is possible this afternoon, but it is a
lesser confidence event.

&&

.MARINE...
Issued at 356 AM EDT Sun Apr 28 2024

A moist airmass remains in place today and Monday with dewpoint
values into the mid to upper 50s. This moist air over cold water
will produce dense fog along the lakeshore, therefore a Marine Dense
Fog Advisory is in effect. Meanwhile, winds and waves should stay
low through today and much of Monday. A cold front will approach the
area late Sunday into Monday and may bring hazardous wind gusts as
well as showers and storms.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
MARINE...Dense Fog Advisory until 8 PM EDT this evening for LMZ844>847.

&&

$$

UPDATE...Ostuno
DISCUSSION...Duke/Thielke
AVIATION...Duke
MARINE...Thielke