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000
FXUS63 KGRR 062328
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
728 PM EDT Mon Apr 6 2020

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 137 PM EDT Mon Apr 6 2020

- Scattered showers/isolated storms tonight

- Storms possible Tuesday

- Windy Thursday and much cooler late this week

&&

.DISCUSSION...(This evening through next Monday)
Issued at 137 PM EDT Mon Apr 6 2020

- Scattered showers/isolated storms tonight

 The High pressure that has brought pleasant weather to Southwest
Michigan the last few days will break down this afternoon and
evening. A warm frontal system will move in, with increasing
clouds this afternoon. A band of showers should set up along a
warm frontal boundary along and south of I 94. The showers might
move slightly northward, with possible light showers toward
Tuesday morning.

- Storms possible Tuesday

Short range guidance continues to show the potential for
convection late Tuesday/Tuesday night. Southwest winds that will
bring warm air advection into the region could allow for
storms to form tomorrow afternoon. There is some variance on the
type of convection. SPC does have Southwest Michigan in a marginal
risk for severe storms tomorrow evening. Latest CAMS move in from
the lake mid to late Tuesday afternoon and make their way across
the region Tuesday evening. Gusty winds will be possible with the
Day 2 SPC outlook showing a threat of hail as well. The question
with this system is in the variation of the different CAMS. The
ARW is showing more of a QLCS structure with super cell
convection in the HRRR. Several of the CAMS also showing very
weak to isolated storms. Even if there is a question on type of
convection, there is good probability in showers and thunderstorms
moving across the region late tomorrow afternoon into tomorrow
evening.

- Windy Thursday and much cooler late this week

 A strong jet behind the cold front will move through the region
Wednesday nigh into Thursday. This will allow for gusty winds
through Thursday. The EC had wind gusts upwards of 40 to 50 mph
with the GFS and NAM lower. Given the mixing aloft and the strong
pressure gradient, expect wind gusts of 40 to 50 mph to be
possible Thursday afternoon. Temperatures will take us on a roller
coaster this week. Expect warming temperatures Wednesday but
Temperatures dropping behind the cold front Thursday into the
weekend. Expect Maximum temperatures to be 10 to 15 degrees below
normal.

&&

.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 728 PM EDT Mon Apr 6 2020

VFR conditions will lower to IFR after midnight then improve to
MVFR by 18Z Tuesday. Winds will be southeast at 5 to 10 mph.

&&

.MARINE...
Issued at 1140 AM EDT Mon Apr 6 2020

The warm front will move into the region tonight with a few
thunderstorms possible over far southern Lake Michigan tonight
and Tuesday afternoon/evening. Persistent winds will cause waves
to become hazardous to small craft Wednesday night through
Thursday and into Friday. Highest winds will be on Thursday and
could reach gale force.


&&

.HYDROLOGY...
Issued at 315 AM EDT Mon Apr 6 2020

All of our river levels continue to drop as the water from the heavy
rain last week works its way to the Great Lakes. The next threat
for heavy rain returns tonight, and is focused along the I-94
corridor. It does not look likely that this will be widespread
enough to cause any of the larger rivers to rise significantly,
but localized impacts are possible. This will be especially true
if showers and thunderstorms track over the same areas repeatedly.
At this time, Van Buren County and Kalamazoo County are the most
vulnerable to excessive heavy rain that could cause ponding of
water on roads and brief overflow of small creeks.

Beyond tonight, several additional rounds of showers will affect
much of Lower Michigan for the next few days. While these
shouldn`t create flooding, it will keep the ground saturated and
vulnerable to runoff if we do start to see any larger heavy rain
events on the horizon.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&

$$

SYNOPSIS...Ceru
DISCUSSION...Ceru
AVIATION...Ostuno
HYDROLOGY...AMD
MARINE...Ceru