Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 141121
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
721 AM EDT Mon Oct 14 2019

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 308 AM EDT Mon Oct 14 2019

-Areas of frost Tuesday morning with rain arriving during the day

-Blustery with lake effect rain showers Wednesday

-Dry period from Thursday into at least Friday

-Unsettled weather possible especially toward the end of the
 weekend into early next week

&&

.DISCUSSION...(Today through next Sunday)
Issued at 308 AM EDT Mon Oct 14 2019

Our next risk for rain will arrive on Tuesday as an area of low
pressure steadily deepens as it moves from central WI to Lake Huron.
The more favorable upper level jet divergence will be located across
the U.P. and northern Lower MI with this system. With the H850 low
moving across northern WI/northern Lower MI it makes sense that the
heavier precipitation will be north of our region. There is a small
window where we could get some rumbles of thunder 18z Tue through
00z Wed as shown by projected MUCAPE by the medium range guidance.
Otherwise, rain showers can be expected at times Tuesday afternoon
and evening especially. Wrap-around lake effect rain showers and
blustery conditions are expected Wednesday as the low deepens into
the mid 990s over Lake Huron. In other words, very October-like.

Prior to this system`s arrival, frost is looking like a possibility
Tuesday morning away from the lakeshore. Some subfreezing
temperatures are not out of the question across interior central
Lower MI. The next threat for frost would occur Friday morning.

Medium range deterministic guidance and respective ensemble members
(ECM/GEFS/GEPS) suggest a mild and wet pattern is possible across
the Great Lakes toward the end of this weekend and into early next
week. Too soon to talk specific amounts of rain but the upper level
pattern (deep southwest flow with an open feed of Gulf moisture
potentially) would support anomalously high precipitable water
values.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 718 AM EDT Mon Oct 14 2019

VFR conditions expected through the period. Only issue to keep in
mind will be potential for brief cigs near 3000 ft, otherwise
dominant cigs near 5000 ft gradually lifting this afternoon.

&&

.MARINE...
Issued at 308 AM EDT Mon Oct 14 2019

Will continue the SCA as is, but there is potential for an earlier
cancellation depending on how quickly the winds/waves settle down.
The reprieve will be brief, however, with winds picking up Tuesday
(S/SW flow event) and waves reaching 4 to 7 ft mainly north of
Grand Haven. Conditions worsen Wednesday (NW flow event) with
lakeshore-eroding waves of 7 to 11 ft once again battering much
of our coastline.


&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Frost Advisory from 2 AM to 8 AM EDT Tuesday for MIZ037>040-
     043>046-050>052-056>059-064>067-071>074.

LM...Small Craft Advisory until 4 PM EDT this afternoon for
     LMZ844>849.

&&

$$

SYNOPSIS...Hoving
DISCUSSION...Hoving
AVIATION...Hoving
MARINE...Hoving


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