Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 250356
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1156 PM EDT TUE MAY 24 2016

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 330 PM EDT Tue May 24 2016

A weak cold front will move south across Lower Michigan tonight but
wash out near US-10 Wednesday. A warm and humid air mass will be in
place for the rest of the week and the air will feel very humid.
Scattered to numerous showers and thunderstorms are expected through
the holiday weekend, but the whole weekend won`t be a washout. Near
to above normal temperatures are anticipated through early next
week.

&&

.SHORT TERM...(This evening through Thursday night)
Issued at 330 PM EDT Tue May 24 2016

Forecast concerns deal with the convective potential through the
period.

Showers/storms are ongoing across northern WI and the UP. A weak
cold front is moving south across southern Ontario and will move over
northern Lower later tonight and Wednesday. Guidance trends have
been to wash this front out near US-10 and then move it back north
as a warm front. With that in mind we may see some showers/storms
across the far northern CWA tonight but probably won`t see much if
any pcpn over the southern CWA tonight or Wednesday. We`ll be stuck
in a warm and humid air mass as dewpoints rise into the 60s by
Friday. A fair amount of instability will be available during this
time. The issue may be a lack of a trigger to fire off convection.
Weak short waves move toward Lower Michigan Wednesday night/Thursday
morning and so that time frame is when we`ll have the highest POPs.
Shear values nose up to around 35 knots Wednesday night and so there
may be some organization to a few of the cells. We`ll keep an eye
out for strong/severe storms. The next wave will arrive Friday.

.LONG TERM...(Friday through Tuesday)
Issued at 330 PM EDT Tue May 24 2016

The southwest flow of warm and generally moist air will continue
through the long term period.  The atmosphere remains unstable as
well...thus some showers and thunderstorms can be expected.

A low level jet is shown to arrive later Friday into Friday night.
This will support one round of thunderstorms.  Depending on  how it
evolves...the thunderstorms could become numerous...with areas of
heavy rain.

A second low level jet is shown for Saturday afternoon and evening.
Instability will be present.  Thus additional thunderstorms can be
expected.  This is also when the Southwest U.S.
mid level low will be lifting out and tracking through the Western
Great Lakes region.  This could act to increase the deep layer shear
and support organized convection.  Right  now this risk looks west
of Lower MI at this time.

The wind decreases for Sunday into Monday...with little in the way
to focus the storms.  Perhaps a lake breeze could initiate a few
storms.  The High Res Euro does decrease pwat values considerably on
Monday...which would decrease the risk for rain.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1156 PM EDT Tue May 24 2016

VFR conditions will continue overnight and through Wednesday. A
few showers could be in the vicinity of MKG but these should not
cause any impacts. Some light haze may reduce visbys blo 6 miles
late tonight or Wednesday morning but this was deemed too
uncertain to include in the forecast. Winds will be mostly from
the southwest aob 10 knots. Thunderstorms are possible Wednesday
evening.

&&

.MARINE...
Issued at 330 PM EDT Tue May 24 2016

Low level dewpoints will slowly rise through the 50s tonight and
Wednesday. As higher moisture flows over the cold lake, areas of fog
will develop. It`s possible that the fog may become dense at which
point a marine dense fog advisory would be needed. That`s not
certain, however, and so a headline was not issued, but something
we`ll keep an eye on.

Otherwise, winds and waves will be fairly tame except in and near
thunderstorms.


&&

.HYDROLOGY...
Issued at 152 PM EDT Tue May 24 2016

Periodic showers and thunderstorms will move through the region
especially Wednesday night, Friday and Saturday. However, overall
rainfall amounts will likely be variable across the area. Some
locations may pick up well over an inch of rain through the
weekend, while other places much less. A good portion of the more
widespread rainfall could occur Wednesday night as a warm front
lifts through. Thursday and beyond will feature some diurnally
driven convection that could produce locally heavy rainfall...but
basin average rainfall is not expected to be excessive. Smaller
creeks and rivers could be susceptible to quick rises given this
setup. Main stem river flooding does not look likely.

&&

.GRR Watches/Warnings/Advisories...
MI...None.
LM...None.
&&

$$

SYNOPSIS...04
SHORT TERM...04
LONG TERM...MJS
AVIATION...Ostuno
HYDROLOGY...Hoving
MARINE...04



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