Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 261927

Area Forecast Discussion
National Weather Service Grand Rapids MI
328 PM EDT FRI AUG 26 2016

Synopsis/Short Term/Long Term/Marine

Issued at 328 PM EDT Fri Aug 26 2016

Low pressure will move toward northern Lower Michigan Saturday.
Showers and thunderstorms are possible and a few could be strong.
After the low moves by, a cold front will sweep through and Sunday
will be mainly dry. More showers and storms will be possible Tuesday
as the next cold front moves through.


.SHORT TERM...(This evening through Sunday night)
Issued at 328 PM EDT Fri Aug 26 2016

We`ll see increasing clouds tonight as mid/high clouds stream
northeastward ahead of the next front. Short range models are fairly
consistent in showing showers/storms developing Saturday morning and
continuing through the afternoon. Much of the upper energy moves
across Wisconsin and northern Lower. In fact, shear increases to 40-
45kts Saturday morning as the llj begins to increase. However,
instability will be highest over the southern cwa Saturday
afternoon. Shear values are progd to be around 35 knots during the
afternoon as instability increases. So, the strongest storms, should
they form, will be south of I-96 tomorrow afternoon.

Heavy rain appears to be a possibility too as pwats increase to
around 2 inches across the southern cwa Saturday afternoon.

Mainly dry weather is expected Sunday and Sunday night.

.LONG TERM...(Monday through Friday)
Issued at 328 PM EDT Fri Aug 26 2016

A few showers and thunderstorms may linger across the far southern
zones early Monday before sfc high builds south bringing a break in
the chance for rain. This is short lived as an area of warm
advection/isentropic ascent begins Monday night with at least
isolated showers and storms moving in from the southwest.

A higher chance of rain follows for Tuesday as a shortwave trough
amplifies with sfc cyclone moving across Canada and trailing cold
front across the Great Lakes. The trough axis shifts east with sfc
and upper ridging bringing generally fair weather Wednesday through


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 158 PM EDT Fri Aug 26 2016

VFR conditions will continue this evening, then rain and lower
ceilings will bring MVFR after 06Z...lowering to IFR around 12Z.
The IFR conditions should improve to MVFR and then IFR around 18Z.
Thunderstorms are possible in the morning but the chances are low
enough to keep out of the forecast for now.


Issued at 328 PM EDT Fri Aug 26 2016

Fairly tame conditions on the lake tonight and Saturday.
Thunderstorms though will create a marine hazard. Strongest south
winds will be found over the northern portion of the lake.


Issued at 328 PM EDT Fri Aug 26 2016

The Portage River is slowly falling and is expected to fall below
flood stage tonight or tomorrow. The only fly in the ointment is
likely rainfall on Saturday. Any thunderstorms will be rather
efficient rainfall producers as humidity increases through the depth
of the troposphere. Locally over an inch of rain is possible.


.GRR Watches/Warnings/Advisories...


LONG TERM...Ostuno
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