Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 290528
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
128 AM EDT MON AUG 29 2016

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 328 PM EDT Sun Aug 28 2016

High pressure will control our weather until Tuesday at which point
a cold front will begin to move through the state. Showers and
thunderstorms are possible Tuesday/Tuesday night. Cooler and much
less humid air will flow into behind the cold front for the end
of the week.

&&

.SHORT TERM...(This evening through Tuesday night)
Issued at 328 PM EDT Sun Aug 28 2016

Forecast concerns deal with fog chances tonight and pcpn chances
Tuesday/Tuesday night.

Latest vis loop shows skies are mostly clear north of I-96 and
partly cloudy south of there. High pressure overhead will result in
calm winds tonight. Abundant low level moisture remains from recent
rain and dewpoints are in the 65 to 70 degree range. These
conditions are conducive for fog formation and we have fog in the
grids after midnight.

A cold front will approach the cwa Tuesday and pass through the cwa
Tuesday night. Scattered showers/storms are possible with the
passage of the front. We don`t expect severe storms with this front.
Shear values less than 20 kts expected Tuesday but li`s are near -
4c. Tuesday night, shear values are a bit stronger...25-30
knots...but instability is limited at best.

.LONG TERM...(Wednesday through Sunday)
Issued at 328 PM EDT Sun Aug 28 2016

Showers and storms will linger across the southern zones Wednesday
morning before the front clears Lower Michigan. Drying and
subsidence follows for Wednesday night through Friday under sfc
ridging and rising heights.

The sfc high moves east by Saturday with some moisture return
Saturday night. Held off on bringing showers in until Sunday when
deeper moisture and warm air advection increases.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 128 AM EDT Mon Aug 29 2016

Early morning fog remains the main concern for the TAFs. Patchy
areas of IFR have already developed, but have not impacted the TAF
sites as of 0530Z. A bit more wind moves in toward daybreak,
making the fog forecast difficult. Feel it will remain scattered
in area, and mainly inland. Believe MKG and GRR will stay VFR or
MVFR, while the rest of the TAF sites run the risk of seeing IFR
fog.

The vsbys in fog should be lowest right around daybreak, but its
hard to say what areas will see the IFR given the increase in
wind. Any fog will burn off quickly as the sun gets higher.
Generally by 13Z most of the fog will be gone, with VFR the rest
of the day.

&&

.MARINE...
Issued at 328 PM EDT Sun Aug 28 2016

Quiet conditions are expected on the lake through Monday.


&&

.HYDROLOGY...
Issued at 1201 PM EDT Sun Aug 28 2016

Will extend the Flood Warning for the Portage River based on the
half-inch of rain that fell on Saturday. The warning will be
maintained until observations can verify it has fallen and will
stay below flood stage. There is a chance of rain Tue-Wed this
week but likely not enough to cause problems. No other significant
rainfall or hydrologic concerns are expected this week.

&&

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

$$

SYNOPSIS...04
SHORT TERM...04
LONG TERM...Ostuno
AVIATION...JK
HYDROLOGY...CAS
MARINE...04



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