Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 291353
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
953 AM EDT THU SEP 29 2016

LATEST UPDATE...
Marine

.SYNOPSIS...
Issued at 323 AM EDT Thu Sep 29 2016

Low pressure will continue to spin near and over Lower Michigan
through the week and into the weekend. This will bring mostly
cloudy weather with periods of showers and a few thunderstorms.

&&

.UPDATE...
Issued at 902 AM EDT Thu Sep 29 2016

Based on the latest radar trends and looking at an ensemble of
the HRRR, HRRRX, and RAP model (using time lagged ensembles) I
redefined the rain area farther north (by about a row of
counties) for today and also updated the QPF to match.

There is some through about flood advisories but at this point I
think the rain band near I-94 is going to break up enough over the
next few hours so that will not be a big issue. Jackson County has
had around an inch of rain so that would be the most venerable.
Again I think that rain band should be moving out of there in the
next few hours. Overall this still will have to be watched.

&&

.SHORT TERM...(Today through Saturday)
Issued at 323 AM EDT Thu Sep 29 2016

Upper cutoff low spins across the Ohio Valley then moves north
back into Lower Michigan by the end of the period. Strong easterly
flow including low level jet will tap into tropical moisture
plume moving up the east coast by Thursday night. Showers will
become more widespread and persist into Friday before beginning to
taper off as the occluded low moves into the forecast area.

Marginally steep lapse rates late Thursday into Saturday make
diurnal enhancement of thunderstorms possible each day. The
persistent nature of the flow regime and the presence of tropical
moisture feeding in will mean that excessive rains are possible
and this will have to be monitored closely.

.LONG TERM...(Saturday night through Wednesday)
Issued at 323 AM EDT Thu Sep 29 2016

The upper low will continue to linger over our region Saturday night
through Sunday and bring extensive cloud cover and scattered
showers.

The pattern should finally become more progressive Sunday night
into early next week when the upper level low will finally
move east of our region as upper ridging builds in from the
west.

As a result fair weather will finally return early next week
with seasonably mild temperatures reaching the lower to perhaps
middle 70`s by next Mon/Tue.

&&

.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 725 AM EDT Thu Sep 29 2016

Areas of IFR can be expected today and tonight with rain showers
and ceilings around 700 to 900 feet AGL. East winds will be around
10 knots with gusts to 20 knots this afternoon.


&&

.MARINE...
Issued at 953 AM EDT Thu Sep 29 2016

We have added waterspouts to the forecast for the nearshore waters
south of Whitehall for today. This is where most of the showers
that could produce waterspouts will be, closer to the center of
the low, and under the cold pool aloft. Most of them should be
offshore with the offshore wind, but it is still enough of a
threat to mention.

&&

.HYDROLOGY...
Issued at 140 PM EDT Tue Sep 27 2016

River levels are around normal for this time of year. Lake enhanced
rain showers are possible through Wednesday. Rain showers continue
to be possible into Sunday. Rainfall totals into the weekend will
range from a half inch up to an inch and a half. Rivers and streams
should remain below bankfull through the weekend.

&&

.GRR Watches/Warnings/Advisories...
MI...None.
LM...Small Craft Advisory until 6 PM EDT Friday for LMZ844>849.

&&

$$

UPDATE...WDM
SYNOPSIS...Ostuno
SHORT TERM...Ostuno
LONG TERM...Laurens
AVIATION...Ostuno
HYDROLOGY...63
MARINE...NJJ



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