Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 162352
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
752 PM EDT Wed May 16 2018

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 314 PM EDT Wed May 16 2018
A weak cold front will drop down from the north tonight. It will
encounter a dry airmass limiting the potential for clouds and
rain. A large area of high pressure builds into eastern Ontario on
Thursday...keeping the dry airmass in place for Lower Michigan.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 314 PM EDT Wed May 16 2018

There is a weak cold front dropping southward from Lake Superior
this afternoon. This feature will drop through Lower Michigan
tonight. The airmass is relatively dry ahead of it so this feature
will likely pass by with no rain and perhaps even no clouds.

High pressure ridges in from the northeast. With a low level
easterly flow developing on Thursday...the warmest daytime
temperatures will likely be along and west of Highway 131. Rather
low humidity levels are predicted for the afternoon once again.

Models are struggling with the weak mid to upper level low over
eastern KS and NE. There is an are of showers and thunderstorms
associated with this feature. Overall there is a trend for this
system to move in Friday night here in MI. Given this trend...I
did add POPs to the forecast.

.LONG TERM...(Saturday through Wednesday)
Issued at 314 PM EDT Wed May 16 2018

The mid to upper level low is shown to tap some Gulf moisture on
Saturday. The combination of lift and added moisture will
support an increased potential for showers during the day. Thus I
bumped up the POPs.

Another mid level wave moves in behind the departing mid level low
Sunday. This feature is shown to develop some instability. Will
maintain the risk for thunderstorms. The system slows down as it
tracks through. Thus the potential for rain will carry over into
Monday. After that the weather drys out as high pressure is shown
to build in.

&&

.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 752 PM EDT Wed May 16 2018

The next 24 hours looks to be solid VFR. Winds will be a little
stronger and from the east at low levels Thursday.

Winds will become strongly enough easterly by Thursday morning to
that MKG should not see a wind shift to the west tomorrow
afternoon (lake breeze). Model soundings look drier than today too
so there should be less cu around Thursday afternoon.

It would seem to me there is enough of a wind increase in the
boundary layer toward morning to keep fog from being an issue.
There is a east wind at low levels so it would not be out of the
question that some fog or low stratus could advect in from Lake
Erie and Lake Huron into the JXN and possibly LAN taf site.

&&

.MARINE...
Issued at 314 PM EDT Wed May 16 2018

A weak cold front will drop down from the north tonight. The winds
will become easterly by daybreak. Thus low wave heights are
expected near the lakeshore for Thursday...along with falling
water temperatures.


&&

.HYDROLOGY...
Issued at 113 PM EDT Wed May 16 2018

River levels are high across southern Lower Michigan due to the
recent heavy rains. The rivers in central Lower Michigan are near to
a little above normal. A river flood warning continues for the
Portage River near Vicksburg. All other sites are forecast to crest
below flood stage, or have already crested.

Dry weather into Saturday will allow runoff to complete and the
flood crests to move downstream without further enhancement.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&

$$

SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...MJS
AVIATION...WDM
HYDROLOGY...63
MARINE...MJS



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