Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 311859
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
259 PM EDT WED AUG 31 2016

LATEST UPDATE...
Synopsis/Short Term/Long Term/Marine/Hydro

.SYNOPSIS...
Issued at 259 PM EDT Wed Aug 31 2016

Much cooler and less humid weather can be expected leading into the
upcoming holiday weekend. The majority of the time also looks to be
dry, except for a low chance of a rain shower on Thursday.

Temperatures will slowly warm then through the holiday weekend with
an increase in humidity levels early next week. The chances for rain
will increase beginning late on Labor Day and more so next Tuesday as
the next frontal system approaches the area.

&&

.SHORT TERM...(This evening through Friday night)
Issued at 259 PM EDT Wed Aug 31 2016

Forecast challenges are rather limited through the short term, with
the threat of some light showers on Thursday really the only
noteworthy item.

There were a few showers and isolated storms that formed north of
the front along I-94 earlier with some residual instability. These
have now sank south of the CWFA, and are no longer an issue here.
Some diurnal stratocumulus is streaming south into the area as the
cooler air aloft and short wave starts to approach the area. Some of
this should diminish once we lose the daytime heating.

We have kept a small chance of light rain showers in for Thu across
the entire area. The short wave now across Wrn Ontario will dive SSE
tonight, and should be moving through the area between 12z and 18z
Thu. Moisture is rather limited, and inversion heights are not all
that high which should limit the coverage and intensity a bit.
Still, with a short wave overhead with some diurnal instability,
this justifies having a small chc in.

Once the short wave leaves the area later Thu afternoon, we will see
ridging build in across the area aloft and at the sfc. This will
persist through the end of the short term Fri night, keeping the
area dry and cool.

.LONG TERM...(Saturday through Wednesday)
Issued at 259 PM EDT Wed Aug 31 2016

A mid level ridge moves into the Great Lakes region over the weekend
and strengthens as we go into early next week.  This system will act
to keep the weather dry into Monday.  Deep southwesterly flow
develops as the the ridge builds east of MI for the middle part of
the week.  Thus in addition to the relatively dry weather...a
considerable warming trend will take place.  Temperatures in the 80s
are expected with a small potential for parts of the region to reach
the 90 degree mark Tue into Wed.  I did not go with 90s at this
point...but did bump up temperatures slightly over the modeled
guidance.

As the mid to upper level heights fall into the middle part of the
week...low level temperatures and moisture will be on the increase.
Thus the destabilization that results will support increasing
pops...mainly Tuesday into Wednesday.  Focusing the precipitation
could be a mid level wave that is shown to near the area for the
middle part of the week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 138 PM EDT Wed Aug 31 2016

The MVFR clouds from KAZO to KJXN will break up over the next 2
hours as drier air moves in from the north. A few showers have
developed in that region...but it looks like they will stay south
of the TAF sites based on the latest radar trends. Once the lower
clouds move out...the TAFs will feature VFR conditions into Thu.


&&

.MARINE...
Issued at 259 PM EDT Wed Aug 31 2016

We will be holding on to the marine headlines through Thursday as
is. Winds are beginning to ramp up this afternoon behind the cold
front. Waves are doing the same. This may not be a solid event
through Thu, with wind direction fluctuating a bit between onshore
and offshore. It remains more simple to just have the headlines in
tact instead of splitting them up and confusing people.

Waterspout potential looks a little too marginal at this time to add
to the fcst. We can not rule one out in a convergence band or
shower. It looks like the combination of instability and cloud depth
will not be enough for many.

&&

.HYDROLOGY...
Issued at 259 PM EDT Wed Aug 31 2016

Scattered thunderstorms produced isolated rainfall amounts greater
than 1.5 inches on Tuesday in several locations, while most areas
received little to none. No river flooding is anticipated. The next
chance for significant rain will hold off until the middle of next
week.

&&

.GRR Watches/Warnings/Advisories...
MI...Beach Hazards Statement through Thursday evening for MIZ037-043-
     050-056-064-071.

LM...Small Craft Advisory until 11 PM EDT Thursday for LMZ844>849.

&&

$$

SYNOPSIS...NJJ
SHORT TERM...NJJ
LONG TERM...MJS
AVIATION...MJS
HYDROLOGY...CAS
MARINE...NJJ



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