Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 171559
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1159 AM EDT Mon Jul 17 2017

LATEST UPDATE...
Update

.SYNOPSIS...
Issued at 330 AM EDT Mon Jul 17 2017

Fair weather is expected today through Tuesday evening with high
pressure sliding through the Great Lakes region. Highs will be near
normal both days, from around 80 today to the low to mid 80s on
Tuesday. A cold front will touch off some showers and storms Tuesday
night, that will last into Wednesday morning. Additional showers and
storms are expected during the latter half of the work week with
highs in the 80s.

&&

.UPDATE...
Issued at 1159 AM EDT Mon Jul 17 2017

A fair amount of low level moisture lingers over the region and
this lines up with the dense over the far SW corner of the state.
Additional diurnal CU is forming, and many areas will go broken
for a period this afternoon. Therefore sent an update with more
cloud cover. Seems like Central Lower will experience the most
sunny, and cloudier to the south.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 330 AM EDT Mon Jul 17 2017

Main forecast challenge in the short term pertains to chances for
showers and thunderstorms late Tuesday night into Wednesday.
Otherwise, fair weather is expected from Today through Tuesday
evening.

High pressure will be situated across Southwest Lower Michigan
today, tonight and Tuesday. Pleasant weather is expected with dry
conditions, mainly clear conditions and comfortable dew points.
Temperatures will be near normal during this period with highs
around 80 today and in the lower to mid 80s on Tuesday.

As for the chance for showers and storms, the main time frame looks
to be overnight Tuesday night into Wednesday morning. This is when
the models forecast the low level jet to be nosing into the area.
The NAM is the most bullish on this feature, with a widespread 30-40
knots at 12z Wednesday over the forecast area. The GFS and ECMWF are
much less on the order of 15 to 20 knots. Best chances for
precipitation will be across Central Lower Michigan closer to the
front. Severe chances at this point look a bit lower given the lack
of consensus in terms of the low level jet strength, not to mention
the time of day.

On Wednesday, the showers and some embedded thunderstorms will move
through the area during the morning which will likely limit
afternoon instability. The front becomes parallel to the upper flow
and stalls across the area, so not hard to imagine it may become a
focus for additional development if we can get some sun in the
afternoon.

.LONG TERM...(Wednesday night through Sunday)
Issued at 330 AM EDT Mon Jul 17 2017

A warm front will be moving north through the cwa Wednesday night
and early Thursday and we`ll likely see scattered showers/storms
with that front ahead of a low that will move across the northern
cwa Thursday. Both the ecmwf and gfs show a short wave aloft to
support the idea of convection. High pressure briefly builds into
the state Thursday night and Friday behind the trailing cold front
which should make it as far south as northern Indiana. As it lifts
north Friday night and Saturday more showers/storms are possible.
The timeframe from Friday night through Sunday could be stormy as
the low that pushes the warm front north tracks across the cwa and
another cold front moves through Sunday.

Pretty typical summer time temperatures are expected through the
period with highs in the mid 80s and dewpoints in the 60s.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 748 AM EDT Mon Jul 17 2017

Low clouds and fog, some of which are to the LIFR range exist this
morning across especially South Central Lower Michigan. We expect
these low clouds to mix out fairly quick this morning. After 15z,
we are forecasting VFR weather.

VFR weather is expected from late morning through tonight. Winds
will be light, under 10 knots through the period. A lake breeze
will shift the wind direction to the west-northwest this
afternoon.


&&

.MARINE...
Issued at 330 AM EDT Mon Jul 17 2017

Will be dropping the Beach Hazards Statement and the Small Craft
Advisory with this issuance. The South Haven buoy is still at 3.9
feet, but the trend is down. Waves should be under 3.5 feet in all
areas fairly soon.

A quiet period out on the big lake is expected from this morning
through the day on Tuesday. High pressure will bring fair weather
and light winds.

Winds and waves will kick up Tuesday night into Wednesday as a cold
front drops into the area. The strongest winds look to be late
Tuesday night into Wednesday morning associated with thunderstorms.


&&

.HYDROLOGY...
Issued at 330 PM EDT Sun Jul 16 2017

Much of Lower Michigan was spared of rainfall last night into this
morning. A few isolated showers developed east of Grand Rapids with
little in the way of measurable precipitation.

The pattern remains fairly quiet through Tuesday. The midweek
timeframe brings thunderstorms back into the picture, but will be
isolated/scattered in nature. Limited rainfall through the next
couple days will allow above normal river levels to continue to fall
off. Improvement may even continue through the middle of the week
with the limited aerial coverage in resulting moisture.

&&

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

$$

UPDATE...JK
SYNOPSIS...Duke
SHORT TERM...Duke
LONG TERM...04
AVIATION...Duke
HYDROLOGY...JAM
MARINE...Duke



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