Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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000
FXUS63 KGRR 141132
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
632 AM EST Sat Jan 14 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 304 AM EST Sat Jan 14 2017

High pressure remains over the Great Lakes Region through the
weekend. This fair weather system is forecasted to provide the
region with dry weather and temperatures relatively close to
seasonable. Early next week a low pressure system is forecasted to
track out of the Southwest U.S. and into the western Great Lakes
Region. This system is predicted to bring a wintry mix of
precipitation to Michigan on Monday followed by some rain and
milder temperatures.

&&

.SHORT TERM...(Today through Monday)
Issued at 304 AM EST Sat Jan 14 2017

High pressure dominates the weather through Sunday. Mid to upper
level clouds will remain abundant through most of today. A small
risk for flurries exists mainly along the I94 corridor from these
clouds...but the low levels are dry. The 00z DTX sounding shows
the dry airmass below 10k ft. Thus I will keep the forecast dry
for now.

The low pressure system that tracks out of the Southwest U.S. will
be slightly delayed based on the latest model runs. So it looks
dry for nearly all of Southwest Lower MI for Sunday night. Also
what precipitation does for on Monday should be light as it will
take some time to saturate the dry airmass and the better lift is
shown to be elevated and above the DGZ.

High temperatures were lowered slightly for Sunday. The
combination of thickening mid to upper level clouds coupled with a
shallow cold airmass may limit the high temperatures.

Good radiational cooling is forecasted for tonight with mainly
clear skies and light winds. I did lower modeled forecasted
values a few degrees because of this.

.LONG TERM...(Monday night through Friday)
Issued at 304 AM EST Sat Jan 14 2017

Mild and wet conditions will start off the extended period. Very
little wintry precipitation is expected, as even warmer temperatures
begin to push in for the second half of the forecast.

As an upper level trough continues to swing into the Midwest, its
associated surface low will track from NW Missouri into the northern
Great Lakes. Despite the possibility that a few locations (Big
Rapids, Mt. Pleasant and Harrison) in central Lower Michigan could
hang near freezing, enough warm air should push north for
precipitation to continue to transition to rain. This initial upper
wave will weaken as it track northeast on Tuesday, but not before it
deposits widespread rainfall amount of around a half inch.

Another upper level trough develops over southern Canada, which will
eventually replace the initial wave. This not only keeps chances for
scattered showers in the forecast, but also brings a brief period of
cooler air late Tuesday into Wednesday. Showers may mix with and
eventually turn to light snow early Wednesday morning before
everything moves east.

Cooler air is very short lived Wednesday as ample ridging develops
over the eastern U.S. by Thursday and Friday. Temperatures could
surge well into the 50s over portions of southern Michigan. Several
pieces of energy look to be pushed out of the southwest, which
suggest any dry period would also be short lived with rain enter the
picture again late Friday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 626 AM EST Sat Jan 14 2017

The MVFR clouds southwest of KAZO are forecasted to remain south
of the MI/IN border today. Thus I will keep the conditions VFR.
The pressure gradient remains relatively weak through the
period...so the forecasts will contain winds under 10 knots.

&&

.MARINE...
Issued at 304 AM EST Sat Jan 14 2017

With high pressure in control of the weather for the next few
day...the wind will remain mostly under 10 knots. This will act to
keep the wave heights low.


&&

.HYDROLOGY...
Issued at 145 PM EST Fri Jan 13 2017

Rivers are running above normal across the area due to rain, melted
snow and ice jams. The Grand River at Robinson Township has an
active warning for minor flooding. Multiple sites also have active
advisories. A period of colder than normal temperatures through the
weekend may allow river ice to thicken.

&&

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

$$

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



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