National Weather Service Raw Text Product

Displaying AFOS PIL: AFDGRR Received: 2018-03-13 05:30 UTC


828 
FXUS63 KGRR 130530
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
130 AM EDT Tue Mar 13 2018

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 330 PM EDT Mon Mar 12 2018

Lake effect snow showers will develop overnight and continue 
through Tuesday evening before tapering off. Fair weather will
return for mid to late week. 

&&

.UPDATE...
Issued at 1002 PM EDT Mon Mar 12 2018

Coverage of diurnally enhanced convective snows has decreased 
substantially with only a few isolated cells now remaining. 
However the arrival of a strong shortwave dropping in from the 
northwest should lead to another flare up of snow showers after 4 
am or so, particularly in the lakeshore counties where the best 
low level convergence will exist. 

The snow showers could become locally intense at times again late
tonight and Tuesday morning as fcst soundings show no inversion 
present aloft and fairly deep moisture, possibly leading to some 
travel impacts for the morning commute. The main threat for 
locally heavy snow showers early Tuesday is west of Highway 131 
initially, but show showers becoming more cellular and spreading 
inland after Noon as is the typical diurnal characteristic this 
time of year with lake effect.

&&

.SHORT TERM...(This evening through Wednesday night)
Issued at 330 PM EDT Mon Mar 12 2018

Light snow showers and flurries will linger late this afternoon
and evening but with no snow accumulation. A few sprinkles are
possible as well. 

Nnw flow lake effect snow showers will develop overnight as h8 
temps fall to -12 to -14 C by 12Z Tue. The lake effect snow 
showers will then continue Tuesday into Tuesday evening. There 
will be decent low to mid level moisture along with inversion 
heights briefly up to around 8-9 kft agl. Lake induced instability
will be ample with delta t/s reaching the upper teens to lower 
20s. 

We expect snow showers to become more cellular in nature during 
the daytime hours tomorrow with some diurnal heating. They will 
also spread a little further inland but with less focus as low 
level wind speeds ramp up to around 15-20 kts. Snow showers will 
linger Tuesday night before gradually ending during the early 
morning hours Wednesday as h8 temps moderate.

Snow accumulations of around 1 to 3 inches are expected in favored
NNW flow portions of our lakeshore counties from late tonight
through Tuesday evening. Relatively highest amounts within that
range are most probable in western Mason... western Oceana and
western Van Buren counties.  

Lighter accumulations of around an inch or less are fcst further 
inland. Fair wx will return Wednesday as a mid level ridge builds 
in from the northwest.

.LONG TERM...(Thursday through Monday)
Issued at 330 PM EDT Mon Mar 12 2018

Fairly quiet weather is expected in the long term period. 
Temperatures will be near normal through the period. Some very light 
snow showers are possible from Thursday into Friday with some colder 
air that will still be hanging on. 850mb temperatures warm into the 
weekend with high pressure building in for Friday into Saturday. Dry 
weather is forecast over the weekend for the most part. There is a 
front centered around the Saturday night time frame that may bring a 
few rain or snow showers to Central Lower Michigan. Timing 
differences make for a lower confidence forecast with this front.  

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 130 AM EDT Tue Mar 13 2018

Snow shower trends will be the main focus of the 06z fcsts.
Occasional waves of snow showers are occurring mainly just
offshore of the area early this morning. It does look like as a
more organized wave aloft will come through in the next few hours,
and snow showers could reach inland to KGRR and KAZO. The best
concentration will remain near the lakeshore at KMKG. Inland areas
will see VFR cloud cover spread in from the North with the wave,
but snow shower chances there are fairly low. VFR conditions will
prevail, but some reductions in vsbys in any snow showers could
briefly drop as low as IFR.

We may see a brief break in the snow showers, before another wave
approaches later in the morning. This wave will also have some
daytime instability helping the chcs of snow showers, even at
inland locations. Again, conditions will be VFR, but localized
IFR will be possible under the heavier snow showers. Winds will 
pick up by afternoon with some gusts topping 20 knots. Snow 
showers and wind gusts will diminish toward sunset Tue night.

&&

.HYDROLOGY...
Issued at 330 PM EDT Mon Mar 12 2018

River levels will continue to fall this week. No heavy precipitation 
is forecast and snowmelt will be gradual.

&&

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

$$

UPDATE...Meade
SYNOPSIS...Laurens
SHORT TERM...Laurens
LONG TERM...Duke
AVIATION...NJJ
HYDROLOGY...Laurens