Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 120725
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
225 AM EST Mon Feb 12 2018

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

.SYNOPSIS...
Issued at 225 AM EST Mon Feb 12 2018

High pressure will bring fair weather the next couple days with
temperatures above freezing by Wednesday. Low pressure will track
south of Lower Michigan on Thursday with rain changing to snow by
Friday.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 225 AM EST Mon Feb 12 2018

Quiet weather in the near term. Sfc high pressure builds over the
central Great Lakes with cold temperatures today and tonight.
Undercut min temperature guidance for tonight as radiational
cooling conditions are optimal. Return flow sets up by late
Tuesday with moderating temperatures for Tuesday night and
Wednesday.

No precip expected until Wednesday afternoon when southerly flow
brings in enough low level moisture for some drizzle or very light
rain showers across the southern tier.

.LONG TERM...(Wednesday night through Sunday)
Issued at 225 AM EST Mon Feb 12 2018

There is not much change needed for the long term portion of the
forecast as the models are fairly stable. Confidence has increased a
bit for the Thu system as there is better agreement with regard to
the timing of the two waves involved.

A small chance for pcpn (mainly rain) exists on Wed night, with a
better chance expected on Thu. The Wed night pcpn comes as a lead
short wave will be passing through the state. This wave will not
have much deep moisture associated with it, so the pcpn chcs are a
bit limited.

The threat of rain, eventually changing to some snow at the end of
the event, looks to affect mainly the srn half of the area. The
latest thinking is that the nrn and srn streams remain separate as
they come through here. The srn system is now expected to move
almost due east with the zonal upper flow in place. Deep Gulf
moisture does not look like it will make it here early enough to
have significant impacts. Then, the nrn stream wave/front pushes
through Thu night, and changes some pcpn over to snow before it
sweeps most of the moisture out.

Colder air will make a brief return for a couple of days in the wake
of the systems. Some lake effect snow showers will be possible,
however the low level flow is fairly anti-cyclonic. This will limit
the intensity and amount of snow showers. Any snow showers should
come to an end by Fri night as the sfc ridge moves right overhead.

Milder air will gradually make a return next weekend. Pcpn chances
will then gradually increase on Sunday and beyond. We see the NW
flow aloft from Fri become more zonal on Sat, and then southwesterly
on Sun as a strong upper trough digs across the West Coast. A sfc
low will eventually emerge from the Rockies, and draw Gulf moisture
north into the area. It may take until after this long term period
to make it this far north.


&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1241 AM EST Mon Feb 12 2018

A lot less impacts expected for aviation interests for this 24
fcst period. Skies have generally cleared out at just about all of
the terminals. Some high clouds are likely visible from KJXN, but
these are not a problem and moving away.

The only real impact we expect is some MVFR cigs likely from late
this morning through much of the afternoon. A pool of some
low level moisture will rotate down over the area by this
afternoon. It will create almost like diurnal cumulus clouds with
the sun angle increasing. They will likely be based around
2000-2500 ft. They should then dissipate and move east toward
sunset, leaving only high clouds for the latter portion of the
forecast period.


&&

.HYDROLOGY...
Issued at 255 PM EST Sun Feb 11 2018

Ice jams and minor low land flooding will continue, at least for a
couple days, as cold temperatures will continue into mid week. A
flood advisory remains in effect for the Looking Glass River near
Eagle due to elevated levels of water/ice from an ice jam. River
levels in the vicinity of ice jams will continue to fluctuate by
several feet until the ice breaks free.

High temperatures above freezing Wednesday and Thursday combined
with occasional sunshine will allow some snow and ice to melt. There
is also a chance for light rain Wednesday night and Thursday. Warmer
temperatures and runoff from rain and snow will increase the
potential for the river ice to shift around. However, it does not
look significant enough to break up the larger ice jams the area is
currently experiencing.

&&

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

$$

SYNOPSIS...Ostuno
SHORT TERM...Ostuno
LONG TERM...NJJ
AVIATION...NJJ
HYDROLOGY...63



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