Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 250759
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
259 AM EST Sun Feb 25 2018

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

.SYNOPSIS...
Issued at 258 AM EST Sun Feb 25 2018

A rapidly deepening storm system, tracking through the Great
Lakes this morning will sweep and occluded front through the area
just before sunrise. That will sweep the rain out of the area but
bring very strong winds with some gusts near 50 mph this morning
into early this afternoon.

High pressure follows for tonight into Tuesday. That will bring
well above normal temperatures to the area by Tuesday with highs
in the mid to upper 50s.

Then the combination of stalled frontal system and low coming out
of the Southern Plains will bring showers Wednesday but a steady
rain, possibly heavy at times, Thursday. That may end as some
light snow Thursday night or Friday morning. There may be enough
rain with this to cause additional river rises.

&&

.SHORT TERM...(Today through Tuesday)
Issued at 258 AM EST Sun Feb 25 2018

A high wind advisory has already been issued and I will maintain
it through the morning.

In the very short term we have a rapidly deepening surface low
under and negative tilt upper trough moving through the area this
morning. Winds will become very gusty once the occluded front
comes through just before sunrise. Winds have been gusting to
around 50 mph near and southwest of Chicago for the past few
hours. With the aid of the sun coming up an strong cold advection,
we should have no problem mixing the 40 to 50 mph winds just
above the surface to the ground this morning. So, I issued a high
wind advisory just before 2 AM, for the entire CWA, that will
remain in effect into early this afternoon. That is in
conjunction with all adjacent offices.

Beyond that once the frontal system moves east of the area this
evening winds will calm down and skies will be mostly clear as
surface high pressure passes south of Michigan on Monday. Since
this is a surface high from the Pacific Ocean, it has mild air
with it and as a result temperatures will be well above normal for
this time of year. Highs will be in the mid 40s Monday. On Tuesday
we get into the return flow on the back side of the surface high,
that in conjunction with the approaching cold front, will bring
up even warmer air so we may have highs pushing 60 degrees on
Tuesday.

So, bottom line once we get through the windy day today, Monday
and Tuesday will be early to mid spring like days with a fair
amount of sunshine too.

.LONG TERM...(Tuesday night through Saturday)
Issued at 258 AM EST Sun Feb 25 2018

We are looking at two periods of precipitation possible in the long
term portion of the forecast. The first looks fairly trivial, while
the second one could bring enough rain to cause some rises on the
rivers which will likely remain swollen from our recent flooding
event.

The first chance of rain comes on Tue night into Wed morning. This
will come as the SW flow aloft sets up again with a Wrn trough
taking shape, and sending some weak lead short waves toward the
area. Right now, it does not look good for all areas to see
measurable rain as the Gulf will not be wide open for the area.

We will see a short break then for later Wed, before rain looks to
come back in by daybreak Thu morning. This system looks to impact
the area a fair amount more than the Tue night/Wed system. We will
see some phasing of a nrn short wave, and a srn stream short wave
that lifts out of the desert SW. This phasing will slow it down, and
will draw a good deal of moisture north into the area. We could be
looking at rainfall amounts of an inch or greater, which would not
help our rivers out.

The pcpn will come to an end Thu night/Fri morning, and could
briefly change over to some light snow before ending as cold enough
air could make it in. We are then looking at drier weather into next
weekend along with cooler air.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1249 AM EST Sun Feb 25 2018

There are two impactful types of weather expected in the 06z
forecasts, IFR conditions and gusty winds.

IFR cloud cover is spreading in from the South and West, with a
few rain showers lagging the low clouds by a couple of hours. We
expect these conditions to last the first 4 to 6 hours before
ending. The IFR will gradually lift then after the rain ends
around 10-13z. Conditions should transition to VFR toward 16-18z
and remain through the remainder of the period.

The end of the rain showers will occur as the front moves through.
When this occurs, winds will shift to become from the SW, and
become gusty. Winds gusts up around 30-35 knots are likely through
much of the daylight hours. Winds should then diminish toward
evening, especially after sunset.


&&

.HYDROLOGY...
Issued at 325 PM EST Sat Feb 24 2018

The Grand River crest is moving through Kent County this weekend and
will move through Ottawa County early in the week. This crest will
likely stay below the levels seen in April 2013. The crest of the
Kalamazoo River is moving out of Kalamazoo and into Allegan county.
Kalamazoo / Comstock Twp river level reached record high levels,
surpassing other historic crests of 2008, 1985, and 1947.
The Thornapple River has crested at levels not seen since at least
1985. River levels in Battle Creek and Lansing were the highest seen
since 1975. Even after river levels crest, flooding will persist
along many rivers for a number of days. Flood impacts/extent in some
communities may differ compared to similar historic crests due to
recent flood mitigation projects or other development, and it will
take rigorous documentation and analysis to adjust flood
expectations for future events along the many river points that have
been affected.

Rainfall Saturday night will amount to a quarter inch and possibly
less. This will not have much impact on river levels, but could
slightly prolong the duration of flooding on some rivers. The next
precipitation event to monitor will be on Thursday. Model guidance
is suggesting the possibility for around an inch of precip (though
perhaps not all of it will be rain).

Please see the latest flood warning/advisory statements or river
hydrographs for details. Hydrographs are available by going to
weather.gov/grr and clicking on the "Rivers and Lakes" link above
the map of flood warnings.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Wind Advisory until 2 PM EST this afternoon for MIZ037>040-
     043>046-050>052-056>059-064>067-071>074.

LM...None.
&&

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...NJJ
AVIATION...NJJ
HYDROLOGY...CAS


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