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Area forecast discussion 
National Weather Service Grand Rapids Michigan
1159 PM EST sun Nov 29 2015

Latest update...

issued at 321 PM EST sun Nov 29 2015

A large high pressure system will be moving northeast away from
the western Great Lakes tonight allowing a developing storm system
from the Southern Plains to head toward western Great Lakes as an
occluded system for Monday night into Tuesday. This will bring a
surge of warmer and more moist air into the area Monday into early
Tuesday. A narrow band of rain will accompany the occluded front
later Monday night into the early morning hours of Tuesday. There
will be a brief clearing behind the occluded front during the middle
morning hours of Tuesday... then the colder air comes back in and
lake effect rain showers will develop by late afternoon then turn
to snow showers after midnight. The snow showers will continue
into Wednesday evening before ending. Milder air with partly
cloudy skies will prevail the rest of the week into next weekend.


Short term...(this evening through Tuesday night)
issued at 321 PM EST sun Nov 29 2015

Our forecast focus now shifts to the next occluded storm system
that will come through the area between Monday night and
Wednesday. The track of the primary surface low will be through
Wisconsin which puts southwest Michigan on the warm side of the
system. The system will have a 110 knot jet exit region pass
overhead of southwest Michigan during the early morning hours of
Tuesday. This will aid in decent isentropic lift as 30 knots
glides up the isentropic surface of the occluded front. The 35 to
40 knot low level jet passing just east of US-131 will also help
the cause as will the .9 inches of precipitable water surging
overhead. Little question this will mean rain... typical of an
occluded front. There is some very limited elevated
instability...enough to cause some convective charter to the
rainfall but not enough for thunderstorms.

Once that is all through... we get dry slotted by middle morning
Tuesday. I would imagine a fair amount of sunshine for a few
hours as that moves through. Then of course the cold air comes in
and that will bring showers to the area by late afternoon or
evening. Overnight the air gets cold enough for the rain showers
to change to snow showers and with west to southwest winds... deep
moisture and lift (lift in the dgz by the way) little question
there will be showers (rain to snow) so I have 80 to near 100 percent
pop near and west of US-131 during the early morning hours of

All this seems good but there is one little glitch. The glitch is
the European model (ecmwf) has been slower with this system than then the NAM or
GFS and over the past two days the European model (ecmwf) has been very consistant
with this storm. That may slow down the cold side of the system by
6 to 12 hours.

Long term...(wednesday through sunday)
issued at 321 PM EST sun Nov 29 2015

The low will move across northern lower Michigan Wednesday and into
Ontario by the end of the day. This will cause the winds to pivot
from westerly early northwest late in the day. This will
cause the lake enhancement bands to pivot from near I-96 to the SW
corner of the County Warning Area. Still not expecting a lot of snow accumulate since
temperatures will be marginal and the ground will be warm...but some areas
may get up to an additional inch of snow on grassy areas. The snow
should end late afternoon/early evening as the low pulls away and
the deeper moisture exits.

Quiet weather returns for the end of the week into the weekend. The
upper flow will be northwesterly...keeping a slight warm up in check
as temperatures stay near normal. However as we get into the weekend upper
ridging should build over the eastern U.S. Pushing temperatures above
normal...into the middle and upper 40s.


Aviation...(for the 06z tafs through 06z Monday night)
issued at 1158 PM EST sun Nov 29 2015

VFR conditions expected through Monday evening. Winds will be
light from the east at less than 10 knots.


issued at 321 PM EST sun Nov 29 2015

It would seem once the cold air comes in we will once again need a
small craft adviosry. That would be in the Tuesday afternoon time
frame. Seems the later runs of the models are not as bullish on
storng winds tomorrow.


issued at 1228 PM EST sun Nov 29 2015

Sycamore Creek at Holt has fallen back below there are
currently no river flood advisories in effect. The pere Marquette
river near Scottville continues to rise steadily...but is forecast
to crest slightly below bankfull. Impacts should be minimal.

Additional light rain is expected Monday evening into
Tuesday...followed by lake effect snow late Tuesday into Wednesday.
Precipitation totals should remain around a half inch or less...which would
not have a big impact on river levels.


GRR watches/warnings/advisories...


short term...wdm
long term...jk

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