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Area forecast discussion 
National Weather Service Grand Rapids Michigan
915 PM EST sun Nov 23 2014

Latest update...

issued at 327 PM EST sun Nov 23 2014

Low pressure developing over Oklahoma and a clipper moving along the
northern tier of states will combine over the Great Lakes Monday.
Rain will move across lower Michigan tonight and Monday before
colder air works in behind the system and turns the rain to snow. A
few inches of snow are possible northwest of a Kalamazoo to Clare
line Monday night and Tuesday.

High temperatures near 50 Monday will give way to highs around 30
along with lake effect snow showers for the rest of the week.


issued at 915 PM EST sun Nov 23 2014

We have issued an update to the forecast this evening to insert a
slight chance of thunder for areas mainly along and southeast of Interstate
69 for late tonight and early on Monday. The models have trended a
little more unstable for this area over the past 24 hours.
Lightning is being detected in SW MO this evening in a pocket of
surface based and elevated Li/S that are a little below zero. This
instability is right on the edge of the dry slot that will move to
the NE through tomorrow morning. No severe weather is expected with
very limited instability.

Otherwise the forecast remains on track. A steady rain covers the
entire County warning forecast area this evening...and should remain this way through most
of the night.


Short term...(this evening through Tuesday night)
issued at 327 PM EST sun Nov 23 2014

Forecast concerns deal with the evolution of the deep low over the
Great Lakes Monday.

A deep upper trough with several short waves are moving toward the
Great Lakes. South flow ahead of a developing low in the plains is
sending quite a a bit of rain north toward lower Michigan. Temperatures
tonight will remain well above freezing so snow or ice won't be an
issue. Am also thinking that any flooding will be minimized by the
unfrozen ground.

The low from the Southern Plains will phase with a clipper moving
across the northern tier of states. Models have been consistent in
showing this phasing occurring over northern lower Michigan. Cold
air will begin to funnel into the County Warning Area Monday afternoon and the rain
will change over to snow. That snow then continues Monday night and
changes over to lake effect. The NAM is the colder of the models and
yields higher snow ratios. Current thinking is that we could see 3
to 5 inches of synoptic and lake affect snow north west of a
Kalamazoo to Clare line Monday night into Tuesday. Travel issues
could occur Monday night/Tuesday morning too as higher winds develop
in the wake of the departing low. The tricky part about the winds is
that a trough remains behind the low and so
we Don/T see a strong gradient over the County Warning Area like there is across
eastern lower Michigan. We hesitated with a Wind Advisory because of
that. Snow showers will continue into Tuesday night. The higher
accums will occur Monday night when there is better lift within the
dgz. By Tuesday...much of the lift is forecasted beneath the dgz
resulting in smaller flake size.

Long term...(wednesday through sunday)
issued at 327 PM EST sun Nov 23 2014

Model consensus calls for cold air through the long term with snow
possible for much of the period. However... the tracks of the short
waves responsible for the snow vary... dependent on model and
forecast cycle. This leads to low confidence in the timing and
amounts of snowfall.

A weak northern stream system is expected to impact the area
Wednesday into Thanksgiving day with light snow. This should be
followed by light lake effect snow into the night. A stronger system
will then move through the Great Lakes region Friday into Saturday.
This could bring measurable system snow and possibly lake effect in
its wake.

Temperatures are expected to be below normal through the long term.
Normal highs are around 40 degrees and normal lows are in the upper


Aviation...(for the 00z tafs through 00z Monday evening)
issued at 623 PM EST sun Nov 23 2014

Impacts to aviators will continue. IFR or lower to prevail into
Monday as a low pressure system tracks through. Colder air will
wrap in from the west to southwest on Monday changing much of the
precipitation over to snow. However down toward kazo...kbtl and
kjxn there is an increased risk for icing given the limited
moisture depth. Also those southern taf sites should see stronger
winds developing as we head through the afternoon. Some of the
snow later Monday afternoon into the evening could end up producing
lower than IFR...primarily for kgrr and kmkg.


issued at 327 PM EST sun Nov 23 2014

Low pressure will move over lower Michigan Monday/Monday night. A
trailing trough is forecasted to set up across western lower Michigan.
The models are not consistent in where this trough will end up. As
such pinning down where the gradient of highest winds will be is
also difficult. Ultimately...we issued a Gale Warning south of Grand
Haven and left the watch north of there.


issued at 327 PM EST sun Nov 23 2014

Regional radar shows rain spreading northward from the southern US.
Quantitative precipitation forecast around an inch is possible from later this afternoon through
Monday before the precipitation changes over to snow. Much of the snow pack
is gone and the ground is unfrozen...SW we think the potential for
widespread flooding is minimal but within bank river rises are


GRR watches/warnings/advisories...
Lm...gale watch from Monday morning through Tuesday morning for

Small Craft Advisory until 10 am EST Monday for lmz844>849.

Gale Warning from 10 am Monday to 7 am EST Tuesday for



short term...93
long term...63

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