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Area forecast discussion 
National Weather Service Grand Rapids Michigan
334 PM EST sun Dec 21 2014

Latest update...
synopsis/short term/long term/Hydro/marine

Synopsis...
issued at 334 PM EST sun Dec 21 2014

It will be wet and warmer than normal for this time of year as we
head into Christmas week. High temperatures will push to near 40 on
Monday and into the 40s on Tuesday. Rain will develop Monday
afternoon and continue off an on into Christmas evening day. Colder air
will work into the area behind a departing low pressure system and
given the area a chance at some light accumulations of snow
Christmas evening night.

&&

Short term...(this evening through Tuesday night)
issued at 334 PM EST sun Dec 21 2014

The short term will be located on the warmer side of the
system...and am expecting all rain for the most part in southwest
lower Michigan through Tuesday night.

The exception may be across far central lower Michigan Monday
afternoon and evening where a light mix of precipitation may be
possible. Feel that the warm air should overtake this area pretty
quickly though and did not include a mix in the forecast. If any mix
occurred it would be across Osceola and Clare counties towards 00z
tomorrow evening.

Otherwise...looking for a good push of rain Monday evening and
Monday night as a low level jet surges into the area ahead of the northern
stream low. There may be lulls in the rain Tuesday afternoon and
evening as the upper trough will undergo phasing during this time
and the focus of the rain will be shifting off to the east ahead of
the developing southern stream low.

Long term...(wednesday through sunday)
issued at 334 PM EST sun Dec 21 2014

Forecast concerns continue to revolve around the evolution of the
midweek storm. Not too much has changed in how we think this will
evolve. The trend of the European model (ecmwf) has been to push colder air a tad
farther east earlier in the day Wednesday.

The southern stream system that moves north from the deep south will
continue to be the main player...augmented by the clipper arriving
from southern Canada. The phasing of the two near the Great Lakes
will cause the southern system to strengthen. The main core of rain
will move into Southern Lower Michigan Wednesday morning and then
change to snow from west to east during the afternoon. The European model (ecmwf)
shows -3c at 800 mb by 00z Thursday with -4c over the eastern County Warning Area by 06z
Thursday. All precipitation should be light snow by late Wednesday. A couple
of inches of snow seem possible late Wednesday through Christmas
day.

Warmer air returns Thursday night as another system moves out of the
plains toward lower Michigan. Mixed rain and snow will be possible
across the southern half of the County Warning Area Friday. A stronger shot of cold
air will flow in behind the system Friday night and continue through
the weekend resulting in some lake effect snow.

&&

Aviation...(for the 18z tafs through 18z Monday afternoon)
issued at 1259 PM EST sun Dec 21 2014

A mix of VFR ceilings and MVFR visibilities are expected through the period.
Low level inflow of moisture will result in visibilities falling to
around 4sm overnight.

&&

Marine...
issued at 334 PM EST sun Dec 21 2014

Extended the Small Craft Advisory north of Holland through the day
on Monday now. Southerly flow remains decent through that time and
actually increases Monday night. Only felt comfortable extending it
through Monday evening at this point as the flow GOES more off shore
into Monday night. Still expecting 3 to 6 footers tonight into
Monday up towards big and little Sable points.

&&

Hydrology...
issued at 334 PM EST sun Dec 21 2014

The rainfall amounts now forecast with this system...more on the
order of a quarter to three quarters of an inch...should not impact
river levels too much. Overall...not expecting any Hydro issues.
River levels are near normal flows.

&&

GRR watches/warnings/advisories...
Michigan...none.
Lm...Small Craft Advisory until 7 PM EST Monday for lmz846>849.

&&

$$

Synopsis...Duke
short term...Duke
long term...93
aviation...93
hydrology...Duke
marine...Duke

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