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Area forecast discussion 
National Weather Service Grand Rapids Michigan
1159 PM EDT Monday Mar 30 2015

Latest update...

issued at 330 PM EDT Monday Mar 30 2015

A clipper type system will slide through the Great Lakes region
tonight into Tuesday morning. Rain and snow will occur tonight with
the snow most prevalent north of Interstate 96 towards central lower
Michigan. Several inches of snow are possible tonight in a narrow
band across center lower Michigan. The precipitation will come to an
end Tuesday morning with dry conditions expected from midday Tuesday
into Wednesday night. The next system to affect the area will move
in late Wednesday night bringing rain into Thursday. Temperatures
will warm into middle week with readings rising into the 50s and 60s on


Short term...(this evening through Wednesday night)
issued at 330 PM EDT Monday Mar 30 2015

Main item in the short term is the precipitation event tonight. A
clipper system will push plain rain into the area after 700pm which
will likely continue through midnight. As the boundary layer cools
overnight we are expecting snow to mix in and even completely change
over across portions of central lower Michigan. There is strong fgen
forcing noted in the 900-800mb layer as well as strong isentropic
lift on the 290k surface. Bottom line...thinking the precipitation
is going to have a convective element too it which will likely lead
to a narrow swath of accumulating snow. At this point thinking the
heavier band of snow is going to extend from the Pentwater area
southeast through Newaygo towards Alma. Have a 1-3 inch swath in the
forecast in these areas. If the changeover occurs a bit quicker and
the convective elements roll over the same areas an isolated 4 inch
amount not out of the realm of possibilities. For I-96 on south
thinking this is a rain event. A touch of light snow is possible on
the tail end towards 12z before the precipitation shuts off along
I-96...but this should not be an issue. Expecting a dry late morning
and afternoon on Tuesday.

Otherwise...skies will gradually become partly cloudy in the wake of
the clipper Tuesday afternoon and night. Wednesday should be a quiet
day as high pressure drifts east. The next system already takes aim
for Wednesday night with decent 850mb moisture transport situated
across the County Warning Area after 06z. Have scattered probability of precipitation in the forecast at
this point...but they may need to be raised with time.

Long term...(thursday through monday)
issued at 330 PM EDT Monday Mar 30 2015

The long term portion of the forecast can be summarized by being
unsettled with up and down temperatures.

The main feature will be the frontal system that will push through
the area on Thursday. The models have come into decent agreement with
allowing temperatures to warm into the 60s for much of the area before rain
would move in by Thursday afternoon. We have mentioned a chance of thunder
as there will be sufficient elevated instability present for the
threat. The agreement comes with the northern stream wave being a little
bit more amplified than the GFS yesterday...but not as amplified as
the Euro was.

We have added a chance of rain back into the forecast for the southeast portion of
the County warning forecast area on Friday. The southern stream system digging into The Rockies will
lift out a bit later now and ride up along the front that will be
just southeast of the area. There is enough of a chance that we will be on the
northwest edge of the precipitation.

We will see the next chance of precipitation come in during the day on Sat. We
will see another short wave come in from the northwest after the wave from
the SW exits the area. This could be rain or rain/snow at the onset.
As colder air moves in...the back edge of the precipitation will likely
change over to snow before ending.

Ridging will build in for sun and bring a dry day. The Sat front
will then drive back north as a warm front on Monday as the upper
trough moves out and ridging builds back in. The moisture return
with the front will bring yet another chance of mainly rain to the


Aviation...(for the 06z tafs through 06z Tuesday night)
issued at 1154 PM EDT Monday Mar 30 2015

Band of rain will March through the taf sites overnight. As
temperatures cool off snow could mix in...especially for klan.
There is a small risk klan could go under continue
monitoring trends. Also a small risk for kgrr and kmkg to switch
over...but that risk is too low to include at this time.

MVFR conditions are likely for much of the area overnight
associated with the rain. Conditions improve as we dry out Tuesday


issued at 905 PM EDT Monday Mar 30 2015

Bumped up winds and waves for this evening based on reports.
Developing offshore flow should support lowering wave heights
through the evening.


issued at 330 PM EDT Monday Mar 30 2015

A few rivers had minor upticks in levels from the precipitation on
Sunday. Rivers are running near to below normal for the time of
year. No heavy precipitation is expected with the upcoming system
tonight... so rivers will remain comfortably below bankfull.


GRR watches/warnings/advisories...


short term...Duke
long term...njj

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