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Area forecast discussion 
National Weather Service Grand Rapids Michigan
328 PM EDT Sat may 30 2015

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

issued at 320 PM EDT Sat may 30 2015

After some thunderstorms south of I-96 this evening...rain is
expected for much of the region tonight and into Sunday morning
with some showers lingering across south central lower Michigan Sunday
afternoon/evening. Much colder weather will be featured on Sunday
with highs only in the 50s with breezy conditions.


Short term...(this evening through Monday night)
issued at 320 PM EDT Sat may 30 2015

Steady rain expected near/south of I-96 tonight and Sunday morning
as the cold front clears the County Warning Area by 00z tonight and the surface low
traverses southern in/OH. The frontal passage will effectively
squash the threat for thunderstorms as revealed by the lack of any
elevated instability on GFS BUFKIT I removed mention
of thunder beyond 00z although a few rumbles are still possible
overnight I suppose. Until then...some surface based cape remains ahead
of the front across our southeast counties along with 30-40 kts of
effective shear and slightly negative Li values. The threat for
storms continues through early evening but severe weather looks

Rainfall totals are expected to be between 1.5-2.5 inches from this
afternoon through Sunday evening east of a line from South Haven to
Lansing...with amounts decreasing significantly north of this line.
The best h500-h850 moisture flux convergence is well agreed upon by
the European model (ecmwf)/GFS/Gem to be maximized 00z-12z Sunday near/east of a lwa-
lan line as mentioned. The h1000-h700 layer wind convergence is a
bit further north with the Gem than the European model (ecmwf) and GFS...which would
suggest the heavier precipitation axis could be shifted north as well...but
feel this difference would not be significant enough from our
current weighted blend for the official quantitative precipitation forecast.

All of this being the case...this is not a classic flood setup for
the County Warning Area with stratiform precipitation being the main player (drawn out over
many hours) and the highest totals occurring across an area that has
seen the least rainfall overall during the past couple weeks.
Locally heavier rainfall with any pre-frontal convection could be a
slight caveat but in terms of areal coverage...not enough concern to
issue a Flood Watch.

Raw and breezy are the two best words to categorize Sunday. With a
1030 mb surface high moving in and a 1011 mb surface low moving out...the
pressure gradient in place will produce some decent winds out of the
NE from Saginaw Bay. This typically gives locations from Lansing to
Grand Rapids some wind gusts in the 25-35 miles per hour range. Combined with
lingering light rain and surface temperatures in the low will not be a
very pleasant day.

Frost potential on Monday morning does not look ideal to ME given
high clouds in place (saturation from 25k-35k ft) and NE winds
holding up overnight probably on the order of 5-10 miles per hour. Have decided
to mention patchy frost mainly north of a Big Rapids to Clare line.
If the trend in cloud cover diminishes...then more frost development
is possible. Some patchy frost is also possible Tuesday morning for
the same areas.


Long term...(tuesday through saturday)
issued at 320 PM EDT Sat may 30 2015

Fairly quiet weather in the extended. Canadian surface high moves east
early in the week with a moist return flow setting up by the middle
of the week. Despite increasing moisture and instability ... is
little to focus any convection and a dry forecast will be maintained
through Thursday.

Zonal flow will prevail most of the week as the Great Lakes will be
in between an upper low across the Gulf Coast that slowly opens up
and fills and a couple northern stream shortwave troughs progressing
across central Canada. The second trough forces a cold front through
by next weekend. This will bring chances for rain Thursday night and
continuing into Saturday.


Aviation...(for the 18z tafs through 18z Sunday afternoon)
issued at 150 PM EDT Sat may 30 2015

IFR conditions will prevail through tonight as rain and low
clouds will be widespread. Conditions will slowly improve Sunday
morning as drier air moves in from the north. Winds will go north
or northeast and increase this afternoon with gusts over 20 knots
continuing through Sunday morning.


issued at 320 PM EDT Sat may 30 2015

Small Craft Advisory will continue into Sunday evening. Gusty
conditions are likely as the cold front moves south over the lake
this evening. Waves in the 3-5 feet range or even higher are
expected especially near the points and also from Saugatuck to
South Haven.


issued at 320 PM EDT Sat may 30 2015

River levels are generally rising due to widespread precipitation.
Of greatest concern are the smaller rivers and streams in the upper
Grand River basin / greater Lansing region. Forecasts based on 1.50
inches of rain being received through Sunday morning have the
Sycamore Creek near Holt and Looking Glass river near Eagle climbing
above bankfull. It is entirely possible this amount of rain will be
received in this area... but will hold off on river flood advisories
for now until confidence increases. Forecasts will be re-evaluated
late this evening and Sunday morning.


GRR watches/warnings/advisories...
Michigan...Beach hazards statement through Sunday afternoon for miz037-043-

Lm...Small Craft Advisory until 6 PM EDT Sunday for lmz844>849.



short term...Hoving
long term...ostuno

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