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Area forecast discussion 
National Weather Service Grand Rapids Michigan
130 PM EDT Monday Jul 6 2015

Latest update...

issued at 328 am EDT Monday Jul 6 2015

Today will be the warmest day of the year so far with considerable
sunshine. Highs will be from the middle 80s to near 90 degrees. An
area of showers and thunderstorms will move into southwest lower
Michigan later this evening then linger into the midday hours of
Tuesday until a cold front moves through the area ending the
showers and thunderstorms bringing cooler air back to the area.
Wednesday will see partly cloudy skies with pleasant afternoon
temperatures. A wave on the front may bring more showers and
thunderstorms to the area later Wednesday night into Thursday.


issued at 1141 am EDT Monday Jul 6 2015

No real issues to the going forecast and only made small tweaks to
the afternoon. Feel highs are generally going to be in the middle to
upper 80s away from the lake...based on 850mb temperatures. MOS guidance
confirms this thinking. High clouds are already trying to spill
in which should keep US from touching should some cumulus
development that should occur.


Short term...(today through wednesday)
issued at 328 am EDT Monday Jul 6 2015

The primary issue for this forecast is the threat for rain and
thunderstorms tonight into Tuesday. A secondary issue is just how
warm it will get today.

Once again we have a non ideal set up for convection ahead of and
just behind the cold front that will come through the area Tuesday
morning. The primary shortwave tracks across southern and central
Canada with a 95 knot to 100 knot jet core that crosses north of
Lake Superior overnight. That puts the right entrance region lift
area over northern Wisconsin and the northern half of lower
Michigan. In response to that the 40 knot low level jet core
drives north across northeast Wisconsin into Upper Michigan early
tonight. This puts southwest Michigan in the tail of the low level
jet. That is very not conducive to strong thunderstorms due to the
speed divergance in with that sort of set up. Also against
strong storms is the time of day (middle of the night). The Storm Prediction Center
sref shows this will the probability of thunderstorms focused over
Wisconsin tonight and only as far east as US-131 with its lowest
probability it plots on the maps in our County Warning Area.

There is still deep moisture in place even so... thus I do
believe we will see rain from this event. There is an area of
isentropic lift just behind the front Tuesday morning in response
to the jet entrance region that crosses just north of here. That
area of lift is what should bring US rain Tuesday morning.
Instability is anemic so strong storms seem nearly out of the
question. Deep layer shear is not all the special either. The
extensive cloud cover will aslo be an event killer for strong
storms. As I keep saying will rain none the less.

Skies will clear tomorrow night as the frontal band moves east of
the area. High pressure will give US a partly sunny and cooler
day Wednesday.

Long term...(wednesday night through sunday)
issued at 328 am EDT Monday Jul 6 2015

As the long term begins...a cold front is forecasted to be located over
central IL/in. This front will being to move north again in response
to a wave on the low moving toward lower Michigan. Models are
actually in pretty good agreement with this wave and paint some precipitation
over the southern half of the County Warning Area Thursday. Friday looks dry. Then
another low is forecasted to develop Friday. The models are trying to
develop this low in the middle of surface high pressure...and generate
precipitation. Confidence isn't high that that will occur. It seems more
plausible that the surface boundary will be just south of the County Warning Area along
with most of the precipitation Friday. Then as the high moves east
Saturday...precipitation will push farther north into lower Michigan as a
quasi warm front.

Temperatures will be warmest over the weekend with highs in the 80s.
Otherwise...highs in the 70s are expected.


Aviation...(for the 18z tafs through 18z Tuesday afternoon)
issued at 129 PM EDT Monday Jul 6 2015

A plume of low level moisture spread into southwest Michigan late
this morning...briefly causing MVFR ceilings at kbtl. Satellite
and model data show this area scattering as it spreads east this will maintain VFR conditions through early

Models in good agreement bringing precipitation into the west
Michigan taf sites overnight ahead of cold front. Latest model
guidance throwing some doubt into the coverage of the showers and
thunderstorms overnight. Will maintain the current thinking and
try to narrow down the timing somewhat.


issued at 1141 am EDT Monday Jul 6 2015

Will be making tweaks to the going beach hazards statement.
Highest concern for the swim day today is the northern beaches.
Winds have already come up in our northern zones. Orchard Beach
State Park out of Manistee this morning reported 2-3 footers that
were building quickly. The south will likely remain below beach
hazard statement criteria...more 2-4 or even 1-3 footers as you
head south down the shore. So...have pushed the start time of the
bhs in the southern three zones to 06z tonight.

Tomorrow a strong north flow develops and I am expecting 3-6
footers for a good portion of the beach day.

Bottom line...areas north of Muskegon will see larger waves and
beach hazards today...all areas tomorrow with the highest waves
south of Muskegon. There will be a bit of a lull in the action
tonight in the baggy gradient near the front...but will not
complicate things by taking down headlines and re-issuing.
Headlines will run through the night.


issued at 1119 am EDT Monday Jul 6 2015

No short term issues are foreseen on area rivers. Long term
forecasts spell some concern with heavier rainfall that may come
into the picture later this week.

Rivers all continue to be stable or falling slightly. Current
levels are a bit higher than normal by July standards due to the
heavier rainfall experienced in June. Rainfall tonight into
Tuesday will generally be one-half inch or less. While localized
areas could exceed this amount...widespread heavy rainfall is not

The second half of the week brings the possibility for multiple
waves of rainfall along a boundary that could set up somewhere
through the Great Lakes region. Confidence is low with expected
rainfall totals...but current consensus with wpc guidance suggests
one to two inches is possible right through next weekend...from
Friday through Monday. Forecast variability with the boundary will
require a bit more attention to updates through the next several


GRR watches/warnings/advisories...
Michigan...Beach hazards statement from late tonight through Tuesday
afternoon for miz056-064-071.

Beach hazards statement through Tuesday afternoon for miz037-043-

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



short term...wdm
long term...04

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