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Area forecast discussion 
National Weather Service Grand Rapids Michigan
811 PM EDT Monday may 25 2015

Latest update...

issued at 330 PM EDT Monday may 25 2015

After a quiet night more rain can be expected Tuesday...especially
into the afternoon and evening. The showers and storms should
become more scattered late Tuesday night...but are expected to
linger into Wednesday and Wednesday evening before finally moving
out of the area. It will remain warm and slightly humid with
daytime highs in the middle and upper 70s. Less humid air arrives
Wednesday night.

The rest of the work week remains warm...but a cool down appears
possible by the weekend. There will be period chances of
rain...Friday and Friday night...and again Sunday night into


Short term...(this evening through Wednesday night)
issued at 330 PM EDT Monday may 25 2015

Drier air was moving into the western Great Lakes this afternoon
and this will pass over SW Michigan tonight. Then more showers and
storms will move into the area Tuesday afternoon and evening. Some
of these storms could be strong to severe. Scattered convection
will persist over the area into Wednesday evening when a cold
front finally brings drier air.

Looks like a quiet night as drier air advects over the region. The
stalled front remains over NE WI much of the have a 20
probability of precipitation over the far northwest...otherwise expect dry.

The next round of precipitation will be caused by a wave riding along the
front on Tuesday. This wave was over OK this afternoon. It will
come with a low level jet that noses into the southeast County Warning Area toward evening.
The actual nose of the jet appears to be pointing more toward the
eastern part of the state and that appears to be where the best
potential over severe storms exists. However there is also right
entrance area of the jet that comes across the northern County Warning Area during
the evening which should at least enhance the precipitation and could produce
a few stronger storms. 0-6km bulk shear should be around 35 kts
which also supports a few stronger storms.

Enough instability and moisture lingers over the area Tuesday night
and Wednesday to maintain scattered showers and storms in the
forecast. A cold front finally swing through on Wednesday bringing
drier air and an end to the better rain chances. However the upper
trough does not come through until Wednesday night and this could
still produce a few isolated showers or storms.

Long term...(thursday through monday)
issued at 330 PM EDT Monday may 25 2015

Next significant weather threat continues to be Friday night into
Saturday. The heavy rain with small stream and urban flooding
concern is now looking to be the greater threat although some
localized severe wind damage is possible.

Scenario wise...a cold front with good northern stream upper short wave
moves through region by midday Saturday. GFS continues to be quicker
than European model (ecmwf) but they are slowly converging on early morning hours of
Saturday at this point.

Rain threat of an inch plus with locally higher amounts is supported
by a relatively slow moving front with deep frontal convergence...
precipitable waters ~ 1.50 inches and moist flux...and enhanced upper divergence
as jetlet ejects from central U.S. Southern stream trough.

Severe potential appears limited by a lack of deep shear. The 0-6km
shear looks to be less than 25kt with fairly unidirectional flow.
Cape will range between 500 and 1500 j/kg depending on Friday evening
versus Sat morning arrival.

Sunday into Tuesday nwp solutions diverge with eventual ejection of
central U.S. Trough. European model (ecmwf) fills the trough as a seasonably cool
surface high pushes into Michigan. The GFS/fim hang onto a stronger
upper system with surface wave and Gulf moisture pushing back into
the region by Monday. Prefer European model (ecmwf) solution at this time...just
looks like the more likely evolution at this time.


Aviation...(for the 00z tafs through 00z Tuesday evening)
issued at 810 PM EDT Monday may 25 2015

VFR conditions prevail area wide at 00z. Expecting the VFR weather
to continue through the evening...with dry weather through the

First concern is the threat of some light (mvfr) fog and MVFR
ceilings developing overnight. Confidence in MVFR ceilings
developing is medium at this point. Multiple guidance sources are
indicating the formation of these lower clouds and have therefore
included it in the forecast. The nearest MVFR ceilings at this
point upstream across southern Indiana.

After the morning low clouds lift towards midday on Tuesday the
next concern will be chances for showers and storms Tuesday
afternoon and evening. Have thunderstorms in the vicinity wording in the tafs at this
point. Expecting a period of storms to sweep through the area
between 21z and 03z Tuesday evening.


issued at 330 PM EDT Monday may 25 2015

Will maintain the headlines through tonight as the southerly flow
gradually diminishes and the waves finally drop off toward daybreak.
Its possible we may have to extend the headline into middle morning
before the waves finally subside. Otherwise winds and waves calm
down Tuesday afternoon through Wednesday night.


issued at 1239 PM EDT Monday may 25 2015

The hydrologic service area has experienced generally less than a
half inch of precipitation with the current system. River levels are
low and stable. Expecting another 1/2 to 3/4 of an inch of
precipitation tonight through Wednesday. This should lead to slowly
increasing river levels by middle week. Expecting no or minor/nuisance
flooding by weeks end.

A potential for more rain Friday into Sunday (over an inch) may push
some streams and rivers above bankfull by next week... if these
amounts are realized.


GRR watches/warnings/advisories...
Michigan...Beach hazards statement until 8 am EDT Tuesday for miz037-043-

Lm...Small Craft Advisory until 8 am EDT Tuesday for lmz844>849.



short term...jk
long term...Cobb

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