Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 271927

Area Forecast Discussion
National Weather Service Grand Rapids MI
327 PM EDT FRI MAY 27 2016

Synopsis/Short Term/Long Term/Marine

Issued at 327 PM EDT Fri May 27 2016

The recent stretch of warm and humid weather will continue through
the rest of Memorial Day weekend. Occasional showers and
thunderstorms will be possible each day with highs in the 80s. A
cold front will push through on Sunday. Memorial Day is shaping up
to be dry with highs in the lower 80s.

Waves of 2 to 4 feet on Lake Michigan are expected Saturday north
of Holland, which may pose a risk to smaller boats.


.SHORT TERM...(This evening through Sunday night)
Issued at 327 PM EDT Fri May 27 2016

Loosely organized convection was ongoing at 3 pm, moving north
through the forecast area. Isolated to scattered storms are expected
through this evening and could produce pea size hail and gusty winds
to 50 mph. Severe weather is not expected. Overall deep layer shear
remains unimpressive with relatively light mid and upper level

The low level jet does increase substantially this evening and
overnight and could fuel overnight showers, with the greatest
coverage across the western half of the forecast area. The LLJ
increases to 30 to 40 kts tonight, and the axis of the best H850
moisture transport will be up through Lake Michigan. Instability
wanes quickly after sunset, so the potential for storms looks fairly
low after 03z. Lows tonight should be fairly mild in the mid to
upper 60s with a fair amount of cloud cover and warm, southerly

The Plains upper low is forecast to swing northeast to the upper
Mississippi valley by late Saturday. Lower Michigan will be squarely
in the warm sector Saturday with deep southerly flow through the
entire profile. Scattered convection is expected once again with
plenty of moisture and instability. Deep layer shear remains
marginal at best.

The upper trough and associated cold front finally sweep through
Sunday and provide a trigger for convection. Stronger storms will be
possible with decent instability developing out ahead of the front.

.LONG TERM...(Monday through Friday)
Issued at 327 PM EDT Fri May 27 2016

A weak ridge of high pressure is forecasted to keep the weather dry
on Memorial Day.  The threat for a brief thunderstorm is not
zero...but confidence is too low to add it to the forecast.  It
looks warm with 850 mb temperatures in the teens.

A few storms are possible Monday Night into Tuesday.  The chances
will increase as we go into Tuesday Night.  This is when a mid level
low will be approaching from the west.  They cyclonic flow will then
keep the environment favorable for thunderstorms through the middle
part of the week.  The strengthening deep layer shear may support
organized storms.

The low level winds do turn northwest for the end of the week. This
will act to cool temperatures down.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 128 PM EDT Fri May 27 2016

The atmosphere has become unstable. Showers were developing at
this time. They should grow into thunderstorms over the next hr or
so. Thus Tafs sites mostly feature a thunderstorm for the next hr
or two...then VCTS for the remainder of the afternoon into the
evening hrs.

Low level winds will increase tonight. This may lead to some
turbulence. I did not go with LLWS...but it was a close call. This
increase in winds could also trigger thunderstorms...especially
Saturday morning.


Issued at 327 PM EDT Fri May 27 2016

Small craft advisory conditions could be realized for a brief time
on Saturday. Southerly winds will ramp up to 15-25 knots tonight
into Saturday. Waves will build into the 2 to 4 foot range north
of Holland on Saturday. Winds and waves will diminish by Memorial


Issued at 108 PM EDT Fri May 27 2016

River levels across the area are near to just above their expected
values for this time of year. Precipitation of up to an inch is
possible over the next week. Convection through the weekend will
produce localized heavy rainfall. Rises will mainly be confined
to smaller creeks and streams and should not reach flood levels.


.GRR Watches/Warnings/Advisories...


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