Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 211459
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1059 AM EDT SAT MAY 21 2016

LATEST UPDATE...
Hydro

.SYNOPSIS...
Issued at 300 AM EDT Sat May 21 2016

Dry conditions will prevail until Tuesday...then from late Tuesday
through Friday there will be a continued chance for showers and
thunderstorms. High temperatures will generally increase from the
mid 70s this weekend to near 80 by the middle of next week. The
exception will be the lake shore which will be substantially
cooler due to lake breezes developing most afternoons.

&&

.SHORT TERM...(Today through Monday)
Issued at 300 AM EDT Sat May 21 2016

No impact weather expected and no real changes to the forecast.
Looking less likely our southeast forecast area will even see
sprinkles this morning. Substantial high clouds over lower Michigan
associated with the deformation zone north of the upper low should
shift east out of the area later today as the low tracks east.

.LONG TERM...(Monday night through Friday)
Issued at 300 AM EDT Sat May 21 2016

We will see a continuation of the dry and warm period linger into
the long term starting with Monday night. The pattern will shift a
bit then starting on Tuesday as a unsettled period is expected with
temperatures remaining warm.

We will see the upper ridge hold for a little while longer through
Monday night, and then move east on Tuesday. This will continue the
warm and dry pattern that we have seen for the past few days. We
will likely have at least a portion of the CWFA hit 80 degrees on
Tuesday before the unsettled weather moves in.

The upper ridge will slide east of the area then late Tue, allowing
for a SW flow aloft to establish itself over the region. This will
open up the door for better moisture to be drawn north out of the
Gulf of Mexico as short wave troughs ride the SW flow up over the
area. Chances for showers and storms will start late Tue and hold at
least into Thu when a stronger wave is shown to pass through. We
will remain on the warm side of the jet.

The forecast becomes a bit uncertain by Fri, mainly because of the
timing of additional waves moving out of the Wrn upper low. The may
be a break between the better wave moving through Wed/Thu and the
next wave poised to move through. It could occur as early as Fri, or
hold off until Sat. We will keep a chance of showers/storms in for
Friday with the moist SW flow holding in across the area.

&&

.AVIATION...(For the 12Z TAFS through 12Z Sunday morning)
Issued at 729 AM EDT Sat May 21 2016

High confidence for VFR conditions through the period with
ceilings staying well above 10000 ft and moving east of the area
today.


&&

.MARINE...
Issued at 300 AM EDT Sat May 21 2016

Some hi-res guidance such as the HRRR suggests that pockets of 15-
20kt winds will be possible near the Sable Points this afternoon and
waves could push 3 feet in spots.  Otherwise winds will generally
remain well under 15 knots with waves mostly under 2 feet.


&&

.HYDROLOGY...
Issued at 1059 AM EDT Sat May 21 2016

There are no river advisories to mention in todays discussion. The
extended period of dry weather has proven beneficial and all sites
are now below bankfull. Dry conditions will continue through at
least Monday. Chances for precipitation increase by Tuesday of
next week and may very well extend through mid and late week.
Model guidance has trended much further west with the upper level
disturbance in time, ultimately elongating the stream of moisture
from the Gulf Coast. Therefore, while moisture levels increase to
1.5-2 times their normal values, the duration and magnitude of
next week`s precipitation is still uncertain. River levels are now
running near to slightly above normal and recent green up may help
to mitigate additional flood potential.

&&

.GRR Watches/Warnings/Advisories...
MI...None.
LM...None.
&&

$$

SYNOPSIS...TJT
SHORT TERM...TJT
LONG TERM...NJJ
AVIATION...TJT
HYDROLOGY...JAM
MARINE...TJT



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