Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 291722
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
122 PM EDT SUN MAY 29 2016

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 258 AM EDT Sun May 29 2016

A few showers and thunderstorms are expected this afternoon across
central and eastern Lower Michigan. Some of the storms could be
strong with hail and gusty winds. Fair and less humid weather will
move in on Monday.

&&

.UPDATE...
Issued at 1123 AM EDT Sun May 29 2016

Adjusted pops across the nw cwa where some scattered wrap around
showers/storms may occur...otherwise little change to the going
forecast.

A weak cold front was moving over Lake Michigan late this morning
and it will slide across the CWA this afternoon. SW flow at the
low level will help keep the western CWA fairly stable...while
inland areas destabilize with LI/s as low as -4C as the front
moves in. Expect scattered showers and storms to develop after
noon, with the bulk of the pcpn moving out of the CWA by 5 PM.
0-6KM bulk shear values will only be around 20 knots...so no
organized storms are expected...but an isolated strong/severe
storm is possible.

It will be a fairly breezy day with gusts to around 25 mph common
this afternoon into early evening.

&&

.SHORT TERM...(Today through Tuesday)
Issued at 258 AM EDT Sun May 29 2016

Severe threat is fairly low this afternoon and appears to be
restricted to areas east of GRR and AZO as diurnal heating
combines with sfc convergence from weak cold front moving through.
Shear profiles show about 25 to 30 knots of 0 to 6 km shear with
MUCAPE around 1000 j/kg. Hail and gusty winds are possible with
the stronger updrafts across the eastern zones this afternoon.

Storms should be ending in the evening as the front clears the
forecast area and drier air advects in and dew points fall back
into the 50s. Memorial Day is looking good and the dry weather
continues into Tuesday.

.LONG TERM...(Tuesday night through Saturday)
Issued at 258 AM EDT Sun May 29 2016

Seasonably warm weather will continue Tuesday night through midweek
with a small chance for showers Tuesday night followed by a better
chance for showers and thunderstorms late Wednesday through
Thursday.

The showers and storms will develop out ahead of an approaching cold
front and in association with an upper level low pressure system
that will drop southeast into the Great Lakes region Wednesday night
and Thursday.

A somewhat cooler and drier airmass will move in behind this system
for very late in the week.  Will maintain mention of a small chance
of mainly diurnally driven showers Friday through Saturday with the
upper trough overhead and as several upper disturbances move
through.

&&

.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 122 PM EDT Sun May 29 2016

Winds are gusting once again at all of the terminals up to around
25 knots this afternoon ahead of the incoming cold front. Some
stratocumulus clouds based around 4-5k ft are moving in and some
cumulus are developing overhead. We expect a few spotty
showers/storms to develop over the next hour or so in the vicinity
of KBTL, KLAN, and KJXN. Other than if a shower/storm were to
impact the terminal, conditions will remain VFR.

Showers/storms should end by 23-00z this evening as the cold front
pushes through. A cloud deck of 4-5k ft may linger for a bit
before likely scattering out overnight. Winds will also diminish
this evening around 00-01z. Some cumulus/stratocumulus clouds may
linger overnight, before some diurnal build ups develop on Monday.
VFR conditions will remain.

&&

.MARINE...
Issued at 1123 AM EDT Sun May 29 2016

Moderate southerly winds late this morning will gradually veering
to the southwest this afternoon...then west toward the end of the
day. The flow will cause the lake to become a bit rough this
afternoon...especially north of Grand Haven. Waves of 2-4 feet are
expected there...remaining just below small craft advisory.
Weaker swimmers should be aware of rougher seas then normal too.


&&

.HYDROLOGY...
Issued at 113 PM EDT Sun May 29 2016

River levels across the area are near normal values for this time of
year. Precipitation of a quarter inch up to three quarters of an inch
is possible over the next week, mainly on Wednesday and Thursday.
River rises will mainly be confined to smaller creeks and streams
and should not reach flood levels.

&&

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

$$

UPDATE...JK
SYNOPSIS...Ostuno
SHORT TERM...Ostuno
LONG TERM...Laurens
AVIATION...NJJ
HYDROLOGY...63
MARINE...JK


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