Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 221900
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
300 PM EDT MON AUG 22 2016

LATEST UPDATE...
Synopsis/Short Term/Long Term/Hydro/Marine

.SYNOPSIS...
Issued at 300 PM EDT Mon Aug 22 2016

High pressure will continue to produce fair weather tonight
through Tuesday evening. A low pressure system approaching from
the west will bring showers and thunderstorms Wednesday through
Wednesday night. Some showers may linger into Thursday before high
pressure builds back in to bring fair weather Thursday night
through Saturday.

&&

.SHORT TERM...(This evening through Wednesday night)
Issued at 300 PM EDT Mon Aug 22 2016

The primary short term fcst challenge is to determine potential
for convection Wednesday through Wednesday night.

Scattered thunderstorms will develop well out ahead of the
approaching low pressure and cold front Wednesday afternoon as
moisture and instability increase as sb/ml cape values reach
around 1000-2000 j/kg in the afternoon. Forcing for convective
initiation to occur prior to the arrival of the front Wednesday
night will come from an increasing llj.

Isolated stronger to marginally severe storms are possible and
this will be largely contingent on how much sun there is Wednesday
and degree of destabilization. Locally heavy rainfall is also
certainly possible given the influx of much more moisture as sfc
dew points reach the lower 70`s by Wednesday evening. Precipitable
water values will also reach around two inches by Wednesday
afternoon and night along with strong 1000-850 mb moisture
transport.

In the near term the departing high pressure ridge will continue
to produce fair weather through Tuesday evening. Winds will become
southerly on the back side of the ridge and help to boost max
temps into the middle 80`s Tuesday.

.LONG TERM...(Thursday through Monday)
Issued at 300 PM EDT Mon Aug 22 2016

Scattered showers will likely linger into Thursday mainly over our
se fcst area depending on exact cold frontal timing. After fropa
a cooler and drier airmass will advect in Thursday night through
Friday into Saturday as high pressure builds in to produce fair
wx.

The next chance for showers is anticipated for Saturday night
through Sunday and possibly into Monday as southerly return flow
develops on the back side of the departing ridge and allows
moisture to increase and allow for warm air advection showers to
develop.

&&

.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1132 AM EDT Mon Aug 22 2016

Vfr conditions will continue through Tuesday afternoon. A bkn fair
wx cu deck of clouds will continue to develop through the
afternoon and persist into the early evening before quickly
dissipating. Skies will be mostly clear overnight. Fair wx cumulus
will redevelop late Tuesday morning.

&&

.MARINE...
Issued at 300 PM EDT Mon Aug 22 2016

South to southwest winds will increase to 15 to 25 kts Tuesday
morning and cause wave heights to build to 3 to 5 feet. Therefore
we will hoist a small craft advisory from early Tuesday morning
through mid Tuesday evening.

Wave heights should subside just a bit to around 2 to 4 feet
Tuesday night as wind speeds diminish. However south winds will
ramp back up to 20 to 25 kts Wednesday when wave heights will
reach 3 to 6 feet... highest up near Big and Little Sable Points.

&&

.HYDROLOGY...
Issued at 300 PM EDT Mon Aug 22 2016

Fair and dry weather will continue through Tuesday evening. A
flood warning remains in effect for the Portage River at Vicksburg
where minor flooding remains possible. However the river level is
forecast to slowly fall to below flood stage by Thursday morning.

The next system will bring potential for around a half an inch to
inch of rainfall Wednesday through Wednesday night. This rainfall
could cause a new rise on the Portage River Thursday into Friday.

&&

.GRR Watches/Warnings/Advisories...
MI...None.
LM...Small Craft Advisory from 5 AM to 9 PM EDT Tuesday for
     LMZ844>849.

&&

$$

SYNOPSIS...Laurens
SHORT TERM...Laurens
LONG TERM...Laurens
AVIATION...Laurens
HYDROLOGY...Laurens
MARINE...Laurens



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