Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 230216
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1016 PM EDT MON AUG 22 2016

LATEST UPDATE...
Update/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.

&&

.UPDATE...
Issued at 1015 PM EDT Mon Aug 22 2016

Convective complex over UPR MI/NE WI is firing on the nose of a
swly 40 kt LLJ. This activity is expected to remain to our north
overnight. It could be close call however since deep layer
thickness progs suggest the convection should curve southeastward
overnight. Will keep the fcst dry but we will have to watch the
far nrn cwfa... near and north of U.S. 10... for the possibility of
a few showers or storms sneaking in overnight.

&&

.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 00Z TAFS through 00Z Tuesday evening)
Issued at 758 PM EDT Mon Aug 22 2016

VFR weather will continue tonight and Tuesday as high pressure and
dry air dominate the area. The threat for shallow/patchy ground
fog late tonight is not zero but is very low since the center of
the sfc high is drifting east.


&&

.MARINE...
Issued at 1015 PM EDT Mon Aug 22 2016

Have started the small craft advisory a bit earlier for the two
northern-most marine zones since south winds have already
increased to 18-23 kts at Ludington with a 3.3 ft wave at the
buoy as of 10 pm.

Meanwhile the small craft advisory for the southern-most zone is
somewhat marginal but have held on to it for now since wind speeds
could be strong enough to warrant the advisory despite wave
heights struggling to reach criteria.

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...Beach Hazards Statement from 4 AM EDT Tuesday through Tuesday
     evening for MIZ037-043-050-056.

LM...Small Craft Advisory until 9 PM EDT Tuesday for LMZ848-849.

     Small Craft Advisory from 4 AM to 9 PM EDT Tuesday for
     LMZ844>847.

&&

$$

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



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