Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 270354
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1154 PM EDT TUE JUL 26 2016

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 330 PM EDT Tue Jul 26 2016

The weather will remain quiet tonight, but become a bit more
unsettled as we head through Wednesday and Thursday. Dry weather is
expected tonight as high pressure remains in the area the bulk of
the night. On Wednesday the high drifts away to the southeast
allowing a weak front to press in from the north. A few showers and
thunderstorms will be possible Wednesday afternoon during the
heating of the day. A disturbance moving through the region
Wednesday night through Thursday night will bring additional chances
for showers and thunderstorms. It will remain warm on Wednesday,
with a slight cooling trend expected for Thursday and Friday.

&&

.SHORT TERM...(This evening through Thursday night)
Issued at 330 PM EDT Tue Jul 26 2016

Main focus of the short term is on chances for showers and
thunderstorms Wednesday afternoon through Thursday night. The
precipitation is associated with a couple of features that will move
through the Great Lakes region. The first of which is a weak cold
front dropping south through the Lower Peninsula Wednesday and
Wednesday night. The boundary will have some convergence associated
with it that may force some scattered showers and storms especially
Wednesday afternoon. Not expecting much tomorrow afternoon, but a
few scattered showers and storms will pop with building instability.
CAPE values may push towards 2000 J/KG, but shear will be very weak
so any storms should remain below severe levels.

The front drops south of the area Wednesday night when the next
feature comes into play. This second feature is an upper shortwave
trough seen in the water vapor imagery moving into the Dakotas from
Montana. This shortwave steadily moves our direction the next 24
hours and will be near Lake Michigan Wednesday evening. The
shortwave will traverse the area Wednesday night and Thursday.
Additional showers and storms should occur Wednesday night and
Thursday. The better chance for anything strong should be Thursday
afternoon with the heating of the day. Shear remains weak so sub
severe storms. Nothing more than scattered pops 30-40 pct Wednesday
night and Thursday.

Another shortwave swings in from the west Thursday night through a
developing upper trough overhead. This wave misses us just south but
we should see a few showers and storms in the south Thursday night.
High pressure is trying to build in so drying conditions from north
to south.

.LONG TERM...(Friday through Tuesday)
Issued at 330 PM EDT Tue Jul 26 2016

Zonal flow becomes more of a trough/northwest flow aloft for the
coming weekend. This pattern would suggest at least periodic chances
for showers and tstms as shortwaves occasionally traverse the area.

However a sfc high builds southeast from south central Canada and
pushes the sfc frontal boundary south of the state. Northeast low
level flow related to this incoming high keeps sfc dewpts relatively
low around 60 degrees. This implies mainly dry weather.

The outlier ECMWF deterministic solution from yesterday which showed
a strong wave coming through on Friday is not present in the latest
guidance, but the possibility of some sort of upper wave coming
through on Friday or Saturday still seems to be reasonable given the
troughing pattern aloft.

Height rises are progged early next week so dry and warmer looks to
be the way to go. Humidity levels should come up by Tuesday as
southerly flow develops and high temps could approach 90 again by
that time.

&&

.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1153 PM EDT Tue Jul 26 2016

There may be some mvfr fog at JXN toward sunrise, otherwise fair
wx is expected through the period.

&&

.MARINE...
Issued at 330 PM EDT Tue Jul 26 2016

Winds and waves are expected to remain below advisory levels through
Wednesday night. The pressure gradient will remain weak tonight with
high pressure still in the area. On Wednesday winds will remain
light with a baggy gradient in place near a weak front dropping
south through the state. Wednesday night and Thursday north to
northeast flow will ramp up some behind the front. A developing low
just south of the area will tighten the gradient on Thursday, Waves
will try to increase into the 2-4 foot range Thursday afternoon, but
given the NNE flow the higher waves may remain off shore. Bottom
line, no headlines with the main focus being on Thursday afternoon.


&&

.HYDROLOGY...
Issued at 150 PM EDT Tue Jul 26 2016

No river flooding is expected into next week. There is a chance of
rain in the forecast Wednesday into Saturday night. Total rainfall
should be under an inch. River levels are around normal for this
time of year. Even with the precipitation, no rivers should approach
flood level.

&&

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

$$

SYNOPSIS...Duke
SHORT TERM...Duke
LONG TERM...Meade
AVIATION...04
HYDROLOGY...63
MARINE...Duke



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