Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 171115
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
715 AM EDT Mon Apr 17 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 305 AM EDT Mon Apr 17 2017

Generally fair weather will prevail today and Tuesday then Low
pressure will bring some showers Tuesday night and Wednesday. High
pressure builds in for Thursday with fair weather into Saturday.

&&

.SHORT TERM...(Today through Wednesday)
Issued at 305 AM EDT Mon Apr 17 2017

Weak shortwave trough moves through today with some quick hitting
showers across the northern forecast area this afternoon then
fair weather until Tuesday evening.

Dry easterly flow early Tuesday goes south during the afternoon with
area of moisture pooling and mid level warm advection ahead of a
cold front trailing from the sfc low tracking across Lake
Superior. Showers and a few thunderstorms will be along the front
as it sinks south through the forecast area and then stalls on
Wednesday just south of Lower Michigan. Lowered temps a bit blo
model guidance on Wednesday as low clouds and showers persist with
shallow cold air on north side of the front.

.LONG TERM...(Wednesday night through Sunday)
Issued at 305 AM EDT Mon Apr 17 2017

We are looking at two more potentially wet periods in the long term,
along with a thunder threat that will mainly be Wed night and Thu.

The wettest period of the long term at this time looks like it will
be right at the beginning of the long term Wed night into Thu. This
wet period will be the result of a bit strong short wave that will
develop to our west and move across Northern MI. There is good
agreement that the nose of a 50+ knot low level jet will be aimed
right at the area Wed night/Thu morning. Strong moisture transport
aloft will be taking place and producing a round of storms likely
over the area. A severe threat will be possible given the strong
dynamics expected, especially further south closer to the sfc based
instability.

Some residual showers will likely hold on for Thursday as the upper
low will be still crossing the state. This should push far enough
east of the area Thu night that all areas should see dry weather and
a little cooler conditions move in. The dry weather should last
through early Sat as broad upper ridging will hold control over the
area.

The forecast for the next system to come in next weekend is a bit
uncertain at this time. We will see jet energy dive in over the
Central Plains states as a strong low over the Ern Pacific will make
the pattern much more amplified than the zonal flow in place early
this week. A stronger storm looks to take shape to our SSW and will
try to advect moisture in over the area. The timing of the
development of this low and where will have big implications on the
low and it`s track. For now, the better threat of rain will come
across the SE portion of the state, with chances tapering off to the
NW.

&&

.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 715 AM EDT Mon Apr 17 2017

VFR conditions will prevail through Tuesday morning. Winds today
with be west to northwest aob 10 knots and then go north to
northeast tonight and Tuesday.

&&

.MARINE...
Issued at 305 AM EDT Mon Apr 17 2017

Winds and waves will gradually increase tonight and Tuesday and
may approach Small Craft Advisory criteria on Tuesday before
decreasing again.

&&

.HYDROLOGY...
Issued at 325 PM EDT Sun Apr 16 2017

River levels are slowly falling toward more normal levels across
Southwest Lower Michigan except for the Muskegon River basin. The
Muskegon River near Evart is now forecast to peak below flood stage
by Wednesday afternoon at 11.3 feet. All area rivers will be
susceptible to flooding from any heavy rain events in the near
future.

Weather models suggest a few possibilities for storm systems Tuesday
night into the weekend. There is low confidence in the amount of
rain to expect over the next week, but staying guarded against the
potential for additional flooding would be prudent.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&

$$

SYNOPSIS...Ostuno
SHORT TERM...Ostuno
LONG TERM...NJJ
AVIATION...Ostuno
HYDROLOGY...63
MARINE...Ostuno



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