083
FXUS63 KGRR 191921
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
320 PM EDT Thu Oct 19 2017

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

.SYNOPSIS...
Issued at 320 PM EDT Thu Oct 19 2017

Mild and dry weather will continue into the weekend.  Temperatures
will be about 15 degrees above normal with highs mainly 70 to 75
Friday and Saturday.  A chance of rain will start over the West
Central portion of the state Saturday night.

The rain is expected to spread across the rest of the state on
Sunday.  More rain will be possible again Monday night into Tuesday.
Temperatures are expected to remain warm through Monday, then we
should cool to highs in the 50s for Tuesday through Thursday.

&&

.SHORT TERM...(This evening through Saturday night)
Issued at 320 PM EDT Thu Oct 19 2017

Upper ridging will continue to build into the region, with the axis
overhead by Friday morning.  This will allow for a deep southerly
flow and temps warming into the 70 to 75 range for Friday and
Saturday.  The days will be mostly clear, with an increase in CI on
Saturday.

By Saturday night the highly amplified pattern will have a long wave
upper trough crossing MN by late at night.  This will be pushing a
cold front across WI overnight, approaching Lake Michigan by
daybreak. Moisture with this system is shown to hug the front, so
most of the rains will hold off until Sunday, but will have POPs for
the NW CWA Saturday night as the nose of a low level jet crosses
Lake Michigan and toward West Central Lower by daybreak Sunday.

.LONG TERM...(Sunday through Thursday)
Issued at 320 PM EDT Thu Oct 19 2017

A wide range of solutions exists regarding the cold front which
comes into the area on Sunday. For now the favored and higher
probability solution is for a progressive cold front which brings
widespread rainfall totals around a third of an inch before exiting
to the east.

However it should be noted that a few model/ensemble solutions of
the past two days (mostly ecmwf) have suggested that the front may
stall out and a srn stream wave lifting north along the front could
give parts of the area more than two inches of rain on Monday and
Monday night. This will need to be watched especially considering
the excessive amounts which just occurred last weekend, but the
probability of this scenario seems low and more realistic to occur
to our east or southeast.

Still expecting an intrusion of colder air (highs in the 50s) and
scattered showers for next Tuesday and Wednesday as deep longwave
trough dips into the Great Lakes Region. This feature is progged to
lift out Thursday with a brief period of warm advection expected
before a potentially more impressive surge of colder air arrives
toward the end of next week.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 123 PM EDT Thu Oct 19 2017

VFR conditions will continue through Friday with only high thin
cirrus clouds anticipated. Confidence is very high. West winds
around 10 kts today will go light tonight then become southerly
around 10 kts for Friday.

&&

.MARINE...
Issued at 320 PM EDT Thu Oct 19 2017

A lull in the winds and waves is underway late this afternoon.  But
by Friday afternoon south winds will be increasing again to 15 to 20
knots.  Waves will building toward the Sable Points Region with the
long fetch.  Have posted a new small craft advisory starting early
Friday afternoon for this set up.  We will probably need to expand
the advisory farther south into Friday night/Saturday as the south
winds are expected to continue to increase as a cold front
approaches.

&&

.HYDROLOGY...
Issued at 320 PM EDT Thu Oct 19 2017

River levels continue to fall as dry conditions prevail following
heavy rain last weekend. Dry weather will continue through Saturday.

The next chance for rain will be on Sunday and Monday as a weak low
pressure system and cold front track through the area. Most forecast
guidance continues to show rainfall amounts of about one-quarter of
an inch, which would not cause flooding or much of a rise in rivers,
creeks, or streams. A lower-potential scenario is for the system to
stall over the area and bring heavier amounts of rain that lasts
into Tuesday. While this scenario is not likely at this time, it is
one we will continue to watch for in forecast models.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...Small Craft Advisory from 1 PM Friday to 8 PM EDT Saturday for
     LMZ848-849.

&&

$$

SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...Meade
AVIATION...Meade
HYDROLOGY...HLO
MARINE...JK