Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 260828
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
328 AM EST Sat Nov 26 2016

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

.SYNOPSIS...
Issued at 302 AM EST Sat Nov 26 2016

An area of low pressure centered over Ontario will track east
today. Meanwhile a high pressure system located over Missouri will
build east into the Central Appalachians tonight. Thus the region
will see decreasing clouds today. Any remaining precipitation will
taper off by this afternoon. Dry weather is then forecasted into
Sunday. A stronger storm will approach the area for early next
week.

&&

.SHORT TERM...(Today through Monday)
Issued at 302 AM EST Sat Nov 26 2016

The short term period starts off with some scattered light snow
and rain showers around the region. The moisture depth decreases
over the next couple of hours. This will support a diminishing trend
to any remaining showers. Will begin the period with a few light
showers around...otherwise we are looking at a dry day. Clouds
will be on the decrease as well...especially this afternoon. The
surface ridge will be pushing in from the west...which supports
the decrease in the cloud cover.

This ridge then passes east of the region tonight and into Sunday.
A warm air advection pattern sets up and strengthens as we go into
Sunday night. Will keep it dry through Sunday evening. Above
normal temperatures are expected given approaching 850 mb thermal
ridge.

Stronger warm and moist air advection occurs later Sunday night
into Monday. The low levels will be initially dry later Sunday
night and that may act to delay the onset of the precipitation.
There is a small risk for mixed precipitation at the onset...but
overall the temperatures in the forecasted soundings look too warm
for this to happen at this time. Will feature light rain arriving
later at night.

A mid level dry slot pushes in from the southwest on Monday. Then
a wave of low pressure forms on the cold front upstream over the
lower OH valley. Models vary on the timing and strength of this
feature. Enough confidence is there to warrant the arrival of more
rain later in the day. Some weakness in the stability is shown on
Monday. At this point enough confidence for thunderstorms to occur
is not there...so will leave them out of the forecast. Considering
the low level jet that will be in place throughout the
day...gusts over 35 mph may occur...especially later in the
afternoon as mixing heights may increase.

.LONG TERM...(Monday night through Friday)
Issued at 302 AM EST Sat Nov 26 2016

We continue to expect a likely threat of rain on Monday night, with
a trend toward cooler and unsettled weather for much of the long
term from Wed and beyond.

Rain is looking like a good bet for Mon night. Strong srly flow out
of the Gulf of Mexico will prime the atmosphere with plenty of
moisture over the area. Pwats are still expected to approach 1.0
inches by Mon night, which is over 200% of average for this time of
the year. The front with the strong low to our west is expected to
pass through Mon night. We can not rule out a chc for thunder as
LI/s drop to near zero. This is a little too low this far out at
this time of the year to add.

We will see a mainly dry period and warmer temps then for Tue and
Tue night. The dry slot will work in over the area during this time
frame. The cold air will lag behind the front a bit with the low,
so a windy and warm day can be expected.

We will see the threat for showers move back in on Wed, which look
to linger then through the end of the week. The supporting upper low
for the Mon night front looks to rotate in over the region. This,
combined with sufficiently cold enough temps coming over the lake,
will support some enhancement to the shower activity. Showers will
be rain at the start, but could start mixing in with snow as we
progress through the end of the week as cooler air slowly filters
in.

&&

.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1255 AM EST Sat Nov 26 2016

Most of the rain and IFR conditions have now moved out across the
area. A few showers remain near KMKG and KGRR. These will likely
remain possible at least through the morning before they diminish
in coverage as moisture becomes more shallow. We will mainly see
MVFR conditions rule with CIGS around 2500 ft. Some isolated pockets
will be a bit higher and lower.

We expect to see the cloud cover diminish from South to North
toward 00z Sun as lake effect dwindles and as winds become more
southerly.


&&

.MARINE...
Issued at 302 AM EST Sat Nov 26 2016

The risk for gales remains for late Sunday night and more so on
Monday. A stronger low level jet arrives then associated with the
approaching storm. Hazardous boating conditions will develop
during that time. Considering the stronger winds do not arrive
until later Sunday night and more so on Monday...will hold off on
a watch at this time.

&&

.HYDROLOGY...
Issued at 330 PM EST Thu Nov 24 2016

Rivers continue holding well within their banks with recent modest
rainfall. The storm system that will impact our weather Monday into
early Tuesday will likely produce a half inch or more of rainfall
across the region. This is not expected to bring rivers above
bankfull. However, locally heavier rainfall could push smaller
rivers and streams closer to bankfull potentially during the early
to mid week period.

&&

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

$$

SYNOPSIS...MJS
SHORT TERM...MJS
LONG TERM...NJJ
AVIATION...NJJ
HYDROLOGY...Hoving
MARINE...MJS



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