Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 232313

Area Forecast Discussion
National Weather Service Grand Rapids MI
713 PM EDT Fri Mar 23 2018


Issued at 323 PM EDT Fri Mar 23 2018

The weekend will continue to be dry and cool.  Both days will only
see high temperatures in the upper 30s to mid 40s.  Each day will
also be rather breezy, adding to the chill.

A pattern change moves in early next week.  A solid chance of rain
will arrive by Monday night and continue through Tuesday night.  It
will also come with warm air, with highs surging to 55 to 60 Monday
and Tuesday.  The latter part of the week could also see a few
showers and temperatures should cool slightly.


.SHORT TERM...(This evening through Sunday night)
Issued at 323 PM EDT Fri Mar 23 2018

Upper lows over New England will hold a pattern where northwest
upper flow continues over the Great Lakes.  We will remain in
between this low and another off to our south, so expect little
overall chance through the weekend.

The pattern remains blocked with a first upper low over Western NY
this afternoon.  Another upper low moves south through Quebec and
into Western NY again Saturday night.  This will result in temps
remaining below normal.  Winds will increase Saturday with gusts to
25-30 mph by afternoon.  They will be slightly less Sunday as the
pressure gradient relaxes some, however it will remain breezy.  See
the fire wx section for details how this impacts the area.

The second upper low finally drifts east by late Sunday into Sunday
night.  This allows an upper ridge to build in.  Temps will begin to
moderate as this occurs.

Only expect periods of high clouds over the region through the short
term as the column remains very dry.

.LONG TERM...(Monday through Friday)
Issued at 323 PM EDT Fri Mar 23 2018

The main focus is on rain potential beginning Monday night and
lasting into Tuesday night. It is not out of the question that some
thunderstorms would be possible as well but confidence is not high.
Rain amounts will likely be in the 0.50"-1.00" across the region
with some locally higher amounts possible. No flooding is

After many days with northerly and northeasterly flow at the surface
and aloft, the pattern changes early next week. The southern branch
of the upper level jet crossing over the southwest U.S. will head
toward the Great Lakes Monday and Tuesday, strengthening as it does.
At H850, the LLJ will take shape off the Gulf of Mexico and bring
moist low level flow into Michigan. The GFS has the strongest LLJ
which is likely contributing to higher precipitation amounts than
other models. The ECMWF keeps the better LLJ dynamics to our south.
The evolution of this feature will be important to watch and has a
bearing on where the heavier rains will be.

As for instability, there may be a brief window of some elevated
instability Tuesday evening. The GEM and GFS indicate this
possibility (50-100 J/kg of MUCAPE) but not the ECMWF. At this point
we will continue to leave it out of the forecast.

Outside of this system, another breezy day is expected Monday with
15-25 mph winds. After milder temperatures in the 50s the first half
of the week, cooler readings are expected by the end of the week.


.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 710 PM EDT Fri Mar 23 2018

The wind may become an impact on Saturday. Gusts over 25 knots
look likely at the TAF sites. How strong the easterly winds become
will be determined by how warm the temperature goes. High level
clouds may limit the temperatures somewhat during the day.
Otherwise the atmosphere remains dry...thus little or no risk for
low clouds exists.


Issued at 323 PM EDT Fri Mar 23 2018

Winds pick up Saturday and continue into Sunday.  However at this
point it looks too marginal for a headline.  Easterly wind gusts to
25 knots will be possible, with even higher speeds well offshore,
into the open waters.


Issued at 323 PM EDT Fri Mar 23 2018

Concern for elevated fire risk into the weekend. Many people will be
doing yard work, but hopefully consider conditions of low RH, dry
fuels, and strong winds that could lead to a quickly spreading fire.
We have sent messages on social media this morning regarding this
increasing threat.

RH values will remain in the 25 to 35 percent range both Saturday
and Sunday. Dry fuels of dead grasses, leaves and brush from the
winter is abundant without any pcpn over the past week and a half.
Sustained winds of 15 to 25 mph from the east is expected each day.
These winds pick up around daybreak on Saturday and continue day and
night through Monday. Gustier winds will be possible Saturday
especially over the Grand River Valley as ENE winds off of Saginaw
Bay funnel through the basin. We should finally get relief from
these conditions by Monday night with a high likelihood of rain.


Issued at 1244 PM EDT Fri Mar 23 2018

With the exception of the Portage River near Vicksburg, area
rivers and streams are holding well within their banks as
streamflow analysis reveals that river flows across the region are
mostly near to below normal. Rain continues to look likely Monday
night into Tuesday night but at this point amounts will likely
produce within bank rises on area rivers and streams, given
projections of 0.50" to 1.00" for many locations.




LONG TERM...Hoving
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