Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 170215

Area Forecast Discussion
National Weather Service Grand Rapids MI
1015 PM EDT Sun Oct 16 2016


Issued at 317 PM EDT Sun Oct 16 2016

Rain has become more spotty this afternoon, but will increase some
tonight as the front that is currently going through will return
north as a warm front tonight and early Monday. Showers and storms
tonight will shift to the north on Monday, with warmer temperatures
expected. The associated cold front will move through on Tuesday,
keeping chances of rain in through then.

More rain will become possible on Wednesday and Thursday, especially
across southern areas as another system approaches the area. Cooler
air will follow for the end of the week and next weekend, with
smaller chances of rain remaining possible.


Issued at 1015 PM EDT Sun Oct 16 2016

I made no major changes to the ongoing forecast. There is light
fog across the area (1 to 3 miles visibilities) with some locally
dense fog near the Lake Michigan Shore. The RAP model has done a
great job of showing where the lowest visibilities are and it
shows the lowest visibilities are near the front over the Lake
shore area. As the front becomes a warm front overnight it lifts
the fog to the north out of our CWA. Given how the winds are
forecast to increase in the boundary layer overnight that totally
makes sense to me so I do not believe we will see widespread dense
fog overnight.

The other issue the developing low level jet. There is a segment
of the jet that is aimed at our southwest CWA between midnight and
3 am. After that it is aimed at southeast Michigan and northern
Ohio. This is shown by the 1000/850 moisture transport vectors
too. Thus as we have forecast there is a good chance we will see
at least scattered showers and isolated thunderstorms during the
early morning hours of Monday.


.SHORT TERM...(This evening through Tuesday night)
Issued at 317 PM EDT Sun Oct 16 2016

Our main focus for the short term portion of the forecast is mainly
rain trends through Tue with the frontal system remaining in the
region through then. Some thunder will be possible tonight through
Mon night, however we are not expecting anything organized that
would be strong at this time.

We are seeing low clouds/drizzle/fog being the prevailing condition
across the area this afternoon. Latest sfc analysis shows the front
has sank south to just north of I-96 as of 19z. It is slowing its
progress south as expected as the upper wave supporting this is
moving NE of the area. Plenty of low level moisture lingering, and
it will only linger through this evening.

We will see rain chances increase some overnight from south to
north. The moisture transport will ramp up as the llj increase to
over 30 knots ahead of the next wave that will be moving in. The
progression of the rain to the north will occur as the llj helps the
sfc front to move back north as a warm front. All of this
shower/storm activity will be of the elevated variety, so severe wx
is not likely.

The showers and storms should shift almost entirely out of the area
for Mon and Mon night. The warm front should lift to near and north
of the Straits area, taking with it the nose of the llj and best
moisture transport. we will be left with windier conditions and
warmth. We expect that many area will see a good deal of sun on Mon,
which should help lift temps well into the 70s and approach 80.

The chance of rain will come back, mainly Tue morning as the cold
front will push through the area. The cold front will be lacking
good deep moisture ahead of it, and will be coming through before
much heating can take place. It looks to be most of the way through
the area by 18z Tue. The rain chances will end at that time, and we
will cool down back to near seasonable levels.

.LONG TERM...(Wednesday through Sunday)
Issued at 317 PM EDT Sun Oct 16 2016

An upper trough amplifies across the eastern CONUS during the period
resulting in cool and possibly wet weather much of the time. Low
pressure tracking through the Ohio Valley will spread its northern
precip shield into Lower Michigan with the highest chances being
across the southern zones Wednesday and Thursday.

Colder air on the backside of the low arrives later Thursday and
Friday with the synoptic rain showers replaced with a few lake
enhanced showers. These should end by Friday night but a clipper
arrives Saturday or Sunday in fast northwest flow.


.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 650 PM EDT Sun Oct 16 2016

Currently we have IFR cigs across the TAF sites with MVFR to IFR
visibilities. There is a stationary front between Route 10 and
Route 10 over central Lower Michigan. I would think that front
will stay were it is for a few more hours then lift north after
midnight as the system from the plains gets closer to Michigan.
Near front front expect locally dense fog but areas south of the
front (all of the taf sites) will stay in low stratus into at
least mid morning Monday. Winds will increase after midnight and
by 09z be as much as 30 knots at 1000 ft agl. That will be to
strong for dense fog. So I believe any fog that develops this
evening should thin some overnight.

There is the risk of showers and thunderstorms after midnight as
the front pushes northward but most of the convection should be
north of the frontal system so I plan on having VCTS to for that
in our 00z TAFs.

By midday we may seem some clearing but I am not really sure about
this so I may leave at least MVFR cigs for now and call that good.


Issued at 1015 PM EDT Sun Oct 16 2016

As it has turned out the fog is not lifting as quickly as I
through it may so I extended the time of the fog advisory until 4


Issued at 317 PM EDT Sun Oct 16 2016

A widespread half inch of rain fell this morning. Over an inch was
common in the lower Muskegon basin and the lower Grand basin. Over
two inches was reported in northern Kent County and northern
Muskegon County. Fortunately, the smaller river basins that received
the most rain have enough room to handle the runoff. Many rivers
will continue running much higher than seasonal normals this week.
The flood threat is limited by a rather low chance of widespread
heavy rain events this week, though Thursday bears watching for the
upper Grand basin if the expected axis of heavy rain shifts


LM...Dense Fog Advisory until 4 AM EDT Monday for LMZ845>849.

     Small Craft Advisory from 5 AM Monday to 4 PM EDT Tuesday for



LONG TERM...Ostuno
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