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fxus63 kgrr 161138 
afdgrr

Area forecast discussion
National Weather Service Grand Rapids Michigan
738 am EDT Mon Sep 16 2019

Latest update...
aviation

Synopsis...
issued at 252 am EDT Mon Sep 16 2019

- patchy dense morning fog this morning and again tonight

- warming trend this week

- scattered showers and thunderstorms next weekend

&&

Discussion...(today through next sunday)
issued at 252 am EDT Mon Sep 16 2019

The main challenges in the forecast period deal with the risk for
fog the next few nights and the potential for thunderstorms next
weekend.

Fog was on the increase over the past couple of hours. Scattered
observations show variable visibilities with several under a mile.
The fog should slowly increase through daybreak as temperature
slowly cools off. At this time...given the cloud cover in place
widespread dense fog looks unlikely. Rather patches of dense fog
should prevail and continue for a few hours after sunrise.

A rather strong inversion sets up tonight. Guidance is showing
moist conditions under this inversion. Thus...low clouds and fog
could become widespread tonight and persist through much of
Tuesday morning. This could cause some impacts on travel and also
create uncertainty in the high temperatures for Tuesday. We will
feature fog in the forecast for the overnight into the morning
periods with high temperatures not quite as warm as some of the
guidance.

Looking ahead...stronger warm air advection develops starting
Friday and strengthens into Saturday. Instability does not move
in until likely after Friday. Thus we will feature some storms
starting up Friday night and then continue the risk into
Saturday. Guidance is scattered on when the surface cold front
will track through with the GFS tracking it through Saturday
night while the high res Euro keeps it west of the area through
Sunday. We will feature a risk for storms into Sunday for now.

&&

Aviation...(for the 12z tafs through 12z Tuesday morning)
issued at 734 am EDT Mon Sep 16 2019

Patches of IFR and lower clouds continue to drift down from the
north at this time...impacting some of the tafs. However as we go
through the morning...a trend toward VFR is forecasted. Then
tonight...perhaps a greater risk for IFR and lower conditions as
fairly decent radiational cooling sets up early in the evening. It
will not take much cooling for the fog/low clouds to form again.



&&

Marine...
issued at 252 am EDT Mon Sep 16 2019

The pressure gradient remains relatively weak over the next couple
of days. Thus the wind will be sub advisory criteria. The waves
as a result will continue to remain low as well...especially with
an offshore component setting up.



&&

GRR watches/warnings/advisories...
Michigan...none.
Lm...none.
&&

$$

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