National Weather Service Raw Text Product

Displaying AFOS PIL: AFDGRR Received: 2020-09-15 19:11 UTC


526 
FXUS63 KGRR 151911
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
311 PM EDT Tue Sep 15 2020

LATEST UPDATE...
Synopsis/Discussion/Marine

.SYNOPSIS...
Issued at 225 PM EDT Tue Sep 15 2020

- Cold front drops down Wednesday afternoon/evening

- Frost/freeze potential end of the week

- Potential warmup for next week




&&

.DISCUSSION...(This evening through next Tuesday)
Issued at 225 PM EDT Tue Sep 15 2020

- Cold front drops down Wednesday afternoon/evening

The mid level low currently dropping down the west side of Hudson
Bay swings a cold front through Lower MI Wednesday 
afternoon/evening. A narrow band of moisture accompanies the 
passage of this front. The lift remains weak. Some weak 
instability is showing up in the models but forecast soundings do 
not support a risk for thunder at this time. If models trend 
toward more instability we may need to add a risk for thunder. We
will feature only low POPs for this event. 


- Frost/freeze potential end of the week

A large Canadian High Pressure System builds down for Thursday
into Saturday. As the winds diminish and skies scatter out for 
late Thursday night...a risk for frost/freeze conditions could 
occur. Guidance continues to support near freezing temperatures 
for our northern zones...including Harrison. Further 
south...urban places like Grand Rapids and Lansing are likely not
to see freezing temperatures for Thursday night. More rural
locations between these cities stand a risk for patchy frost. A
similar setup exists for Friday night as well. Temperatures start
to go up for Saturday night with overnight lows expected to be 
not quite as cold. No headlines at this time but we will continue
to highlight the risks in social media. 



- Potential warmup for next week

Warm air advection develops Sunday and strengthens into Monday.
This will force a moderation to the low level temperatures. At
least near normal values look likely by the time we get to
Tuesday. Temps at 925 mb are progged to reach 20 deg C so that
should easily allow for some 70s. Monday or Tuesday could end up 
rather breezy depending on the timing of the next low level jet. 


&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 121 PM EDT Tue Sep 15 2020

The low level moisture remains limited so any cloud cover will
likely remain VFR. Gusty winds are possible today and again on
Wednesday as a front nears from the north. Values could approach
25 knots. This front is not expected to push through until after 
18z Wed.


&&

.MARINE...
Issued at 225 PM EDT Tue Sep 15 2020

The Beach Hazards and Small Craft Advisories will continue into 
Wednesday. We could see a lull in the winds and waves 
overnight...but as the front drops down Wednesday...the winds veer
and strengthen again. We may need to monitor Allegan and Van 
Buren Counties for possible expansion of the headlines as there 
are some indications 4 footers and gusty winds could reach those 
zones/counties as well. 



&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement through Wednesday afternoon for MIZ037-
     043-050-056.

LM...Small Craft Advisory until 5 PM EDT Wednesday for LMZ846>849.

&&

$$

SYNOPSIS...MJS
DISCUSSION...MJS
AVIATION...MJS
MARINE...MJS