National Weather Service Raw Text Product

Displaying AFOS PIL: AFDGRR Received: 2017-07-16 23:10 UTC


019 
FXUS63 KGRR 162310
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
710 PM EDT Sun Jul 16 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 330 PM EDT Sun Jul 16 2017

The weather will stay quiet through Tuesday evening, then a chance 
of thunderstorms moves in from the northwest late Tuesday night. The 
showers should continue into Wednesday.  More scattered showers and 
storms should arrive about every other day, Friday, and again next 
Sunday.

After being a bit cooler than normal Monday and Tuesday, with highs 
in the upper 70s to lower 80s, we will see mainly 85 to 90 for the 
rest of the week and into next weekend.

&&

.SHORT TERM...(This evening through Tuesday night)
Issued at 330 PM EDT Sun Jul 16 2017

Quiet and temps slightly below normal for the next couple of days. 
Then we will see a chance of storms return by late Tuesday night.

Surface and upper ridging will build over the region through the 
next 48 hours.  The upper ridge axis will stay to our west through 
Tuesday morning, so we will stay a few degrees below normal for this 
time of year through Monday night, then near normal by Tuesday.

Once the ridge moves south and east, a cold front will approach from 
the northwest into Tuesday night.  The front is only progged to be 
over Northern Lake Michigan to Central Wisconsin by 12Z Wed, so the 
main impact will be over the NW CWA and mainly after midnight.  At 
this point there appears there will be a jetlet over the U.P. or 
Lake Superior.  We will have to see if enough dynamics arrives 
overnight to expect showers and storms.  Will keep POPs in the 
chance category for now.

.LONG TERM...(Wednesday through Sunday)
Issued at 330 PM EDT Sun Jul 16 2017

The pattern does not change during the extended period with a 
continuation of the fast west-northwest flow regime between a 
sprawling subtropical high to our south and upper troughing over 
central and eastern Canada. 

So we will continue to see the recent pattern of sfc lows tracking 
across the northern Great Lakes with a trailing cold front touching 
off showers and thunderstorms followed by a fair weather interlude 
as a bubble high moves in...then showers and thunderstorms returning 
as the cold front moves north as a warm front in advance of the next 
sfc low.

The timing of features in this fast flow is tricky and leads to low 
confidence in the specifics, especially for the latter half of the 
week. For now highest confidence forecast for rain will be on 
Wednesday with a cold front. There will be a brief period of fair 
weather and then convection, possibly in the form of an MCS, 
increases along and north of the sfc warm front and rolls into Lower 
Michigan on either Thursday or Friday, followed by fair weather 
Friday or Saturday then another round of convection on Sunday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 701 PM EDT Sun Jul 16 2017

High pressure will be building into the region tonight and into
Sunday. This will result in generally clear to scattered cloud
conditions and relatively light winds through the forecast period.
Late night fog will be possible considering the good radiational
cooling that is expected. I did add fog to the forecast for KLAN
and KJXN. It is possible that sub IFR conditions could develop.



&&

.MARINE...
Issued at 330 PM EDT Sun Jul 16 2017

Buoy and webcams confirm very rough conditions on the lake this 
afternoon.  The small craft advisory and beach hazard statement will 
be continue into tonight.  Winds will be dropping off around 
midnight as the pressure gradient eases.  Waves will gradually 
lessen toward daybreak when the headlines should be allow to expire. 
The lake will be calmer through the rest of the short term.


&&

.HYDROLOGY...
Issued at 330 PM EDT Sun Jul 16 2017

Much of Lower Michigan was spared of rainfall last night into this 
morning. A few isolated showers developed east of Grand Rapids with 
little in the way of measurable precipitation.

The pattern remains fairly quiet through Tuesday. The midweek 
timeframe brings thunderstorms back into the picture, but will be 
isolated/scattered in nature. Limited rainfall through the next 
couple days will allow above normal river levels to continue to fall 
off. Improvement may even continue through the middle of the week 
with the limited aerial coverage in resulting moisture. 

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Beach Hazards Statement until 4 AM EDT Monday for MIZ037-043-050-
     056-064-071.

LM...Small Craft Advisory until 4 AM EDT Monday for LMZ844>849.

&&

$$

SYNOPSIS...JK
SHORT TERM...JK
LONG TERM...Ostuno
AVIATION...MJS
HYDROLOGY...JAM
MARINE...JK