National Weather Service Raw Text Product

Displaying AFOS PIL: AFDGRR Received: 2019-01-11 08:00 UTC


781 
FXUS63 KGRR 110800
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
300 AM EST Fri Jan 11 2019

LATEST UPDATE...
Synopsis/Discussion/Marine

.SYNOPSIS...
Issued at 300 AM EST Fri Jan 11 2019

- A few light snow showers are possible this afternoon and evening
  mainly along and northwest of a line from Holland to Evart.

- While the brunt of snow associated with a weakening low pressure
  system will stay south of Lower Michigan Saturday, there are
  hints that light lake effect snow off Lake Huron may make it as
  far west as central Lower Michigan Saturday evening. 

- There is an increasing signal that the pattern will become
  active toward the end of next week. 

&&

.DISCUSSION...(Today through next Thursday)
Issued at 300 AM EST Fri Jan 11 2019

Quiet weather has returned to Lower Michigan with really no 
impactful weather expected in the next few days. There may be a few 
light snow showers this afternoon and evening mainly west of a line 
from Holland to Evart associated with southwest flow and shallow 
moisture off Lake Michigan, but minimal accumulations are expected. 

The low pressure system expected to bring wintry weather to portions 
of Iowa, Illinois, and Indiana Saturday is still poised to stay well 
south of Lower Michigan thanks to weakening upper-level support and 
a dry low-level airmass supplied by a high pressure system to our
north. We were happy to see the ECMWF EPS backed off 
significantly on precipitation potential along I-94, building our 
confidence that the system will indeed stay to our south. However 
there'll likely be a tight gradient in snowfall along the northern
edge of the system somewhere near the Michigan/Indiana border. 
Interestingly the 00Z suite of high resolution model guidance has 
started to hint at the potential for a mesolow or two to develop 
over southern Lake Huron Saturday morning and drift westward 
within the broad cyclonic flow of the low to our south. 
Climatologically speaking, it's pretty rare for lake-effect 
precipitation off Lake Huron to reach western Lower Michigan, but 
the lake-induced instability and wind direction will certainly be 
favorable (not to mention the concavity of Lake Huron), and 
mesolows tend to be more organized than your average lake effect 
snow shower. Thus, it's feasible that at the least flurries will 
make it to Clare, Isabella, Osceola, and Mecosta counties with 
snow showers not out of question Saturday night. Impacts would 
still be limited, however, as the mesolows (should they indeed
develop) would be weakening as they work their way into our area.

Sunday through Tuesday still look quiet and unseasonable warm with 
highs in the low to mid 30s and ample opportunities to get a peek of 
the sun. 

Forecast deterministic and ensemble guidance is in fair agreement 
that a cold front will sweep through the Great Lakes around the 
Wednesday timeframe. While sufficient lake-induced instability will 
be present for the development of snow showers, the wind direction 
may prove detrimental at least for Lower Michigan with the favored 
zone setting up in northwestern Indiana (if not on the western side 
of the lake). The pattern then may become rather interesting toward 
the end of next week as a reinforcing surge of cold air takes aim at 
the eastern United States. While differences exist within 
deterministic and ensemble model guidance on the exact details 
(maybe a storm system or uptick in LES around the January 20th 
timeframe?), there is definitely a signal that the upper-level pattern
will become decidedly more active if not wintry for the end of 
January.

&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1130 PM EST Thu Jan 10 2019

A stratus deck rooted at about 2200 feet will continue eroding
from east to west tonight with all TAF sites reaching VFR cigs by
8Z/3AM tonight. The exception may be at MKG where lower cigs may 
take longer to erode. Otherwise, light and variable winds tonight 
will become predominantly southeasterly after sunrise. 

&&

.MARINE...
Issued at 300 AM EST Fri Jan 11 2019

Winds and waves will remain below 21 kts and 4 ft, respectively, 
through early next week. Conditions may become hazardous for small 
crafts thereafter. 

&&

.HYDROLOGY...
Issued at 330 PM EST Wed Jan 9 2019

Water levels are generally above normal for this time of year, but 
this will be changing this week with the return to winter 
temperatures. Precipitation will be in the form of snow, thus a 
trend toward dropping water levels is expected to take hold by the 
week's end across most of the rivers in West Michigan. Water 
temperatures are generally in the mid to upper 30s, except on the 
Muskegon River where lower 30s can be found. These values will 
fall through the weekend, and ice formation may be possible on 
rivers by next week. 

The Maple River at Maple Rapids continues to hover near bankfull, 
and is expected to remain around this level before a dropping trend 
starts by this weekend. No flooding is expected.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&

$$

SYNOPSIS...Borchardt
DISCUSSION...Borchardt
AVIATION...Borchardt
HYDROLOGY...63
MARINE...Borchardt