Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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259
FXUS63 KGRR 201139
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
739 AM EDT Fri Apr 20 2018

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 330 AM EDT Fri Apr 20 2018

Clear to partly cloudy skies can be expected through the weekend
with dry weather forecast. High pressure will slowly drift through
the area into early next week ensuring a precipitation free
forecast. Temperatures will continue to moderate for those folks
looking for spring. Temperatures will reach the upper 50s today and
hit the lower 60s over the weekend. Even warmer temperatures are
anticipated early next week when mid to upper 60s readings are
forecast.

&&

.SHORT TERM...(Today through Sunday)
Issued at 330 AM EDT Fri Apr 20 2018

Limited weather concerns in the short term, with dry weather
forecast through the weekend. The only real forecast issue is how
much in the way of cloud cover moves through the Great Lakes region
tonight into Saturday. The clouds are associated with the upper low
currently moving through the 4 corners region. High clouds with this
upper low will spread into the area tonight and affect our area
primarily on Saturday. The high clouds may shade a few degrees of
max temperatures but other than that have little sensible affects.
Saturday will likely be a partly cloudy day. Otherwise, expecting
mainly clear conditions.

The model blend temperatures that are input for our forecast had a
low bias yesterday and therefore bumped up max temperatures for
Friday, Saturday and Sunday. Thinking we are looking at 55-60 for
highs today and 58 to 63 over the weekend.

.LONG TERM...(Sunday night through Thursday)
Issued at 330 AM EDT Fri Apr 20 2018

High pressure will continue to provide quiet weather through Monday
night. Clouds will begin to increase Monday ahead of an approaching
low pressure system, but we should remain dry.

Forecast models continue to struggle with how to handle the track of
upper level low pressure currently moving through the Desert
Southwest. Solutions both model to model and run to run differ with
how much phasing (or even if) occurs between this low and a northern
stream trough that will drop into the Upper Midwest early in the
week. 00Z models have also started to struggle with how to handle
another piece of energy ejecting out of the Pacific Northwest, and
whether this phases into the system as well. If the desert low does
lift up into the area ahead of the approaching trough, we would see
a few rain showers across the area on Tuesday. Otherwise, showers
look to hold off until a cold front passes through Wednesday and
Wednesday night.

High temperatures Monday and Tuesday look to run above normal
(except immediately near the lakeshore) with most locations hitting
the mid 60s. Upper 60s are not out of the question, and will watch
temperature response over the next few days to see if further bump
upward is warranted. Should see a little bit of a cool down by
Thursday as the upper trough moves through the area, providing
clouds and a push of cooler air.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 739 AM EDT Fri Apr 20 2018

VFR weather will prevail the next 24 hours. Some cirrus clouds
with bases at or above 20,000ft will stream in from the west this
afternoon and especially tonight. Winds today will be from the
west and northwest at 5 to 10 knots. Calm winds are anticipated
tonight.

&&

.MARINE...
Issued at 330 AM EDT Fri Apr 20 2018

A lengthy period of high pressure (through the weekend) over the
Great Lakes will bring light winds and limited wave action. Waves of
1 foot or less are expected in the nearshore waters through Monday.


&&

.HYDROLOGY...
Issued at 740 AM EDT Thu Apr 19 2018

Lowland flooding near riverbanks will be ongoing over the next
several days as water from last weekend`s mixed precipitation event
moves through the river basins. Since no heavy rain events are
anticipated through at least early next week, river levels will
gradually crest then subside. The exception may be the Muskegon
and Chippewa Rivers, which still have a fair amount of surface
water locked up as snow/sleet. That snowpack will gradually melt
with warmer temperatures this weekend, so flood concerns are
limited though river levels will remain elevated.

&&

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

$$

SYNOPSIS...Duke
SHORT TERM...Duke
LONG TERM...HLO
AVIATION...Duke
HYDROLOGY...CAS
MARINE...Duke



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