Area Forecast Discussion
Issued by NWS Grand Rapids, MI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48

000
FXUS63 KGRR 211757
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
157 PM EDT Sat Apr 21 2018

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 330 AM EDT Sat Apr 21 2018

Dry weather is forecast through Monday night courtesy of an area of
high pressure that will be anchored across the Great Lakes region.
Some cloud cover today will keep high temperatures a bit lower than
what would be achieved under sunny skies, but we are still expecting
upper 50s once again today. Highs will push into the low 60s on
Sunday and rise into the upper 60s on Monday. Most of2 this month
has seen temperatures average below normal, so for those looking
for spring they will enjoy Sunday and Monday.

&&

.UPDATE...
Issued at 1059 AM EDT Sat Apr 21 2018

No significant changes to the forecast this update. Very little
precipitation reaching the ground beneath a band of weak radar
reflectivity /~20 dBZ/ extending from northeast IA into NW IN.
This is not surprising given the very dry layer below ~10000 ft
seen on the morning soundings. Although this band may drift over
extreme Southwest Lower MI, no surface precipitation is expected.

&&

.SHORT TERM...(Today through Monday)
Issued at 330 AM EDT Sat Apr 21 2018

Only real item of contention in the short term, and its a small one,
is how much and how dense are the high clouds today. Models continue
to show solid high clouds streaming in from the west today with 500-
300mb layer RH values of 75-80 percent which usually results in a
mostly cloudy sky. GOES-16 IR imagery does indicate dense mid and
high clouds off to the west moving our direction. Decided to shave a
few degrees off of MOS numbers into the upper 50s given the
expectations of a dense mid/high cloud deck. We should see some hazy
sunshine, but it certainly will not be full sun.

The high clouds should peel away to the south tonight leaving behind
mainly clear skies for the remainder of the short term. Highs should
reach the low 60s on Sunday and the mid to upper 60s on Monday. We
have had only 1 daily average temp above normal the entire month.
So, back to back days of a good deal of sunshine and above normal
highs will be welcomed by most.

.LONG TERM...(Monday night through Friday)
Issued at 330 AM EDT Sat Apr 21 2018

Fair weather will continue through Monday night. An upper level
trough will move into the lower Great Lakes region Tuesday and
several upper level disturbances will bring a chance of rain
showers. Some rain showers will linger Tuesday night into early
Wednesday as a weak cold front and stronger upper level disturbance
moves through.

Fair weather will briefly return Wednesday afternoon through most of
Thursday as a high pressure ridge builds in. However a stronger cold
front will bring another chance of showers Thursday night into
Friday.

After a prolonged period near normal temperatures Tuesday through
Thursday temperatures will return to below normal for this time of
year by Friday into the weekend with an upper level trough in place
over the eastern CONUS by then.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 157 PM EDT Sat Apr 21 2018

Very high confidence for VFR through the period. Ceilings with
bases well above 10000 feet AGL should exit overnight. Winds will
likely go calm tonight at most terminals. The possible exception
might be MKG which could see the current onshore winds from the
west-northwest becoming from the east-northeast.

&&

.MARINE...
Issued at 330 AM EDT Sat Apr 21 2018

High pressure is still forecast to be situated across the Great
Lakes region into Tuesday. The high will provide light winds and
limited wave action. Wave models have forecast wave heights at a
foot or less through Tuesday.


&&

.FIRE WEATHER...
Issued at 1059 AM EDT Sat Apr 21 2018

Have updated the forecast to feature RH values dropping below 30
percent in many areas this afternoon. However, winds are expected
to stay light this afternoon with a weak onshore flow of 10 mph
or less developing roughly within 10 miles of Lake Michigan.

&&

.HYDROLOGY...
Issued at 124 PM EDT Fri Apr 20 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, rivers will gradually
crest then subside with only nuisance level impacts.

&&

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

$$

UPDATE...TJT
SYNOPSIS...Duke
SHORT TERM...Duke
LONG TERM...Laurens
AVIATION...TJT
FIRE WEATHER...TJT
HYDROLOGY...CAS
MARINE...Duke



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.