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 49 50

FXUS63 KGRR 231146

Area Forecast Discussion
National Weather Service Grand Rapids MI
746 AM EDT Fri Mar 23 2018


Issued at 325 AM EDT Fri Mar 23 2018

A dry forecast is expected right through the weekend with a
persistent area of high pressure situated from Ontario and Quebec
into the Great Lakes. The high will bring fair weather and
seasonable temperatures. Highs the next few days will generally be
in the lower 40s.

An area of low pressure will move through the Great Lakes region
early next week bringing moderating temperatures for Monday and
Tuesday when highs will push into the 50s. The warmer readings will
come with some rain however from Monday night into Tuesday night.
Rainfall amounts of a half inch to an inch appear possible during
this time frame.


.SHORT TERM...(Today through Sunday)
Issued at 325 AM EDT Fri Mar 23 2018

The main weather feature of note in the short term will be an area
of low pressure that will bring mixed precipitation and a swath of
snow across Illinois and Indiana tonight into Saturday. The upper
wave associated with the system will eject out of the Rockies today
and into the plains tonight and slide just southwest of our area on
Saturday. All the models keep Southwest Lower Michigan dry, so not
expecting much more than a canopy of mid clouds and possibly some
mid level virga in the far southwest corner of the forecast area.

It will be brisk on Saturday with a stiff east to northeast wind.
Expecting winds of 12 to 25 mph. A tight pressure gradient will be
found across the area between a 1040mb high near James Bay and a
1005mb low moving into the Ohio Valley.

As for the details of the forecast (all cloud related), we should be
mostly sunny today with increasing high clouds tonight, especially
across the south. Clouds across the south during the morning on
Saturday will move south out of the area during the afternoon.
Mainly clear skies are expected Saturday evening. Saturday night
into Sunday morning we may see some stratocumulus develop off of
Lake Huron in a northeast flow. Delta T`s will increase to in excess
of 10C and the NAM is indicating some moisture spreading in around
2000ft. The clouds look to mix out for Sunday afternoon.

Not much change in temperatures from what we have been seeing. Highs
the next few days will be in the low to mid 40s. Lows will remain in
the upper teens to lower 20s.

.LONG TERM...(Sunday night through Thursday)
Issued at 325 AM EDT Fri Mar 23 2018

Temps will undergo a moderating trend for the early to middle
portion of next week as southerly flow develops on the back side of
the departing ridge Monday. High temps early to mid next week should
reach the lower to middle 50`s.

The continued southerly flow will result in increasing moisture and
a chance of light warm air advection showers by Monday night. A slow
moving low pressure system will bring more widespread showers
Tuesday through Tuesday night into Wednesday. No convection is
expected at this time mainly due to weak instability.

A colder airmass will advect in behind that system late in the week
when temperatures will return to near normal for this time of year.


.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 746 AM EDT Fri Mar 23 2018

VFR weather is expected the next 24 hours. A few stratocumulus
clouds are possible today with bases around 4,000ft, otherwise
skies will be mostly sunny. Tonight some high clouds will push in
from the west, but bases will be at or above 20,000ft. Winds today
will be from the northwest to north at 5 to 10 mph.


Issued at 325 AM EDT Fri Mar 23 2018

Winds and waves will remain below Small Craft Advisory criteria
today and tonight. North winds today of 10-20 knots will shift to
the east late tonight increasing towards daybreak. Waves will likely
reach the 2 to 4 foot range today.

It is not out of the realm of possibilities that we may need a SCA
for winds on Saturday into Saturday night with sustained winds of 20
to 30 knots away from shore. The winds will be off the land, but
once you get out a few miles the stiff east wind will be noticeable.
The easterly winds will persist right through the weekend. Waves
this weekend with a limited fetch (east winds) will generally be in
the 1 to 3 foot range.



River levels will continue falling during this dry period. Some
rises may be possible early next week with a return of rainfall to
the region. It is too early to tell how significant of an impact
this will have on the rivers but it certainly bears watching.




LONG TERM...Laurens
MARINE...Duke is the U.S. government's official web portal to all federal, state and local government web resources and services.