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

000
FXUS63 KGRR 270546
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1246 AM EST Sun Nov 27 2016

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 300 PM EST Sat Nov 26 2016

High pressure will continue to bring dry weather through Sunday
evening. A warm front to the southwest will cause scattered rain
showers to develop during the early morning hours Monday. Occasional
rain showers will continue to develop Monday night through
Wednesday and it will be unseasonably mild Monday through
Wednesday due to persistent southerly winds. A cooler airmass will
move in late this week.

&&

.SHORT TERM...(This evening through Monday night)
Issued at 300 PM EST Sat Nov 26 2016

Primary short term fcst concerns involve determining probabilities
for showers from early Monday morning through Monday night. High
pressure will continue to bring fair and dry wx tonight through
Sunday evening with seasonable temperatures.

A warm front approaching from the southwest will result in
development of scattered rain showers during the early morning
hours Monday. Scattered showers will continue to develop through the
day and for Monday night.

It will become milder Monday through Monday night due to persistent
southerly winds that will help to boost max temps into the upper
40`s to perhaps lower 50`s Monday. It will become a little breezy
Monday with south winds increasing to around 15-25 mph.

.LONG TERM...(Tuesday through Saturday)
Issued at 300 PM EST Sat Nov 26 2016

The long term period begins on Tuesday with Southwest Lower Michigan
moving into the dry slot of a strong wrapped up system off to our
west in the Upper Midwest. The system by Tuesday morning is
vertically stacked with a filling surface low. The surface low
pressure rises from 982mb`s on Tuesday morning per the ECMWF to
997mb`s by Wednesday morning. Bottom line, the system will be
weakening and will begin to have lessening affects.

We expect the precipitation to move off to the north of the area on
Tuesday fairly quick in the morning with increasing amounts of
sunshine through the day. Model guidance is pretty consistent in
showing highs on Tuesday in the mid to upper 50s, if not around 60.

Secondary low development on the southeast flank of the system is
still quite uncertain with the ECMWF showing mainly dry conditions,
while the GFS brings in some light precipitation. The trend has been
toward much less of a low and correspondingly lower precip.

The Wednesday through Saturday time frame looks cooler and showery
(rain and snow) as the upper low pivots overhead. We will generally
be in a westerly flow with air plenty cold enough for lake generated
precipitation. Feel surface temperatures will be marginal much of
the time for rain/snow so included both precip types. -7C to -8C air
will produce Delta T`s over Lake Michigan in the upper teens C.
Expecting steady light rain/snow, but nothing major in terms of
impacts or accumulations.

&&

.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1246 AM EST Sun Nov 27 2016

Some lower clouds based around 1500-3500 ft are persisting along
the lakeshore early this morning. This is likely due to the added
moisture coming in off of Lake Michigan above a shallow layer at
the sfc where winds are from the SE. Pieces of these clouds are
then occasionally breaking off, and moving inland along I-96. We
have this accounted for at KGRR and KLAN in addition to KMKG. This
will persist until the winds start to back a bit and the
trajectory does not come off of the lake.

We have included in some light fog along the I-94 corridor. Some
is starting to form under mainly clear skies. Winds aloft should
limit the fog from becoming too dense.

Otherwise, a decreasing cloud trend should take place on Sun.
Some high clouds will come in later.

&&

.MARINE...
Issued at 300 PM EST Sat Nov 26 2016

Fairly minimal wind speeds and wave action is forecast through Sunday
afternoon but winds and wave heights will remain below small craft
criteria through then. However southerly winds will ramp up to at
least 20 to 25 kts Sunday night which will cause wave heights to
build. A small craft advisory will likely be needed by then and
the wave heights will then stay up into early next week due to
continued strong south to southwest winds.


&&

.HYDROLOGY...
Issued at 300 PM EST Sat Nov 26 2016

It continues to look like the basin average rainfall will be 0.50"
to 1.00" Monday into Tuesday. If higher amounts toward 1.00" or
greater occur over numerous locations, it appears the Grand River
would have considerable within bank rises for many locations as well
as potential rises over the banks at a few locations. Smaller rivers
and streams would be prone to within bank, and perhaps out of bank,
rises. Trends will be monitored, but flooding looks localized and
not significant if the heavier rains materialize. At this point, it
appears that the Muskegon and Kalamazoo Rivers would stay well
within banks.

&&

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

$$

SYNOPSIS...Laurens
SHORT TERM...Laurens
LONG TERM...Duke
AVIATION...NJJ
HYDROLOGY...Hoving
MARINE...Laurens



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