Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 160056

Area Forecast Discussion
National Weather Service Grand Rapids MI
856 PM EDT Sat Oct 15 2016


Issued at 326 PM EDT Sat Oct 15 2016 A cold front will move into
central Lower Michigan tonight and then stall before moving north
Sunday. Showers and thunderstorms are expected tonight and Sunday.
Warm weather is expected through mid week...before a strong cold
front moves through Thursday.


Issued at 854 PM EDT Sat Oct 15 2016

I decreased POPs slightly for this evening but increased the for
later tonight. The band of showers will continue to strengthen as
it moves in from the west. With elevated instability moving in...
a few embedded thunderstorms could develop. Sunday morning is
looking wet with the rain tapering off from west to east through
the morning.


.SHORT TERM...(This evening through Monday night)
Issued at 326 PM EDT Sat Oct 15 2016

Forecast concerns deal with convective trends tonight.
National radar loop shows quite a bit of mid level echos over the
upper Midwest. However, much of it isn`t hitting the ground.
Stronger echos were noted over southwest Minnesota along the cold
front. Models indicate that the front will move to the nw cwa late
tonight. Convergence and increasing moisture via a 35kt llj ahead of
the front will produce showers/storms mainly after midnight. The
pcpn will move southeast through the cwa late tonight and Sunday.
The front stalls and moves north again Sunday afternoon/night in
response to developing low pressure in the northern Plains. Although
initially around 40kts at 06z...shear decreases overnight and
instability isn`t very high to begin with. Thus we don`t expect svr
storms tonight nor Sunday.

Once the front moves north Sunday very warm and humid air will move
back over Lower Michigan. Highs Monday will be near 80 with
dewpoints in the mid 60s.

.LONG TERM...(Tuesday through Saturday)
Issued at 326 PM EDT Sat Oct 15 2016

There is better agreement on the longwave trough affecting the
eastern half of the CONUS next week and it is looking more likely
that a cool and possibly wet period develops for much of the
period,especially across the southeast zones.

A cold front sags south across Lower Michigan on Tuesday as low
pressure tracks off to the east. There may be a sharp gradient in
max temps as clouds and showers will keep the northern zones cooler
while maxes will in the upper 70s across the south. We will have to
watch the potential for any convection along the front Tuesday
afternoon and evening as 0 to 6 km shear values are forecast to be
near 50 knots.

Much cooler weather follows for the rest of the week as an upper
trough amplifies across the eastern CONUS with the southern end of
the trough cutting off over or just north of the Gulf Coast and low
pressure slowly lifting northeast from there. The precip shield
could extend into southern and eastern zones from Thursday into
Saturday, although the highest chances will be late Thursday into
early Friday. Some solutions are cold enough for wet snowflakes
across the northern zones by the weekend but this is low confidence
at this point.


.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 725 PM EDT Sat Oct 15 2016

VFR weather is forecasted to prevail this evening...but around or
after midnight...conditions will begin to change. A band of
showers with embedded thunderstorms will be strengthening as it
moves into the TAF sites from the west after midnight. It may take
until daybreak for them to reach KJXN. Impacts will increase after
midnight and it looks likely that all sites will become IFR or
lower by Sunday AM. The band of precipitation will push east of
the TAF sites most likely by noon Sunday.

How quickly the conditions improve on Sunday is not certain. The
low level moisture is forecasted to slightly decrease Sunday
afternoon but this may not happen. At this point will feature a
slow increase to the ceilings during the afternoon.


Issued at 326 PM EDT Sat Oct 15 2016

No changes to the marine headlines. Strong south winds ahead of the
cold front will create hazardous conditions for small craft tonight.


Issued at 1146 AM EDT Sat Oct 15 2016

River levels are running above normal for this time of year in the
upper half of the Grand basin, including Hastings, Ionia, and
points upstream. Basin average rainfall amounts approaching one
inch are possible Saturday night through Sunday in a portion of
the area. The typically flood-prone points of tributaries in the
upper half of the Grand River basin may deal with rises to above
bankfull if widespread greater than one inch of rain is received,
but this is not the most likely scenario.


LM...Small Craft Advisory until 11 AM EDT Sunday for LMZ844>849.



LONG TERM...Ostuno
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