Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 191857
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
157 PM EST Thu Jan 19 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 326 AM EST Thu Jan 19 2017

Expect warmer than normal temperatures through at least Wednesday
of next week. The warmest temperatures will likely be Saturday and
Sunday when we could see highs in the 50s (around 25 degrees above
normal). Rain is expected Friday morning,then another storm
system may bring more rain to the area late in the weekend into
early next week.

As for today,typically a large high pressure system passing over
Michigan would mean mostly clear skies. However for Southwest
Lower Michigan, in January, not so much. Still there is a risk
for sunshine this afternoon.

&&

.SHORT TERM...(Today through Saturday)
Issued at 326 AM EST Thu Jan 19 2017

Two primary issues, the cloud cover today and risk for rain for
Friday morning. There is little question temperatures will remain
above freezing through the weekend across the area. So, no issue
there.

As for the large scale weather pattern, we still have that
segement of the east Asian jet heading toward the west coast
(central and southern California) by Saturday morning. It is
currently just east of the Dateline around 40N. It has max winds
of near 200 knots. It is that feature that is keeping most of the
CONUS warmer than normal. So until it comes on shore and all the
energy from is dissipated it will stay warm too. Anyway, that same
feature boots the closed upper low, that was over the Southwest
CONUS northeast into the Northern Plains as a sheared out upper
wave. This brings a negative tilt upper wave through Michigan
Friday morning. The large scale forcing associate with that
shearing out upper waves brings precipitable water values to near
all time record values for this time of year (around an inch). It
also has strong deep dynamics with it and a trowal feature with
it. Little question, this means it will rain here Friday morning.

Once that feature moves north of the area (Saturday morning) the
main jet core will be coming on shore. That will result in a much
more powerful storm developing over the southern Plains by early
Sunday. We will remain in deep southerly flow through the weekend
until all of that upper wave energy gets east of this area, and
that will not be until the middle of next week. This means we will
see weak shortwaves move through the area following the lead
system Friday morning.

With that deep southerly flow temperatures will gradually warm
into the 50s by midday Saturday. Do not expect much sunshine
through as the southerly flow is moist so we will have mostly
cloudy skies with scattered showers Friday night through Saturday.

The bottom line is for the most part cloudy skies and temperatures
slowly warming into the 50s by Saturday.

.LONG TERM...(Saturday night through Wednesday)
Issued at 326 AM EST Thu Jan 19 2017

Mild and wet weather will continue through the early to middle
portion of next week before a colder airmass finally moves in late
in the week.

A trough of low pressure will bring extensive cloud cover and
scattered rain showers Saturday night through Sunday. There is
potential for a strong low pressure system to get organized and move
northeast into the mid Atlantic region by Monday.

However all of the synoptic pcpn associated with that system will
likely stay se to south of our area. Even so some lighter rain
showers will likely linger into early next week with an upper trough
over our region resulting in a continuation of unsettled wx.

Some showers will likely linger through midweek and some wet snow
flakes may mix in as well before a pattern change finally begins to
occur late in the week with nw flow cool air advection. Therefore
while it certainly will not be an arctic airmass temperatures should
finally return to closer to normal for this time of year by Thursday
or Friday.

&&

.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 157 PM EST Thu Jan 19 2017

An area of clearing has developed across Southern and Central
Lower Michigan as of 18z. This trend will continue through the
afternoon with most sites expected to scatter out. There will be
some mid and high clouds streaming in, but bases on these clouds
will be above 6000ft.

This evening, the low clouds will likely start to redevelop with
ceilings below 1000ft forecast by midnight. Rain will develop as
well, spreading in from south to north after 03z. By 12z on
Friday, we will likely have widespread IFR and LIFR in place with
low ceilings, rain and fog. The poor aviation conditions should
persist through the morning hours of Friday.

&&

.MARINE...
Issued at 326 AM EST Thu Jan 19 2017

At this point I do not see winds or waves being strong enough for
a small craft advisory through the weekend. Just periods of rain,
cloudy skies and some fog through the weekend.


&&

.HYDROLOGY...
Issued at 1210 PM EST Wed Jan 18 2017

The Grand River at Robinson Twp is rising after Mon/Tue`s inch of
rain and a continued restriction of waterflow due to ice. Most
other rivers are rising due to the recent rain but seem to have
less notable ice impacts now. Temperatures (and dew points) will
be above 32 degrees for much of the next 7 days, with highs around
50 possible Sat/Sun. Melting river ice should eventually break
up, at which time flooding at Robinson Twp would likely alleviate.
Nonetheless, rivers across the area, especially in the greater
Grand basin and lower Kalamazoo basin, continue to run high due to
above- normal liquid precipitation this month. A quarter to half
inch of rain on Friday won`t make matters much worse, but it won`t
help either. Low-land flooding near riverbanks is occurring at
multiple forecast points, but impacts to property are not too out
of the ordinary. The Maple River near Maple Rapids will approach
Minor Flood Stage this weekend.

&&

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

$$

SYNOPSIS...WDM
SHORT TERM...WDM
LONG TERM...Laurens
AVIATION...Duke
HYDROLOGY...CAS
MARINE...WDM



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