Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 201748
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1248 PM EST Fri Jan 20 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 320 AM EST Fri Jan 20 2017

A surge of warmer air is bringing the rain to the area this
morning. Expect scattered showers into Sunday as we stay in the
warmer air. Saturday will be the warmest day with highs in the
lower to mid 50s. Colder temperatures slowly return next week.
After Wednesday it should be cold enough for snow showers and
temperatures should for the most part be below freezing.

&&

.SHORT TERM...(Today through Sunday)
Issued at 320 AM EST Fri Jan 20 2017

As I have been writing about for the past few days a upper low
being sheared out but the 200 knot jet core from that East Asian
jet feature is bringing the rain promised us this morning. As the
system continues to shear out the rain will come to an end from
south to north. Some freezing rain is possible over the Northeast
CWA this morning but amounts should be minimal so I see no need
for a headline.

Once the upper wave shears out, we have a large upper level trough
moving through the Great Lakes with that jet energy. The primary
surface low will track south of Michigan this weekend into early
next week. Still we have southerly flow at a deep level tonight
into Saturday night. So each shortwave tracking northeast in the
upper flow will bring a few scattered showers.

By Sunday the main system develops and tracks south of the area.
We will have enough moisture to keep showers going even so. It
will remain warmer than normal.

.LONG TERM...(Sunday night through Thursday)
Issued at 320 AM EST Fri Jan 20 2017

Mild and unsettled wx will continue Sunday night and Monday as a sfc
and upper trough will combine to bring extensive cloud cover and
scattered rain showers. Upper level ridging will briefly build in on
Tuesday and bring a short period of dry wx Tuesday morning and
afternoon.

A fairly strong low pressure system will move into the Great Lakes
region Wednesday and bring potential for mixed pcpn. At this time a
consensus of most medium range guidance suggests that pcpn would
likely fall in the form of rain near to south of I-96. A rain/snow
mix is possible across our northern fcst area.

A wx pattern change will finally begin to occur behind that system
late in the week in a northwest flow cool air advection regime. The
cooling trend will begin Thursday and by Friday temperatures should
return to near normal for this time of year. Scattered snow showers
are also anticipated late in the week with an upper level trough in
place over the Great Lakes region by then.

&&

.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 1248 PM EST Fri Jan 20 2017

LIFR ceilings and visibility will be common through 00Z. We could
see CIGS briefly rising from LIFR to IFR this afternoon at some
terminals, particularly at MKG. However, whatever improvement
occurs should be short lived with solid LIFR expected after 00Z
and lasting well past 12Z Saturday.

&&

.MARINE...
Issued at 320 AM EST Fri Jan 20 2017

No major issues as the winds should stay below Small Craft
Criteria.


&&

.HYDROLOGY...
Issued at 330 PM EST Thu Jan 19 2017

The Grand River at Robinson Twp has risen several inches in the past
couple days as runoff from rain earlier this week is being routed
downriver and ice continues to restrict the flow. Most other rivers
are rising due to the rain but seem to have less notable ice impacts
now. Temperatures (and dew points) will be above 32 degrees through
about the middle of next week, with highs at or above 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 help either. Runoff efficiency is high due to saturated ground
and a lingering frozen soil layer. 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
has some risk of reaching Minor Flood Stage this weekend.

&&

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

$$

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



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