Area Forecast Discussion
Issued by NWS Grand Rapids, MI

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FXUS63 KGRR 200501
AFDGRR

Area Forecast Discussion
National Weather Service Grand Rapids MI
1201 AM EST Mon Feb 20 2017

LATEST UPDATE...
Aviation

.SYNOPSIS...
Issued at 313 PM EST Sun Feb 19 2017

Spring like weather to continue through much of this week. A little
light rain is expected Monday night through midday Tuesday.
Otherwise...a pleasant week with more unsettled weather returning
Friday into the weekend along with more winter like temperatures.

&&

.SHORT TERM...(This evening through Tuesday night)
Issued at 313 PM EST Sun Feb 19 2017

Another nice night tonight and another beautiful day tomorrow
before a little rain moves in Monday night into early Tuesday. The
bulk of the rainfall still on track to be mostly between midnight
Monday evening and noon on Tuesday with around one quarter of an
inch totals looking like the most likely outcome. Instability
remains really weak so continue to keep thunder mention out for
this brief event.

Tuesday afternoon/evening should be a return to pleasant and spring
like conditions...though lingering clouds could limit sunshine and
hold back temperatures just a bit.

Otherwise..some patchy light fog possible again tonight
but hazardous conditions as a result of this fog are not expected.

.LONG TERM...(Wednesday through Sunday)
Issued at 313 PM EST Sun Feb 19 2017

Extended period begins with northern stream sfc low tracking across
northern Lower Michigan Wednesday into Wednesday night. Model
soundings show dry air persisting through mid levels across the
forecast area and omega fields are weak, suggesting a dry forecast.
Dropped slight chance POPs for Wednesday night. A trailing front
from this low lays out just south of Lower Michigan on Thursday as
Plains cyclogensis is underway. Overrunning precip breaks out along
and north of the front Thursday night with the main low arriving
Friday into Saturday. There is elevated instability and strong
isentropic ascent so thunder is possible Thursday night, but is left
out of the forecast for now given low confidence. Worst case
scenario is convection occurring well north of the sfc front where
easterly flow holds in cold air as suggested by the 12Z GFS.

There still remains a lot of ensemble spread with the track and
intensity of the low, and run to run consistency of the operational
runs of the ECMWF and GFS have shown some variations as can be
expected that far out in time. The general idea is that the sfc low
will track close to or north of the forecast area with rain on
Friday,  changing to snow at some point Friday night into Saturday,
followed by a few lake effect snow showers later Saturday into early
Sunday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1200 AM EST Mon Feb 20 2017

The main issue overnight may be some fog that develops around 10z.
Thinking 4-5sm br and may be patchy. Otherwise, vfr expected.

&&

.MARINE...
Issued at 313 PM EST Sun Feb 19 2017

Winds and waves will gradually increase during the afternoon and
evening hours Monday. These may pose hazards to small craft.  Winds
and waves should diminish early Tuesday with little hazard to small
craft from winds and waves expected through at least early Friday.


&&

.HYDROLOGY...
Issued at 313 PM EST Sun Feb 19 2017

Light rain late Monday night into early Tuesday will occur in
lower Michigan but will not result in any hazardous hydrologic
conditions. A stronger weather system might impact lower Michigan
on Friday...but it is too early to tell for sure if it will for
sure impact the region and whether it would result in any
hazardous hydrologic conditions.

&&

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

$$

SYNOPSIS...Maczko
SHORT TERM...Maczko
LONG TERM...Ostuno
AVIATION...04
HYDROLOGY...Maczko
MARINE...Maczko



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