National Weather Service - Area Forecast Discussion

FXUS63 KAPX 191442

Area Forecast Discussion
National Weather Service Gaylord MI
1042 AM EDT Fri Oct 19 2018

Issued at 1042 AM EDT Fri Oct 19 2018

...Showers Spreading Into The Region...

Morning composite analysis reveals a lead low amplitude short-
wave advancing through the Upper Midwest this morning with a
stronger wave dipping down through Manitoba into the Dakotas.
Surface low pressure is over Ontario with a warm front arcing into
Quebec and cold front down through Minnesota into the central
Plains. Narrow theta-e axis stretches ahead of the front through
the Midwest into northern Michigan. Short wave and warm advection
forced rain showers along that axis are currently in the process
of advancing into the region.

Rest of today: Short-wave, narrow theta-e axis and attending
showers will swing across the region through the course of the
afternoon into the evening, giving most locations some light rain.
No big changes planned to the going forecast other than minor
timing/coverage tweaks. Secondary stronger short-wave and colder
air once swings through the region tonight with a transition back
to lake effect heading into Saturday. Largely rain showers
anticipated through tonight, although temp profiles do cool
enough for a mix or even a complete changeover to snow in the U.P.

Meanwhile, bigger issue through the afternoon will once again be
gusty winds. Core of 45 to 55 knot low level winds is expected to
slide through northern Michigan this afternoon. With rain moving
through and a trend to saturated lower layers, low level mixing
and resulting gust potential will not be especially great. But
gusts of 30 to 40 mph are a good bet particularly over the lakes
and along the windward facing shoreline areas.


.NEAR TERM...(Today through Tonight)
Issued at 304 AM EDT Fri Oct 19 2018

High impact weather potential: Maybe a rumble of thunder this

Pattern synopsis and forecast:

Minor shortwave ridging was over the Great Lakes early this morning,
with a positively tilted shortwave trough and associated sfc low
pressure and cold front pressing through south central Canada and
the Plains. There were some areas of showers and even a few rumbles
of thunder out ahead of these features, within increasing theta-e
advection, DPVA and potential upper divergence from a 90kt jet. The
thunder was only in MN, just north of Minneapolis, aligned along a
mid level instability gradient.

The mid level trough and cold front will quickly race into/through
nrn Michigan today and this evening, bringing an expanding area of
showers due to strengthening forcing and theta-e advection ahead of
the cold front. The instability gradient also makes it`s way into
nrn Michigan and may provide a rumble of thunder or two. The
strengthening forcing is expected to be attributed to increasing
upper divergence with the upper jet, as well as stronger DPVA from
reinforcing shortwave activity dropping in from srn Canada.  There
may be a brief lull in the precipitation, before even stronger
shortwave energy dives into the western Great Lakes overnight. This
will bring in a secondary cold front, with H8 temperatures dropping
to -4c to -8c by daybreak for a more than sufficient delta t range
of 17C to 18C for the development of lake effect rain showers.
Freezing levels look to be 2kft or slightly higher, but the large
overlake instability and potential relatively drier air below that,
may be able to result in snow mixing in at times for inland areas.
This would not surprise me at all. Little to no accumulation through
tonight however.

High temperatures today will be in the middle 50s most areas, with
lows tonight falling back into the mid and upper 30s.


.SHORT TERM...(Saturday through Sunday)
Issued at 304 AM EDT Fri Oct 19 2018

...Colder; some snow showers Saturday...

High Impact Weather Potential...Accumulating snow possible
late Saturday and Saturday evening in some areas.

Strong cold air advection through the day Saturday as a trough digs
into the region leading to brisk winds. In addition, a decent short
wave dives into the developing trough. With the colder air, there
will be increasing over lake instability with the flow veering from
northwest in the morning to north northwest by evening. So expect
scattered to numerous rain showers to change over to snow showers
fairly quickly. Could see some accumulation on the order of around
an inch or perhaps two in north northwest flow favored areas in the
afternoon and evening. Roadways may become slick as a result. Drier
air (mean 700-850 mb 348.
     GALE WARNING until midnight EDT tonight for LHZ345-349.
LM...GALE WARNING until midnight EDT tonight for LMZ323-341-342-
LS...SMALL CRAFT ADVISORY until midnight EDT Saturday night for



NWS APX Office Area Forecast Discussion