Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 301049
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
649 AM EDT Sun Apr 30 2017

.NEAR TERM...(Today through Tonight)
Issued at 337 AM EDT Sun Apr 30 2017

...Increasingly soggy...

High impact weather potential...heavy rain at times.

Surface low is slowly deepening as it lifts NNE out of the far ne
corner of OK. A warm front extends ene-ward into the OH Valley. High
pressure is near James Bay, contributing to substantial f-gen in the
southern Great Lakes. Still, better precip rates will wait until
that high is displaced eastward, allowing a richer airmass to push
into the central lakes. Precip trends and amounts are the main
concerns this morning.

Today...occluding surface low will continue nne, with the original
center drawing back into nw KS, while a triple point pushes into w
central IL. Initial push of f-gen-related precip will impact locales
s of a Leland-Rogers line early this morning. A bit of a lull
follows that this morning, before the next surge of precip (now in
MO/southern IL) moves in for the rest of the day. This will also
expand precip across the vast majority of the forecast area, with
far nw Chippewa Co this one possible exception. However, this area
will still diminish somewhat as it moves in, as dry 1000-850mb
easterly flow will take a slight toll. QPF totals here, while
healthy, will be somewhat less than upstream. Expect daytime QPF
totals to be around 0.75 inches in much of northern lower, less
along the Lake MI coast and much less in eastern upper (away from se
Chip Co). Don`t anticipate a lot of thunder during the daylight
hours, but models prog a few hundred j/kg of muCape as far north as
Saginaw Bay and the Thumb. Will mention some thunder possible south
of an HTL-Harrisville line from midday thru the afternoon.

Max temps will of course be held back by precip, clouds, and that
easterly surface wind. Highs near 40 to the mid 40s.

Tonight...original low moves to eastern Iowa, original triple point
to central Lake MI, while another triple point takes shape over
southern Lake Huron very late. Another surge of theta-e advection
arrives on ssw 850mb winds that increase to near 50kt by 06z. This
initiates another (and final) period of heavier precip. By late in
the overnight, the dry slot will be pushing into nw lower MI, and
precip coverage will diminish there. Surge of warm/moist air at low
levels will also contribute to marginal instability returning, with
muCape pushing 500j/kg in far southern sections. Thus chance for
thunder and convectively-enhanced rainfall in the south half of the
forecast area. QPF for tonight will range from 1-1.5" across most of
northern MI, with western Chip/Mack seeing a little less. Runoff
from this event may result in some flooding, especially/mainly in
the far se (where our soils are less sandy). For now, no need for
a flood headline (other than the continuing ESF for the Rifle and
Manistee Rivers).

Occluded front will work into southern portions of the forecast
area overnight. Temps there will rise into the mid and perhaps
upper 40s very late. To the north, temps will remain steady.

&&

.SHORT TERM...(Monday through Tuesday)
Issued at 337 AM EDT Sun Apr 30 2017

...Heavy rains exit early Monday morning, then breezy with light
showers Monday afternoon through Tuesday...

High impact weather potential...Runoff from expected bout of heavy
rainfall ending Monday morning may lead to substantial rises
and possible minor flooding of some streams and rivers later Monday
into Tuesday.

Pattern Synopsis/Forecast...Monday morning the occluded low will be
located over Iowa with a secondary low along a triple point lifting
into the Upper Peninsula. The best forcing (and hence the last
round of heavy rain with possibly some lingering thunderstorms) will
be on its way out of northern Michigan as the LLJ and upper level
divergence are shunted farther east and the band of frontogenesis
along the occluded front pushes northward into Ontario. A pronounced
dry slot in the mid-levels will quickly nose into the area after
daybreak, allowing for a brief lull in rain for perhaps a few hours.
However, wrap-around low level moisture will start rotating in by
midday, with CAA steepening up the low level lapse rates. This will
lead to the development of additional light showers Monday
afternoon, with the shower activity expected to continue through
Monday night and even into Tuesday, though gradually decreasing in
coverage with time on Tuesday. These prolonged light showers could
yield another quarter to third of an inch of rainfall.

Breezy conditions can be expected Monday afternoon through Tuesday
with the steep low level lapse rates allowing for efficient mixing,
even Monday night to some extent. But Monday afternoon looks to be
the period of strongest winds with gusts of 25 to 35 mph expected to
be fairly widespread south of M-32. Isolated gusts approaching 40
mph may be possible along Lake Michigan from around Manistee to
Frankfort. As for temperatures, Monday will be substantially warmer
than Sunday with highs in the low 60s across northeast Lower (where
the dry slot may allow for a bit of sun) and 50s elsewhere. Tuesday
will bring a return to chilly 40s to low 50s for highs.

Primary Forecast Concerns...Runoff from this bout of heavy rainfall
shouldn`t be too much of an issue across most of northern Michigan,
as it`s been more than a week since we`ve had any substantial
rainfall and the soils should happily absorb much of it. That being
said (as previous shift mentioned), if the expected 2 to perhaps 3"
rainfall amounts are realized, there will likely be substantial
rises and possible minor flooding of smaller streams and susceptible
rivers (particularly the Rifle and Manistee) heading into Monday and
Tuesday.

.LONG TERM...(Tuesday night through Saturday)
Issued at 337 AM EDT Sun Apr 30 2017

High impact weather potential...None.

Much drier air will filter into the region Tuesday night as the low
departs and high pressure builds into the Upper Great Lakes. This
will bring an end to the showers by around midnight. While the
mid/upper levels over the region will remain active through the
second half of the week with a few passing shortwaves, the
atmosphere over northern Michigan will remain very dry with PWATs
hovering around a quarter inch. This should allow for a period of
dry weather through pretty much the remainder of the work week,
even a return to some sunshine. Models have come into better
agreement with keeping a potent system south and east of our area
for Thursday into Friday, so northern Michigan should remain largely
unaffected. Temperatures for the second half of the week look to be
near seasonal normals with highs warming into the 50s to low 60s.

&&

.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 648 AM EDT Sun Apr 30 2017

MVFR to IFR cigs slowly moving northward into northern MI, along
with a broad area of rain. Precip will see a slight lull over the
next few hours, before a slug of heavier rain (now advancing
across IL) arrives. Cig and occasional vsby restrictions will be
seen thru the rest of the forecast.

Easterly winds, gusty near Lake Huron today.

&&

.MARINE...
Issued at 337 AM EDT Sun Apr 30 2017

Easterly winds will increase a bit further today, ahead of low
pressure moving nne from the southern plains. Winds will diminish
tonight, especially late, while veering southerly as the system
crosses the region. S to sw winds will be in place Monday and
Monday night.


&&

.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...SMALL CRAFT ADVISORY until 8 PM EDT this evening for LHZ345>349.
LM...SMALL CRAFT ADVISORY until 8 PM EDT this evening for LMZ323-341-
     342-344>346.
LS...SMALL CRAFT ADVISORY until 8 PM EDT this evening for LSZ321-322.
&&

$$

NEAR TERM...JZ
SHORT TERM...MEK
LONG TERM...MEK
AVIATION...JZ
MARINE...JZ



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