Area Forecast Discussion
Issued by NWS Gaylord, MI

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260
FXUS63 KAPX 251743
AFDAPX

Area Forecast Discussion
National Weather Service Gaylord MI
143 PM EDT Tue Apr 25 2017

.UPDATE...
Issued at 1018 AM EDT Tue Apr 25 2017

A shallow shortwave and associated area of weak low pressure was
at the MN/WI border this morning, with a warm front extending down
across srn lower Michigan. Inverted sfc troughing extended from
the low pressure into Ontario. There was also an even weaker
shortwave and narrow axis of somewhat deeper moisture and some
possible sprinkles seen on satellite and radar, moving into Lake
Michigan. This is thinning out with time as it is moving into our
still very dry air mass. Maybe a few sprinkles could scrape
coastal NW lower and into a few sections of eastern upper, but
this will likely dissipate in a couple hours. We are actually
trying to moisten up though. The east to southeast wind has
gradually been drawing in some lower level moisture from the
closed low over the Carolinas. This has resulted in lower level
clouds creeping across the SE CWA, with even some spotty light
rain and sprinkles across the thumb, which are more likely to just
miss the NE lower shoreline through the day, remaining over Lake
Huron.

Finally, there was another wave lifting into SW Iowa, with more
elevated higher based warm advection and forcing, resulting in
light rain and sprinkles. Deeper low level moisture was however
being taped from the Gulf, out ahead of the associated sfc low in
Kansas.

So, many features around the region, but nrn Michigan remains in
drier air and is far enough away from better forcing mechanisms
to produce any expected precipitation for today.

&&

.NEAR TERM...(Today through Tonight)
Issued at 305 AM EDT Tue Apr 25 2017

...Increasing chances of rain across our NW CWA tonight.

High Impact Weather Potential...None.

Pattern Synopsis/Forecast...SE low level flow continues across all
of Michigan early this morning between departing high pressure now
centered over Northern Quebec and developing low pressure over the
Central and Southern Plains. An inverted trough extends from the low
northeastward into the Upper Mississippi Valley. Increasing moisture
within this region combined with weak lift from the inverted trough
are producing an area of shower activity across Eastern Minnesota...
NW Wisconsin and Western Upper Michigan. Closer to home...high
clouds continue to increase from NW to SE across our CWA well in
advance of this system...with some mid cloud and thicker cirrus now
moving into our far NW CWA as inferred by mid level returns on the
latest KAPX base ref loop as well as colder cloud tops per latest IR
satellite images.

As we move into today...mid/high clouds will continue to increase/
thicken/lower throughout the day...with low clouds developing
tonight as moisture surges northward ahead of the surface low which
lifts into Eastern Iowa by 12Z Wednesday. Latest short term models
have backed off on the timing of increasing precip chances from NW
to SE across our CWA tonight. This appears to be reasonable given
the rather dry low level air in place across our area. Expect it may
take awhile for this dry air to erode with increasing low level
moisture tonight. Thus...chances of precip will be confined to areas
along and NW of a line from PZQ to TVC and MBL tonight...with all
locations SE of this line remaining dry thru 12Z Wednesday. Expect
Northern Michigan will see another relatively mild day today...with
afternoon highs ranging from the upper 50s in Eastern Upper Michigan
to the lower 70s in our far SW CWA. Low temps tonight will range
from the lower 40s in Eastern Upper Michigan to the mid 50s in our
far SW CWA.

&&

.SHORT TERM...(Wednesday through Thursday)
Issued at 305 AM EDT Tue Apr 25 2017

...April showers...

Low pressure finally emerges out of the eastern Plains and heads
northward into the western Great Lakes while deepening. Models are
struggling with the details but most agree that it takes on a
negative tilt. Moisture initially looks like it affects
west/northwestern portions of the forecast area Wednesday morning
with a slow eastward progression through the day. Will likely see
the development of daytime instability as well. Just how much and
how far north is a tough call but thunderstorms are possible. Lots
of wind aloft as well with 0-6km bulk shear values of 40 to 50 knots
and mixed layer capes in the 800 to 1200 J/Kg range. The Storm
Prediction Center has the forecast area in general thunder but with
a marginal risk lurking just off to our southwest. It does look like
a close call with the amount of solar insolation likely determining
strength of any storms that do manage to form. Moisture continues to
head eastward across the forecast area Wednesday night increasing
shower chances with continued chances for thunderstorms. A surface
cold front then moves through the forecast area Thursday afternoon
drying the area out Thursday night. It will remain warm through
Thursday morning with cooler temperatures advecting in for Thursday
afternoon into Thursday night.

.LONG TERM...(Thursday night through Monday)
Issued at 305 AM EDT Tue Apr 25 2017

...Continued unsettled...

Extended models are all over the map during this time period,
especially early on. Some guidance brings another area of low
pressure across the region late Friday into early Saturday while
other guidance doesn`t even have a system at all. Extended guidance
then converges on another potent area of low pressure moving into
the Great Lakes by Sunday which lingers into Monday. This scenario
will result in more shower chances as well as cool temperatures.
Although am not buying it at this time, there are hints that it
could turn cold enough for some wet snow (mainly Monday). Overall
confidence is fairly low through Saturday with increasing confidence
in a rainy second half of the weekend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 131 PM EDT Tue Apr 25 2017

One area of low pressure was in far nrn Wisconsin, while another
was in Oklahoma, and a cold front connecting the two. An ill-
defined warm front was off to the SW, with higher level clouds
occasional passing by with sct-bkn cumulus developing this
afternoon. Sfc dew points were slowly on the rise, being fed in
via southeast dragging this moisture from a strong system across
the SE states. Not really expecting anything too exciting in the
through afternoon, but there are fairly agreed upon signals by
several data sets that the increased low level moisture continues
to feed in through Lake Huron, possibly impacting APN with stratus
and potentially fog. Am a little skeptical at this point, but it
is possible. Several waves of upper level disturbances will cross
nrn Michigan tonight through Wednesday that will keep skies more
cloudy than not. They will also bring some possible sprinkles
tonight with better rain possibilities Wednesday, mainly in the
afternoon. Thunder is not out of the question Wednesday afternoon.

&&

.MARINE...
Issued at 305 AM EDT Tue Apr 25 2017

SCA conditions are expected for all of our nearshore areas thru
today as S/SE winds continue to gust to 15 to 25 kts. Winds will
diminish tonight...but will likely strengthen again to SCA criteria
on Wednesday. Chances of rain will increase for NW portions of our
nearshore areas tonight...with rain chances gradually spreading
southeastward Wednesday night into Thursday ahead of low pressure
lifting into Southern Wisconsin.


&&

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

$$

UPDATE...SMD
NEAR TERM...MLR
SHORT TERM...AJS
LONG TERM...AJS
AVIATION...SMD
MARINE...MLR



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