Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 291428

Area Forecast Discussion
National Weather Service Gaylord MI
1028 AM EDT Mon May 29 2017

Issued at 1027 AM EDT Mon May 29 2017

Fog north of the Bridge has lifted into a low stratus deck that
should slowly erode late this morning. A cluster of showers that
developed over Lake Michigan is moving through northern Lower late
this morning as a lobe of 500mb vorticity and the left exit
region of an upper jet streak pivot through the area. Expect this
activity will gradually fill in some more over the next couple
hours as it interacts with increasing diurnal instability over
northern Michigan. 12Z APX sounding shows a convective temperature
of 70F (several locations over northern Lower already in the mid
60s) with decent low level lapse rates in place. However, mid
level lapse rates are weaker than yesterday due to a slight warm
bulge above 700mb. Factor in lower dewpoints/PWATs than yesterday
as well, and we`re looking at a smaller chance of showers and
thunderstorms with less areal coverage. A stronger cell could
produce some sub-severe gusty winds, but overall not expecting
intense storms this afternoon/evening. Also expecting breezy
synoptic-scale winds to develop midday with gusts up to 25 mph
fairly common...perhaps a few up to 30 mph south of M-72.


.NEAR TERM...(Today through Tonight)
Issued at 327 AM EDT Mon May 29 2017

High impact weather potential: Scattered thunderstorms. Severe
storms not expected, but gusty thunderstorm outflow certainly

Pattern synopsis and forecast:

A fairly stacked low pressure system was centered over western Lake
Superior early this morning, with several vorticity maxima rotating
through portions of central Canada, the upper Mississippi valley,
and the western Great Lakes. Scattered showers continue underneath
and around the low and it`s cold core, helped along through the
night by the individual vorticity centers. Most of the convection
was largely diurnal in nature however, as much of the activity has
waned into the night. A similar scenario in nrn Michigan, with the
last of the showers dying off a couple of hours ago. Skies have
cleared out, and radiational cooling has helped along the
development of pockets of fog and stratus, the fog dense in spots.

Things are expected to be rather quiet this morning, with good
morning sunshine eating away at the stratus amd fog, improving those
pockets of greatly lowered visibility. Clouds should start to
develop through the latter portion of the morning, with the arrival
of the next shortwave/vorticity center. Plus, diurnal cumulus will
quickly develop as -21C air at H5 settles in over the area. Lapse
rates aloft will be decent at 6.5c/km. Timing of any other
individual shortwaves/vorticity maxima is always challenging, but
pure diurnal instability showers and scattered thunderstorms are
expected, primarily in the afternoon, and maybe some decent coverage
into the evening (projected arrival of one of those vort centers).
No severe weather is expected with SFC-6km shear less than 25kts.
However, several hundred j/kg MLCAPE found off modified soundings,
with interestingly, up to 500j/kg of DCAPE as well. Any decent storm
will be able to bring about some very gusty downdrafts, as was seen
across SD/MN yesterday afternoon. Maybe gusts up to 50mph or so, and
will highlight that in the HWOAPX. While activity wanes through the
night to more isolated showers, there will likely be more
cloudiness, as the southern flank of the upper low is associated
with deeper moisture.

Fairly gusty gradient winds as well, with 25 mph being fairly common
across the region. Highs in the low to mid 50s eastern upper to the
lower 70s in downsloping areas of NE lower.


.SHORT TERM...(Tuesday through Wednesday)
Issued at 327 AM EDT Mon May 29 2017

...Cooler and Unsettled...

High Impact Weather Potential...None

Pattern Synopsis/Forecast...Tuesday starts out with little
precipitation, until the 500 mb low rotates another spoke of energy
and moisture over the Upper Great Lakes. Coupled with the diurnal
heating, showers result. CAPE is less than 200 J/kg, so will leave
out the thunder as it is unlikely. Rain showers diminish as we lose
the heat of the day during Tuesday evening. Showers make a come back
on Wednesday, but the main 500 mb trough moves through the forecast
area, and heights begin to build, so things dry out for a time.
There is a shortwave trough that moves into E Upper late/overnight
on Wednesday night. It arrives late, and it`s still over Lake
Superior on the GFS. So will go with the slight chance that the
blends give.

Primary Forecast Concerns...Not a lot to be concerned with at this
point. Wednesday may turn out drier as the dewpoints could be lower
than progged. Models are beginning to catch onto lower dewpoints,
and thus lower Min RH on Wednesday.  SREF plumes give a low chance
for thunder with a few members producing MUCAPE of over 500 J/kg,
but nothing severe.

.LONG TERM...(Wednesday night through Sunday)
Issued at 327 AM EDT Mon May 29 2017

...Below Normal Temperature Trend...

High Impact Weather Potential...thunder chances Friday, Saturday,
Sunday afternoon, otherwise none.

Extended (Thursday through Sunday)...Thursday, a shortwave moves
through E Upper briefly, but it look rather weak, so not expecting
much in the way of rain with it. Friday, Saturday and Sunday are the
most unsettled portion of the forecast period. A stronger shortwave
at 500 mb rotates into the low causing another cutoff which moves
east to the near New England by Sunday morning. The deterministic
models show dry for the day on Saturday, but the 00z/GEFS shows mean
QPF everyday with some groupings of members to around a couple of
tenths. So will have chances of rain showers through the end of the
weekend. Think that there could be a drier period and that the
models are a little too wet, but with this being days 5-7, will
leave the chance rain showers. It is interesting to note that Sunday
on the GEFS has the highest potential for Thunder, but the ECMWF
deterministic model is drier than dry so will let the chance pops
ride for now.


.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 620 AM EDT Mon May 29 2017

A clear start to the day for all but PLN, when dense shallow fog
continues to bring poor visibility. This fog ought to wear off
pretty quickly however. Cold air aloft and additional shortwave
energy will rotate into northern Michigan today and this evening.
This will re-develop a sct-bkn cumulus deck at 5-6k and result in
scattered showers/tstms. Conditions will generally be VFR, with
MVFR around showers/storms.

Winds will become gusty from the southwest, with gusts of 20kt to
25kt during the afternoon. Winds subside some this evening while
showery activity to become increasingly isolated.


Issued at 327 AM EDT Mon May 29 2017

Low pressure in Ontario will slowly drift into Hudson Bay through
Tuesday, with several disturbances passing through the western Great
Lakes bringing showery weather with scattered storms, mainly in the
afternoon and evenings. At the same time, a tighter pressure
gradient will slide in today and into Tuesday, bringing some low end
advisory level wind gusts to portions of Lake Michigan and Huron.
The storms themselves could produce stronger more erratic wind


LH...SMALL CRAFT ADVISORY until 5 AM EDT Tuesday for LHZ348-349.
LM...SMALL CRAFT ADVISORY until 5 AM EDT Tuesday for LMZ323-342-


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