Area Forecast Discussion
Issued by NWS Gaylord, MI

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FXUS63 KAPX 210725

Area Forecast Discussion
National Weather Service Gaylord MI
325 AM EDT Wed Jun 21 2017

.NEAR TERM...(Today through Tonight)
Issued at 255 AM EDT Wed Jun 21 2017

...Dry (for a change) and milder today; Shower/storms return

High impact weather potential...Nothing too significant. May see
some late night thunderstorms, a few of which may push severe limits
across parts of our area.

Pattern synopsis/forecast...Changes occurring aloft, with yesterdays
shower producing shortwave now well to our east, allowing subtle but
steady height rises to begin across the northern Lakes. At the
surface, large area of high pressure has built right across the
heart of the area. Showers have long ended and skies have largely
cleared (don`t get used to it) as a result, although cool
temperatures (many areas in the 40s) and lingering low level
moisture from rather bountiful rains of recent days has resulted
in some patchy fog development and pockets of stratus.

Those changes mentioned above keep on a`going right through this
evening, with core of northern stream jet bowing north of the region
as mid level height rises continue. Northern stream takes on a much
more zonal appearance heading through tonight as strong shortwave
trough digs across the southern Canadian Prairies. Energy racing east
withing this more progressive environment will couple with that
northward displaced upper jet core, forcing rather robust low level
jet development across the southwest lakes tonight. This, coupled
with northeast pivoting deep moisture plume and axis of increasing
elevated instability will likely trigger development of an MCS
across central Wisconsin this evening, with this complex of showers
and thunderstorm expected to race east into at least parts of our
area later tonight. Told ya the break wouldn`t last long.

Primary forecast concerns/challenges...Temperature trends today.
Shower and thunderstorm evolution tonight.

Details...Mostly sunny start to the day will give way to diurnally-
driven cumulus development, especially across eastern areas and in
the favored wind convergence area across central upper Michigan.
However, unlike the past several days, these cu will remain much
shallower and unable to generate showers given warming aloft and
continued loss of boundary layer moisture. One possible exception
could be across that central upper corridor, with at least some
hints in hi-res guidance of enough forced low level convergence to
allow deeper cu development and perhaps a light shower. Will not go
this route just yet, with those warming mid levels looking to put a
decent cap in place. May see some increasing higher level clouds by
late in the day as initial stages of top-down saturation begin.
Combination of beginning stages of waa, and more importantly
sunshine, will give a rather significant boost to temperatures, with
afternoon readings pushing much closer to normal readings.

Dry weather continues into at least the start of the evening. Shower
and thunderstorm complex on nose of rapidly developing low level jet
to our west makes a run into our area overnight. Definitely not
overly confident on exact timing or placement of better rains,
although with regards to the latter do have to say expected
development area of MCS and typical morning veering of low level jet
would place best rains primarily south of M-72. Latest SPC
convective outlook continues to place a very small portion of our
area down near Manistee under a marginal risk for severe
thunderstorms later tonight. While surface based instability would
be lost, increasing elevated cape pushing 1k J/Kg and rapid spike in
deep layer shear (0-6km bulk shear in excess of 50 knots) does
support at least some wind concern. This would be especially true if
the MCS takes on bowing characteristics as it crosses Lake
Michigan...which we have seen a couple times already this year.


.SHORT TERM...(Thursday through Friday)
Issued at 255 AM EDT Wed Jun 21 2017

...Heavy rain possible...

High impact weather potential...Possible severe storms Thursday
afternoon and potential for heavy rainfall Thursday night.

Things may get very active around here. First off, instability
driven showers and thunderstorms expected to develop Thursday
afternoon (mixed layer capes of between 1500 and 2500 j/kg northeast
lower). This will be followed by a possible mcs Thursday night from
the combination of an approaching trough from the north and a
surface cold front. With 0-6 km bulk shear in the 40 to 50 knot
range damaging wind gusts are a possibility Thursday afternoon into
Thursday night, especially south of M-72 in northern lower. In
addition, precipitable water values spike to near 2 inches Thursday
night possibly leading to very heavy rainfall Thursday night on the
order of 2+ inches (especially across northern lower). Models are
now in general agreement that a swath of very heavy rain falls
across at least the southern half of the forecast area so will have
to monitor the latest trends in this regard. Another factor which
will have to be watched is moisture from Tropical Storm Cindy
(currently in the Gulf of Mexico). Models keep this moisture to our
south but the approaching cold front may try to draw it farther
north than currently progged. Things should tend to dry out Friday,
though can not rule out a few instability driven pop up showers.
Temperatures should be close to normal for both Thursday and Friday.


.LONG TERM...(Friday night through Tuesday)
Issued at 255 AM EDT Wed Jun 21 2017

Increasing chances for showers over the weekend as a long wave
trough digs down from the north. More of the same for Monday as the
trough lingers. Perhaps some relief Tuesday but still could be
afternoon shower development, especially across northeast lower.
Temperatures will be 5 to 10 degrees below average during the
daytime through the period with lows near average for late June.


.AVIATION...(For the 06Z TAFS through 06Z Wednesday night)
Issued at 1143 PM EDT Tue Jun 20 2017

Some early morning fog APN/PLN/MBL.

Low pressure in northern Quebec is losing influence, as high
pressure moves ese from MN/WI. Quieter wx is expected for the
upcoming day and evening. However, some ground fog will form
overnight, most likely impacting all sites but TVC.

Light winds.


Issued at 255 AM EDT Wed Jun 21 2017

Light winds expected to today, with lake breeze development
expected off all the big waters this afternoon. Winds become south
and increase in speed tonight, although gusts look to remain mostly
below small craft advisory criteria. Winds veer southwest on
Thursday ahead of an approaching cold front, slowly decreasing in
speed in the process. Will need to be on the lookout for a few
thunderstorms later tonight through Thursday night, any of which
could produce brief gusty winds and locally heavy rain.




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