Area Forecast Discussion
Issued by NWS Marquette, MI

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FXUS63 KMQT 270533

Area Forecast Discussion
National Weather Service Marquette MI
133 AM EDT FRI MAY 27 2016

.SHORT TERM...(This evening through Friday)
Issued at 347 PM EDT THU MAY 26 2016

Complicated convective forecast as coverage and intensity depends on
smaller scale shortwaves within broad sw flow aloft. Those type of
features are tough to pin down even 12 hours out.

Currently, shortwave moving across became enhanced by convection
late last night and that shortwave with sharp drying has forced the
showers and thunderstorms this aftn. Wave will continue to north of
Upr Michigan this evening so overall should see downward trend to
shra/tsra over the area currently. Thus far the main hazards from
these storms have been lightning and heavy rain. Have had multiple
reports of heavy rain especially over western Upr Michigan. Since
heating has not been as much as expected, instability has been
meager with sfc/ML/MU CAPES staying blo 500j/kg. Effective shear
also around 30 kts which is on the low-end with the weak
instability. LCLs are low enough around 1000m for brief spin up
tornado due to the higher dwpnts around, but this is being offset by
limited low-level shear which is well under 20 kts. Away from these
initial showers/storms could see isold shra/tsra try to reform over
northwest WI where sfc based CAPES this aftn are rising back up to
1000j/kg in wake of the shra/tsra that moved through earlier. A lot
of subsidence behind this initial shortwave per WV loop, so not sure
on the coverage in this redevelopment area. A bit of an enhanced cu
field trying to form currently. Supercell composite (looks at
effective shear and instability) does indicate there could be
supercells, but mean storm motion and right moving motion point to
majority of this activity staying along WI border or farther into WI,
if it occurs at all.

By late evening overall setup should be more quiet. Lots of low-
level moisture with generally lack of cloud cover and light winds
points to widespread fog which may be dense. Any fog will linger
into Fri morning, especially where light winds are onshore off the
Great Lakes.

Looking upstream there is a minimum in convective activity until
southern Neb and northwest MO where more concentrated shortwaves are
along with upper level jet and stronger sfc low. Some remnants of
this with possible additonal waves due to showers and storms forming
farther north across Neb/IA/Ill should will allow chances for
showers and storms to increase by Fri aftn. We`ll see if clearing
is more widespread than today. If so, readings will be able to reach
mid-upr 70s while dwpnts are around 60 degrees. Result will be sfc
based CAPES more in the 1000-1500j/kg range which will be plenty
high enough for organized severe storms since deep layer shear is
forecast to be 35-45 kts. As was case today, everything will depend
on how much insolation we receive before the shortwave(s) arrive by

.LONG TERM...(Friday night through Thursday)
Issued at 314 PM EDT THU MAY 26 2016

Upper air pattern forecasted to be a trough in the Pacific NW and
another trough in the central plains 00z Sat. There is also a broad
500 mb ridge over the ern U.S. 00z Sat that builds into the upper
Great Lakes region Fri night. This trough moves east into the Upper
Great Lakes Sat night into Sun.

Continues to look unsettled this forecast period through Sun and
hard to pin down any details with the numerous shortwaves moving
through. Will not be a total washout as there could be some brief
dry periods mixed in there from Fri night into Sun, but timing these
is next to impossible with convection that has not even developed
yet. Easiest course is to go with persistence and broadbrush this
forecast. Overall, did not make too many changes to the going
forecast for temperatures or weather.

In the extended, GFS and ECMWF show two broad 500 MB troughs across
the western and eastern U.S. 12z Mon. The trough over the western
U.S. moves into the Rockies 12z Tue and into the northern plains 12z
Wed which remains into 12z Thu. Still looks unsettled and
temperatures look to be near normal to slightly above normal for
this forecast period.

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 132 AM EDT FRI MAY 27 2016

Expect low clouds and fog at all the TAF sites overnight into Friday
morning. Conditions will drop to LIFR/VLIFR, lowest at CMX where
light onshore winds are expected and widespread fog could advect in
fm Lk Superior. after improvement back to VFR late Friday
morning/afternoon expect another round of showers and thunderstorms
to move in late Friday afternoon/evening with deteriorating

.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 347 PM EDT THU MAY 26 2016

Expect winds at or below 20 knots through the forecast period. Fog
will continue to be a problem. Have dense fog advisory through Fri.

Upper Michigan...
Lake Superior...
  Dense Fog Advisory until 6 PM EDT /5 PM CDT/ this evening for

Lake Michigan...


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