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Area forecast discussion 
National Weather Service Marquette Michigan
744 am EDT Friday Jul 31 2015

Short term...(today and tonight)
issued at 452 am EDT Friday Jul 31 2015

Like yesterday...a couple shortwave dropping southeast across the
area will be the main features controlling the weather for the area
today. The first shortwave is currently dropping southeast across
Lake Superior and western Upper Michigan. At the surface...there is
a weak trough of 1009mb at over Central Lake Superior. There were
showers earlier in the night...but most have since diminished and
there are only a few showers northeast and southwest of the Keweenaw
at 430am. These weak showers should continue east with limited
precipitation potential. As the shortwave and trough continue east
this morning..could see some redevelopment over the far eastern County Warning Area
as diurnal heating develops. But latest trends in the models are
starting to back away from that idea...largely due to the faster
arrival of the shortwave and surface trough...which will likely push
it through too early for much of the eastern County Warning Area. Will continue to
monitor over the next couple of hours...but may need to trend down
the chance probability of precipitation in place in that area. Shifting the focus towards
the central County Warning think that isolated to maybe even scattered
showers and thunderstorms will develop in the north central u.P. And
largely with diurnal heating and along a weak convergence zone due
to veering winds from a subtle lake breeze (eastern Marquette into
western Alger and northern Delta counties). Best instability is to
the east of the area in Chippewa/Mackinac counties (ml cape of
nearing 1000 j/kg)...but still should see values around 500-750 over
the eastern County Warning Area. Like inverted-v look to the sounding
(dcapes ahead of model convection shows values approaching 800-1000
j/kg) will lead to the potential for brief gusty winds with any of
the stronger thunderstorms.

The second shortwave is currently near Lake Winnipeg and will follow
a similar and maybe slightly farther to the southwest track as the
one this morning. This wave will be reaching the western u.P. Around
middle-late afternoon and will take advantage of peak heating to lead
to the possibility of showers over the interior west late this
afternoon. Overall...think most of the showers will arrive from the
northwest...shifting southeast into the area from the tip of the Minnesota
arrowhead and and northwest Ontario. High resolutions models matched
that idea...along with ncar ensemble WRF neighborhood have spread slight/chance probability of precipitation southeast from
that area late in the afternoon and into the evening before slowly
diminishing overnight.

Outside of the shortwaves...will continue to see some gusty winds
out there today...but expect them to be a little lower than the last
2 days due to slightly lower with the mixed layer winds. That being
said...with mean momentum Transfer values indicating gusts in the
low 20kt range this afternoon...have followed suit with the gust
forecast. Have the highest gusts over the Keweenaw due to the more
exposed locations and being within a pocket of stronger 925mb winds.
Think there will be more widespread diurnal cumulus today and have pushed
some areas over the central into the mostly cloudy category.
This...combined with low level temperatures being a touch cooler than
yesterday...will produce highs a touch cooler than yesterday. Will
need to keep an eye on fire weather conditions again the
dry low level air should lead to relative humidity values mixing out into the 30s
for areas outside of the rain showers. With the continued windy and
dry conditions...wildfire potential will remain heightened.

Finally for tonight...there are hints at another shortwave dropping
southeast across the area overnight tonight. Models are varying on
the intensity and location of the wave and with little noticeable
feature upstream...won't go too high on probability of precipitation but will follow a
similar situation as this past night with slight chance probability of precipitation over
Northern Lake Superior and diminishing through the night as they
slide southeast.

Long term...(saturday through thursday)
issued at 345 am EDT Friday Jul 31 2015

NAM shows a strong 500 mb ridge over the western U.S. 12z Sat with a
trough over the lower Great Lakes. NAM continues to have northwest
upper flow over the upper Great Lakes this forecast period with
upper level troughing nearby. What this will mean is a cooling
trend. There will be some chance probability of precipitation in for Sun afternoon and
Sunday evening as a shortwave moves through the area. Did not make
too many changes to the going forecast overall.

In the extended...GFS and European model (ecmwf) show a 500 mb ridge over the western
U.S. 12z Monday with a deep trough over Ontario into the eastern U.S.
This deep trough remains stationary 12z Tuesday with little change into
Wednesday and Thursday. A cold front moves through on Monday and then slowly moves
south and stalls out well south of the area this forecast period.
Temperatures look to be below normal for this forecast period as

Aviation...(for the 12z tafs through 12z Saturday morning)
issued at 744 am EDT Friday Jul 31 2015

Another surface trough and upper level disturbance is moving across
the u.P. This morning...leading to scattered 8-10kft clouds. Behind
this trough...gusty west-northwest winds will occur again today
with the strongest winds at kcmx. Expect diurnal cloud development
and a few showers and rumbles of thunder near or just east of ksaw
around middle day before moving to the southeast. Then another
disturbance moving out of Manitoba will move southeast into the
western u.P. Late this afternoon and evening. This too could produce
some showers and an isolated thunderstorm. With the showers...there
could be a brief period of high end MVFR ceilings...otherwise VFR
conditions are expected.

Marine...(for the 4 am Lake Superior forecast issuance)
issued at 452 am EDT Friday Jul 31 2015

A low spinning over southern Hudson Bay will sweep a series of
trough across Lake Superior through this weekend. A trough
moving across Eastern Lake Superior this morning will reinforce
westerly winds of 10-20kts with a few gusts up to 25kts. Winds will
remain in the 10-20kt range through the start of the weekend. A
broad surface trough will move across the upper Great Lakes region
on Sunday before high pressure from the Canadian prairies gradually
moves into the region for the start of next week.

MQT watches/warnings/advisories...
Upper Michigan...
Lake Superior...
Lake Michigan...


Short term...srf
long term...07

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