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Area forecast discussion 
National Weather Service Marquette Michigan
148 am EDT Tuesday Jul 22 2014

Short term...(this evening through tuesday)
issued at 827 PM EDT Monday Jul 21 2014

Upper air pattern consists of a 500 mb rodge across the Southern
Plains with a closed 500 mb low across northern Manitoba. The
westerlies are between these two systems across the north central
U.S. With the upper Great Lakes on the periphery of the ridge and in
the ring of fire convection zone. Any little shortwave moving
through the westerlies could spark convection which makes this
forecast more difficult and confidence is lower than it normally
would be. The one shortwave of interest is in southern Montana and
northern Wyoming this morning and this heads east into northern Minnesota late
tonight and across the area on Tuesday. NAM...GFS and 12z Canadian
appear to be suffering from convective feedback issues and their
solution are suspect.

Used the 00z European model (ecmwf) and 00z Canadian models for this forecast which
was fairly similar to the going forecast. 12z GFS does have a hint
of the heaviest quantitative precipitation forecast and convection staying off to the north of the
area which there could be something to this. Further south could be
capped. Will go more with this scenario and have a line of
convection move through the area starting late tonight and go with
high probability of precipitation as this moves through late tonight through Tuesday. Quantitative precipitation forecast
amounts look to be 0.25 inch to 1.4 inches with the lightest amounts
in the south and east and the heaviest over the west and north.
Agree with Storm Prediction Center thinking with slight risk over the western County Warning Area for
late tonight with possibility of some forward propagating mesoscale convective system moving
through or nearby. Overall...did not make too many changes to the
going forecast as most of the models were contaminated with
convection which would also mess up the surface winds on Tuesday. Used the
Canadian and European model (ecmwf) winds for the afternoon as the contaminated
models were all going gales which seemed way cold
marine layer will be there to cut the winds off before they hit the
water surface.

Long term...(tuesday night through monday)
issued at 302 PM EDT Monday Jul 21 2014

The long term forecast begins with an evening of busy weather...then
enters into a more quiescent period before the next system graces
Upper Michigan with its presence.

Tuesday evening will be largely dependent on the progression of
the frontal boundary and remnants of the mesoscale convective system that may bring severe
weather to the area Tuesday. By Tuesday instability
will be sinking southeastward ahead of the cold front...with
generally only around 500 j/kg of MUCAPE in the far east and along
the WI border in the early evening. This will keep chances for
precipitation in the forecast for the far east...and even some
rumbles of thunder through the first part of the night. Some of the
models keep bumping up the winds on Eastern Lake Superior to
gale-force in the evening...which may just be convective feedback
from the mesoscale convective system. Went middle of the Road for now...with north-northwest winds at
15 to 25 knots. Otherwise...dry air and subsidence begin to work
their way into the region.

High pressure will dive down from the Canadian prairies into the
Great Lakes for Wednesday and Thursday...bringing a brief break from
the stifling heat...humidity...and precipitation. With 850mb temperatures
ranging from around 6-8c and diminishing cloud cover...expect high
temperatures to range from the upper 60s to the 70s. Temperatures
will be coolest near the Lake Superior shoreline with cool
north-northwesterly flow on Wednesday...then near both Lake
Michigan/Superior Thursday with lake breeze development. Depending on how
strong north-northwest winds will be Wednesday...waves on Lake
Superior along Marquette and Alger counties could reach 3 to 5
feet...warranting a moderate to high swim risk at local beaches and
possibly a beach hazards statement. This is especially true given
the potential for seiche-induced rip current activity on Lake
Superior through Wednesday afternoon...which depends on the track
and strength of the mesoscale convective system.

Active weather will return to Upper Michigan for the weekend. The 500mb
high pressure center that has been firmly anchored over New Mexico
this week will remain in place...expanding a highly amplified ridge
over the northern plains and Manitoba Thursday night.
Meanwhile...low pressure over the Gulf of Alaska drops into the far
northwestern United States by Thursday morning. Models are
consistent in bringing the low into Alberta by Friday
afternoon...flattening the ridge across the northern plains. They
are also consistent in keeping the low pressure system that brought
active weather to Upper Michigan in the beginning of the week over Quebec
through this time.

Differences between models show up with respect to the location of
the associated longwave trough. The European model (ecmwf)/Gem have the trough
sinking southward over the East Coast. They also build the ridge
over the west and force the low northward...resulting in a large
ridge over the southwestern United States. This pattern would put
Upper Michigan in fairly zonal flow/a slight trough through the
weekend...with several shortwaves swinging through the Great Lakes
through Sunday.

Conversely...the past few runs of the GFS have consistently plowed
the low crossing Alberta Friday afternoon southward into the Great
Lakes by Sunday afternoon...merging it with the low over Quebec.
This would put the eastern United States in a deep longwave trough
/with the low centered over Quebec/the Great Lakes/ and a strong
ridge firmly anchored over the west. Previous runs of the European model (ecmwf) were
similar to the I am inclined to lean towards the GFS
solution. Kept chance/slight chance probability of precipitation in starting Friday evening
and continuing to expand across Upper Michigan through the weekend and
Monday. The forecast troughing pattern will keep temperatures in the
Great Lakes region below normal for this time of year.

Aviation...(for the 06z tafs through 06z Tuesday night)
issued at 138 am EDT Tuesday Jul 22 2014

VFR conditions will prevail at kiwd/kcmx/ksaw into the overnight
hours. Rain showers/thunderstorms over the northern plains this evening will
move...likely reaching western upper including kiwd/kcmx toward
daybreak...around 08z or later. MVFR conditions should accompany the
precipitation with potential for IFR. Confidence with storms and wind
directions is low after 09z at all sites as the storms due to the
uncertain influence of a large complex of thunderstorms. Winds
however should veer to the west by afternoon and become gusty. MVFR
are most likely at cmx into the afternoon with lingering low level
moisture and upslope flow.

Marine...(for the 4 PM Lake Superior forecast issuance)
issued at 302 PM EDT Monday Jul 21 2014

Southerly winds will continue over most of Lake Superior tonight.
On Tuesday...a low pressure system will pass across the upper
lakes...bringing a wind shift to the north. Again...the stronger winds
of 15-25kt will likely occur over Eastern Lake Superior. In addition...
depending on strength/coverage and evolution of thunderstorms moving across
Lake Superior tonight/Tuesday ahead of low...there may be a period of
strong winds across much of the lake for a time late tonight and
Tuesday. High pressure will settle into the Great Lakes late Wednesday through
Sat...providing a period of light winds.

On a final note...fog may expand across Lake Superior through
Tuesday...especially once precipitation occurs.

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


Short term...
long term...mesoscale discussion

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