Area forecast discussion
National Weather Service Marquette Michigan
514 am EDT Wednesday Jun 19 2013
Short term...(today and tonight)
issued at 513 am EDT Wednesday Jun 19 2013
The surface high that was directly overhead on Tuesday...will push from
the eastern County Warning Area and north lower Michigan this morning to Central Lake Huron
and far S Ontario by 00z. Expect good mixing today...to around 800mb
will help dew points fall into the middle to upper 30s over the eastern
fire zones. On a positive note...winds should not be quite as strong
as was expected just 24 hours ago...with gusts staying around 18kts or
less. The strongest winds will likely be over the east /with a
slightly tighter pressure gradient/ and over the favored downslope
areas. Temperatures should be able to climb into the 70s today. With
the lack of a Lake Superior lake breeze today...middle and even upper
70s look reasonable near much of Lake Superior. Isq will be the cool
spot...topping out in the middle 60s /after the cool morning in the 30s
under a clear sky with light winds/.
Look for increased moisture over the far west...with dew points rising
into the upper 40s and 50s by middle/late afternoon. Afternoon heating
and a nearing surface trough stretching from NE Ontario should help pop
a few showers and thunderstorms across north Minnesota by late afternoon.
Assisted by a series of disturbances in the northwest flow aloft...expect
storm motion to push them across Lake Superior and to western Upper
Michigan mainly after midnight. With the loss of daytime heating only
scattered showers and isolated ts are anticipated. Fog should
quickly develop over far West Lake Superior through after midnight.
With the warm humid air moving in...lows in the 50s should be
common...with a few middle to upper 40s far east.
Long term...(wednesday night through tuesday)
issued at 409 PM EDT Tuesday Jun 18 2013
Area will be under northwest flow aloft to start the period as the
upper Great Lakes is on the eastern side of the ridge over the
northern plains and upper Mississippi Valley. A weak shortwave will
be sliding across Northeast Lake Superior on Wednesday night...while
a surface trough drops southeast across the County Warning Area during the overnight
period. There will likely be some showers and a few thunderstorms
with this trough on Wednesday night and will follow a general
consensus for the timing of the probability of precipitation as it moves in.
This front looks to stall across Upper Michigan on Thursday and
will combine with developing lake breezes to produce afternoon
showers and thunderstorms. The strength of these thunderstorms will
depend on the amount of diurnal heating...increasing southerly
flow with a developing warm front on the boundary...and the arrival
of the another weak shortwave during the late afternoon and
evening. Ml cape values of 500-1000 j/kg over the western 2/3rds
of the County Warning Area and 0-6km bulk shear values around 30kts supports
thunderstorms and some tilting of the updrafts. Heavy rain and
small hail will be the primary threats...as ncape values around .1
should keep any hail from growing too large. Will continue to
highlight the highest probability of precipitation over the interior west/central...closest
to Lake Superior lake breeze and then follow the storm motion to the
southeast.
Thursday night through the weekend is shaping up to be a fairly
active pattern for thunderstorms in the upper Mississippi Valley
and upper Great Lakes region. This is due to the upper ridge
gradually shifting east into the upper Great Lakes.
Meanwhile...weak surface low will remain fairly stationary over the
central/northern plains. From this low...a warm front will looks to
setup from the stalled trough on Thursday and remain located around
the upper Great Lakes region through the weekend. Looking at this
large scale pattern...it is very conducive periods of showers and
potentially strong thunderstorms. But trying to pin down the
exact location and timing is difficult due to the variability of the
shortwaves and position of the warm front. Instability will
gradually grow from Friday into the weekend...as persistent
southwesterly flow ahead of the low pulls plenty of Gulf moisture
into the area. Using ml cape values to remove some of the low
level moist biases in the models for Friday into the weekend...there
are still some decent values for u.P. Standards. Friday they look to
peak in the 750-1500 j/kg range over the west and then grow to
1500-2500 j/kg for Sat/sun depending on the model. The GFS is the
most aggressive on the northward extent of the warm front...while
the Gem/European model (ecmwf) try to keep the front a touch south of the area. It
will probably be a variety of thunderstorm types during that period.
Convective complexes moving east /via forward prop corfidi vectors/
around the ridge will likely be the main threat...but with the
instability present and limited inhibition...diurnal thunderstorms
will also be possible. The only concerns would be if the ridge and
warm front build far enough north to slide most of the thunderstorm
complexes north of Upper Michigan or the more likely scenario of it
becoming hung up south of the area /especially as convection holds
them south/. With the growing confidence...will add a mention of
strong thunderstorms for the weekend in both the severe weather potential statement and ehwo. Heavy
rain is also possible during this period with the thunderstorms...as
precipitable water values rise above 1.5 inches which is well above the 75th
percentile for climatology for this area.
It will be pretty humid for Friday into the weekend /dewpoints in
the upper 50s and 60s/ and the temperatures will depend on the
positioning of the warm front. Will continue to show temperatures in the
middle 70s to lower 80s for most locations...with the warmest values
near the Wisconsin border. If the GFS ends up being correct...would
have to bump temperatures up well into the 80s for the end of the weekend.
Uncertainty really grows heading into Monday/Tuesday...as a lot
depends on the weekend weather. The general idea from the models is
that the ridge breaks down and the area will be under zonal flow
aloft. This will continue to bring waves across the area and keep
the thunderstorm potential in place for that period. At this
time...models are indicating a cold front dropping south out of
Canada on Wednesday...which may bring an end to the warm/humid
weather.
Finally...will continue to mention patchy fog developing on Lake
Superior on Wednesday night and then continuing into early next
week. Will likely need to expand it to areas or even dense fog as it
nears. Also...added a mention of fog over Lake Michigan nearshore
areas starting late Thursday night as the precipitation and higher
dewpoints start to affect that area.
&&
Aviation...(for the 06z tafs through 06z Wednesday night)
issued at 1203 am EDT Wednesday Jun 19 2013
With high pressure in control...VFR conditions expected to continue
through the period.
&&
Marine...(for the 4 am Lake Superior forecast issuance)
issued at 455 am EDT Wednesday Jun 19 2013
Winds should remain below 25kts through the period...with relatively
low waves. The main threat will be strong winds/hail/lightning with
any thunderstorms moving across Lake Superior from late tonight
through the weekend and beyond...and patchy to areas of fog that
develop as a result of increased moisture and shower activity.
High pressure centered over Lake Huron will continue to sink
southeastward...as a low over northern Ontario swings into Quebec. A
trough extending from the Canadian low will drift across Lake
Superior late tonight into Thursday. The trough should strengthen
Thursday night through Saturday...as high pressure pushes across
Ontario...and an elongated area of low pressure organizes across the
northern and Central Plains. The trough will further deepen over
Lake Superior on Sunday as the main low pushes northward through the
Dakotas and into south central Canada.
&&
MQT watches/warnings/advisories...
Upper Michigan...
none.
Lake Superior...
none.
Lake Michigan...
none.
&&
$$
Short term...kf
long term...srf
aviation...07
marine...kf
