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fxus63 kdlh 232358 aaa 

Area forecast discussion...updated
National Weather Service Duluth Minnesota
658 PM CDT Tue Jul 23 2019

issued at 658 PM CDT Tue Jul 23 2019

An updated aviation discussion covering the 00z taf issuance is


Short term...(this evening through wednesday)
issued at 329 PM CDT Tue Jul 23 2019

High pressure was seen over the northern plains this afternoon and
this area extended into western and central Minnesota as well.
Flow around the high was leading to breezy winds over much of
northeastern Minnesota. A subtle wave in the flow over
northeastern Minnesota was providing lift for isolated showers in
northern St. Louis County. Per the Storm Prediction Center mesoanalysis, MUCAPE of
1000-2000 j/kg was seen over the Minnesota arrowhead. With the
weak wave moving over, this could lead to a few additional
thunderstorms over mainly lake and Cook counties late this
afternoon and evening. With mainly unidirectional shear in place,
not expecting much organization with these storms and any storms
that do form should diminish quickly after sunset. A few of these
showers/storms may hold together across the lake and make it into
northwest Wisconsin, but hi-res cams are not keeping things going
that long for the most part, and those that do are not bringing
anything in until close to midnight which seems unrealistic with
the loss of daytime heating. Quiet conditions are then expected
for the remainder of the overnight, although the GFS is hinting at
a few more showers/storms around daybreak in the tip of The
Arrowhead. Lows tonight will will be in the 50s.

The high will continue to drift east for Wednesday with mostly
sunny and dry conditions expected. An isolated shower or two will
again be possible in the tip of The Arrowhead during the afternoon
hours. Dry conditions will persist overnight as the high moves
into the Ohio Valley. A few showers and storms may approach our
western zones by daybreak Thursday per the GFS, but the NAM/European model (ecmwf)
are weaker and slower with this system. Highs will be a touch
warmer in the lower to middle 80s Wednesday with lows in the
middle 50s to lower 60s.

Long term...(wednesday night through tuesday)
issued at 329 PM CDT Tue Jul 23 2019

A well-advertised closed upper-level low will move through the
region Thursday and Thursday night. Thunderstorms from Wednesday
night should hold together and move into our western zones
Thursday morning and will weaken as they progress eastward
through the morning hours. Ahead of the associated cold front
southwesterly winds in the low-levels will result in Theta-E
advection during the day. Moderate instability is forecast with a
ribbon of mixed-layer cape of 1500-2000 j/kg expected by late
afternoon and early evening. A few storms may fire in the warm
sector during the afternoon, but better forcing for ascent
arrives with the cold front during the late afternoon and evening
hours. Deep layer shear will be sufficient for storm-scale
organization with 0-6 km bulk shear values of 35 to 40 knots
forecast. Large hail, damaging wind gusts, frequent lightning,
and locally heavy rain are possible with the strongest storms.
Another round of thunderstorms is possible Friday afternoon and
evening in response to cold air advection aloft as the upper-
level low moves across northern Ontario. Quasi-zonal flow returns
for Saturday night and lasts into Monday. A few scattered showers
and storms are possible Saturday afternoon through Sunday morning
in response to a shortwave trough moving through the flow.
Scattered showers and isolated storms are possible again Monday,
but coverage should be much smaller than the previous days.


Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 658 PM CDT Tue Jul 23 2019

Pesky isolated thunderstorms persist early this evening between
kdlh and khib, moving almost directly southward in northerly flow
aloft. These storms should dissipate rather quickly the first
couple of hours of this taf valid period as daytime heating wanes
with little large scale support, and these should miss all of the
taf sites. Surface high pressure will move off to the east
tonight and Wednesday, allowing for south/southwest winds to
develop. This will begin the process of higher quality moisture
return in the boundary layer by the end of the taf period, along
with scattered to broken cumulus the last 6-9 hours of this taf
period. It is not out of the question that we could see isolated
thunderstorms once again develop during the afternoon tomorrow,
but the chances of anything directly affecting a taf site preclude
any mention in the official forecast for this issuance.


issued at 329 PM CDT Tue Jul 23 2019

High pressure over the Minnesota this afternoon will keep
conditions fairly quiet over the waters during the next 48 hours.
Winds will generally be light, 5 to 15 knots.


Preliminary point temps/pops...
dlh 59 85 60 84 / 0 0 0 10
inl 54 84 59 85 / 0 0 0 20
brd 58 85 63 85 / 0 0 0 10
hyr 55 85 57 84 / 0 0 0 0
asx 59 86 58 86 / 0 0 0 0


Dlh watches/warnings/advisories...

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