Area Forecast Discussion
Issued by NWS Duluth, MN

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FXUS63 KDLH 231747
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
1247 PM CDT Sat Sep 23 2017

.UPDATE...
Issued at 1247 PM CDT Sat Sep 23 2017

Updated for the new 18Z Aviation Discussion below.



&&

.SHORT TERM...(Today through Sunday)
Issued at 331 AM CDT Sat Sep 23 2017

The area remains in a very summer like pattern, pinched between a
large trough out over the far western CONUS, and ridging just
east of the Mississippi river valley, with then troughing within
which are embedded hurricane Maria and the remnants of hurricane
Jose. This pattern is expected to continue through the next 36
hours. This pattern will bring warm and relatively humid
conditions to the area with waves of showers and thunderstorms
moving across the forecast area. Some of these waves will be more
active than others. Our main show of the night with the best upper
level support and mid level is now up in Canada, but we have a
somewhat secondary wave that developed over central Minnesota.
This wave is in the plume of best moisture and is in the low level
jet, but there is less support at the mid and upper levels for
stronger convection. However, it has produced a decent area of
showers and thunderstorms and have kept fairly high pops for the
remaining early morning hours going. Today this wave will continue
off to the northeast, likely dissipating during the morning
hours. It should be followed by a lull in the convection before
another wave of storms move through mainly Minnesota this evening.
Sunday morning there should be another lull, only to be followed
by another round of showers and storms in the afternoon and
evening for mainly northwest and north central Minnesota. This
pattern is also going to keep temperatures on the warm and humid
side, with cloud cover keeping a lid on things, and have kept
mostly to the consensus through Sunday.

.LONG TERM...(Sunday night through Friday)
Issued at 331 AM CDT Sat Sep 23 2017

The persistent southwest flow pattern across the central United
States will finally break down next week leading to near to below
normal temperatures returning after a warm weekend. Precipitation
chances continue through Tuesday as the main longwave mid-level
trough exits across the region, then a break in the precip on
Wednesday. However, with northwest flow developing in the wake of
the mid-level trough a low chance for light rain showers returns
late-week.

On the synoptic scale a mid-level ridge parked over the lower Great
Lakes region and a slow-moving deep longwave trough over western
states has resulted in a persistent southwest flow pattern at
mid/upper levels across the Great Plains through the weekend into
early next week. The Upper Midwest will remain within the warm
sector ahead of the quasi-stationary frontal boundary parked along
this southwest flow pattern through Monday before the front finally
pushes east Tuesday. Once the front moves through Wednesday cooler
air will move in from the northwest with at least partially clearing
skies expected. Late week a fast-moving clipper-like mid-level
shortwave trough will approach the region leading to a chance for
light rain showers. Highs in the 50s to around 60 Wed-Thurs-Fri with
lows in the upper 30s to low 40s. Broad area of high pressure
building in late-week should result in clearing skies, which could
result in a widespread frost/freeze.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1247 PM CDT Sat Sep 23 2017

A slow-moving cold front will continue advancing east and south
into the Arrowhead, Twin Ports, and northwest Wisconsin this
afternoon. There will be widespread IFR/MVFR ceilings and some
light showers on the cool side of the front. The front will lift
back north tonight with the development of a strong low-level jet.
Expect this jet and passing weak disturbances to provide the
forcing to trigger some showers and weak storms this evening and
overnight, especially areas closer to the front. Significant low-
level wind shear will develop later tonight once the jet increases
to about 30 to 40 knots of flow from the south-southwest aloft.

There will likely be some lowering ceilings and visibility in
areas overnight, with most of the area seeing a trend to LIFR/IFR
conditions. Northwest Wisconsin and KHYR may remain mostly clear
and VFR. There will then be some improvement from the south as
warmer and drier flow picks up.



&&

.PRELIMINARY POINT TEMPS/POPS...
DLH  78  60  78  59 /  20  30  10  60
INL  64  53  69  50 /  40  90  60  70
BRD  70  60  79  55 /  60  60  30  70
HYR  87  65  85  63 /  10  20  10  30
ASX  89  61  85  62 /  20  20  10  30

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
LS...None.
&&

$$

UPDATE...Grochocinski
SHORT TERM...LE
LONG TERM...JJM
AVIATION...Grochocinski


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