Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 220350
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1050 PM CDT SUN AUG 21 2016

.UPDATE...For 06Z Aviation discussion below

&&

.SHORT TERM...(This evening through Monday)
Issued at 334 PM CDT Sun Aug 21 2016

A highly amplified upper level trough over the Great Lakes region
will continue to shift east today, and upper level subsidence will
lead to surface high pressure across the Upper Midwest. This will
keep the region dry through Monday.

As of early this afternoon, the surface ridge was centered across
western MN. The cool air to the east of this ridge led to some
afternoon clouds across eastern MN and western WI. These clouds will
dissipate overnight. Meanwhile a surface low will form over the
western Dakotas overnight which will allow the surface pressure
gradient to tighten across the region leading to southerly winds.
These winds will gust 20 to 30 mph by Monday afternoon and high
temperatures will approach 90 along the upper Minnesota River
Valley.

.LONG TERM...(Monday night through Sunday)
Issued at 334 PM CDT Sun Aug 21 2016

Strong warm air advection will continue Monday night and Tuesday.
Gusty south winds ahead of the approaching trough and mixing to
875 mb will allow us to reach the mid 80s to lower 90s Tuesday.

Low pressure associated with the trough will track eastward across
the Dakotas and across the northwestern corner of Minnesota
Tuesday night. A trailing cold front should spark off some
thunderstorm activity across western MN by late Tuesday afternoon
or early evening, particularly as deeper moisture arrives in
earnest between 21-00Z. However, a developing low along the
southern end of the front over Kansas, with a surface warm front
extending to the east along the IA/MO border, may produce clusters
of storms or an organized MCS along I-80 which could prematurely
steer the healthy 45-55 kt low level jet to the east. If that were
to happen, it would be tough to get widespread storms across MN
and WI, particularly being in the entrance region of a secondary
LLJ centered over northern MN. Models have backed off on this
somewhat from yesterday`s solutions, aside from the Canadian, so
kept pops in the 50-70 percent range which is similar to the
overnight shift.

If Iowa doesn`t steal the show, Tuesday night`s convection may be
yet another event that has potential for heavy rainfall totals.
NAM/GFS/ECMWF 850 mb dew points rise to a very respectable +16 to
+19C range, 850-300mb bulk wind shear is expected to be 25 kts or
less, pwats increase toward 2 inches, and long skinny CAPE given
moist lapse rates all point toward heavy rainfall.

Cooler and drier weather follows for Wednesday night through
Friday before the next system approaches Saturday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1050 PM CDT Sun Aug 21 2016

VFR conditions will persist through the period. Skies will be
mostly clear overnight, with only a few-sct mid/high clouds on
Monday. Light southerly winds overnight will become gusty by late
Monday morning...reaching sustained speeds of 15-20kts with gusts
from 25-30kts.

KMSP...
High confidence in VFR through the period. Sustained speeds will
reach around 17 kts by 18z Monday with gusts to around 25 kts.

/OUTLOOK FOR KMSP/
Tue...VFR. -TSRA possible late. Wind SSW 15-20G25 kts.
Wed...VFR with -TSRA/MVFR possible. Wind SW 5-10 kts becoming W.
Thu...VFR. Wind NW 5-10 kts.

&&

.MPX Watches/Warnings/Advisories...
WI...None.
MN...None.
&&

$$

SHORT TERM...JRB
LONG TERM...BORGHOFF
AVIATION...LS


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