Area Forecast Discussion
Issued by NWS Twin Cities, MN

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579
FXUS63 KMPX 301736
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1236 PM CDT SAT JUL 30 2016

.UPDATE...
Issued at 1229 PM CDT Sat Jul 30 2016

Updated to include 18z aviation discussion below.

&&

.SHORT TERM...(Today and tonight)
Issued at 451 AM CDT Sat Jul 30 2016

Today will be another mostly sunny day with light winds and highs
near 80. A few showers and thunderstorms are possible along the
Mississippi River Valley during the afternoon, but coverage will
be very scarce.

Split flow remained in place across the region meaning very light
winds from the surface up through 300mb. Later today the upper
level jet will increase slightly to around 25-30kts as the back
side of an upper level trough moves across the region. This should
promote subsidence and hold off any chance for showers and
thunderstorms, but forecast soundings off the GFS and NAM show a
thin layer of instability along the MN/WI border during the
afternoon. HiRes models show spotty showers and thunderstorms, so
added a 15 percent chance of precipitation for this afternoon.
Have pretty high confidence that a few showers and thunderstorms
will be around, but most locations will remain dry. The threat for
severe weather is very low. Tonight will be dry as well for most
location, but a bit warmer as southerly winds keep overnight lows
near 60 for most locations. A few thunderstorms are possible in
far western MN.

.LONG TERM...(Sunday through Friday)
Issued at 451 AM CDT Sat Jul 30 2016

Not much change to the extended part of the forecast. Heat and
humidity remain on track for the middle of the week with highs
near 90 and dewpoints in the lower 70s. This will lead to heat
indices around 95 to 100F Wednesday afternoon, while
MaxWetbulbGlobe temperatures reach the mid 80s. In other words, it
will be hot and uncomfortable, but should not be dangerous if
proper precautions are taken. There are a few chance for
thunderstorms, but by far the highest risk day in terms of both
coverage and severity is Wednesday evening/night.

Of course the temperatures are dependent on cloud cover and
precipitation. There are slight chances for showers and
thunderstorms most of next week, but the best chances appear to be
Monday night and Wednesday night. Right now there is not an
outlook by SPC for severe weather, but forecast soundings show
veered wind profile with around 1500 to 2000 J/kg Monday night.
Wednesday has higher CAPE with values near 5000 J/kg, but the wind
profile is less favorable, but still supportive, for organized
convection. At this point the highest threat for severe storms is
across northern MN and northern WI where the deep layer shear is
stronger, but will continue to monitor the trend and would not be
surprised to have the area outlooked within the next couple of
days. Looking ahead, cooler less-humid weather will move in for
next weekend.

&&

.AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon)
Issued at 1229 PM CDT Sat Jul 30 2016

Mainly VFR conditions expected throughout this TAF set. However,
am concerned of having isolated SHRA/TSRA along and E of the I-35
corridor and along and S of the I-94 corridor, so mainly E-central
and SE MN into W-central WI (affecting KMSP-KRNH). Chances are
relatively low but VCTS looks warranted as development has already
commenced. Storms would have little motion and produce localized
rain and with some lightning. Storms look to hang around until
about 00z then mid-to-high SCT-BKN clouds will prevail.

KMSP...Have added a VCTS for the 20z-00z time period this
afternoon and evening since short-term models are generally in
agreement on the development of isolated TSRA around the area
though not so much directly over MSP. Could even see a few more
hours beyond that but confidence not high enough to put actual
precipitation into the terminal at this point.

/OUTLOOK FOR KMSP/
Mon...Mainly VFR. Chance MVFR/TSRA. Winds SE 5-10 kt.
Tue...Mainly VFR. Chance MVFR/TSRA early. Wind light/variable.
Wed...Mainly VFR. Chance MVFR/TSRA late. Wind SE 5-10 kt.

&&

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

$$

UPDATE...JPC
SHORT TERM...JRB
LONG TERM...JRB
AVIATION...JPC



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