Area Forecast Discussion
Issued by NWS Twin Cities, MN

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490
FXUS63 KMPX 240408
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1108 PM CDT MON MAY 23 2016

.UPDATE...
Issued at 1103 PM CDT Mon May 23 2016

Updated to include 06z aviation discussion below.

&&

.SHORT TERM...(This evening through Tuesday)
Issued at 319 PM CDT Mon May 23 2016

A moist and unstable corridor has developed today from eastern
Nebraska on northeast into central Minnesota. PWAT values by this
evening are progged to be well above the 90th percentile across
southern MN and actually just about a tenth of an inch below the
daily max of 1.64 inches.

The CAMS have been back and forth today on the initiation of the
afternoon convection across southern MN and points northeast. It
appears now that by around 4 pm there should be some scattered
storms from near Redwood Falls to north of the Twin Cities metro.
The kicker for this activity is a short wave over eastern Nebraska
that will drive northeast this evening. Hence, likely to
categorical pops remain in place from south central through east
central MN and west central WI for a time tonight. The better
showers and thunderstorms will be capable of brief heavy downpours
due to the high PWAT values. There remains some concern for severe
storms through this evening, but the low level wind field is weak
and rather unorganized at this point. Still, a few storms with
wind gusts to 35 knots and small hail can`t be ruled out.

Another concern overnight is the potential for extensive stratus
and fog in the wake of the showers and thunderstorms. This is
due to the weak wind field and clearing expected overnight along
with a nearly vertical hydrolapse. Areas of eastern/southern MN
and west central WI are most vulnerable.

Tuesday still looks like a mostly dry day although a few random
showers can`t be ruled out across central MN and west central WI.
It should be a warm day across central and southern MN with 850mb
temperatures climbing to around 16 deg C here in the Twin Cities
to around 18 deg C at the western border. Mix-down from 750mb
yields highs in the middle to upper 80s from the Twin Cities on
west.

.LONG TERM...(Tuesday night through Monday)
Issued at 319 PM CDT Mon May 23 2016

An active long term forecast period will ensue as active southwest
mid level flow prevails through the Memorial Day weekend. Expect
several bouts of widespread showers and thunderstorms through
then, with several inches of rain expected. Temperatures will be
slightly above normal /5-10 degrees/ through Friday, and then
retreat back closer to normal for the weekend.

Confidence in the shift to a more active pattern as described
above is high, although timing of the precipitation rounds will be
a bit tricky due to them being a product of rather weak shortwaves
in the southwest flow. That being said, it does appear that
Tuesday evening will be a dry window of time, and then soggy
weather arrives for Wednesday as a shortwave and warm front lift
across the area. The next break appears to arrive Wednesday night
into Thursday, although given the variability in models, there is
at least a 30 percent chance Thursday into Friday. The next
stronger wave and surface trough are progged for late Friday and
Saturday, so 50-60 percent chances for showers and thunderstorms
were justified during that time frame.

So, in summary, Wednesday and Saturday look to have the highest
potential to have widespread showers and thunderstorms, with more
fleeting and less concentrated activity possible on the other
days. Although severe weather cannot be ruled out for any of those
days at this point, it would more likely occur in conjunction with
the surface lows...currently progged for Wednesday/Saturday.

&&

.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1103 PM CDT Mon May 23 2016

The bulk of the precipitation has slid to the north of all WFO MPX
terminals at the time of the 06z initialization so have started
out all TAFs as such. Only KEAU looks susceptible to additional
showers come 06z but the sparse and light nature of any showers in
western WI allows for only vicinity mention. As the showers shift
away and winds diminish, there is still the possibility of pre-
dawn ground fog, especially for sites in eastern MN into western
WI which saw the bulk of the precipitation today. Have gone the
TEMPO route to advertise the drop in flight condition. After
daybreak tomorrow, solid VFR conditions will prevail with
generally light winds.

KMSP...VFR expected to prevail throughout this TAF set although
some MVFR fog is possible around the morning push. Only high
clouds will then remain beyond daybreak Tuesday. Winds will be
variable through late morning due to several weak boundaries left
over in the wake of the precipitation so trying to pin down a
direction will be problematic. However, speeds will be 5 knots or
less. Winds will then take on a southwesterly direction tomorrow
afternoon before winds back to southeasterly tomorrow evening.

/OUTLOOK FOR KMSP/
WED...Mainly VFR. TSRA/MVFR Likely. Wind SE 8-12 kts.
THU...Mainly VFR. Chc TSRA/MVFR. Wind S to SW 5 kts.
FRI...Mainly VFR. TSRA/MVFR likely. Wind SE 5 kts.

&&

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

$$

UPDATE...JPC
SHORT TERM...RAH
LONG TERM...LS
AVIATION...JPC



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