Scientific Forecaster Discussion
fxus63 kmpx 252326
Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
626 PM CDT Thu may 25 2017
issued at 626 PM CDT Thu may 25 2017
Updated to include 00z aviation discussion below.
Short term...(this evening through friday)
issued at 245 PM CDT Thu may 25 2017
Main issue this period is the incoming frontal boundary and
associated weather concerns as showers and thunderstorms will be
possible tonight through tomorrow.
Low pressure system continues working east across southern
Saskatchewan with a southward trailing cold front currently across
the central Dakotas. We continue to see south-southeast winds ahead of the
front which is mainly expected to move through our area tomorrow.
For the rest of today and tonight, isolated showers will move
through thanks to weak warm air advection and a subtle upper low
ripple in the flow. More broad precipitation has developed in the
eastern Dakotas thanks to the proximity to the frontal boundary, and
those should impact western Minnesota this evening.
For tomorrow, temperatures should be a few degrees warmer in
southerly flow ahead of the front. By 18z, expect the front to be
draped from north to south through The Heart of Minnesota and
continued to advertise the chance for showers and thunderstorms
tomorrow afternoon along and east (ahead) of the frontal boundary.
Limited forcing and instability are the reasons we went with 40-50
pops for now but those certainly could be increased if confidence the
chance for shower and storm development and coverage increases.
Long term...(friday night through thursday)
issued at 315 PM CDT Thu may 25 2017
For the upcoming Holiday weekend, it looks as though the best day
for outdoor activities will be Saturday. Sunday and Monday look to
be cooler and breezy as another frontal boundary moves southward from
Not much change in the last several model runs as the
mean upper pattern remains locked in from a ridge in the west, and
a deep upper trough centered north of the Great Lakes. This will
keep our region cooler than normal, especially early next week as
the core of the coldest air mass moves overhead. Under the cooler
air mass, instability showers will likely develop, especially
Sunday and Monday afternoons during the typically diurnal period.
Highs on Monday, which is based on 92/85h temperatures, could
easily be lower than 60 degrees.
However, before the next front moves southward late Saturday, and
in between a storm moving across the Central Plains, our region
should see temperatures near normal with highs in the low to mid
70s. Typically the last week of may has average highs in the low
to mid 70s which hasn't occurred for most of southern Minnesota
since the 16th.
There is a sign that this pattern will begin to change late next
week as the mean upper ridge in the west moves over The Rockies,
and into the plains. Even some of the longer range /gefs/
ensemble members have temperatures starting to modify late next
week, with a few members forecasting highs above 80 degrees. This
pattern change will also lead to more stormy conditions as the
upper level flow becomes more west/southwest the first week of
Aviation...(for the 00z tafs through 00z Friday evening)
issued at 626 PM CDT Thu may 25 2017
Things look fairly similar to the earlier forecast issuance, so
didn't make any significant changes. Main things of interest are
the area of mainly mid-level clouds and a few light
showers/sprinkles associated with it that are currently working
east across the area. This is associated with the leading edge of
warm advection ahead of a short wave trough working through
southern Canada and a frontal boundary extending south through the
northern plains. Don't foresee much other than some VFR ceilings
and perhaps a shower with it tonight, so just included some vcsh
at most sites. The next feature of interest will be the
aforementioned front as it tries to work east across the area
tomorrow. It looks like it should get through the western sites
without anything of interest developing, but could see a few
rain showers/thunderstorms and rain as it tries to work through the east. The front will
essentially be washing out as it works into the eastern portion of
Kmsp...taf reflects expectations with main uncertainty being the
potential for rain showers/thunderstorms and rain tomorrow afternoon, as well as some
possibility of seeing MVFR ceilings for a brief time tomorrow
/Outlook for kmsp/
Friday overnight...VFR. Northwest wind 5 kt or less.
Saturday...VFR. West wind 5 to 10 kt becoming southwest 10 to 15
Saturday night...VFR. Southwest wind 10 to 15 kt.
Sunday...MVFR possible with a chance of showers and
thunderstorms. West wind 10 to 20 kt.
Sunday night and Monday...MVFR possible with a chance of showers
and thunderstorms. Northwest wind 10 to 20 kt.
Monday night...VFR. Northwest wind 10 to 20 kt.