Scientific Forecaster Discussion
Return to Local Conditions & Forecast
Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
551 am CDT Wednesday Apr 23 2014
Short term...(today and tonight)
issued at 419 am CDT Wednesday Apr 23 2014
Short term concerns are shower/thunder threat today into tonight and
strong winds over the western County Warning Area today.
Latest radar trends indicate band of light rain lifting
east/northeast...close to the 00z hires nmm model was indicating.
Will follow this general trend of the light rain band moving into
eastern Minnesota through 17z. Thunder limited to the southwest during the
morning...with the possibility of this translating more to the east
through 00z Thursday. Instability not impressive over the far eastern
during throughout the day.
Other issue for today remains strong southeast winds developing to
the west into Wednesday morning. Pressure gradient increase and low
level jet should be able to mix out in the showers. Will continue
the wind advection for today in west central to southwest through 7 PM.
Main upper trough still prognosticated to lift northeast...becoming more
negatively tilted later tonight into Thursday morning. This brings
in strong forcing into the eastern County Warning Area during this period.
Precipitable water values increase over the southeast area to around
1 inch which is about 200% of normal. This along with the strong
forcing should be able to generate some heavier rain over the
southeast County Warning Area into Thursday. Rain totals of an inch or more look
good here. Thunder looks best over south central
Minnesota...perhaps clipping the southern suburbs into a part of
west central WI late tonight.
Temperatures should be limited by clouds and rain today...and remain
stable overnight as the upper low...and surface low tracks close to
the Minnesota/Iowa border.
Long term...(thursday through tuesday)
issued at 419 am CDT Wednesday Apr 23 2014
A wet long term forecast seems to be a given...with an amplified
and blocky large scale pattern forecast to evolve. Forecast
confidence /and model agreement/ is decent through Sunday...but then
degrades into next week due to differences in how quickly a
central Continental U.S. Closed low ejects eastward and a Rex block pattern
The first rain-maker will be ongoing at the start of the long term
period /Thursday/...especially north and east of the i94 corridor
from the Twin Cities to Eau Claire. Said areas are expected to see
an additional one quarter to near one inch of rainfall during the
daytime Thursday /on top of what falls Wednesday night/. Thursday
highs will ranged from the middle 40s in areas where precipitation
lingers...to the lower 60s in west central and southwest Minnesota where
afternoon clearing is more probable.
The baroclinic zone associated with the middle level low drifting
across northern ND/MN/WI will take residence near the area on
Friday. Its forecast position has wobbled a bit over model
runs...but has trended north with time. Therefore nudged precipitation
chances a bit north...and also leaned toward the warmer
temperature guidance. Did not go as high as what the NAM/met
guidance indicate...but do think low/middle 60s are achievable
generally south of the i94 corridor...with low/middle 50s more likely
to the north.
Friday night brings high pressure ridging into the area...along
with the possibility of near to sub-freezing low temperatures. Saturday
looks to be a dry day...but with temperatures around 10 degrees below
normal /low to middle 50s for highs/ and a brisk east/northeast wind.
The high pressure ridging and respite from precipitation will be
short lived...as a Four Corners middle/upper low meanders east and
slightly north during the weekend into the upcoming week. Expect
related showers to start lifting into southern Minnesota late Saturday
night...gradually expanding north and east on Sunday as the low
drifts toward the area. Areas along/north of i94 could stay mostly
dry until closer to Sunday evening. As mentioned
previously...confidence decreases notably by Monday given the
uncertainty with how quickly the low shifts east. Clouds and light
precipitation could linger into Tuesday. Have included 20-30 probability of precipitation through
Tuesday. Snow and/or rain/snow could also enter the picture on
Monday/Tuesday nights...but any accumulations would be minimal.
Aviation...(for the 12z tafs through 12z Thursday morning)
issued at 539 am CDT Wednesday Apr 23 2014
VFR conditions initially across the area...becoming MVFR late
afternoon/evening most areas. Ceilings are expected to lower to IFR
especially after 05z...west and spreading east through 10z. Band
of light rain to affect mainly Minnesota sites during the day...working
into west central Wisconsin this evening. Best chance of thunder
spreads northeast across south central Minnesota into west central
Wisconsin mainly after 05z as well. Looks to be isolated at taf sites
so left out out for now. Expect IFR conds through most of the Thursday
morning for now...as trough/occluded front moves east. Southeast
surface flow to increase from west to east as well today...with
the strongest winds found over western taf sites. Winds are expect
to relax some tonight but should remain gusty most areas.
Kmsp...VFR conds expected through the day with some light rain
moving into the region after 15z. MVFR ceilings/visibilities in -ra br
developing after 02z with IFR conditions by 08z Thursday. Some threat
of thunder as well...but confidence is low at this time. If it was
to happen...greatest threat between 06z/11z Thursday. Southeast winds
expected to increase this morning...and remain gusty into the
/Outlook for kmsp/
Thursday afternoon...MVFR conds with rain showers possible. Southeast wind 5-15 knots shifting northwest.
Thursday night...VFR. Northwest wind 5-10 knots.
Fri-Sat...VFR. North wind 5-15 knots.
Minnesota...Wind Advisory from 10 am this morning to 7 PM CDT this evening