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Area forecast discussion 
National Weather Service Twin Cities/Chanhassen Minnesota
338 am CDT Tuesday Sep 23 2014

Short term...(today and tonight)
issued at 322 am CDT Tuesday Sep 23 2014

Today-tonight...surface analysis shows an area of high pressure centered
over the central Ohio Valley region with its western extent still
covering the upper miss River Valley this morning. Aloft...an upper level
ridge is centered just about over Minnesota...extending southward over IA/MO. With
this ridge slowly moving eastward over Minnesota into WI and the surface high pressure
allowing for decent radiational cooling conds over eastern portions of
the weather forecast office mpx County warning forecast area with clear skies and nearly calm winds...the
coolest readings will be felt over western WI. In addition...patchy fog
is also being seen this morning whereas the Minnesota portion of the County warning forecast area with
warmer temperatures and a more S-SW component of winds around 5 miles per hour will
remain free from fog development. Any fog will gradually burn off
shortly after daybreak...then attention turns to a compact rotating
upper level low making its way eastward over the northern plains. With a deep
southerly fetch ahead of this upper low bringing in higher levels of
moisture to be wrapped into this system...enhanced Omega lift ahead
of the low will be responsible for creating isolated to scattered showers over
western and southern portions of the County warning forecast area by midday today. Though clouds will
certainly be on the increases from the SW...the lack of a surface low or
front along with drier lower levels will make low level lift and
moisture convergence a mitigating factor to better precipitation coverage
and quantitative precipitation forecast amounts...but with better model agreement on at least -shra
over southwestern portions of the County warning forecast area today and even through tonight...have
maintained slight-low chance probability of precipitation for those portions of the County warning forecast area. Since
the upper level low is expeceted to run into the drier upper ridge...open up
to a trough and lift north...precipitation is not expeceted to make much more
progress eastward than central Minnesota through tonight so have been able to leave
much of eastern Minnesota into western WI dry through this part of the forecast period.
Even the Twin Cities /and the I-35 corridor as a whole/ may have a
tough time receiving precipitation through this short-term period but cannot
be ruled out completely so some slight chance probability of precipitation are included along and
east of Interstate 35. As for temperatures...after quite the spread in
low temperatures this morning...ranging from the lower 40s in western WI to the lower
50s in western Minnesota...temperatures will even out for highs this afternoon into the lower
70s underneath an expected decent coverage of clouds...albeit
middle-to-high level. Modest warm air advection tonight with deep S-SW
flow at the surface and aloft along with the blanket of cloud cover will
spell much warmer temperatures for overnight Tuesday into Wednesday. Lows Wednesday morning
will range around 50 in western WI to near 60 in western Minnesota.

Long term...(wednesday through monday)
issued at 322 am CDT Tuesday Sep 23 2014

Main forecast issues of note were the continued probability of precipitation through
Wednesday night...which resulted in cooler temperatures on
Wednesday. Also...increased temperatures later in the weak above guidance
based on the mass fields.

At the start of the period light rain showers should be ongoing
across the western half of the forecast area. Hires models depict
this...and forecast soundings off the NAM/GFS show deeper
moisture...stronger vertical motion...and therefore generate more
precipitation. Middle level clouds will limit the afternoon heating...so
decreased temperatures on Wednesday...especially in western WI.

An upper level ridge will build across the High Plains as this
system gets sheared apart in the northern stream. A thermal ridge
will build to the west...and by Friday afternoon h850 temperatures will
be on the order of 17-19c along the Minnesota/Dakota border.
Forecast soundings show clear skies...and although the surface
winds initially start out southeast...afternoon mixing gradually
transfers southwesterly winds throughout the boundary layer which
will be a favorable setup for warm temperatures...especially along
the Minnesota River Valley. This setup has the potential to bring
middle and even upper 80s across western Minnesota by the end of the
week...so raised temperatures above the model consensus.

&&

Aviation...(for the 06z tafs through 06z Tuesday night)
issued at 1027 PM CDT Monday Sep 22 2014

Winds remain light and variable overnight...particularly at west
central WI sites /krnh and Keau/ near the surface ridge axis. Kept
the mention of fog at WI sites given similar conditions to last
night and dewpoints around 50 degrees this evening. Western sites
will have a canopy of high clouds moving in and winds will be a
few knots stronger...so fog is less of a concern there. By 00z
Wednesday...middle level saturation occurs at western sites with a
broken-overcast deck circa 5kft expected along with a few showers. South-
southeast winds prevail on Tuesday with gusts developing at kaxn
and kstc.

Kmsp...
clear skies overnight with middle/high clouds increasing
throughout the day on Tuesday. Still expect patchy fog in nearby
valleys but not at the site. South-southeast winds at or below 10kts through
Tuesday.

/Outlook for kmsp/
Wednesday...VFR. MVFR ceilings possible overnight. Winds south-southeast 12-15g25 kts.
Thursday...VFR. Winds S 7-10 kts.
Friday...VFR. Winds south-southeast 5-10 kts.



&&

Mpx watches/warnings/advisories...
Minnesota...none.
WI...none.
&&

$$

Short term...jpc
long term...jrb
aviation...ls

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