Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
548 am CDT Friday Jul 31 2015
Short term...(today and tonight)
issued at 320 am CDT Friday Jul 31 2015
A quiet short term period ahead...with no precipitation expected.
The deep low over the Hudson Bay remains in place...with
persistent northwest flow continuing for US with this setup. This
dry air mass/high pressure will stay with US right through the
short term period. Expect a very similar day to yesterday...with
diurnally driven winds increasing during the day...with gusts
commonly to 20+ miles per hour. Temperatures will also be similar to
yesterday...maybe a degree or so cooler but not a noticeable
difference...highs will be in the low to middle 80s. Dew point
temperatures will remain comfortable...in the 50s through the
Winds will decrease in the evening once the sun is on the horizon
and the temperature inversion forms. Lows will again fall into the
upper 50s across most of the area...except for low 60s in the
Long term...(saturday through thursday)
issued at 304 am CDT Friday Jul 31 2015
Saturday and Sunday...the period will commence with the perpetual
eastern noam trough and western noam ridge continuing aloft...promoting the
development of a surface frontal boundary from the northern rockies southeastward
into the Tennessee River valley. As the day progresses on Sat...several
shortwave disturbances will develop within the prevailing northwest flow
aloft while the surface front slides slowly eastward...transitioning into
more of a warm front with a surface low forming over South Dakota by late day Sat.
These features are expected to shift eastward overnight Sat night into
sun...moving into an increasingly unstable environ with the
potential for scattered thunderstorms. Dewpoints will climb into the lower 60s
as winds shift to a more southwesterly low level flow. This will make for a
veering of winds going aloft...particularly due to strengthening
low- and middle-level jetting in vicinity of the warm front. The intersection of the
low level jet within a more unstable environ will make for bulk shear
approaching 40kt over southern Minnesota by Sat night. This would promote
strong/severe thunderstorms overnight Sat night into Sun morning...
including the potential for supercells and/or a eastward/southeastward movingmcs.
Storm Prediction Center has delineated much of southern Minnesota into southwestern WI within a slight risk
which certainly seems reasonable. The activity will be mainly east/southeast
of the mpx County warning forecast area by Sun morning...with mainly eastern portions of the County warning forecast area
susceptible to re-development Sun afternoon. However...the best severe
potential looks to be well southeast of the mpx County warning forecast area...in the warm sector
of the departing system. Temperatures will still run seasonably
warm with highs in the 80s across the entire County warning forecast area.
Monday through Thursday...with the weekend system shifting away to
the east and a cold front having moved through the region by Monday morning...
cooler high pressure will prevail for the first part of the week...
bring brought into the upper miss River Valley region from west-central
Canada. Dry weather will be the rule Monday-Tuesday while high temperatures drop into
the middle-upper 70s...below normal for the start of August. Upper level
flow turns a bit more zonal Wednesday-Thursday as the western noam ridge breaks
down slightly...allowing for the development of a low pressure center
over the northern rockies which will strengthen through midweek. This low
will then gather in Gomex moisture while it travels into the northern
plains and upper miss River Valley regions. Due to uncertainties in
the path of this system...have maintained only chance probability of precipitation for the
middle of next week. Temperatures will continue to run slightly
below normal for Wednesday-Thursday with highs still in the 70s with lows in
Aviation...(for the 12z tafs through 12z Saturday morning)
issued at 544 am CDT Friday Jul 31 2015
Continued VFR expected for this period. High pressure continues to
dominate...skies will be mostly clear today but we'll see some middle
and high level cloudiness increase tomorrow. The main concern for
this forecast is the wind...highly confident in the forecast with
diurnally driven northwest gusts...which will quickly diminish in
Kmsp...gusty northwest winds again today. Otherwise VFR with
mostly clear skies and winds weakening at sunset.
/Outlook for kmsp/
Sat...VFR. MVFR within rain showers/thunderstorms and rain possible late. Winds west 5-10kt.
Sun...VFR. Wind SW at 5-10kt.
Monday...VFR. Wind northwest at 10g20kt.