Scientific Forecaster Discussion
fxus63 kmpx 191108
Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
608 am CDT Thu Sep 19 2019
Short term...(today through friday)
issued at 605 am CDT Thu Sep 19 2019
Early this morning, thunderstorms were occurring along the I-90
corridor in south central Minnesota and eastward. A frontal boundary was
draped from Iowa northeast through southeast Minnesota and into
northern Wisconsin. Instability along the front has been able to
sustain thunderstorms overnight, impacting far southern Minnesota.
The front will continue a gradual sag to the south today, so expect
showers and storms to come to an end this morning. Much of the area
will see mid and clouds through the morning, leftover from early
morning thunderstorms to the south. Clearing skies are expected this
afternoon though and highs should be able to make yet another run
into the 80s.
A low level jet will develop across the High Plains tonight, which
will push the aforementioned front northward through southern and
central Minnesota, and west central WI by Friday morning. We continue to
see disagreements between the guidance in terms of precipitation
potential during the day on Friday. Precip potential during the day
hinges upon forcing and overcoming a cap in place south of the
frontal boundary. Forcing is rather limited given the fact that the
main trough is well to the west of our area during that time, and
with the cap in place, could foresee a few showers and weak storms
developing on an isolated basis across the local area during the day
Friday. The arw/nmm/namnest don't indicate much storm coverage
locally, but the hrrr has been more bullish with producing
thunderstorms. Continued with chance wording and would expect
another warm and humid day on Friday.
Long term...(friday night through wednesday)
issued at 605 am CDT Thu Sep 19 2019
The large scale pattern looks to be quite progressive through the
period, with an overall trend toward lower heights and a low
amplitude troough across the northern Continental U.S. By the end of the
period. The current western upper trough will move through over
the weekend, with some shortwave ridging in its wake before we see
a series of shortwave troughs work to reinforce general
troughiness near the international border for the remainder of the
week. Guidance is reasonably similar on the overall trends, and
don't have sufficient confidence in any particular solution to
stray much from a consensus (nbm) forecast at this point.
Warm advection and moisture return will bring chances for showers
and storms across much of the area late Friday night into
Saturday. Cold front looks to push through the area during the
mid to late afternoon on Saturday, with things drying out for the
evening. Strong cold advection will be in place Saturday night
into Sunday. Some diurnal showers could occur Sunday with decent
lapse rates and cyclonic flow, otherwise dry weather looks to
prevail until Tuesday when we could see a few rain showers/thunderstorms and rain in
association with a quick moving front/trough. Difference in the
timing and amplitude of this feature result in keeping some chance
pops around into Wednesday, with a better consensus on dry weather
returning by Thursday.
Aviation...(for the 12z tafs through 12z Friday morning)
issued at 606 am CDT Thu Sep 19 2019
Early morning fog in Wisconsin will lift by mid morning, with an
otherwise VFR forecast through 06 tonight. Fog formation will be
possible once again overnight. Winds will be light and variable,
but eventually favor an easterly component tonight.
Kmsp...no additional concerns.
/Outlook for kmsp/
Fri...VFR. Chance MVFR/tsra. Wind southeast 10g20 kts.
Sat...am MVFR/thunderstorms and rain likely. Wind SW 15g25 kts.
Mon...VFR. Wind west 10g20 kts.