Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus63 kmpx 291051 
afdmpx

Area forecast discussion
National Weather Service Twin Cities/Chanhassen Minnesota
551 am CDT Wed Mar 29 2017

Updated for 12z aviation discussion below...

Short term...(today and tonight)
issued at 338 am CDT Wed Mar 29 2017

The main short term concern is rain development today...its timing
and extent as the upper low lifts east. Temperatures today are
conditional and will be determined on how thick the higher level
clouds will be into the afternoon.

Water vapor imagery showing upper circulation remains over the
southwest/New Mexico/Texas Panhandle region. Broad south to
southwest flows remains with embedded convection ahead of the
system. Models lifts this moisture northeast during the day...to the
Minnesota/Iowa border by afternoon and into the south Metro by evening. We
increased likely pops coverage a bit farther north into the south
Metro into the evening. Latest guidance had broad southeast flow
developing into the evening with 290k isentropic surface indicating
saturation developing. We expect any precipitation to be light on
this northwest fringe of the main rain shield which will move across
the southeast portion of the cwa.

Cloud cover is expansive with convective debris for the Central
Plains convection transported north into the area. This combined
with the northern stream trough should be enough to help thicken
clouds and generate the rain across mainly the eastern half of the
cwa. High temperatures today will be determined by the opaqueness
of the clouds cover...with a 60 again possible out west if the
cloud cover remains thin enough.

Colder temperatures will move into the area as the upper circulation
drifts east. This will drop thickness levels close to critical
values after 06z Thu...mainly to the far east. There could be a
rain/snow mix into a portion of west central Wisconsin then...but
little if any accumulation is expected. Quantitative precipitation forecast amounts could range
around 0.25 to 0.50 inches mainly across far south central Minnesota
during the event.

Long term...(thursday through tuesday)
issued at 338 am CDT Wed Mar 29 2017

The longer term period looks to be dominated by split flow across
the Continental U.S. With a series of upper lows cutting off over the
southwest US, then meandering eastward with our area mainly north
of the best moisture and forcing. We'll have some lingering light
precipitation across the southeast portion of the area early on
Thursday as the surface low moves through the mid-Mississippi
Valley. A ridge of high pressure then looks to build in from the
north and keep things dry through Sunday. We look to get into some
weak return flow by Monday, but solutions have been trending drier
across our area with more robust large scale and convective
precipitation expected to the south with another surface low
moving from the plains through the Mississippi Valley. The European model (ecmwf)
has come more in line with a slightly more southern solution as
shown by the GFS and Canadian. Maintained some low pops from
Monday into Tuesday, as we could see a bit get wrung out as a weak
northern stream wave moves through the area. However, the bulk of
any significant precipitation looks to stay well to our south
during that time frame.

&&

Aviation...(for the 12z tafs through 12z Thursday morning)
issued at 520 am CDT Wed Mar 29 2017

VFR conditions at tafs sites through 00z. After that...MVFR cigs
develop at krwf/kmsp/Keau with some -radz a good bet. The northern
taf sites should remain VFR until most likely after 06z. The
precipitation should taper from west to east across east central
Minnesota and west central Wisconsin through 12z. Surface winds should
remain east/southeast 8-13kt during the period.

Kmsp...still have high confidence of VFR through about 00z Thu as
upper trough moves east over the Central Plains. After
that...-radz br looks to develop with MVFR conditions by 04z.
Cigs may drop to ovc015 by 07z and may remain there through Thu
morning. The overall -ra should end after 07z. Surface winds
should remain east through most of the period.

/Outlook for kmsp/
Thu night...VFR. Wind east at 5-10 kts.
Fri...VFR. Wind NE 5-10 kts.
Sat...VFR. Wind variable less than 5 kts.

&&

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

$$

National Weather Service Glossary of Abbreviations