Area Forecast Discussion
Issued by NWS Twin Cities, MN
FXUS63 KMPX 270454
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1054 PM CST Sun Feb 26 2017
.SHORT TERM...(This evening through Monday)
Issued at 220 PM CST Sun Feb 26 2017
The short term period, tonight and Monday, looks to be fairly quiet
across the area. The frontal boundary currently bisecting the area
from southwest to northeast will continue to slide south/east and
essentially wash out overnight. This will take the few flurries
currently over the east out of our area by evening. We could see a
little light snow over the far northern portion of the forecast area
overnight as a weak shortwave moves by and helps moisten things
enough to take advantage of some weak isentropic ascent north of an
incipient surface trough/warm front. But, wouldn`t expect much more
than a dusting from that activity overnight. Otherwise, we`ll just
see an increase in mid/high clouds overnight, which may thin some on
Monday, although the northern part of the area will likely hold onto
a thicker deck for most of the day.
.LONG TERM...(Monday night through Sunday)
Issued at 240 PM CST Sun Feb 26 2017
The main forecast concerns are precipitation type and QPF amounts
late Monday night, and into Tuesday which will have some impact
on travel if freezing precipitation develops.
The EC & GFS differ on how the northern short wave and southern
short wave interact late Monday night and into Tuesday which leads
to surface low placement and overall QPF amounts. The GEM is
closer to the GFS but has more energy on the initial warm air
advection regime which producing more QPF in southeast Minnesota,
and into portions of west central Wisconsin late Monday night.
The comparison between the EC & GFS is related to the phasing of
the two waves. The GFS has more influence on the northern wave
which keeps the bulk of the precipitation north/northeast of MPX
forecast area. The EC keeps the northern short wave further to
the west and allows more energy northward with the southern short
wave. This will allow for a broader area of precipitation to form
across southern Minnesota, vs the GFS Tuesday. The 12Z run of the
GEFS also supports the deterministic GFS which keeps the bulk of
the precipitation across central and northeast Minnesota.
Neither the GFS/EC doesn`t support a lot of QPF Monday
night/Tuesday morning when temperatures are close to the freezing
mark. Thus, if precipitation develops, it should be more drizzle
than steady rainfall as temperatures aloft will be warm enough.
Therefore, leading to a higher probability of icing. The forecast
will continue to support a mixture of freezing precipitation/snow
in areas where the depth of the moisture is greatest in central
Minnesota. Otherwise, no major impacts are expected.
Another element which is related to the northern wave influence of
the GFS is the faster ending of the precipitation Tuesday
afternoon before colder air arrives, changing the precipitation over
to snow. However, the EC, which holds both waves further to the
west/southwest, holds onto the precipitation longer and
eventually changes the precipitation over to snow late Tuesday,
into Wednesday morning. This could lead to light snowfall amounts
as far south as the Twin Cities by Wednesday morning.
Otherwise, the main extended period will transition to a cool
period for Wednesday, Thursday and Friday before more zonal flow
develops and temperatures begin to modify next weekend. 40s/50s
are still likely for next Saturday, and possibly into Sunday.
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 1054 PM CST Sun Feb 26 2017
Extensive low VFR ceilings late this evening along and north of a
warm front that stretches from west central MN through the south
metro to near KEAU. A few spots of MVFR ceilings to the west of
KMSP are moving northeast and may clip KSTC in the first couple
hours of the TAF. In addition, some light snow has formed in west
central MN and will lift northeast across KAXN through 08z with
MVFR or lower conditions occurring. The warm front will lift
northeast on Monday with VFR conditions occurring along with
southerly winds increasing to 10 knots. Low level moisture will
increase across the TAF sites Monday night as a low pressure
system moves our way from Nebraska. MVFR/IFR ceilings are likely
near the end of the TAF period for KEAU and for the rest of the
TAF sites after 28/06z. Drizzle will likely be developing as well
across southern MN and west central WI.
KMSP...There is a small threat ceilings could lower to 030 for an
hour in the 06z-07z time frame. Ceilings will lift there after
with VFR through the day on Monday. MVFR ceilings/vsbys/drizzle
developing after 28/09z. Ceilings could become IFR by daybreak.
/OUTLOOK FOR KMSP/
Tuesday...MVFR expected, IFR possible. Chance of light rain.
Southeast wind 5 to 15 kts becoming west.
Tuesday night and Wednesday...MVFR possible. Chance of light
snow. Northwest wind 10 to 20 kts.
Wednesday night...MVFR possible. Chance of light snow. Northwest
wind 5 to 15 kts becoming northeast less than 10 kts.
Thursday...VFR. North wind 5 to 15 kts.