Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 290816

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
316 AM CDT SUN MAY 29 2016

.SHORT TERM...(Today and tonight)
Issued at 330 AM CDT Sun May 29 2016

Confidence is low with the forecast this morning with regards to
precipitation chances. We currently have an upper low over central
Minnesota that is moving very slowly east. Cloud top cooling has
been occurring around the low since midnight with showers increasing
in coverage and intensity across portions of central Minnesota as
well as southeast Minnesota and west central Wisconsin. It`s the
showers in central Minnesota that are troubling. The CAMS are having
a tough time with the showers with several indicating them too far
north. Others that use a hot start fade the showers in 1 to 2 hours
which has not been the case. Therefore, opted to drive scattered
showers all the way southeast through the Twin Cities early this
morning before allowing things to diminish some off to the east.

This then feeds into what happens from late morning onward as more
showers are shown in the CAMS developing from Alexandria all the way
down to the Iowa border and then back northeast across west central
Wisconsin. Feel a little more confident about these showers given
the steep lapse rates seen from the SFC-700 mb along with a skinny
CAPE profile. The showers shouldn`t be too widespread with isolated
wording used in the forecast. The showers will fade early this
evening will the loss of daytime heating and ridging aloft spreading
in from the west.

It will be dry from late evening onward. A concern overnight is the
potential for fog development, especially from central Minnesota
through west central Wisconsin. These areas have the lowest temp/dew
point spreads under weak high pressure. You also have the damp
ground from the recent rains. Indicated areas of fog developing
after midnight for the aforementioned areas.

Highs forecast for today remain on the high side of most guidance.
The forecast is closer to the NAM then anything else given some
breaks in the cloudiness during the afternoon along with the cold
trough at 850 mb moving east of the area. Little change to the lows
forecast for tonight with around 50 in the central Minnesota to the
upper 50s in the Twin Cities on southward.

.LONG TERM...(Monday through Saturday)
Issued at 330 AM CDT Sun May 29 2016

The longer term concerns are the development and movement of the
next closed low moving through the northern stream Tuesday
through wednesday night.

initially on monday...waa/theta-e advection lifts northeast
across the southwest portion of the cwa by Monday evening. We
will likely see at least some elevated thunder develop perhaps as
early as Monday morning over the far southwest per latest trend
of the NAM WRF and ECMWF which both paint some light qpf into
southwest MN before 18z. Instability increases with the surface
warm front lifting northeast into southwest MN monday night. This
should generate more widespread activity along with some threat
large hail and wind gusts into Monday night.

On Tuesday...CIPS Analog guidance is indicating at least a chance
of severe weather as the trough swings east along with a surface
cold front. The 00z gfs was showing moderate instability
developing and increasing shear as the trough approaches. Only
real limiting factor will be cloud cover/heating concerns with
possible morning activity lingering. This shifts east tuesday
night and should take any significant thunder threat with it.
Rainfall for the Monday night through Tuesday night period
approaches the 1 inch mark for most of the cwa. With PW`s
increasing to 1.5 inches...this looks feasible considering the
amount of forcing indicated. As the trough exits the area
wednesday...we still could see some showers/perhaps some isolated
thunder as it moves through into Wednesday night.

The warmest day of the upcoming forecast looks to be Memorial Day
with some lower 80s indicated. We should see plenty of sunshine at
least early in the day...with increasing mid/high level clouds
from the west during the afternoon. After that...we trend to
below normal through Thursday with the passage of the trough.
Then warmer conditions develop with increasing sunshine. Some
chance of showers/thunder returning to the area next Friday night
into Saturday as both the GFS and ECMWF bring in a frontal system


.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1110 PM CDT Sat May 28 2016

There is a mix of VFR/MVFR ceilings out there this evening. We
think some of these low clouds will expand tonight and could even
lower with time. We are not completely sold on this scenario,
especially given the time of year, but the moisture will hang
around tonight and any amount of nocturnal cooling should help
keep the low clouds in place. Our computer models disagree on how
low the clouds get tonight, adding to the uncertainty.


MVFR conditions are possible late tonight and early tomorrow
morning given all the residual moisture low in the atmosphere.
It`s also possible the airport bounces from VFR to MVFR tonight.

MON...Mainly VFR. Chance of MVFR and -TSRA late. Winds S 5-10KT.
TUE...Mainly VFR. Chance of MVFR, -TSRA likely. Winds S 10-20KT.
WED...Mainly VFR. Chance of -SHRA. Winds W 10-20KT.


.MPX Watches/Warnings/Advisories...


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