Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 221716

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1216 PM CDT Mon Apr 22 2019

.SHORT TERM...(Today through Tuesday)
Issued at 419 AM CDT Mon Apr 22 2019

Surface analysis early this morning shows a low pressure center
near KOMA with a quasi-stationary front extending northeast into
northeastern WI and a cold front extending southwest across
Nebraska into western Oklahoma. Aloft, split flow has nearly zonal
flow along most of the Canadian international border while a
pivoting H5 trough lumbers east over South Dakota through Kansas.
This trough, taking on a negative tilt, will nudge the surface low
ENE today through tonight, moving it to the Iowa/Wisconsin border
by this evening and into northern Michigan by Tuesday morning.
The trough will open up and evolve over the MN/WI border by Monday
evening, helping push the surface low away from the WFO MPX
coverage area Monday night. Drier northwest flow aloft will then
accompany incoming high pressure for Tuesday.

KMPX radar this morning shows plenty of rain/thunderstorm activity
over western through central MN in a generalized SW-NE
orientation, akin to the frontal boundary orientation over the
area. Moisture depth is certainly not an issue as PWATs over much
of the coverage area is around 1". Given the orientation of the
upper trough and fairly deep southerly flow off the surface in
advance of the surface low, additional moisture advection is not
much of an issue for this low. Pockets of heavy rain are certainly
viable thru the rest of this morning and the first half of the
afternoon as the low slowly shifts east across northern IA and the
leading front punches N into southern MN and central WI. Spotty
0.5"-1.0" hourly rates would not at all be unreasonable, with
overall totals in the 1-2" range feasible through this event. The
spotty nature of the heavy rain plus relatively drier soils after
the snowmelt precludes any kind of flood watch but mention of
heavy rain is made in the Hazardous Weather Outlook (HWO). As for
thunderstorm potential, MUCAPEs this morning are only in the
250-500 j/kg range and much of that is elevated. So while some
spotty CC/CG lightning strikes are certainly possible, no
strong/severe thunderstorms are expected. There may be some
clustering of storms which may also lead to heavier rain and
possibly some stronger wind gusts but all activity is expected to
be sub-severe.

The precipitation will gradually diminish in terms of intensity
and coverage as the afternoon progresses, with only scattered
showers remaining for far eastern MN into western WI this evening.
By midnight, all precipitation looks to be east of the WFO MPX
coverage area, thus no longer an issue. Skies will then gradually
clear out late tonight through Tuesday morning, allowing for
plenty of sunshine and mild conditions for the rest of Tuesday as
drier high pressure moves into the area.

As for temperatures, the warmer and more unstable conditions will
remain to the south of the frontal boundary and low pressure
system, thus keeping cooler low level ENE flow in place today.
Highs will only range from the upper 40s to around 60 degrees
today. As the system exits to the east tonight, modest cold air
advection will kick in, helping drop lows into the 30s area-wide.
On Tuesday, plenty of sunshine will aid in allowing highs to climb
into the 60s area-wide.

.LONG TERM...(Tuesday night through Sunday)
Issued at 419 AM CDT Mon Apr 22 2019

Wednesday will start out warm, with highs expected to warm back
into the 70s as 850 mb temperatures increase to 10-12 C ahead of
a frontal boundary to our northwest. This front drops through the
area Wednesday evening, but brings little cold air behind it
along with fairly dry air to work with. Some scattered showers
look possible Wednesday night as the front passes and divergence
aloft increases, but precipitation amounts are expected to remain

Models have come into a bit more agreement with handling the next
system, as split flow aloft transitions into an active jet stream
setting up overhead towards the weekend. The first of these waves
look to approach on Friday, but little moisture in place should
keep us dry. A stronger wave approaches sometime on Saturday, with
a surface low developing over the central Plains and skirting
across southern MN/northern IA. This system looks to be our next
shot at widespread precipitation, and potentially heavy
precipitation as PW values again surge above 1". Temperatures are
still all over the place with this system however, with a 20-30
degree spread between the GFS/CMC/ECMWF Saturday afternoon. The
GFS brings the warm sector into southern Minnesota along with a
thunder threat, while the ECMWF keeps temperatures in the 30s and
40s along with a cold steady rain. Until models converge on these
details, it`s tough to mention any specifics, but the
precipitation does now appear more likely on Saturday. The active
jet remains overhead into early next week along with continued
unsettled weather.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1210 PM CDT Mon Apr 22 2019

Isolated TSRA`s are still possible in south central/southeast
Minnesota, as well as west central Wisconsin this afternoon.
However, coverage will be too small to include in the TAF, with
the exception of KEAU. Otherwise, high end IFR/low end MVFR will
continue this afternoon with scattered/numerous SHRA across the
eastern 1/2 of MPX TAF area. Only KAXN will have VFR conditions
throughout the TAF period. Skies will begin to clear from
northwest to southeast overnight with VFR conditions throughout
the area by 18z Tuesday. Gusty north/northeast winds will continue
through the evening, but decrease and become west by Tuesday


Occasional IFR cigs are possible this afternoon, with SHRA. MVFR
cigs will develop late this afternoon/evening, with VFR after 4z.
Confidence in IFR/MVFR cigs are high this afternoon along with a
north/northeast wind of 12-14 kts, gusting to 22-24 kts.


Wed...VFR. Wind SW 10-15G25 kts.
Thu...VFR. Chance -RA early a.m. Wind bcmg NW 10-15 kts.
Fri...VFR. Wind W 5-10 kts becoming SW late.




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