Area Forecast Discussion
Issued by NWS Twin Cities, MN

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FXUS63 KMPX 200352
AFDMPX

Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1052 PM CDT Wed Apr 19 2017

.SHORT TERM...(This evening through Thursday)
Issued at 358 PM CDT Wed Apr 19 2017

Early afternoon water vapor imagery together with RAP13 surface
analysis and obs identified an upper level wave across Nebraska with
an inverted surface trough extending into western Iowa. The warm
front associated with this surface trough was very evident via both
the surface obs and also the GOES16 satellite imagery. This warm
front tilted poleward with height, and an area of elevated showers
and thunderstorms was moving across the forecast area producing a
cool, light to moderate rain.

Expect a few hours of dry weather once this rain moves though, but
another round of precipitation will develop in the form of deep
convection in the warm sector of the aforementioned surface
trough/low. Supercells storms will quickly become severe across
Iowa, and a few of these storms could propagate north of the warm
front and produce a threat for large hail across the southern part
of our forecast area near I-90.

Cold air will rush in on Thursday as the parent cyclone quickly
matures. Forecast soundings show some instability atop the boundary
layer so have included chance of showers through Thursday afternoon
for the eastern part of the forecast area. Highs will struggle to
reach 50 for many locations.

.LONG TERM...(Thursday night through Wednesday)
Issued at 358 PM CDT Wed Apr 19 2017

Looking ahead, the weekend looks dry as high pressure builds across
the region. Precipitable water will drop below a quarter of an
inch. Expect light winds with seasonable temperatures. On Sunday
night an upper level wave will move across the high plains and
develop a compact surface low which will bring showers and
thunderstorms across the region. The mass fields in this system
appear quite similar to the storm system that is moving across
Iowa today, but the major difference is moisture content.

Next weeks storm will have lower dewpoints by about 10 to 15
degrees which means much less available potential energy and a
reduced severe threat. Could see some thunderstorms, but at this
point the instability is very marginal and the LCLs are too high
to merit more than a monitor phase. Cooler weather will follow in
the wake of this system, so could have a freeze concern in the
typical cold parts of the forecast area.

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1051 PM CDT Wed Apr 19 2017

MVFR/IFR ceilings will dominate across the TAF sites through much
of the period as a moist low level cyclonic flow encompasses the
region. Confidence is highest for the IFR ceilings in the 08z-16z
period. In addition, periods of MVFR visibilities will occur
overnight and Thursday in -RA/-DZ/BR. Improvement will begin
Thursday afternoon with ceilings lifting to VFR by evening. NE
wind overnight 10-15 knots becoming NW early on Thursday at 15
knots gusting 20-25 knots.

KMSP...IFR ceilings will spread in from the north and west shortly
after TAF issuance and persist through much of Thursday morning.
Periods of -RA/-DZ will also occur. Ceilings becoming MVFR
Thursday afternoon and then VFR early in the evening.

/OUTLOOK FOR KMSP/
Fri...VFR. Wind NE 5 kts.
Sat...VFR. Wind light and variable.
Sun...VFR. Wind NE-E 5 kts.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
WI...None.
MN...None.
&&

$$

SHORT TERM...JRB
LONG TERM...JRB
AVIATION...RAH



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