890 FXUS63 KMPX 100313 AFDMPX Area Forecast Discussion National Weather Service Twin Cities/Chanhassen MN 1013 PM CDT Tue Jul 9 2019 .UPDATE...For 06Z Aviation discussion below && .SHORT TERM...(This evening through Wednesday night) Issued at 254 PM CDT Tue Jul 9 2019 Model guidance has had a poor handle on timing the line of showers through the area today, averaging about 2-3 hours too slow with the evolution of the showers. As of mid afternoon, showers across eastern MN were continuing northeast at about 30 MPH in response to lead shortwave energy well out ahead of the main upper trough across Montana and the western Dakotas. The forcing has outpaced the instability, which remains across the Dakotas into far western MN. The expectation for the remainder of this afternoon and evening is for the line of showers continue to slowly weaken and exit the area to the east. Meanwhile, thunderstorms developing in North Dakota could lead to far west central MN seeing storms between 6-9 PM this evening, but those could skirt north of the area tied to the better forcing with the main trough approaching from the west. Overall, risk of storms is isolated. As the main trough axis pushes through tonight into tomorrow, the front will be sent southeast of our area. This will lead to lowering dew points into the upper 50s and lower 60s, as opposed to the upper 60s and lower 70 dew points present today. Lapse rates will steepen tomorrow with the main upper trough moving through, so made little change to the going forecast for isolated/scattered showers and a few storms possible. High pressure will work into the area tomorrow night, leading to clearing skies and light winds. .LONG TERM...(Thursday through Tuesday) Issued at 254 PM CDT Tue Jul 9 2019 The majority of the latter portion of the forecast period will be characterized by west northwesterly upper flow and the periodic passage of shortwave troughs embedded in that flow and associated precipitation chances. Toward the end of the period the upper ridge become more pronounced and heights rise more significantly across the area. Overall, the pattern lends itself to increasingly warm temperatures with humidity rising as well (particularly after the weekend). Model guidance is in decent agreement on the overall evolution of the large scale pattern, but the expected disagreements on the details lead to longer periods of chance PoPs as we get into the weekend and beyond. Tried to generally tie precipitation chances to identifiable shortwave features, but differences in timing and location make it tough to do so beyond Saturday. High pressure centered over the region will keep things dry and seasonably cool Thursday, with a shortwave trough and associated frontal boundary pushing across the area late Thursday night into Friday. Included some chance PoPs with that feature, but limited moisture return ahead of it should limit coverage to a large extent. More widespread precipitation is possible during the second half of the weekend as the upper ridge asserts itself and more robust warm advection is coupled with much better moisture return. After that things become a bit more uncertain, with the upper ridge position dictating whether we will be capped or in the path of occasional MCS propagation around the ridge. Given the uncertainty, higher chance PoPs over the second half of the weekend trend toward low chance PoPs for the first part of the week. The opportunities for very heavy rainfall will increase early next week as forecast precipitable water standardized anomalies increase above 2.5 across much of the area. && .AVIATION...(For the 06Z TAFS through 06Z Wednesday night) Issued at 1013 PM CDT Tue Jul 9 2019 Skies will be mostly clear overnight, with the only threat being the potential for patchy light fog from central MN into west central WI. Winds should stay up enough to prevent anything dense from forming, with MVFR visibilities being the worst case scenario at affected sites (KSTC-KRNH-KEAU). An MVFR-level stratus deck spreads in from the west on Wednesday morning, with additional (cumulus) clouds developing area-wide. While widely scattered showers/thunderstorms will be possible tomorrow afternoon, the anticipated coverage/probability is still too low to include in the TAFs. Southwest winds will shift to the west then northwest on Wednesday, with gusts to between 20 and 30 knots. KMSP...Could see the deck circa 2KFT go broken at times Wednesday afternoon, but overall 3KFT+ ceilings are expected at the site. Also can't rule out a shower, but the odds are too low to warrant a mention. /OUTLOOK FOR KMSP/ Thu...VFR. Winds NW 5 to 10 kt. Fri...VFR. Slight Chc TSRA/MVFR. Winds SW 5 to 10 kt. Sat...VFR. Winds light and variable. && .MPX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. && $$ SHORT TERM...SPD LONG TERM...TRH AVIATION...LS