Scientific Forecaster Discussion
000 FXUS63 KPAH 180814 AFDPAH Area Forecast Discussion National Weather Service Paducah KY 314 AM CDT Wed Oct 18 2017 .SHORT TERM...(Today through Friday night) Issued at 134 AM CDT Wed Oct 18 2017 The short term forecast will see surface High pressure holding strong/shifting east, and returning low level southerlies to the FA. H5 heights, already starting to rise, will build some additional 60 meters plus by Friday, as its ridge axis builds across the Mississippi and Tennesse river valleys. 850 MB temps respond with a good 4-5C increase over the course of the short term forecast. Time/height cross sections show a predominantly dry column save for some moisture showing up at/above 400 mb off and on thru the period, mostly Friday. All of this adds up to us, and neighboring offices, favoring a collaborative nudge upwards from the blend, for High temps daily, similar to how we've done each of the past couple nights. Other weather features of note include early morning fog, esp near water bodies, probably most pronounced this morning. In addition, driest rh mins in the pm hours will range thru the 30s percentile, w/the SEMO Ozarks again experiencing the lowest of these min RH's. .LONG TERM...(Saturday through Tuesday) Issued at 313 AM CDT Wed Oct 18 2017 A cold front will be approaching the middle Mississippi valley on Saturday. ECMWF, GFS and the Canadian are in good agreement showing the front reaching the western fringes of the PAH forecast area by 12z Sunday. A few showers and thunderstorms may reach our far southwest counties Saturday afternoon, with showers and thunderstorms becoming scattered to widespread Saturday night across all but our far east counties. Confidence is pretty high that we will see widespread precipitation across the entire region on Sunday into Sunday night. Despite the agreement in frontal position Sunday morning, all models have been going back and forth on timing of the movement of the front late Sunday night into Monday night. The latest ECMWF has the front across our region by 06z Monday, while the previous run had it through by 00z Tuesday. The latest GFS takes the front through by 12z Tuesday, while the previous run had it through by 12z Monday. The inconsistency of the models leads to low confidence for Monday and Monday night. Went with slight to low chances Monday into Monday night, with the best chances across our eastern counties, and dry conditions in our west by late Monday into Monday night. Went with dry conditions across the entire area on Tuesday for now. Models continue to indicate the best instability across our area will be Saturday night into early Sunday, so this is when the best thunderstorm chances are included. Went with slight chances of thunderstorms Sunday afternoon decreasing to just showers from northwest to southeast by Sunday night. It will remain very warm ahead of the front on Saturday into Saturday night with breezy south winds. Readings will drop off to near seasonal on Sunday with the precipitation and cloud cover, near seasonal conditions by Monday, then below seasonal by Tuesday with breezy northwest winds. && .AVIATION... Issued at 134 AM CDT Wed Oct 18 2017 IR Satellite pics reveal sharp contrast between warm water/cool land and offer best areal zones for another pre dawn development of Fog, already showing up at some local sites if not yet at terminals. These could result in some short lived drops in vsbys or low lift/cloud heights prior to/just after sunrise, similar to Tuesday morning. High pressure controls an otherwise VFR forecast, but southerly return winds do pick up this pm, with some gusts into the teens kts possible at times. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...None. MO...None.