000 FXUS63 KEAX 100558 AFDEAX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 1157 PM CST THU FEB 9 2012 ...UPDATED EVENING DISCUSSION... .DISCUSSION... Have added low chance pops for light rain to the far southern counties as northern edge of rain may graze that area. Latest progged soundings and upstream obs indicate mainly rain although there could be a small window of a couple hours where either rain or snow could fall. Have also adjusted temperatures to reflect a slower arrival of the approaching cold front. Low may actually be reached around 14z/15z and then become steady or slowly fall due to strong cold air advection on gusty northerly winds. MJ && .PREV DISCUSSION... /331 PM CST Thu Feb 9 2012/ It's been yet another cloudy day across the region, thanks in part to rather weak low level flow, stubborn stratus, and the continual advection of mid- upper level cloud cover ahead of a weak disturbance over Colorado. For tonight, weak upper shortwave to the west will gradually slide eastward overnight. Low-level warm advection will continue though the night as a weak prefrontal trough moves into the cwa by Midnight. Cloud cover is expected to remain fairly substantial through the overnight hours and light southwesterly winds will prevent temperatures from falling too substantially. As a result, have bumped up readings over much of the CWA. Friday: The much anticipated arctic front currently residing over the Dakotas will begin to overtake the prefrontal trough after midnight, surging into northern Missouri by 12Z. Cloud cover may thin just a bit ahead of the trough, but be quickly replaced by an elongated band of MVFR to IFR stratus. Given ongoing trends in the Dakotas will introduce flurries to the grids for Friday morning. Min and max temperatures will likely occur within a few hours of each other on Friday. Given the time of arrival of colder air tomorrow morning, max temperatures may occur in the morning, with temperatures flatlining or falling throughout the day. Friday night into Saturday: A 1046 mb surface high will begin to push toward the CWA. Skies will generally be clear, absent some lingering cirrus spilling over the Rockies. High temperatures on Saturday will struggle to climb out of the teens near the Iowa border, with lower to middle 20s further south. Saturday night: Depending on where the core of the surface high resides, temperatures may plummet by Sunday morning. In fact, given the amount of dry air mixing down Saturday afternoon, decent radiational cooling could force temperatures into the single digits in many areas. Dux Medium Range (Sunday through Thursday)... Sunday - Tuesday: Models in good agreement through this period as NAM/EC/GFS all advertise cold high pressure dominating the area on Sunday. Late in the day on Sunday/Sunday night high pressure shifts eastward. A fast moving upper shortwave will move from the Central Rockies into the Western Plains. Out ahead of this system, on the back side of the surface high pressure, Gulf moisture will begin to stream back northward as a 40kt southerly LLJ enhances WAA into the region. As the upper shortwave approaches the region on Monday morning... light precipitation will over spread the forecast area. With cold air in place...precipitation will fall in the form of snow and it is looking more likely that it will bring our first real accumulating snowfall to much of the area. Consensus models are producing total snowfall amounts of 1-3 inches. This upper level system again will be a fast mover with just very light rain/snow or even drizzle expected by Monday afternoon. Otherwise, by Tuesday, surface high pressure will build back into the area as weak upper level ridging builds into the region in response to another upper level trough digging southward along the Pacific Coast. High temperatures by Tuesday should rebound into the mid 30s to mid 40s. Wednesday - Thursday: Model solutions diverge through this timeframe as the EC and GFS differ in their handling of the evolution of the Pacific system. The GFS is much more progressive in moving the trough quickly across the Rockies Tuesday night into Wednesday bringing rain to the forecast area on Wednesday. The EC, on the other hand, takes a piece of the energy from the system in the form of a weak shortwave and moves it towards the area by Wednesday night producing at best a few light showers. The main system however continues to dig southward along the Pacific Coast before closing off over the Baja where it moves little through Thursday. To account for the wide array of precipitation chances through the period have not strayed from the initialization. 73 && .AVIATION... For the 06Z TAFs: MVFR cigs have remained in place as expected and will continue into the pre-dawn hours until passage of the upper trough. Still think there is a window of several hours when low clouds will be scoured out before arrival of post frontal stratus. Satellite imagery still supports MVFR cigs reaching the terminals shortly after sunset. Much drier air will quickly pour in and should scour out these low clouds by late morning. Blustery north winds with gusts in the mid to upper 20s likely for the daylight hours but pressure gradient will support stiff winds into Friday evening. MJ && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ WFO EAX