Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/26/17

Area Forecast Discussion
National Weather Service Green Bay WI
517 PM CST Sat Feb 25 2017 Updated aviation portion for 00Z TAF issuance .SHORT TERM...Tonight and Sunday Issued at 224 PM CST Sat Feb 25 2017 The latest RAP analysis and satellite/radar imagery show a large low pressure system continuing to exit the region over northwest Quebec. Cloud cover, snow showers, and flurries wrapping around the low are persisting early this afternoon over north-central and eastern Wisconsin. The back edge of the clouds are pushing into western Marathon and Wood counties, and should exit northeast Wisconsin by late this afternoon or early this evening. Looking to the west, a corridor of clearing has moved into western Wisconsin and eastern Minnesota in close proximity to a surface ridge axis. The next system, however, is already diving southeast across the northern Plains with scattered snow showers over North Dakota and northern Minnesota. Forecast concerns revolve around cloud trends this afternoon, followed by snow shower chances late tonight into Sunday with this next system. Tonight...A weak surface ridge axis will pass across the area and provide a brief period of clearing during the first half of the evening. Then will see increasing clouds again from the west as warm advection pushes in aloft ahead of a weak shortwave. Saturation looks deep enough over north-central and central WI for a chance of snow showers overnight, but not expecting much in the way of accumulations. With cloud cover and a tight pressure gradient, low temps should not fall much, and will go with lows in the teens. Sunday...That shortwave will slide across the area while pushing a cold front into central and north-central WI. The front looks relatively sharp with decent convergence that will provide a focus for snow shower development with heating of the day. Would not be surprised if a few snow showers become briefly heavy given mid-level lapse rates around 7 c/km. Up to an inch of snow looks possible over Vilas county. Chances of snow showers are less over eastern Wisconsin but dont think can rule them out with passage of the shortwave and aforementioned lapse rates. High temperatures will rise to near 30 degrees in the north, to the middle 30s south and east. .LONG TERM...Sunday Night Through Saturday Issued at 224 PM CST Sat Feb 25 2017 A weak ridge near the surface will help keep the area dry Sunday night and into Monday night, ahead of an approaching surface low with associated upper level trough. As precipitation enters the region, a brief period of wintry mix is expected to move across areas of northern Wisconsin while rain remains the primary weather type towards the Fox Valley. As warm air advection takes over near the surface in the mid to late morning, rain will overspread the remaining areas in the north. A slow switch back to snow is anticipated in the evening. This transition will spread north to south as weak cold air advection filters in behind this system. A brief break in the action is expected as some dry air works its way in the back end of this system in the early morning Wednesday before another shortwave comes through to fill in some additional snow shower chances for Wednesday morning to afternoon. A brief clipper system is still expected to follow Thursday as northwesterly flow dominates, bringing additional snow chances mainly to the northern areas. Weak lake effect snow signals then linger on into next weekend. A warming trend is expected ahead of the trough through Tuesday as temperatures rise to well above normal, followed by a slow cooling trend back to near normal by Thursday. Northwesterly flow into the weekend will then bring temperatures to a few degrees below normal by Saturday. && .AVIATION...for 00Z TAF Issuance Issued at 517 PM CST Sat Feb 25 2017 A brief period of clearing will track through the region this evening, before additional clouds arrive from the west ahead of a weak clipper system. These clouds should lower overnight into low mvfr range over central and north-central WI, with potential for scattered light snow flurries/showers. Scattered snow showers will likely persist across northern Wisconsin for much of Sunday with arrival of a cold front, and possibly push into the Fox Valley/Lakeshore areas during the morning. IFR visibilities will be possible within any snow showers. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......Uhlmann AVIATION.......Kurimski
Area Forecast Discussion
National Weather Service Phoenix AZ
859 PM MST Sat Feb 25 2017 .SYNOPSIS... Slightly cooler than average temperatures will persist through early next week as two fast moving weather disturbances move into the region Sunday, then again Monday night and Tuesday. The weather system Monday night and Tuesday will have best potential for spreading rain across the area. Dry conditions and much warmer temperatures will return by the middle of next week. && .DISCUSSION... Latest water vapor imagery shows a well-defined vort max at the base of a short-wave trough across the northern California coast extending eastward into the intermountain West. However, there is little precipitation to show for it at the present time. Latest model guidance continues to indicate that mid and high clouds will stream across the forecast area tonight. Most recent runs of the HRRR suggest conditions will continue to moisten in the lower- levels of the atmosphere late Sunday morning and early afternoon for a few showers across the lower deserts. However, any rain that develops is expected to be brief and light. In the short-term, only minor adjustments were needed to the temperatures and dewpoints. Otherwise, the forecast remains on track. && .PREVIOUS DISCUSSION... High clouds continue to stream eastward across southern and central California within predominantly westerly flow established over the Southwest. Slightly below-normal temperatures will continue today and tomorrow as midlevel heights remain suppressed with an active storm track to the north. A series of upstream shortwave troughs, noted as two features evident on water vapor off the northern California coast and near the Alaska Panhandle, respectively, will move through the region through mid-week. The first will be a fast-moving system that will deamplify while rapidly moving eastward tomorrow. Forcing for ascent associated with this feature will be rather focused, and could produce some showers across central and northern portions of Arizona, but the lack of moisture will limit the potential for any widespread or substantial precipitation. Slight chance PoPs exist tomorrow morning and afternoon across roughly the northern half of the CWA, including the higher terrain of Maricopa and southern Gila counties, and Joshua Tree National Park. An increase in mid-to- high-level clouds is also expected. Attention then turns to a more substantial upper trough which will deepen along the Pacific coast through Monday. This feature will phase with a narrow southern stream plume of moisture, and bring increased rainfall potential beginning late Monday and Tuesday. Similar to the last major system, the trajectory of the preceding moisture plume should favor the most widespread precipitation across central and northern portions of Arizona through early Tuesday, before shifting into eastern Arizona by late Tuesday. As a result, PoPs have been adjusted upward again for Monday evening and Tuesday. QPF amounts have also been increased to be more in line with the latest WPC guidance, with roughly 0.5-1 inch expected from near Phoenix and areas to the north/east. A few of the higher elevation locations may locally receive over one inch of rain. Given the orientation of the moisture plume relative to the positively tilted system, snow levels should remain high enough to preclude snowfall over the higher elevations of southern Gila and northeast Maricopa counties. A second, drier disturbance is forecast to move through the area Wednesday, but will be moisture-starved, before more substantial midlevel ridging builds over the western CONUS and ushers in a return of above-normal temperatures and dry conditions late next week. && .AVIATION... South-Central Arizona including KPHX, KIWA,and KSDL: Southeast California/Southwest Arizona including KIPL and KBLH: A low pressure system centered off the northern California Coast will weaken as it moves inland. It will spread increasing cloudiness over the forecast area from west to east tonight through Sunday morning with ceilings getting progressively lower. However, anticipate ceilings to remain above FL080. There will be a lot of virga with some spotty very light showers/sprinkles reaching the ground (mainly after 10Z over southeast CA and after 14Z over south-central AZ). Westerly winds aloft will strengthen with the passage of this system. Westerly surface winds will strengthen over southeast California tonight with occasional gusts of 20-25 kts (especially over, and west of, the Imperial Valley). Those breezes will slowly expand eastward during the day Sunday. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Monday through Friday... A Pacific low pressure system will bring good chances of wetting rains mainly Monday night through Tuesday morning focused especially across the high terrain of Arizona. Below normal temperatures are expected through next Wednesday with a significant warming trend likely late next week. Breezy conditions for Monday and Tuesday are expected in most areas with breezy conditions persisting down the Lower Colorado River each afternoon through at least Thursday. Increased humidities with minimum readings between 25 to 35% through Tuesday will dry out starting Wednesday with afternoon readings closer to 15% over the deserts for Wednesday through Friday. && .SPOTTER INFORMATION STATEMENT... Spotter reports will not be needed through the weekend. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook, Twitter, and at DISCUSSION...Hirsch PREVIOUS DISCUSSION...Rogers AVIATION...AJ FIRE WEATHER...Kuhlman