Area forecast discussion National Weather Service Green Bay WI 352 am CDT Friday may 24 2013 Forecast discussion for routine morning forecast issuance Synopsis... issued at 343 am CDT Friday may 24 2013 Amplified upper pattern in place across noam...with upper troughs over the Pacific northwest and eastern noam...with a Sharp Ridge in between. The eastern trough will linger through the Holiday weekend...then pull off to the NE. Strong jet will work eastward across the Pacific the next few days...eventually adding considerable energy to the western trough. That will cause it to expand eastward into the plains during the latter half of the forecast period...with the downstream middle-continent ridge broadening and expanding eastward behind the departing eastern trough. The changes will eventually result in a longer wavelength pattern with upper trough centered over The Rockies...and broad ridging over most of the eastern Continental U.S.. Northwesterly upper flow has ushered a chilly air mass into the area...so temperatures will start out below normal. But a warming trend is expected during the period as upper heights rise...with readings reaching above normal levels by the middle of next weak. Humidities will probably also be on the increase. There is little chance for sig precipitation the next few days...but prospects for such will be much higher during the middle to latter part of next weak when the warm humid air arrives in the area and a frontal boundary likely sets up across the region. && Short term...today...tonight...and Saturday issued at 343 am CDT Friday may 24 2013 Quiet weather expected. Low-level anticyclone will linger across the Great Lakes region through Sat. Plenty of sunshine expected today. Guidance temperatures still seemed a little cool...so stuck close to previous forecast. Middle-level shortwave will force its way through the central noam ridge posn tonight...then turn southeast and head into the base of the eastern noam trough Sat. Upper speed maximum sliding down the eastern side of the upper ridge will be pulling through the lower Great Lakes region at the same time. The combination of forcing from the shortwave...divergence in the rrq of the upper jet...and some isent lift on the back side of the low-level anticyclone will lead to the formation of a band of precipitation to our west early tonight. That precipitation will push east toward the forecast area late tonight... but will encounter very dry air as it does so. Question is how far east precipitation can get before it wipes out. The models have struggled with this for several days...but now seem to be in comimg into better agreement. Followed the latest European model (ecmwf) and NAM...both of which suggest some light precipitation will brush the west late tonight and very early Sat morning before dissipating. Since we/ll probably have precipitation falling out of a middle-deck and into dry air at low-levels...opted to go with just sprinkles. The arrival of the clouds will mitigate the frost/freeze potential for the north...but the far NE could still fall off enough earlier in the night to allow some patchy frost. Once the shortwave shifts off to the southeast later Sat...dry air from the east will strengthen its grip on the area. That should lead to some decr in clouds during the day. Long term...Saturday night through Thursday issued at 343 am CDT Friday may 24 2013 Another cool night is in store for much of the area Saturday night. Areas of frost are possible again across portions of north- central and far northeast Wisconsin. As been the case the last several nights...the models continue to show differences in how far east convection from the plains makes into Wisconsin from Saturday night through Memorial Day. Have trended toward the more consistent European model (ecmwf) model for this time period...thus kept it dry for Saturday night through Sunday night. Again followed the European model (ecmwf) on Monday which indicated most of the precipitation would dry up by the time it reached Marshfield and Wisconsin Rapids. Do have a small chance of showers across the far southwest on Memorial Day just in case a few sprinkles or light showers sneak into central Wisconsin. A change in the weather pattern is expected next week as 500mb ridge builds across the eastern United by the end of the week. If the European model (ecmwf) is correct...we will be on the northern periphery of the 500mb ridge which is commonly known as the ring of fire. Could be an unsettled period from Tuesday through Thursday depending on how quick warm front left northward on Tuesday/Tuesday night and then where surface boundary/outflow boundaries from convection set up. With the amount of heat and humidity to the south of the warm front and on the convective parameters...some of the storms could become strong or severe and would also produce locally heavy rain. When this would occur it still very highly uncertain. Also maximum temperatures also problematic depending on timing of these convective complex...thus highs Wednesday/Thursday could be several degrees warmer if there is more sunshine than what is currently expected. && Aviation...for 12z taf issuance issued at 343 am CDT Friday may 24 2013 VFR conditions expected for the next few days. Even any sprinkles that develop late tonight/early Sat should be falling out of a middle cloud deck with high bases. && Grb watches/warnings/advisories... frost advisory until 7 am CDT this morning for wiz020-022-030- 031-035>040-045-048>050-073-074. Freeze warning until 7 am CDT this morning for wiz005-010>013- 018-019-021. && $$ Synopsis.......skowronski short term.....Skowronski long term......eckberg aviation.......skowronski