Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/31/18

Area Forecast Discussion
National Weather Service Green Bay WI
909 PM CST Tue Jan 30 2018 New Information added to update section .UPDATE... Issued at 902 PM CST Tue Jan 30 2018 Backed off on pops a bit for the late evening and early overnight hours, then increased pops over northern WI later tonight into Wednesday morning. Also increased QPF and snowfall amounts a bit over the north, and especially far northeast WI. There is some concern that a winter weather advisory may be needed for Door county (for 2-4 inches of snow north of Sturgeon Bay), but confidence is just a little too low to pull the trigger on it at this time. We upgraded our small craft advisory to a gale warning earlier this evening, after coordination with MKX. Gusts are already pushing 30 kts, and we should get occasional gusts to 35 kts overnight. && .SHORT TERM...Tonight and Wednesday Issued at 243 PM CST Tue Jan 30 2018 The latest RAP analysis and satellite/radar imagery show a strong area of low pressure passing across the Saskatchewan/Manitoba border early this afternoon. In the warm advection ahead of the low, mid-level fgen is producing an area of light to moderate snow which is crossing into NW WI. This band of snow remains on track to move into the Vilas-Wood county corridor between 3 and 4 pm and the I-39/route 51 corridor between 4 and 5 pm. A quick half inch to inch of snow could fall right at evening commute time which could make for some slippery roads, so will issue a SPS. A cold front trails the low over NW ND, and will arrive late tonight. Forecast concerns mainly revolve around light snow chances and trends. Tonight...A strong cyclone will track east across Manitoba and Ontario tonight and Wednesday. The RAP and HRRR agree that mid- level fgen in the warm advection zone ahead of the cyclone will push a band of light snow across the area from late this afternoon through about mid-evening. Because the band will be moving east relatively quickly, mainly looking at around a half inch of accumulations, though isolated locations over northern WI could see up to an inch. Forcing with the tail of the main shortwave and along a weak surface cold front will then generate a second band of light snow after midnight across north-central and northeast WI. An inch or two of snow is possible across the north, with lesser amounts in central and east-central Wisconsin by morning. With the clouds and gusty southwest winds, temps will be considerably more mild tonight that yesterdays readings, and range from the mid teens in the north to mid 20s south. Not much of a change from todays high temps. Wednesday...The light snow will be exiting northeast WI during the morning. Up to an additional half inch will be possible over Door county. Combined with the snow that will fall tonight, slick roads can be expected for the morning commute. Behind the front, drier air will invade the region from the northwest to southeast from about mid-morning through early afternoon. Should therefore see ample sunshine in the afternoon with highs ranging from the mid 20s in the north to mid 30s in the south. .LONG TERM...Wednesday Night Through Tuesday Issued at 243 PM CST Tue Jan 30 2018 Very cold wind chills and the prospect of snow for Friday night and Saturday are the primary weather concerns for this period. A strong upper trough will swing across the area Wednesday night accompanied by a cold front at the surface. The air is dry but there should be sufficient support for light snow. The NAM and ECMWF look on the right track with this, while the GFS is dry. Think around an inch is likely. The cold front will be followed by much colder air Thursday and Friday. Wind chill advisories are likely north and west of the Fox valley Thursday night. Surface waves moving northeast along an arctic cold front should bring some snow Friday night and Saturday. Model differences are too big to determine exact snow amounts, but a few inches look possible. Even colder air will arrive Saturday night and with a fresh snow cover temperatures should fall below zero across the entire region. Wind chill warnings and advisories look likely. Temperatures could remain below zero from Saturday night through midday Monday in far northern Wisconsin. && .AVIATION...for 00Z TAF Issuance Issued at 538 PM CST Tue Jan 30 2018 A band of snow with MVFR/IFR conditions will quickly shift east through the forecast area this evening, and should taper off within the first hour of the TAF period at the western sites, and during the mid to late evening in eastern WI. A lull in the snow and mainly mid-level clouds will occur late this evening into early overnight. Then additional snowfall with MVFR/IFR conditions will develop along a cold front late tonight into early Wednesday morning. MVFR ceilings may linger for a few hours after the snow ends Wednesday morning, but partial clearing and VFR conditions are anticipated for the late morning and afternoon. LLWS will overspread the entire area through mid-evening, then ease from west to east late tonight into early Wednesday. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE.........Kieckbusch SHORT TERM.....MPC LONG TERM......RDM AVIATION.......Kieckbusch
Area Forecast Discussion
National Weather Service Lincoln IL
849 PM CST Tue Jan 30 2018 .UPDATE... Issued at 840 PM CST Tue Jan 30 2018 Latest satellite data indicating a large area of mainly high level clouds across the region this evening in advance of a frontal boundary that will push across our area on Wednesday. A tightening pressure gradient from the departing high pressure system that brought the cold weather to our area this morning and low pressure tracking just north of Minnesota this evening has brought gusty south winds to central Illinois. A few gusts around 35 mph have been reported early this evening and expect that to continue overnight. That, coupled with the extensive shield of high level clouds, will keep temperatures steady or even rise a few degrees overnight. Not looking that favorable for viewing the lunar eclipse towards dawn on Wednesday as the cirrus shield extends west of the Missouri River this evening. The HRRR does indicate a few breaks develop in that band of clouds over central Illinois late tonight but based on what we are looking at on the IR loop this evening, not looking that promising at this time. As the cold front moves across the area, the stronger winds should translate into eastern Illinois during the morning with rather mild temperatures expected as highs top out in the upper 40s north to the lower 50s over southwest Illinois. Colder weather moves back into our area later Wednesday and for the rest of the work week with early morning lows on Friday dropping back into the single digits over all but far southeast Illinois. Made some minor adjustments to the wind/wind gusts this evening, but for the most part, the grids are in great shape. As a result, no ZFP update will be needed at this time. && .SHORT TERM...(This evening through Wednesday) ISSUED AT 320 PM CST Tue Jan 30 2018 The short term will be highlighted by increasing southerly winds tonight into tomorrow morning, as a 60KT southwesterly low level jet (LLJ) cranks up in the 2-4K FT layer. The surface pressure gradient will be tightening up over night, as high pressure departs to the southeast of IL and a low pressure system approaches from the Plains. Sustained south winds look to climb into the 15-25 mph range, with gusts of 30-35 mph at times after midnight and into Wed morning. The combination of strong south winds and gradually warming low to mid levels will create a non- diurnal temperature profile overnight. Low temps will most likely be in the evening, with temps either steady or slowly rising as the night progresses. Evening lows tonight will be in the upper 20s to low 30s, with temperatures by 6 am in the low to mid 30s and climbing. A warm front is expected to lift to the northeast across Illinois Wed morning, to aid in the warm-up. Despite 850 mb temps peaking in the 4-6C range just before sunrise then falling off slightly during the day, high temps should be able to climb into the upper 40s to low 50s. South wind gusts will begin to subside from west to east Wed afternoon, as the cold front progresses to near I-72 by 6 pm, and the surface pressure gradient weakens. Previous model runs had some sprinkles developing as early as Wednesday afternoon, but the 12z models have delayed much in the way of precip until after midnight Wed night. .LONG TERM...(Wednesday night through Tuesday) ISSUED AT 320 PM CST Tue Jan 30 2018 The cold front is expected to stall out just south of our southeast counties Wed eve, and a 500 mb vort max is expect to progress east along the front. That will help create some forcing for precip in our east counties between midnight and 6 am, and for areas south of I-70 Thursday morning. We have narrow areas of slight chance and chance PoPs /15-30%/ from late Wed night into Thursday afternoon. Precip type looks to start out as a mix of rain and snow or all snow Wed night, then transition to all rain as temps warm on Thursday. Flurries could develop well north of the front Wed night into Thur morning, north of I-74 where another 500mb wave pushes across northern IL. Overall, little to no snow accumulation is expected from this system, as the better forcing for precip has continued its southerly trend. A cold blast of air will follow that front, as Arctic high pressure builds into Illinois. Low temps Thurs night will drop into the single digits north of I-70, with low teens south of I-70. The other issue Thursday night into Groundhog Day morning will be gusty northwest winds of 10-20 mph putting wind chills down to -5 to -10F. A transition to southerly winds Friday afternoon will begin a brief warming trend into Saturday, before another strong cold front pushes across IL Saturday night. Highs Saturday should climb to near normal for early February, but a reinforcing push of cold air will change the last half of the weekend into early next week. The cold front looks to have enough F-gen forcing for light snow to progress across Illinois Saturday afternoon and Sat night. Snow amounts look to remain light, with a half into to an inch for areas along and north of I-74, and lesser amounts the farther south of I-74 you go. High pressure should provide dry conditions for Sunday and Monday, along with below normal temperatures. Lows Sunday night may drop to colder numbers than Thursday night, especially if any snow cover remains into early next week. Another shortwave could trigger light snow late Monday afternoon through Tuesday, with some light snow accumulation possible. However, there are large differences in position and track of the weather features, so PoPs were kept low for now. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 515 PM CST Tue Jan 30 2018 Main forecast concern will be with the LLWS threat tonight into Wednesday morning. Forecast soundings and time height cross sections indicate 45-55 kt winds between 1500-2000 feet tonight into Wednesday morning out of the south to southwest. We look for the winds to gradually subside after 16z Wednesday as a frontal boundary approaches the forecast area during the day. Mainly some VFR mid and high level clouds around tonight and Wed with surface winds gusty out of the south at 12 to 17 kts with gusts up to 25 kts. Surface flow will then veer into the southwest and west as the front approaches Wednesday morning with speeds decreasing to 10 to 15 kts after 18z. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Smith SHORT TERM...Shimon LONG TERM...Shimon AVIATION...Smith
Area Forecast Discussion
National Weather Service Marquette MI
1020 PM EST Tue Jan 30 2018 .UPDATE... Issued at 1020 PM EST TUE JAN 30 2018 So far, fcst appears to be on track. WAA/isentropic ascent generated band of snow is quickly spreading e across the area. This snow is generally on the light side, but there should be some enhancement off Lake MI over the eastern fcst area as the snow progresses eastward. This snow should then tend to diminish for a while overnight. Of a bit more concern is the pcpn breaking out across mainly SD recently. This pcpn is tied to a shortwave and more importantly to the left exit of 130kt upper jet streak. 00z NAM and hourly RAP runs this evening show a rather impressive upper divergence signature taking shape across central and eastern Upper MI late tonight/Wed morning as nose of this upper jet shifts e to WI by 12z Wed. It appears there will even be some coupling with the right entrance of a 100kt upper jet streak located ne of Lake Superior, boosting the upper divergence depicted by the models. NAM/RAP/HRRR show a corresponding increase in qpf over the central and eastern fcst area early Wed morning. So, may see 1-2hrs, maybe 3hrs, of mdt/hvy snow in the 6am to 10am time frame across the e half of the fcst area, just in time for the morning commute. Thus, ongoing advy over the eastern fcst area appears on track. Dickinson/Marquette/Menominee counties will also be impacted by the intensifying area of snow. Increased snow amounts some in these counties. Given the timing of the snow in this area just before and during the morning commute, may need to consider an advy issuance for these 3 counties later in the night, depending on how upstream developing pcpn evolves over the next several hrs. && .SHORT TERM...(This evening through Wednesday) Issued at 410 PM EST TUE JAN 30 2018 WV imagery and RAP analysis indicated nearly zonal mid/upper level flow from the Pacific Northwest through the n cntrl CONUS. A vigorous shortwave trough extended from n cntrl Manitoba into the nrn plains. At the surface, a trough extended through the cntrl Dakotas from a 988 mb low over w cntrl Manitoba. Radars/obs indicated a band of snow from ne MN into wrn WI supported by strong WAA 285k-295k isentropic lift ahead of the trough. Otherwise, mid/high clouds were thickening across Upper Michigan ahead of the snowband. Tonight into Wednesday, models and radar trends suggest that the initial snow band will move across the cwa this evening with a lull overnight before the snow increases again from 06z-09z as 700-300 mb qvector conv associated with the Dakotas shrtwv moves in. Overall snow amounts should remain in the 1 to 3 inch range over most of the cwa. However, lake enhancement with srly flow off of Lake Michigan will bring the potential for heavier snow in the 3 to 7 inch range, especially east of a line from Manistique to Grand Marais. There is still some uncertainty with the additional amounts given the limited instability (850 mb temps near -9C) amount of 900-700 mb directional shear, and steady eastward movement of the greatest low level conv btwn 06z-15z. So, the winter wx advisory was maintained. Expect the snow to quickly end from west to east in Wed morninng. Blustery west winds will then develop, especially over the Keweenaw where gusts to around 45 mph (advisory), per momentum transfer prog, will be possible as CAA increases mixing depth. Although temps will remain steady or slowly falling over the west, highs should still reach 30 or the lower 30s, central and east. .LONG TERM...(Wednesday night through Tuesday) Issued at 353 PM EST TUE JAN 30 2018 General trend in the extended part of the forecast will be much colder temperatures along with intermittent chances for lake effect snow. Additionally, wind chill values will approach or drop lower than thresholds for wind chill advisory criteria most morning through the extended. A steady/reinforced overall troughing pattern will continue through the extended forecast over much of the eastern CONUS. The main targets for the more concentrated lake effect/enhanced snow will be the west to northwest wind favored snow belts through next Tuesday. 850mb temperatures are expected to fall from around -15C to -20 Wednesday to the -20C to -25C range through the rest of the extended. This again is favorable for lake effect/enhanced snowfall through much of the extended. There are a couple periods where lake effect snow may intensify, which would be Wednesday night into Thursday, Friday night into Saturday and again Monday night into Tuesday. This will be associated with stronger shortwaves rotating through the overall troughing pattern in place. There may be more subtle waves that enhance the snowfall at times, but these will have to be pinned down with more confidence as models grasp these features over the next several days. Otherwise, temperatures will be roughly 10 to 15 degrees below normal for both highs and lows throughout the extended forecast. Wind chill values will approach advisory criteria for most mornings in the extended with values approaching or dropping below the -15F to -25F range. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 655 PM EST TUE JAN 30 2018 Approaching disturbance will spread a couple of bands of snow across the area tonight into Wed morning along with gusty south winds and LLWS. Conditions at KCMX/KSAW will likely fall to IFR or near IFR for a brief time this evening. Otherwise, MVFR conditions should set in. Snow will be lighter at KIWD with mostly VFR conditions expected until late tonight when MVFR conditions should develop. On Wed, MVFR conditions should prevail at KCMX, but with gusty w winds up to around 35kt, -shsn/blsn could lead to periods of IFR. KIWD/KSAW should see a period of VFR conditions during Wed in the wake of cold fropa. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 410 PM EST TUE JAN 30 2018 Long period of gales is expected starting this evening as south gales tonight shift to the west on Wednesday. Gale warnings run from tonight through Thursday afternoon. Heavy freezing spray is expected Wednesday night into Thursday night. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Winter Weather Advisory until noon EST Wednesday for MIZ006-007- 013-014-085. Lake Superior... Gale Warning until 4 PM EST Thursday for LSZ264>267. Gale Warning until 1 AM EST /midnight CST/ Thursday for LSZ162- 263. Lake Michigan... Gale Warning until 1 PM EST Wednesday for LMZ248-250. && $$ UPDATE...Rolfson SHORT TERM...JLB LONG TERM...KEC AVIATION...Rolfson MARINE...JLB