Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/17/17


Area Forecast Discussion
National Weather Service Albany NY
939 PM EST Thu Nov 16 2017 .SYNOPSIS... Rain showers will transition to snow showers tonight, with some accumulating snowfall over the higher terrain mainly north of the Capital District. Cold and brisk conditions in store for Friday, as high pressure builds eastward from the Great Lakes. A stronger storm system will approach on Saturday, bringing the next chance for widespread precipitation. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... Gusty winds this evening across the CWA. 00Z ALY sounding showed steep low level lapse rates - sfc to 850mb of 8C/km. VAD depicting winds to 45 knots up to about 850mb. RAP soundings show good mixing to continue through the night. Bumped up wind gusts particularly down the Mohawk Valley. Rain showers have transitioned to snow showers across the Adirondacks. Temperatures are still too warm most other locales, so just rain showers now. HRRR shows a decided diminishing trend in precipitation through the night. This is accounted for in current forecast. The winds and mostly cloudy conditions should prevent temperatures from falling as much as they could but the deepening cold advection will help temperatures fall to around 30 to the mid 30s but mid to upper 20s in the southern Adirondacks. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... Upper energy exits and the cold advection continues with breezy west to northwest winds. Sources of guidance suggest quite a bit of sunshine Friday but with wind off the warm lakes, there may be intervals of clouds and sun until afternoon when the winds diminish more rapidly. Still some sun and wind should help temperatures reach solidly in the 40s but 30s in the southern Adirondacks. The next system approaches through Friday night with warm advection rapidly increasing. Some question as to the timing of the onset of thicker cloud cover and increasing low level winds. Current sources of guidance suggest a period of clear and calm conditions Friday evening, allowing temperatures to fall to the upper teens and lower 20s before thicker clouds and increasing south winds help temperatures to rise into the upper 20s by daybreak Saturday. The timing of the onset of precipitation looks to be after daybreak to mid morning Saturday in western areas, when temperatures rise above freezing. Boundary layer temperatures are expected to be above freezing at that time, so other than a possible brief light mix of rain, snow and/or sleet for an hour or two, precipitation over our region Saturday and Saturday night should be rain. No accumulation is expected. Southwest boundary layer flow becomes quite strong Saturday along with strengthening isentropic lift and upper dynamics, supporting a widespread rain through Saturday night. Highs Saturday in the mid 40s to around 50. Temperatures will fall with the frontal passage mainly just after daybreak Sunday into the mid 30s to lower 40s. Deep cold advection spread across the region Sunday with very strong west to northwest boundary layer flow, much of which is likely to mix to the surface. The cold air over the Great Lakes should aid in the development of some lake effect snow shower activity that should extend east into our region, with the best coverage in the southern Adirondacks but scattered activity that could extend through the region into western New England. Highs Sunday in the 40s to near 50 but 30s in the southern Adirondacks and temperatures falling in the afternoon. && .LONG TERM /SUNDAY THROUGH THURSDAY/... Sunday night-Monday looks to remain active in the wake of the strong weekend storm system. Lingering Lake Effect/Enhanced snow bands look to potentially impact portions of the western Mohawk Valley and western Adirondacks through Monday, with additional enhancement possible across west facing higher terrain of the southern Greens and northern Berkshires. Some filaments of snowbands could occasionally extend into valley areas. It should remain windy, with some gusts possibly approaching or exceeding 40 mph within portions of the Mohawk Valley/Capital Region and Berkshires. It should remain cold, with Sunday night lows ranging from the teens across the Adirondacks, to the 20s elsewhere. Highs Monday ranging from the upper 20s across the Adirondacks, to the mid 30s/lower 40s in valley areas. For Tuesday-Wednesday, most 12Z/16 global deterministic models and ensembles suggest a fast moving northern stream system passes north of the Great Lakes and across SE Canada. A brief surge of milder air should allow temps to reach into the 40s/lower 50s for much of the region Tuesday afternoon, except cooler across the Adirondacks. Some rain/snow showers will be possible within the warm advective regime, possibly combining with some Lake Enhanced moisture, across the western Adirondacks Tuesday afternoon. Then, slightly greater coverage of rain/snow showers for Tuesday night into Wednesday morning, as a cold front associated with the system moves through. Temps should fall into the 20s and 30s by daybreak Wed, with highs Wed mainly in the 30s to lower 40s. High pressure looks to build into the region Wednesday night and Thursday, assuming southern stream moisture/energy does not track farther north. It should be rather chilly, with lows Wed night in the teens and 20s, with Thursday highs mainly in the 20s and 30s. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... Expect VFR conditions at most terminals through the period. Exception will be KPSF where westerly upslope flow will induce some MVFR clouds tonight. Expect gusty winds to persist through the period at all terminals. Winds should be stronger at KALB and KPSF. Outlook... Friday Night: No Operational Impact. NO SIG WX. Saturday: High Operational Impact. Likely RA. Saturday Night: High Operational Impact. Breezy Definite RA. Sunday: Moderate Operational Impact. Windy With Gusts To 39.0 Chance of SHRA. Sunday Night: Low Operational Impact. Breezy Isolated SHSN. Monday: Low Operational Impact. Breezy Isolated SHSN. Monday Night: No Operational Impact. NO SIG WX. Tuesday: Low Operational Impact. Breezy NO SIG WX. && .FIRE WEATHER... Rain showers will transition to snow showers tonight, with some accumulating snowfall over the higher terrain mainly north of the Capital District. Cold and brisk conditions in store for Friday, as high pressure builds eastward from the Great Lakes. A stronger storm system will approach on Saturday, bringing the next chance for widespread precipitation. Gusty west to west winds expected tonight and Friday, up to 35 mph in some spots. Winds diminish to light and shift to south Friday night, increasing to around 15 mph Saturday. RH values remaining above 35 percent through Saturday with widespread rain expected Saturday. && .HYDROLOGY... No hydrologic problems are expected on the main stem rivers through the next week. High pressure will briefly build in on Friday before a strong low pressure system approaches from the Great Lakes Region on Saturday. Widespread rain may begin as a mix with snow in the western Mohawk Valley and southern Adirondacks but then change to to all rain that will continue through Saturday night. A cold front will sweep through Sunday morning with additional precipitation. At this time, total QPF from this system looks to range from a half inch to near an inch. For details on specific area rivers and lakes, including observed and forecast river stages and lake elevations, please visit the Advanced Hydrologic Prediction Service /AHPS/ graphs on our website. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...NAS NEAR TERM...OKeefe/NAS SHORT TERM...NAS LONG TERM...KL AVIATION...KL/OKeefe FIRE WEATHER...NAS HYDROLOGY...NAS
Area Forecast Discussion
National Weather Service Bismarck ND
942 PM CST Thu Nov 16 2017 .UPDATE... Issued at 940 PM CST Thu Nov 16 2017 Band of 700-650MB frontogenetical forced precipitation materialized as the RAP/HRRR portrayed from west central ND into my north central. Area web cams showed precipitation started to reach the surface around Dunn County though air temperatures are on the rise with the precip with no travel hazards reported as of yet west. However, road sfc temperatures over my northeastern CWA at Rugby and Dunseith in the 20s so expect even light rain to freeze on contact with the ground so we opted to throw out a winter weather advisory for freezing rain across my northeast and east central through 3 am CST. UPDATE Issued at 700 PM CST Thu Nov 16 2017 Main forecast challenge this evening will continue to be the threat for light freezing rain and/or sleet and associated impacts to travel. Combination of low, mid, upper level forcing generating clouds and some light radar returns at the moment. Most of the radar returns across western ND are elevated with cloud bases at or above 10K FT AGL. However, across far southwestern ND cloud bases have been dropping the past hour or two along with a few obs reporting light rain where 700-650MB frontogenetical forcing is developing, north of sfc low pressure across northwest SD and ahead of a cold front dropping south from Canada. Models portray this frontogensis increasing this evening east-northeast across west/central ND along with both the HRRR and RAP showing a decent band of light precipitation. Warm air aloft ahead of the cold front will allow a window of freezing rain/sleet coupled with road surface temperatures already dropping to freezing and below. Have mentioned this in the HWO and considering a special weather statement for now rather than a winter weather advisory for freezing rain as expect any precipitation to quickly move to the northeast with minimal amounts of QPF. && .SHORT TERM...(This evening through Friday) Issued at 217 PM CST Thu Nov 16 2017 Challenges for the short term include clouds and temperatures associated with wrm/cold frontal passages well as a light mix of rain/snow and sleet/freezing rain. All this would be of significance except the precipitation amounts are very light. Its hard to find much QPF in the models. So kept the POPs low tonight and let the process generate the precipitation type. Mostly rain/snow chances southwest and central with some snow/sleet and freezing rain across the northern James River valley late this evening and after midnight. With trace amounts of QPF do not think this will rise to a significant event. Daytime Friday will start with the cold front moving through the region and high pressure building into the north. The frontal baroclinic zone will remain across far southern North Dakota and this is where a chance of rain and snow will linger through the day. .LONG TERM...(Friday night through Thursday) Issued at 217 PM CST Thu Nov 16 2017 After Friday, a dry period is forecast through Tuesday as the h500 flow remains westerly and dry. A short wage trough will move across southern Canada Early next week bringing a cold front through and cooling temperatures for Tuesday. Some light rain or snow shows up on Wednesday as return flow brings warm advection into teh region. So far Thanksgiving looks mainly dry with near to above average temperatures. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 700 PM CST Thu Nov 16 2017 VFR conditions at all terminals through the 00Z period. There will be a window for light freezing rain/sleet this evening for mainly KDIK and KMOT. For now held off on mentioning in the TAFs with uncertainty high. && .BIS WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 3 AM CST Friday for NDZ004-005-012- 013-022-023-025. && $$ UPDATE...NH SHORT TERM...WAA LONG TERM...WAA AVIATION...NH
Area Forecast Discussion
National Weather Service Caribou ME
1010 PM EST Thu Nov 16 2017 .SYNOPSIS... Low pressure will track northeast through the Gulf of Maine this evening, then move into the Canadian Maritimes overnight and into Friday. High pressure will build in for Saturday, following by another low pressure system for Sunday. && .NEAR TERM /THROUGH FRIDAY/... 940 PM Update: No sig chgs from prev update, with latest radar imagery showing a developing deformation band ovr Ern and Cntrl ptns of the FA. Despite sfc winds now coming and to the N across the Rgn, max wrmg is currently occurring in the 1000 to 3000 ft abv ground lvl across Nrn areas, as evident with mixing reports from the KFVE ASOS. Dynamic cooling from alf will be soon arriving from the NW with the next 2 to 3 hrs as the upper low apchs ovrhd. One concern is how sharp the precip cut-off is ovr Wrn ptns of the Rgn, with mid lvl dry air evident encircling W in close proximity of the upper low. This could result in sharper total snfl cut-off ovr NW Aroostook county then we currently show. Otherwise, fcst hrly temps/dwpts were adjusted from latest sfc obs to msly unchgd fcst ovrngt lows posted near 7 am Fri. Orgnl Disc: A vigorous shortwave in southern New England is moving northeastward in a broader upper trough centered over Quebec. Cyclogenesis occurred this morning in response to this shortwave, a powerful upper jet and a strong baroclinic zone. The deepening low pressure system is currently just south of Cape Cod and will track towards Washington County later tonight and onward into New Brunswick Friday morning. The low will bring rain to most of the area with amounts over a half inch over large portions of the forecast area and some areas could get an inch. Snow will be a factor for locations in northwest Aroostook County this evening before mixing with rain late this evening. However, as the cold upper low moves over the area after midnight, snow will return with a trowal-like structure. As a result, have issued a Winter Weather Advisory for northwest Aroostook County and will be carefully watching northeast Aroostook where rain will change to snow after midnight. At this point, am expecting just 1 to 2 inches with temperatures near 33-34F and have not extended the advisory eastward. However, recent HRRR runs are trending a bit colder with a faster changeover and more intensity along the northeast border of the state. Snow will wrap up early Friday morning in the northeast portion of the forecast area. Northwest winds will then become the primary item of interest as the low continues to deepen in the Canadian Maritimes. Gusts to 40 mph will be possible with some power outages possible. Added patchy blowing snow to areas that are forecast to receive snow overnight into Friday morning. High temperatures will occur Friday morning and temperatures will be falling by mid afternoon. Apparent temperatures will fall into the teens Friday afternoon. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... Weak cold advection can be expected for Friday night on the backside of low pressure that will be moving through the Canadian maritime provinces. With a bit of a gradient remaining across the area and at least some lingering stratocumulus clouds, mainly across the north, it doesn`t look like an ideal radiational cooling night. Nevertheless, lows are still expected to be below normal for this time of year. High pressure briefly builds in from the south early Saturday before increasing high and mid clouds will be advancing across by afternoon, ahead of low pressure tracking east from the lower great lakes region. Expect some light overunning precipitation to develop across the western sections by later Saturday afternoon but most of the region should remain dry through the daylight hours Saturday. Expect light overrunning precipitation to overspread the entire area overnight Saturday as the low level warm advection strengthens in advance of intensifying low pressure approaching from the west. Although we could see a brief period of snow or mix across the north and west at the onset, the southerly flow in advance of intensifying low to our west will assure a change to all rain across all areas by daybreak Sunday as temperatures slowly rise overnight. Sunday will be a wet and unseasonably mild autumn day as low pressure tracks just to our west and into Quebec. Expect the steadiest rain early Sunday to then become more showery in nature as the low tracks off to our north during the afternoon. One concern on Sunday is the potential for stronger southwest winds along the down east coast where gust to 40 to 45 mph cant be ruled out as low pressure intensifies to our west. It will be unseasonably mild on Sunday with high temperatures climbing into the low to mid 40s north and upper 40s to lower 50s downeast. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... Strong cold advection commences Sunday evening as low pressure intensifies to our north. A few evening snow showers cant be ruled out Sunday evening but the bigger concern could be freezing of any standing water from Sunday`s rainfall, as temperatures start to tumble below freezing by evening. The work week starts on the blustery and cold side on gusty northwest winds with partly to mostly cloudy skies north, and partly cloudy down east. Highs on Monday across the north not likely to get out of the low to mid 20s, and only to near the freezing mark down east. Monday night will see increasing high clouds in advance of low pressure tracking well off to our northwest across central Canada. Tuesday will see a significant rebound in temperature as strong southwest flow between the low to our northwest and high pressure east of the mid atlantic sends the temperature into the mid to upper 30s north and low to mid 40s downeast. Tuesday night will see a cold front crossing the region with the potential for a few rain or snow showers later Tuesday night. Early indications for the big travel day next Wednesday and Turkey day looks quiet with no significant precipitation expected to hamper travel, although it does turn cooler on Wednesday and for the Thanksgiving day holiday. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... NEAR TERM: FVE will be LIFR to IFR into Friday morning due to low cigs and snow. Other sites will trend to IFR due to cigs and drizzle initially...and then to LIFR at times in snow after midnight for terminals north of HUL. BGR and BHB will improve to VFR in the predawn hours and stay VFR through the day. When snow ends Friday morning north of HUL, conditions will improve to MVFR cigs...and then VFR in the afternoon. Strong gusty northwest winds will affect all terminals on Friday. Gusts may reach 35 to 40 mph at times. SHORT TERM: VFR Friday night through Saturday. Conditions then lower to MVFR and IFR Saturday night and Sunday in lowering clouds and developing precipitation. Sunday night through Tuesday we are expecting VFR conditions to rule. The main concern Monday will be the gusty northwest winds that are expected. && .MARINE... NEAR TERM: Winds and seas will increase later tonight...and reach gale strength on Friday. Left the headline in place without change with the start time now at 9am Friday. SHORT TERM: Gale Warnings are up into Friday evening but winds should be diminishing later Friday night through Saturday afternoon. By Sunday we could once again see strong SCA, if not Gale Force conditions in the southwest flow ahead of advancing low pressure to our west. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...Winter Weather Advisory until 11 AM EST Friday for MEZ001. MARINE...Gale Warning from 9 AM to 10 PM EST Friday for ANZ050>052. && $$ Near Term...VJN Short Term...Duda Long Term...Duda Aviation...VJN/Duda Marine...VJN/Duda
Area Forecast Discussion
National Weather Service State College PA
1032 PM EST Thu Nov 16 2017 .SYNOPSIS... High pressure will build across the state through Friday. A frontal system will move into the area Saturday with much colder and blustery conditions following it for the end of the weekend into early next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... Isolated showers or rain and snow continue to decrease in intensity and coverage. HRRR dissipates these completely by 06z but it appears they may linger just a bit longer. Still gusty west- northwest blowing 25 to 35 mph in spots...slowly decreasing in the pre dawn hours. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... Friday will be fair and uneventful as we get a break between frontal systems. Highs will be a tick or two cooler than today with a diminishing wind as high pressure moves over the area. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... The next impactful weather system will be a storm system that will move through the eastern Great Lakes Saturday. A warm front-cold front combination will bring a period of rain to the area that will be moving in from the west by sunrise Saturday, progressively spreading eastward across the region during the day. QPF into Sat night will be around an inch over the NW mountains tapering to 0.25-0.50 over the SE. The associated cold front is made to pass through the state Saturday evening and overnight, ushering in a shot of cold air and setting the stage for an early season bout with lake effect snow showers for Sunday and Monday. The usual snowbelt areas of NW Warren county into northern McKean County will be the most likely so see several inches of snow, with lesser accums even down into the Laurels. High pressure moving to our south will influence the weather to start Thanksgiving week, bringing a couple of cool-dry days. Temperatures will begin to modify Tuesday with a SW flow expected to develop. Though jet stream will remain north of the region, a quick moving trough will brush the region on Wed followed by a weak shortwave Wed night, which will bring chance for light snow showers back into the NW along with a return of slightly cooler air. GFS hangs on to this trough into Thanksgiving weekend, while the ECMWF brings a flatter 500mb flow pattern. So forecast confidence remains on the low side in the 7-10 day range. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... MVFR/IFR conditions will persist at KBFD/KJST through tonight with periods of snow showers. Soundings suggest pockets of light fzdz are possible later tonight but will not mention in TAFs. KAOO/KUNV may see some MVFR cigs at times but VFR will be the dominate flight category. Downsloping winds will maintain VFR flying across the eastern 1/2 of the airspace over most of ZNY sector. Surface winds from 280-310 degrees gusting 20-25KT early will subside into Friday morning. Expect low clouds to gradually break on Friday with return to widespread VFR by the afternoon. Outlook... Sat...Widespread showers. LLWS possible. Transition to snow showers behind strong cold front late Saturday night with MVFR/IFR likely western 1/3. Sun...MVFR/IFR in snow showers NW. MVFR to low VFR cigs and ocnl rain/snow showers central and east. Gusty winds 25-30kts from 280-310 degrees. Mon...MVFR cigs/sct -shsn psbl early NW 1/4; otherwise VFR. Tue...Breezy. Mainly VFR. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Gartner NEAR TERM...DeVoir/Gartner SHORT TERM...La Corte/Gartner LONG TERM...La Corte/RXR AVIATION...Steinbugl
Area Forecast Discussion
National Weather Service Duluth MN
654 PM CST Thu Nov 16 2017 .SHORT TERM...(This evening through Friday) Issued at 200 PM CST Thu Nov 16 2017 After a mostly dry day today across much of the Northland, we once again will be dealing with an incoming system that will bring a wintry mix of precipitation, which should make for hazardous road conditions, especially for the Friday morning commute. A one-two punch of a warm front, followed by a push of cold air advection on the backside of a sfc low that is progged to translate across southern Saskatchewan and Manitoba Canada, will be the culprits for this precipitation. Model soundings indicate that the atmospheric profile will saturate this evening and overnight due to seeder-feeder processes. The push of warmer air behind the warm front will complicate the forecast as far as p-types are concerned. RAP soundings indicate a warm layer of roughly 1 to 2 degrees Celsius at around the 800 mb level, with perhaps even warmer maximum temperatures possible. This would support a range of p-types, including snow, rain/snow mix, drizzle, freezing drizzle, and sleet. Overnight, temperatures should remain cold enough through the atmospheric profile to support mainly snow, with some isolated drizzle/freezing drizzle. The p-types become more eclectic just in time for the Friday morning commute, with drizzle, freezing drizzle, sleet, and snow all possible during that time. Confidence in the exact timing and placement of each p- type is rather low with this setup. The good news is that the freezing precipitation will diminish by Friday afternoon as temperatures look to warm up to the lower to middle 30s across the area, with most locations seeing temperatures above freezing. However, freezing precipitation will return Friday night and Saturday morning. New snow should mainly fall over our northeastern portions of the forecast area, especially over the Minnesota Arrowhead, where up to 1" to 2" of new snow is possible over Lake and Cook counties Friday. Ice accretions appear to be very light, if any, with the best chances of icing over Price, Ashland, and Iron counties in northwest Wisconsin. Due to the lack of heavier accretions of ice, we will hold off on any headline issuances at this time. Also, due to a tight sfc pressure gradient moving in from the west, southerly winds will be gusty across the area overnight, with gusts between 20 to 25 knots possible. .LONG TERM...(Friday night through Thursday) Issued at 200 PM CST Thu Nov 16 2017 The area of low pressure will move through northwest Wisconsin Friday night, being pushed along by an upper level trof. The wintry mix of ptypes persists, but expecting more of a drizzle/freezing drizzle ptype, along with light snow. Dry over northeast Minnesota. The precipitation diminishes in northwest Wisconsin as forcing departs. Have some small pops Saturday morning as the wind aligns for an opportunity for some light lake effect snow showers. However, model differences in the amount of dry air advecting over Lake Superior may offset the favorable wind. Ridging moves over the rest of the forecast area Saturday. Confidence is low on lake effect snow through Sunday morning with the dry air appearing to prevail. Warm and dry air surges into the area Sunday night and Monday ahead of the next system. Monday night finds this next system moving along the international border region through Tuesday. A cold front is progged to move through the region and bring the next round of snow showers. As ridging returns for Tuesday night and Wednesday, lake effect processes begin again with a northwest flow. Have adjusted pops accordingly. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 637 PM CST Thu Nov 16 2017 For the most part MVFR, but believe IFR in -shsn band that is crossing the area. Band may produce a quarter of an inch of snowfall at KDLH. Elsewhere, most TAF sites miss the band of snow. Afterward 05Z, a general transition towards IFR as more -shsn moves in eventually mixing with rain. Expect poor flight conditions. && .PRELIMINARY POINT TEMPS/POPS... DLH 27 35 23 27 / 30 60 10 0 INL 24 35 18 22 / 50 20 0 10 BRD 30 38 23 28 / 20 30 10 0 HYR 30 36 27 31 / 20 80 40 10 ASX 29 38 29 31 / 30 80 30 10 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. LS...Small Craft Advisory until 3 PM CST Friday for LSZ140>142. && $$ SHORT TERM...JTS LONG TERM...GSF AVIATION...Wolfe
Area Forecast Discussion
National Weather Service Green Bay WI
947 PM CST Thu Nov 16 2017 Updated aviation portion for 06Z TAF issuance .SHORT TERM...Tonight and Friday Issued at 222 PM CST Thu Nov 16 2017 The latest RAP analysis and satellite/radar imagery show high pressure moving across Wisconsin early this afternoon. Low clouds remain stubborn so far today, though partial clearing has taken place south of route 29. Think clearing will continue to slowly lift north for the rest of the afternoon. Meanwhile, the jet stream is already bringing in broken cirrus into western Wisconsin ahead of the next system. Precip chances and potential impacts from this system are the main forecast concerns. Tonight...The high pressure system will exit to the east over the central Great Lakes. As this occurs, winds will shift to the southeast, which should continue to cause the low stratus to lift north over northern WI through the early evening hours. However, clouds over Lake Michigan may also return west into eastern Wisconsin. Combined with a thick blanket of cirrus arriving this evening, will show increasing clouds across areas where skies cleared for a time. Progged soundings indicate that ample mid- level dry air will likely hold off precip for most locations overnight. Some models create a band of precip over northern WI after midnight despite this dry air, and suppose its possible that a few snow flakes could survive the trip to reach the ground. So left a small chance in the forecast, with a tenth or two of accum possible. As a result, think the threat of impacts to the roads is rather minimal. Friday...A stronger push of deeper moisture will occur from west to east during the morning hours. The mid-level dry wedge will become significantly eroded as the moisture arrives, with wet bulb temps aloft rapidly rising into the 3-5C range. This should lead to a transition into more of a rain/drizzle scenario by mid to late morning. There may be a brief few hour window when surface temps are at or just below freezing with liquid precip falling, which could result in hazardous roadways. Because of such a narrow window and uncertainty about timing and precip type, will issue an SPS to draw more attention to this potential hazard. As precip moves across central and into eastern WI by late morning through the afternoon, temps should warm into the mid 30s to low 40s. .LONG TERM...Friday Night Through Thursday Issued at 222 PM CST Thu Nov 16 2017 The main focus continues to be the beginning of the extended period for potential wintry mix and high winds through Saturday. Colder air will move into the region after midnight Friday night. Initially, primarily drizzle and rain are expected to continue initially overnight as drier air returns aloft and cuts off the supply of ice crystal growth. Active weather will then transition over to snow in the north as the cold air continues to push into the region. Mixed precipitation is likely across central Wisconsin in the morning while the Fox Valley keeps mostly rain chances. Bufkit soundings suggest a brief chance to see mixed precipitation reach the Fox Valley in the afternoon. There will be a small chance to see some light snow across the area into the evening, but currently favor dry air moving in more quickly in the end of this system, thus kept pops minimal in the evening for Saturday. The last of the snow showers will be in the far north as some lake enhancement continues in far northern Wisconsin. Models have backed off some on the wind speeds over land Saturday, with gusts closer to around 25 to 30 knots likely Saturday afternoon and evening. Drier conditions follow all the active weather on Sunday into Monday. Models currently suggest the next chance of precipitation arriving Tuesday into Wednesday as we return to a more meridional flow, although timing confidence is low at this time. Temperatures during this time will fluctuate with the passing systems, with highs hovering in the 30s Saturday, dropping towards the 20s Sunday, 40s on Monday, and then returning to the 20s and lower 30s through the rest of next week. && .AVIATION...for 06Z TAF Issuance Issued at 946 PM CST Thu Nov 16 2017 MVFR clouds have retreated to far eastern Wisconsin and southern Wisconsin late this evening. Drier air, as per MSP and GRB soundings, have worked into the state with mainly mid level clouds over the area. Nearest precipitation was a band of snow showers near DLH where some better saturation was occurring. Anticipate MVFR cigs will increase in coverage later tonight into Friday, however the trend may be slower along with the coverage of precipitation. Pcpn type may be more snow initially due to the colder dry air in place before turning to a mix Friday morning. Boundary layer expected to warm enough to become mainly rain Friday afternoon. && .MARINE... Issued at 222 PM CST Thu Nov 16 2017 Another low pressure system could bring additional chances for gale force winds, first from the south on Friday ahead of the system, then from the northwest behind the system on Saturday and Saturday evening. Confidence is high enough to upgrade to a gale warning for Lake Michigan, but not for Green Bay. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......Uhlmann AVIATION.......TDH MARINE.........MPC
Area Forecast Discussion
National Weather Service Lincoln IL
852 PM CST Thu Nov 16 2017 .UPDATE... Issued at 852 PM CST Thu Nov 16 2017 Updates this evening are mainly for cloud cover as overcast skies that were prevalent from Galesburg to Paris northward earlier this evening have been eroding and are now mainly from Peoria to Champaign northward. Have updated short term forecast to account for this, but may need further updates later this evening as well. Otherwise, temperatures across the area are already in the low to mid 30s, near forecast lows for tonight, and this looks good as well as light southeast winds and cloud should keep temperatures relatively steady. && .SHORT TERM...(This evening through Friday) ISSUED AT 246 PM CST Thu Nov 16 2017 A narrow ridge of high pressure is located over IL and the Mississippi River Valley this afternoon/evening. The high pressure and relatively subsident air effectively trapped a layer of moisture over the region, resulting in a more cloudy day in the northern half of the state. Models are struggling with what to do with the cloud remnants as not enough mixing today to make a significant impact. HRRR had the best handle on the clouds earlier, and latest runs keeps the stratus in for the overnight and expands across the region. Have kept the temps up a bit from last night...may need some minor adjusting, particularly in the south if the clouds expand. By morning, winds come around to more southerly behind the ridge as the next front moves into the Midwest. Low pops in place for sct showers/mostly drizzle in the first half of the day. Precip approaching the NW in the afternoon/evening...and thunder increasing into tomorrow night. .LONG TERM...(Friday night through Thursday) ISSUED AT 246 PM CST Thu Nov 16 2017 SPC Day 2 outlook has all of Central IL in a general thunder threat, mainly for tomorrow evening. Rain chances better for Friday night and into Saturday. Day 3 Outlook has a general thunder... and a marginal risk in the far SE...south of I-70. Concern would be surrounding early morning convection invof the Ohio River Valley with the rapid development of the storm system as it moves out to the east. Threat should end early as the heavier precip moves out. However, on the other side of the boundary, some models hinting at a weak round of precip through the afternoon, with the temperatures NW of the IL River allowing for the potential to see some snowflakes mixed with the rain threat through the afternoon. Threat is brief and surface temperatures should remain warm enough to melt most of it. Winds become very strong behind the front as well, and Saturday afternoon will see gusts to 30kts at times. Temps plummet into the 20s again for Sat night and Sun night with colder air moving into the Midwest. A period of quiet weather sets up through the remainder of the forecast. Temps warm briefly with southerly flow and the western ridge shifts eastward slightly for Monday. Next system moves into the Upper Midwest/Great Lakes for Tuesday. Pops previously in forecast have come out of the blend for Tuesday night as the front passes dry in the past few runs of both the GFS and the ECMWF. A mentionable difference is that the front is not only dry, but not as cold in the ECMWF...and the GFS is deeper with the upper trof and colder. Should the trend of the GFS following suit with the ECMWF shift on a Day 5 forecast...the temps in the GFS/the blends should start to modify somewhat Tuesday night and beyond. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 551 PM CST Thu Nov 16 2017 MVFR cigs over KPIA-KDEC northeastward, with trends toward expanding slowly southwestward. Models generally follow this trend as well, although perhaps with a bit of a break overnight just before stratus and drizzle expand northward out of southern IL. Have not incorporated a break in low cloud cover into TAFs as this scenario is too uncertain for inclusion at this point. Overall, ceilings will trend lower and have IFR cigs by 06Z-09Z. Winds E-SE 5-10 kts overnight, becoming SSE 10-15 kts with gusts 20-25kts after 15Z. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...37 SHORT TERM...HJS LONG TERM...HJS AVIATION...37