Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/16/21

National Weather Service Albany NY
953 PM EST Mon Nov 15 2021 .SYNOPSIS... Chilly weather remains with us through Wednesday, before becoming mild on Thursday ahead of a cold front. This cold front will bring rain showers later Thursday which could end as snow showers over the higher terrain Thursday night. Colder temperatures and some snow showers are expected on Friday. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... .UPDATE... A few mostly cellular bands of snow or rain showers continue this evening, with one long band that extends from the western Mohawk valley southeast across central Schoharie County and then further southeastward across northern Columbia and southern Berkshire Counties. Temperatures have only slowly dropped due to cloud cover and gusty northwest winds. Most locations are in the 30s with some 20s in the higher terrain. Snow/rain shower activity should slowly diminish overnight and gradually sink southward as flow becomes more northwest. Gusty winds should diminish after midnight. Higher elevations that see snow shower activity tonight will see a light accumulation as temps there are at or below freezing. .PREVIOUS... As of 4PM...our upper level trough axis has shifted into New England with west-northwest ushering in a chilly Canadian air mass. The combination of moist cyclonic flow aloft and lake effect has resulted in scattered rain and snow showers for most of the day today under mostly cloudy skies. The west-northwest wind direction continued to direct most of the showers into the Mohawk Valley and eastern Catskills but the tight pressure gradient in place has tightened low level winds and these showers have tracked well downstream into the Hudson Valley and even the Berkshires. Latest ENX radar scans show multiple bands heading southeastward through our area with ground truth observations picking up a few hundredths of an inch up to around a tenth of precipitation. While p-type in the valley has been mainly rain, the higher terrain areas above 1500ft have seen mainly wet snow and these bands have resulted in a fresh coating of wet snow. Winds have also remained breezy with gusts to 20 to 25kts and with temperatures only in the low to mid 40s (low to mid 30s in the higher terrain), it felt like a typical chilly autumn day. Our trough exits into New England tonight with low level backing to the northwest. This should redirect snow showers into our eastern Catskill zones through 06 UTC before winds back enough to the northwest that showers stay to the south/west of our area. However, upper level ridging starts to rebuild into the Northeast towards 09 - 12 UTC which should low level flow to veer to the west enough that some snow showers return to far western Ulster/Greene/Schoharie and even southern Herkimer County through sunrise. However, the westerly flow will bring in warmer air thereby reducing the delta-T between the incoming air mass and Lake Ontario and the winds in the 925-850hPa layer weaken. As a result, additional lake effect bands may reach into our far southwestern zones with total snowfall amounts likely only around a coating to a few tenths at worst. Otherwise, temperatures tonight will be seasonably chilly with lows in the mid to upper 20s with near 30 degrees in valley locations. Sfc winds remain a bit breezy tonight, albeit not as breezy as the daytime. Still, sustained winds near 5 - 9kts will provide sufficient mixing to prevent temperatures from becoming too chilly in the face of partial clearing skies. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/... West-northwest flow tomorrow morning gradually veers to the west through the day as flat upper level ridging from the Ohio Valley shifts eastward. Since guidance is in good agreement that the ridge axis remains to our west through 00 UTC/Wed, west- northwest flow should persist most of the day, maintaining a fetch of moisture off Lake Ontario directed down the Mohawk Valley. High res models paint a similar solution with the initial lake effect rain/snow showers and clouds penetrating into the eastern Catskills Tuesday morning shifting northward towards the western Mohawk Valley through the afternoon in response to the wind shift. While of the guidance keeps showers confined to the terrain areas, the HRRR points to the possibly that a skinny band of showers could actually reach into the Capital District towards 21 UTC. WPC QPF guidance also is in agreement. Daytime temperatures reaching into the low to mid 40 will keep p-type as rain for valley areas but still, we increased POPs to slight chance to account for perhaps a late day shower near Albany. Otherwise, p-type in the higher terrain areas of western Greene/Ulster, Schoharie County, the Helderbergs and southern Herkimer County with upslope showers in the southern Greens/Taconics/northern Berkshires, should be rain/snow mix. No accumulations expected. Otherwise, tomorrow will be another seasonably cool day with highs in the low to mid 40s with slightly breezy winds continuing (gusts up to 20-25mph down west-east oriented valleys). Skies should be a mix of sun and clouds, with more sun expected downstream of the Adirondacks and Catskills due to downsloping effects. On the other hand, more clouds expected where west-northwest winds maintain lake effect moisture in the eastern Catskills, Mohawk valley into the Capital District. Upper level ridging then builds into the Northeast Tuesday night resulting in initially mostly clear skies which should assist radiational cooling and temperatures dropping into the 20s for most of the area. Coldest temperatures expected in the Upper Hudson Valley and southern Adirondacks where skies should clear the longest resulting in lows in the upper teens to mid 20s. Mid and upper level clouds increase for the second half of the night but this should only reduce the the rate of cooling. Clouds continue increase during the day Wednesday as the ridge axis shifts into New England and west - southwest flow ushers in a milder air mass. Expect high temperatures in the mid to upper 40s although cool air appears to be caught in the southern Adirondacks which could prevent highs from climbing out of the 30s. Persistent and strengthening southwest flow Wednesday night will actually allow a non-diurnal trend with temperatures reaching their respective lows before Midnight and then warming up the rest of the night into the 40s. Despite the continued WAA, guidance is in good agreement that the region stays dry thanks to strong upper level ridging ahead of the approaching cold front. && .LONG TERM /THURSDAY THROUGH MONDAY/... A pocket of anomalously warm 850 mb temps, averaging around 8C (+1 to +2 standard deviations), is modeled to be over the forecast area on Thursday. However, a strong cold front is expected to push across the area from NW to SE late Thursday into Thursday night. Areas from the Mohawk Valley to the Glens Falls area and points southeast have the best potential for being in the warm sector during the daylight hours, so forecast highs are well above normal in the low to mid-60s there. Showers may spread into the southern Adirondacks by late morning/early afternoon (although there is still uncertainty with the timing, so highs there are expected to remain mainly in the 50s and possibly fall during the afternoon. Models are not forecasting any instability with the frontal passage, so thunder will be omitted from the forecast. A sharp temperature drop and a band of showers is likely to accompany frontal passage late Thursday into Thursday night, with rain turning to snow across the higher terrain, and lows falling into the upper 20s to mid-30s. Lake effect snow showers should start up Thursday night into Friday as surface to 850 mb delta-T values increase to 15-20C, with low-level mean wind flow veering from westerly (favoring the western Adirondacks) to northwesterly (western Mohawk Valley, Schoharie Valley, and eastern Catskills). Some upslope showers are also possible across the southern Greens. PoPs were increased over NBM values during this time frame in these locations. Otherwise, Friday appears to be a seasonably cool, mostly cloudy, and breezy day. High pressure is forecast to build in Friday night into Saturday night, with a seasonably cool but otherwise tranquil period expected. The midlevel flow is forecast to amplify once again Sunday into Monday, with upstream troughing inducing strengthening low-level southerly winds and isentropic lift. Chance PoPs return to the forecast Sunday night into Monday. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... Through 00z/Wednesday...Mostly VFR conditions can be expected through the 00z TAF cycle as ceilings are by and large expected to remain at or above 3,000 ft. There could be some clouds that range between 2,000-3,000ft (MVFR territory) tonight, especially at KPSF due to upsloping. Winds through tonight will remain out of the west-northwest 5-10 kts. On Tuesday, west-northwest winds will remain 5-10 kts with gusts between 15-20 kts developing mid to late morning and persisting into the afternoon. Outlook... Tuesday Night: No Operational Impact. NO SIG WX. Wednesday: No Operational Impact. NO SIG WX. Wednesday Night: No Operational Impact. NO SIG WX. Thursday: Moderate Operational Impact. Chance of SHRA. Thursday Night: High Operational Impact. Likely SHRA. Friday: Low Operational Impact. Breezy. NO SIG WX. Friday Night: No Operational Impact. NO SIG WX. Saturday: No Operational Impact. NO SIG WX. && .FIRE WEATHER... After a chilly and breezy start to the work week with some valley rain and higher terrain snow showers, temperatures turn milder by Wednesday and especially Thursday. A potent cold front should usher in our next chance for more widespread rainfall by Thursday night. RH values rise to 80 to 95 percent tonight before dropping to 45 to 60 percent tomorrow afternoon. In addition, sustained west- northwest winds tomorrow afternoon will remain elevated between 6 and 12mph with gusts to 25mph. && .HYDROLOGY... No river flooding is expected at least through Wednesday. A few lingering lake effect rain and snow showers tonight into tomorrow will produce an additional tenth of an inch or less of precipitation, mainly for the southern Greens, Taconics, northern Berkshires, eastern Catskills and southern Greens due to upslope and lake enhancements. While rivers remain elevated from the weekend rainfall events, the light precipitation amounts will not raise any flooding concerns for the rivers in the NWS Albany Hydrologic Service Area. Our next widespread rainfall event appears to arrive Thursday night but guidance suggests this event will be fairly progressive which should mitigate most flooding concerns. 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...SND NEAR TERM...SND/Speciale SHORT TERM...Speciale LONG TERM...Thompson AVIATION...Evbuoma FIRE WEATHER...Speciale HYDROLOGY...Speciale
Area Forecast Discussion
National Weather Service State College PA
1036 PM EST Mon Nov 15 2021 .SYNOPSIS... An upper level trough will exit the region to the east tonight. Lake effect snow showers will continue through tonight with minor accumulations. A nice moderating trend will set in for mid week, pushing temperatures above normal by about 10 degrees on Wed. Cooler weather will follow another cold front later Thursday. No big rain events are expected with the cool down. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... 730 pm/0030z update... A lake-effect band remains in place this evening from the western southern tier of NY into northern Warren, McKean, and western Potter counties. Although the appearance of the band looks a bit more ragged recently, we still expect it to remain generally in its current position for another 6 hours or so. Thus, the Winter Weather Advisory will remain in tact. Elsewhere, a band of lighter lake enhanced/upslope snowfall continues to stream into southwestern Clearfield, Cambria, and northern Somerset counties. RWIS cameras over the more elevated terrain within this region indicates snow of very light intensity, and if anything conditions will become less favorable later tonight with backing flow, so we don`t expect much in the way of accumulations/impacts. One thing we may have to watch for later tonight over the Laurels is patchy freezing drizzle, as the moisture perhaps becomes too shallow for ice production in the cloud bearing layer. At this juncture, it looks like light snow will just taper off to precipitation free conditions, with any freezing drizzle very limited. Just the same though, we`ll keep a close eye on it. Generally light snow showers/flurries over the northern mountains (east of Coudersport) and also into Clinton county (north of Lock Haven) should be tapering down with time. Over the Middle and Lower Susquehanna Valleys where downsloping has taken full effect, skies should remain clear-partly cloudy overnight. Lows by daybreak will range from the mid 20s over the higher terrain, to the lower 30s in the Lower Susquehanna Valley. 5 pm/22z update... We`ve issued a near-term Winter Weather Advisory for Warren and McKean counties (mostly northern sections of these counties) through most of the overnight hours (until 4 am). A steady-state Lake Erie band continues early this evening from the western southern tier of NY into northwestern PA (Warren, McKean, and Potter counties). Given a moist and elevated mixed/unstable layer, little expected variation in band placement through this evening, and occasional in-cloud flashes seen within this band, we feel it will be intense enough to drop locally 3-6" of snow over the next 6-12 hours. Most of this snow is likely to fall through about midnight and be emphasized over the higher terrain. These amounts also jive well with the latest high-resolution model output, including the HRRR and HREF. This lake-effect band should begin to weaken and drift northward during the pre-dawn hours, as the flow backs and warm advection commences just above the boundary layer. Earlier discussion... Upper trough axis pushing off the northern Mid Atlantic and through southern New England. Scattered lake enhanced snow showers persisting especially north of I80 after a relative lull early this afternoon, likely thanks to a fast moving secondary shortwave traversing the region. High resolution models sharpen and solidify activity into a few narrower bands which target Warren and parts of McKean County this evening with some additional light accumulations. Large scale subsidence behind the departed upper trough has brought partial clearing to many areas east of the Alleghenies. NW flow regime for the rest of central/western/northern PA through tonight with lake enhanced, orographic snow showers across the Allegheny Plateau with boundary layer flow tapping moisture from Lakes Huron and Erie. The fast moving shortwave may support some brief rain or snow showers into the Middle Susq River Valley this evening. Favored snowbelt of Warren and Mckean counties appears likely to see an additional 1-2 inches through early Tuesday morning. Lake effect snow showers over northern PA dwindle and winds diminish late tonight, as surface ridge builds in from the Ohio Valley. Expect mainly flurries from the predawn hours until sunrise. Mins to range from the mid 20s north to the lower 30s southeast. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... The arrival of surface ridge should bring fair and somewhat milder conditions Tuesday with light winds. As the high pushes off the east coast, expect a warmer southerly return flow on Wednesday. Large scale subsidence under upper ridge should ensure dry weather for most of the area Wednesday. However, models indicate a surge of low level moisture, combined with an upsloping southerly flow, could yield some low clouds and patchy drizzle over the northwest mountains on Wednesday. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Evening update to the long range is pretty uneventful. The rain moving in along/behind a cold front on Thursday will not be heavy, and the air should not get cold enough in the NW to snow until sunset or after Thurs night. Lake effect pattern resides for a day, but then a couple of dry days. As noted below, another chance for precip exists early next week. It will be interesting to watch the long range the next few days to see just how deep the trough progged to dive down from the Canadian Rockies will be. EC is sharper and deeper and even tilts it negative as it swings over the eastern US. It deepens a sfc low over the DelMarVA Mon/night (Day 7+). The GFS is slightly more progressive with this significant long wave trough. It does not develop anything near as powerful as the EC does, keeps it moving, and takes any potential development out to sea. That`s 7 days away...still a long way out. Many model/ensemble runs will be forthcoming over that time to help make the best forecast. Prev... High pressure and dry weather to start Wednesday will soon be overtaken by an approaching cold front from the west, which will lead to rain showers beginning late Wednesday/Thursday morning and stick around all day Thursday. Cold air behind the front may turn some of that rain into snow flurries for late Thursday evening/Thursday night. Eventually, all precip will transition to snow or a rain/snow mix as the system exits early Friday morning. Lake-effect snow showers will linger in the far northwestern counties for Friday. Dry weather is expected for Saturday. The next system moves in sometime during the day on Sunday bringing another round of precipitation. The rain/snow mix will linger into the beginning of the week. Temperatures will vary greatly this week, with high temperatures on Wednesday and Thursday getting into the 50s and 60s. The next day on Friday, however, high temperatures plummet to the 30s and 40s and will likely stay there for the remainder of the period. && .AVIATION /04Z TUESDAY THROUGH SATURDAY/... Lake effect snow bands were able to get well inland from the Great Lakes at mid evening. Bands now weakening a bit. Minor adjustments made to the TAFS as of late evening. Earlier discussion below. For the 00Z TAF package, looking at some snow bands into BFD overnight. Some light snow showers into AOO, UNV, and JST at times. Used a TEMPO group at BFD to handle the heavier snow showers. VFR conditions across other sites like IPT, MDT, and LNS. After about mid morning, CIGS will become VFR across the whole area. Good conditions expected for the rest of Tuesday into Wed. Outlook... Wed...MVFR cigs possible. Thu...Restrictions in SHRA. Gusty. Fri...Becoming VFR. Sat...Dry with VFR conditions. && .CTP WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 4 AM EST Tuesday for PAZ004-005. && $$ SYNOPSIS...DeVoir NEAR TERM...Jurewicz/DeVoir SHORT TERM...DeVoir LONG TERM...Dangelo/Gutierrez AVIATION...Martin
Area Forecast Discussion
National Weather Service Quad Cities IA IL
542 PM CST Mon Nov 15 2021 ...AVIATION UPDATE... .SYNOPSIS... Issued at 221 PM CST Mon Nov 15 2021 Early afternoon temperatures ranged from the mid and upper 30s over the northeast to the 40s and low 50s across far southeast Iowa and northeast Missouri, where skies were mostly clear. Clouds streaming across eastern Iowa and northwest Illinois in the northwest flow aloft were slowly thinning. The primary NW-SE band of F-GEN precipitation had shifted from northwest IL to an axis from southern WI through Chicago into NW Indiana. A separate area of warm advection/FGen that moved across southeast Iowa into west central IL with only very light rain or snow observed today was about to exit Bureau and Putnam counties. Further south, a warm front was analyzed at the surface from roughly Omaha to St Louis, marking the leading edge of breezy southwest winds and temperatures in the 60s over MO and eastern KS. These conditions will prevail over much of our forecast area tomorrow as the warm front shifts northward. && .SHORT TERM...(This Evening through Tuesday) ISSUED AT 221 PM CST Mon Nov 15 2021 Temperatures are the primary challenge, with seasonably cool values tonight, then much above normal highs Tuesday. Tonight, the current trend on satellite showing a very gradual eastward retreating of the NW-SE axis of low to mid level clouds into northern IL should continue into this evening, to be then replaced by thin high clouds in the northwest flow out of the plains for an overall partly cloudy night. This should lead to lows in the upper 20s to around 30 across the central and north. The south should be bit warmer due to slightly stronger southeast winds, holding lows in the lower to mid 30s. There is some indication in the models suggesting enough low level saturation north of the warm front for at least light fog and possibly low clouds, but this fog is not expected to be significant enough of an issue to include in the public forecast. Tuesday, a developing frontal system advances into the plains, leading to a broad south to southeast low level flow over the area which essentially washes out the warm frontal boundary. Even with shallow mixing, temperatures should climb into the low to mid 60s south and mid to upper 50s north. This is close to the NBM highs and for now have discounted the much cooler NAM, which appears to be holding onto low level moisture and cloud cover limiting its highs to the 40s north and 50s south. .LONG TERM...(Tuesday Night through Monday) ISSUED AT 221 PM CST Mon Nov 15 2021 Key messages: 1) Rain chances decreasing for most on Wednesday. 2) Roller coaster temperatures for middle of the week towards the weekend, with dry conditions. Tuesday night-Wednesday...a cold front will be making its way across Iowa at the start of the period and will be through most if not all of the CWA by 12z Wed. While there will be some convergence along the front, moisture will be the limiting factor. Model 1000-700mb RH progs and cross sections show quite a bit of dry air in the low levels and thus expect a dry fropa for most hometowns. PoPs have been lowered some more and shifted slight southeast. The higher chances (30-40%) is now south and east of a line from Keokuk,IA to Geneseo,IL. The latest 15z RAP/12z HRRR model runs also support this and later shifts can monitor trends to make any adjustments. Temperatures will be warm enough for all rain and if any rain does fall, it will be light and less than a tenth of an inch. After a nice warm day Tuesday, 850mb temps will drop from 15C at 00z Wed to minus 1C at 00z Thu. The CAA aloft and at the surface will keep temperatures from rising much during the day Wednesday despite the sunshine, with readings remaining in the 40s. Highs for the calendar day will likely occur early in the day prior to cold front passage. Wednesday night-Thursday...even colder air will filter into the region with 850mb temps dropping down to -10C on Thursday. Forecast soundings indicate deep mixing near 850mb will occur Thursday and combined with a steepening pressure gradient will bring strong northwest winds. The NBM has a 90% probability of wind gusts greater than 25mph Thursday afternoon. These winds will make for a rather chilly day and keep temperatures in the 30s. Thursday night-Monday...winds will subside after sunset Thursday as surface ridge axis begins to slide east towards eastern IA. With mostly clear skies, this will set the stage for temperatures to drop off rather quickly Friday morning into the lower 20s. Some lower teens are not out of the question if winds remain calm and high clouds streaming in from the west stay thin. A nice weekend is forecast, with dry conditions and temperatures near to slightly above normal. Another cold front is progged to move through late Saturday night and have kept the forecast dry for now given model timing and strength differences. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening) ISSUED AT 539 PM CST Mon Nov 15 2021 VFR conditions expected next 6 to 10 hours before a MVFR deck overspreads MLI. There are low chances for this occurring at CID and DBQ, so added a few015 to hedge that way. Otherwise expect VFR conditions from 16z on tomorrow at all sites. Winds could gust into the 20kt range tomorrow afternoon as well. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...Sheets SHORT TERM...Sheets LONG TERM...Gross AVIATION...Gibbs
Area Forecast Discussion
National Weather Service Marquette MI
638 PM EST Mon Nov 15 2021 .SHORT TERM...(This evening through Tuesday) Issued at 354 PM EST MON NOV 15 2021 Water vapor imagery and RAP analysis show eastern N America troffing shifting eastward. Upstream, trof approaching the Pacific NW will be the next feature of interest, and it will already be an influence on the weather here by late Tue aftn. Btwn these 2 features, mid-level ridging is over the Rockies. LES continues off Lake Superior under 850mb temps around -9C. Locally hvy shsn continued thru the morning hrs, mainly across Alger County where snow accumulations up to 10-12 inches occurred locally over the interior w half of the county since late yesterday. The LES has become increasingly disorganized this aftn under weakening low-level wind fields, resulting from approaching sfc high pres ridge which has reached far western Lake Superior. Lowering inversions and the negative effect of daytime heating are also contributing to the diminishing LES. Sfc high pres ridge will drift across the fcst area during the night, bringing an end to lingering LES. However, it may not be until late tonight that the last of the LES shifts offshore e of Marquette. Additional snow accumulations should mostly be under 1 inch. Opportunity will be there tonight to get quite cold under very light or calm wind with passing sfc high pres ridge. There is uncertainty in how long the lake stratocu will linger under the light wind fields. In addition, high clouds are already streaking toward the Upper Mississippi Valley under waa regime developing well in advance of the shortwave trof approaching the Pacific NW. Looks like there may be a short window with limited cloud cover, and it shouldn`t take much to get temps to fall quickly. Thus, opted to hedge fcst toward some of the lwr guidance interior w and central where at least some snow cover exits. Temps may tumble to the lwr teens F at traditional cold spots. Shortwave trof currently approaching the Pacific NW will rapidly deepen, closing off a mid-level low over southern Saskatchewan by Tue aftn. This low will then reach Manitoba Tue evening. At the sfc, low pres at around 980mb will be unusually deep for that part of the continent. As a result, wind fields will be ramping up downstream into the Upper Lakes during the day. WAA/stability will limit sfc wind to some degree, but mixing potential suggests gusts up to around 35mph will be possible over the western fcst area late in the day, particularly high terrain and areas that see downsloping with a se wind. Elsewhere, gusts to 20-30mph should become common by evening. WAA/isentropic ascent may generate some light pcpn by late aftn across the w and central, though there is some question whether this ascent will be sufficient to overcome drier air at the lower levels before it shifts to the e. Included schc/chc pops later aftn, highest over the Keweenaw where it appears sufficient low-level moistening is more likely to occur. Ptype should just be rain, but there is a small potential that evaporative cooling could support some snowflakes for a time. Temps should reach the upper 30s/lwr 40s at most locations. .LONG TERM...(Tuesday night through Monday) Issued at 334 PM EST MON NOV 15 2021 Very little change in the thinking from previous forecasts for the long-term period. Tuesday night, a strong vertically-stacked low will be located along the Saskatchewan/Manitoba border. This cyclone`s LLJ will be passing over the U.P. briefly advecting warmer air in. It still looks like there will be enough WAA forcing for scattered rain showers to continue from tomorrow afternoon into the evening, mainly over Lake Superior, the Keweenaw, and the eastern U.P. After those showers lift through, models continue to show a period of around 4-6 kft of surface-based saturation moving across the area thanks to moist upslope SE flow off of Lake Michigan. This means a transition to drizzle. However, seeing as temps will be safely above freezing, this difference is purely academic. With the ground having cooled and there likely still being at least some snow holding on, there will probably be fog overnight as well. Have introduced patchy fog with this forecast but would not be surprised if it ends up being more widespread and/or locally dense. Temps will be nearly steady in the mid to upper 30s west half and actually rise somewhat through the night into the low to mid 40s south central and east. Some of that drizzle will linger into Wednesday morning over the east half, but otherwise Wednesday looks dry. The strong low pressure system will track eastward into northwestern Ontario on Wednesday, dragging a cold front across the U.P. behind that front, winds will increase, especially over the Keweenaw where a period of 30-40 mph westerly winds looks likely Wednesday afternoon and evening. Wednesday night, with cold air now in place (850 mb temps still look to be around -9 to -11 C) and deeper moisture advecting in as the low passes by to the north, lake effect snow will ramp up quickly. It still looks like this LES will mainly impact the west wind LES belts over the Keweenaw and far eastern U.P. through Thursday morning before winds gradually veer around to WNW on Thursday and then NW Thursday night into Friday. Overall this looks like a fairly standard lake effect snow event with scattered to numerous snow showers in the snow belts accumulating a few to perhaps locally several inches by Friday morning. Thursday will be a blustery day with highs struggling to get above freezing over the western half of the U.P. Ridging building in from the west on Friday will cause the column to warm and dry out, bringing the LES to an end by afternoon. That ridge passes overhead Friday afternoon, quickly followed by another strong southerly LLJ on its western periphery moving over the area Friday night and Saturday. This will make for more breezy conditions, especially on Saturday. There could be some rain or snow as well, but chances don`t look too great at the moment. Looking even further out, it still looks like there will be another shot of even colder air early next week. Model ensemble plumes show considerable spread, mostly due to timing uncertainty, but the median of both the GEFS and EPS approaches -15 C by next Tuesday. That would of course mean more lake effect snow chances. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 630 PM EST MON NOV 15 2021 Sfc high pres ridge will drift slowly e across the area tonight, bringing an end to lake effect shsn. At IWD, this improvement has already begun. Expect VFR conditions to prevail at that terminal thru this fcst period. At CMX, conditions could fluctuate btwn VFR and MVFR early this evening before becoming prevailing VFR into Tue. Improvement will occur latest at SAW. Expect MVFR to VFR conditions to prevail through the evening in scattered -shsn before prevailing VFR settles in overnight into Tuesday. South-southeast winds will become gusty to 25-30 kt by mid-late Tue afternoon ahead of strong low pressure system developing over southern Saskatchewan. Strongest winds will likely be at IWD. LLWS could develop late in the period at CMX. && .MARINE.. Winds across the lake will continue to be less than 20 kts through midday tomorrow. Tomorrow afternoon, SE winds will increase to 20-30 kts across most of the lake, becoming gales by early evening. It looks like there will be a short period (around 3 hours) of strong gales to 40-45 kts north-central and east, and a brief rogue storm- force gust can`t be completely ruled out. However, it will be a short-lived event as winds will subside below gale force by daybreak Wednesday. Have upgraded the Gale Watch to a Warning with no changes to the timing or location. There will be a period ~12 hours long Wednesday morning when winds subside into the 20-30 kt range. However, by Wednesday afternoon, a cold front moving across the lake will cause WSW winds to strengthen to gales on the west half. A short period of 40 kt gales is possible Wednesday afternoon, particularly in the favored funneling region between the Keweenaw and Isle Royale. But outside of that short period, these will mostly be low-end gales. Stiff westerly winds will continue on Thursday. However, models continue to trend away from gales. Instead, it looks like winds will be in the 30-35 kt range with just a few gale force gusts at times, rather than persistent gales. Winds will subside below 20 kts by Friday morning. One more system to talk about, this one Friday night and Saturday. It looks like there could be another brief southerly gale during this period, similar to what`s expected tomorrow night, though at the moment with the wind signal not as strong. Have capped winds at 30 kts during this period for now. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Gale Warning from 5 PM Tuesday to 3 AM EST Wednesday for LSZ244- 245-249>251-264>267. Gale Watch from Wednesday afternoon through late Wednesday night for LSZ162-240>244-263-264. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...RJC AVIATION...Voss MARINE...RJC
Area Forecast Discussion
National Weather Service Sacramento CA
235 PM PST Mon Nov 15 2021 .SYNOPSIS... Light showers are possible over far northern California tonight. Areas of patchy Valley fog Tuesday morning. Breezy north to northeast winds Tuesday into Wednesday morning. Chance of more widespread showers Thursday into Friday. && .DISCUSSION... Areas of dense fog have mostly lifted as of 2:00 PM this afternoon. However, cloudy conditions remain widespread across interior northern California. Visible satellite imagery shows increasing high clouds moving across Northern California associated with a trough forecast to pass over the Pacific Northwest. The tail end of this system is forecast to pass over our area this evening. Little precip is expected with many Valley locations remaining dry. A few hundredths are expected for the far northern Sierra and southern Cascades. HREF and HRRR point at the possibility for redevelopment of Valley fog again tomorrow morning with best chances generally along the east side of the Valley. Northerly winds are expected to begin to increase through the Valley tomorrow morning as the trough pushes to our east. Gusts of 20 to 30 mph are forecast with the strongest winds expected in the Sacramento Valley. Continued northerly to northeasterly flow overnight will limit the potential formation of Valley fog on Wednesday morning. By Thursday ensembles depict another trough moving across northern California. IVT analysis shows the bulk of the moisture from this system will stay to our west. Interior northern California is expected to see widespread chances for generally light showers. Snow levels are forecast to start around 6500 to 7500 feet, lowering to 5000 to 5500 feet by early Friday morning. Uncertainty still exists in expected precip and a few inches of snow at pass levels can`t be ruled out. && .EXTENDED DISCUSSION (Friday THROUGH Monday)... Pacific frontal system moves through interior NorCal on Friday bringing mainly light precip to portions of the forecast area. Best chances for precip are in the foothills and mountains north of I-80 in the Central Valley. Rain chances diminish by the overnight hours Friday into Saturday. Drier and warmer weather develops over the weekend into Monday as high pressure builds inland. && .AVIATION... Widespread MVFR with local LIFR/IFR conditions due to fog and stratus continue through tonight in the Central Valley. A weak weather system will bring light precipitation chances to areas north of Chico 01-06z Tuesday. North to northeast winds increase after 15z Tuesday, especially in the northern Sacramento Valley, with gusts to 20-25 kt. && .STO WATCHES/WARNINGS/ADVISORIES... None. && $$
...Update to aviation forecast discussion...

.DISCUSSION... Issued at 247 PM CST Mon Nov 15 2021 20Z water vapor imagery continues to show northwest flow over the Northern and Central Plains ahead of broad low-amplitude upper ridging over most of the western CONUS. This is ahead of an upper trough off the coast of British Columbia and the Pacific Northwest. Closer to the surface, dry air in the low and mid levels has kept little more than some wispy cirrus across the area. Weak low surface pressure has been passing through near the KS/NE border, with southerly winds and WAA combining with plenty of insolation to bring temperatures into the 70s faster. Have bumped highs up a couple of degrees for today, but even this may not be quite enough. With this in mind, have trended on the warmer side of guidance for highs tomorrow given the continuation of WAA tonight into tomorrow and breezy south winds. There are some indications that east central KS could see more of an increase in clouds during the afternoon, which could hinder temperatures if we see more cloud cover than currently forecast. Agree with previous thinking that the NAM appears to be overdone in its saturation of the low-levels, particularly during the afternoon and early evening. However, based on this and the 15Z RAP showing an increase in 925mb RH, can`t entirely rule out the possibility of stratus moving in from southeast KS. Am not overly confident in that scenario, however, so overall think the entire area has another good shot at reaching the low to mid 70s within the WAA regime. The bigger forecast question continues to be whether there will be any precip ahead of an advancing cold front, which is progged to move across the area Tuesday evening and overnight. Isentropic ascent increases ahead of the boundary in east central KS, with the best chances of precip looking to be after 06Z if it occurs, which is in line with the latest ECMWF. Have continued with only light rain or drizzle given sounding profiles and weak ascent. This should move out of the area Wednesday morning with more widespread clouds and CAA keeping temperatures cool. Not much of a warmup is expected with highs in the upper 40s near the KS/NE border to mid 50s southeast of the Turnpike. It`s also worth mentioning that brisk northwest winds at 15-25mph along with much drier air, especially in north central KS where afternoon RH could drop as low as 25 percent, could result in some elevated fire concerns. Confidence is low at this time given the cloud cover and cool temperatures, but it is something worth monitoring. Surface ridging builds in behind the front and upper trough, allowing for clearing skies Wednesday night and lows in the 20s to low 30s by Thursday morning. Although the CAA should be coming to an end on Thursday, we don`t really see any meaningful change to temperatures again until Friday, when low-level winds turn back around to the south ahead of a developing lee trough within zonal upper flow. This brings a slight warm-up into the weekend before another weak cold front on Saturday. A lack of moisture until the boundary passes south keeps a dry forecast at this time. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 522 PM CST Mon Nov 15 2021 VFR conditions will prevail through the TAF period. Winds will increase tomorrow with gusts up to 25 from the south at all terminals. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Picha AVIATION...Gargan