Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/13/18

Area Forecast Discussion
National Weather Service La Crosse WI
617 PM CDT Mon Mar 12 2018 .SHORT TERM...(This evening through Tuesday) Issued at 149 PM CDT Mon Mar 12 2018 Main forecast concern in the short term will be light snow/flurry chances in the northeast part of the forecast area this evening/tonight. An upper level short wave will move southward through Wisconsin late this evening. RAP soundings have generally shown saturation above 900 mb, though also show near-surface levels remain mixed/dry. May be tough to get anything through the dry layer, but 12.12Z NAM soundings show a bit better saturation in these lower levels for a brief time. Have elected to keep slight chance PoPs in the far north, with flurry/sprinkle chances farther south along and northeast of Interstate 94. High pressure will build in on Tuesday, with breezy northwest winds once again. Anticipating highs in the lower to mid 30s, but if cloud cover is sparse like Monday, may need to bump those up a bit. .LONG TERM...(Tuesday night through Monday) Issued at 149 PM CDT Mon Mar 12 2018 12.12Z models have remained consistent in showing an extended period of quiet weather for the region. The upper level pattern looks to slowly evolve this week as the large trough over the eastern part of the continent moves slowly to the east. This will allow the upper level ridge currently over the Rockies, to become established over the Missouri River Valley by Thursday. In the low levels, a cold front will pass through the region Wednesday in association with a short wave trough moving into the eastern long wave trough, but this is expected to pass through without producing any precipitation. As the upper level ridge moves east, a cut off low and long wave troughing will form behind it along the West Coast. The models have been suggesting a short wave trough will get ejected from this system and impact the region starting Friday. What the models have not been consistent on is whether this will come through as a strong short wave trough with an upper level low and pass by south of the area like the 12.00Z ECMWF is showing or whether the short wave trough will be weaker and move over the top of the ridge with more of a direct impact on the area like the 12.12Z GFS is showing. After this system moves by, both models then suggest the ridge will temporarily re-establish itself over the region for Saturday into Sunday. After that, the remains of the Pacific system should be moving toward the region but differences on how this is handled. The ECMWF suggests a rather strong northern stream system will move rotating south across eastern Canada and will push the remains of the Pacific system south of the region. The GFS does not show this northern stream influence and brings the Pacific system right across the area as a strong short wave trough and upper level low. Averaging out these differences will lead to a small chance of some light rain/snow Friday night and Saturday with another chance for Sunday night into Monday. The overall pattern is expected to allow for temperatures to moderate early in the period and be near the seasonal normals Wednesday through Friday. Potential for a bit more warming over the weekend with some 50s possible across the south. Overnight lows should generally be in the 20s. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 617 PM CDT Mon Mar 12 2018 General VFR conditions in place with northwest flow across the area. Main aviation forecast concern is extent of broken cloud deck over mainly Wisconsin and how things will trend as short wave drops into western Great Lakes. Short term models continue to overdue ceilings so chose a bit more optimistic approach with general quiet stretch ahead. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...CA LONG TERM...04 AVIATION...Shea
Area Forecast Discussion
National Weather Service Denver/Boulder CO
912 PM MDT Mon Mar 12 2018 .UPDATE... Issued at 906 PM MDT Mon Mar 12 2018 No major adjustments at this time. A narrow line of light rain showers extends from around Ft Collins to Last Chance. The HRRR and RAP show these showers diminishing and shifting eastward this evening. These trends already reflected in the grids. && .SHORT TERM...(This evening through Tuesday) Issued at 313 PM MDT Mon Mar 12 2018 Isolated shallow convective showers have been developing this afternoon across the mountains and Wyoming border area. Those will likely continue for a few more hours into early evening before the airmass stabilizes, and the tail end of short wave moving through Nebraska passes by. On the plains, scattered to broken mid level clouds abound with some virga, and can`t rule out a sprinkle/ flurry briefly reaching the ground. Otherwise look for clearing skies later tonight as weak subsidence and drying move in. On Tuesday, drier northwest flow aloft will prevail as a high amplitude upper level ridge moves toward the state. This will lead to more sunshine and dry conditions, and temperatures a couple degrees warmer than today. .LONG TERM...(Tuesday night through Monday) Issued at 313 PM MDT Mon Mar 12 2018 Weak northwest flow continues across Colorado Tuesday night as another Pacific long wave trough moves onshore by early Wednesday. Downstream of the trough, we will have a ridge overhead through Thursday afternoon or so. No chance of precipitation area-wide and the 700 mb ridge and associated warm air builds significantly from Wednesday into Thursday. 700 mb temps warm from 0 to -2 degC on Wednesday to +4 degC on Thursday. This will support high temperatures in the low 70s both days across the Plains. As early as Thursday afternoon the global models being to diverge. GFS and NAM advect colder air from 700-500 mb as the west coast trough approaches Colorado, dropping the temperatures across the mountains on Thursday, while the ECMWF keeps the colder air west of us until late Thursday into Friday. Will drop temps a bit in the mountains for highs on Thursday but it should still be in the 40s to low 50s there. Main impacts through Thursday afternoon would be for fire weather across Elbert and Lincoln county where RH will be more than low enough and winds should come up out of the southwest in the 20 mph range with higher gusts. Things get interesting from a Numerical Weather Prediction standpoint late Thursday. The trough approaches Colorado and moisture embedded in the flow should kick off orographic snow showers in the Central and northern Mountains late thursday into Friday. Models vastly differ on the pattern as the ECMWF has a fairly deep 700 mb low across eastern Colorado Friday morning and the GFS has a 700 mb ridge. The GFS hangs the trough back over the Pacific northwest as another strong Pacific short wave trough digs southwest. The ECMWF splits off a decent short wave trough that moves east over the state by Friday morning. Obviously snow amounts would be greater across the mountains under the ECMWF solution and there would even be a decent chance of convective precipitation across our area, though along the I-25 corridor the low-levels remain quite dry. The best chance of convection with the ECMWF solution would be the mountains and far northeast Plains. We can`t bite off on either solution yet because there is so much disagreement and the bulk of the long wave trough is still a ways off the Pacific coast. All that said the forecast confidence starting early Friday is very low and the PoPs area- wide reflect this: high in the mountains, slight chance on the plains. If the ECMWF verifies a good batch of wrap-around precipitation is possible across much of the Plains, including the I-25 corridor. Will wait for some run-to-run consistency from all models before leaning either way. In terms of temperatures the GFS has strong return flow across the Plains while the ECMWF has a surface cold front and colder temperatures aloft throughout Friday. With the 700 mb trough, a surface cold front, and low clouds across E. CO, the ECMWF has highs in the 30s across the northeast Plains, while the dry and heavily downslope flow with the GFS has highs in the 60s to low 70s. The Canadian model is sort of in between the two models, perhaps siding a tad more with the ECMWF. With neither solution looking more likely than the other, will split the difference and go with near 60 Denver metro to Fort Collins and Greeley and near 50 northeast Plains. These numbers will surely change as new data come in and model agreement hopefully increases. Over the weekend the models have a long wave trough across the Pacific northwest and moist southwest flow increasing across Colorado and continued low confidence in the forecast. Saturday should be dry and seasonably warm with highs in the low 60s possible across the Plains. Late Saturday into Sunday precipitation chances increase across the mountains, but the ECMWF takes the best lift to our north, leaving the Plains dry. The GFS is much wetter, especially later on Sunday with good mountain snows and banded precipitation across the far northern quarter of the Plains. Support for the banded precipitation on Sunday from the GFS is strong frontogenesis around from the surface to 700 mb and a strong subtropical jet stream just south of Colorado. It also has a 992 mb low across southeast Colorado Sunday, with a deformation zone supporting precipitation across northern Colorado wrapping back into the Denver metro area. GFS temperature profiles would support rain across most of the Plains, and snow possible above 6000 feet. The ECMWF lifts the trough north of us, leaving the Plains dry and seasonably cool this weekend. Regardless of solution(s) mountain snow with the moist southwest flow is a safe bet and will retain chance PoPs there starting late Saturday and continuing into early Monday. The Plains are a blend of the dry ECMWF and wet GFS, with 10-25 percent PoPs. We`ll be watching the trends closely given this unusually challenging predictability. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) Issued at 906 PM MDT Mon Mar 12 2018 VFR conditions will persist through Tuesday. Scattered to broken mid level cloud deck around 10 thousand feet, briefly lower to around 7000 feet over the next hour or so, with some virga around as well through about 05Z. Then look for gradual clearing after 05Z. East/northeast winds up to 10 knots should slowly decrease 03Z-05Z, and then eventually become light and variable late tonight after 08Z. Light diurnal east/southeast expected to develop by 18Z-19Z Tuesday. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Cooper SHORT TERM...Barjenbruch LONG TERM...Schlatter AVIATION...Cooper
Area Forecast Discussion
National Weather Service Taunton MA
707 PM EDT Mon Mar 12 2018 .SYNOPSIS... Low pressure off the Carolina coast rapidly deepening into a coastal storm, affecting southern New England tonight into Tuesday night. This storm will deliver significant accumulating snow, strong to damaging winds, coastal and marine impacts. Blustery and chilly weather continues Thursday and Friday followed by moderating temperatures this weekend. Dry weather probably dominates late in the week through next weekend. && .NEAR TERM /THROUGH TUESDAY/... 7 pm update... Storm structure evolving, deepening off the Carolina coastline. The N-stream influence, diving S, tucking in behind the closing low as observed via latest satellite trends. Cyclonic steering evident, pulling in all the way from the the Pacific, a sub- tropical connection out of the Gulf, the baroclinic leaf pattern fanning, its cyclonic stream packing up against the diving N-stream negatively-tilted trof, also against the rex block / suppressing wave over SE Canada. Deep synoptic lift evident as observed from latest WSR-88Ds, especially over Carolinas, though likely some bright-banding contamination (noting Dual-Pol CC). Tieing together, the near-term trends exhibiting the surface low to rapidly deepen S/E of the 40N / 70W benchmark, noting some of the guidance further out. However the N-stream pull, back to the W beneath mid-level features, noting some of the model guidance briefly tugging on the surface low, retrograding back beneath lower heights with occlusion. Something to watch with respect to frontogenetical outcomes / snow-banding along with winds that`ll stretch all the way back towards the Berkshires. For now, E winds enhancing per isallobaric / pressure gradient response with the surface low deepening off the Mid-Atlantic during the overnight period. Clouds still on the increase with mid to upper level decks spreading from S/W with low ocean- generated stratus drifting in from the E. Lowering and thickening with time. Dewpoint depressions still remain rather large, and got the suppressing wave downstream. Precipitation onset closer to midnight, things get cranking during the early morning hours 4a if the HRRR is correct. Tuesday... */ Highlights... - Moderate to heavy snow, some locations seeing upwards of a foot to perhaps two feet total accumulation - 1-3"/hr snowfall rates at times, producing visibility less than a quarter of a mile. Winds expected to yield blizzard conditions to the east coastal shoreline of MA. - Strong to damaging winds, E gusts up around 65 mph possible for far E/SE MA coast, brunt of the winds around Tuesday morning into early afternoon - Impacting the Tuesday AM commute with difficult, near impossible travel - Especially the Tuesday morning high tide, strong E onshore flow yielding around a 2 to 3+ foot surge, minor to moderate coastal flooding issues, especially ocean-facing shores, vulnerable areas impacted by earlier storm systems */ Discussion... Combination of negatively tilted trough pushing thru the Great Lakes Region and southern stream energy contributing to intense cyclogenenesis overnight into Tuesday. Operational models indicating low center pressure drops about 30 mb in 24 hrs, deepening to around 970 mb and passing just SE of the 40N/70W benchmark around 12Z- 15Z Tue. The strong cyclogenesis should result in a pronounced lower fronto- genetical band in the 850-700 mb layer. At this time better shot for setup of this band looks to be over eastern MA, but can`t rule out another band potentially setting up to the west. Temperatures cold enough to support snow, except there might be some mixing with rain for a time on Nantucket Tue morning before turning back to all snow. */ Uncertainty... Continue to favor a consensus approach with the track of this low pressure. Thermal profiles increasingly look to favor all snow, with the exception of Nantucket and the outer Cape where a period of mix or a changeover to rain should occur. This introduces some uncertainty on snowfall accumulations. */ Snow... Looking at snowfall totals of 12-18 inches along the Worcester Hills and far NE CT eastward, with some higher totals around 20 inches possible. Where the mesoscale banding sets up will ultimately indicate where the highest snowfall totals will be. Closer to the I-91 corridor from Greenfield to Hartford and vicinity thinking snowfall totals will range mainly from 8-12 inches. Blizzard Warnings issued earlier today for coastal Essex County MA, Plymouth County and the Cape and Martha`s Vineyard. Elsewhere across southern New England Winter Storm Warnings remain in effect for overnight thru Tuesday. */ Winds... 925-850 East winds 3-5+ standard deviation from normal, with 925 mb winds 50-70 kts along far eastern SNE. Low level lapse rates indicate sufficient mixing, when combined with precipitation drag, to generate very gusty winds along the east coast of MA, particularly the Cape and Islands. Continuing thinking that N/NE winds will gust up to 60-65 mph for the east coastal MA shoreline, with the exception of the immediate Boston area. Blizzard Warning area includes the area where these strongest wind gusts are expected, with the exception of Nantucket. For Nantucket a switchover or mix with rain should keep this area from hitting blizzard criteria. Hence a High Wind Warning has been issued for Nantucket. Again, the brunt of the winds will be Tuesday morning into early afternoon. Have gone with snow/liquid ratios comparable to previous forecast, which is a model blend. Expecting a mainly dry/fluffy snow for much of the interior. Plymouth County and the Cape and islands are at greatest risk for a heavy/wet snow plus strong winds, yielding some potential tree damage and power issues. && .SHORT TERM /TUESDAY NIGHT/... Tuesday night... Nor`easter departs, resulting in slowly improving conditions from SW to NE. Snow showers and clouds may linger along and north of the Mass Pike. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... */ Highlights... - Wednesday, possibly Thursday, scattered snow showers / squalls - Starting as early as Thursday into early next week, cold and dry - Monitoring the following week for any storm activity */ Overview... Continued La Nina influence over the N Pacific. Variable Pacific jet however preferred H5 ridging lending to downstream trof-ridge-trof pattern across the CONUS (Rossby wave train) continues. Subtle shift yet energy is bowled over SE Canada round which cold air will pour S over the NE CONUS, also N stream energy. Prolonged period of colder than average temperature. Snow shower/squall activity early on, then mostly dry. However, any N-stream energy timed with any coincident S- stream energy, potential exists for additional Nor`Easter activity. Winter is not over yet. Short and sweet discussion below due to the oncoming storm activity. */ Discussion... Wednesday, possibly into Thursday... Scattered snow showers, squalls. Cold air advection yielding steep lapse rates up to H7 beneath cyclonic flow, deep low-level moisture. Potential exists for convective activity, potential instability, the likelihood of quick accumulating snows with any activity, near white- out conditions, sudden impacts to travel conditions. Wind headlines likely extended along with possible short-fused headlines for snow activity anticipated. As early as Thursday through early next week... Keep it mostly cold and dry. Can`t rule out a mild, more seasonable period in-between when winds become light rather than persistent NW winds. Definitely will be talking about some cold wind chills for mid-March, especially Thursday into Friday. An eye on potential Wind Advisory headlines. Next week... With energy continually bowled over SE Canada, suppressed from going any further E by persistence of -NAO, should N energy rotating thru become coincident with S-stream activity, encapsulation, interaction between the two could net further Nor`Easter storm activity. For now very low confidence given being it`s well out in time, however not ignoring some ensemble signals. && .AVIATION /22Z MONDAY THROUGH SATURDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday Night/...High confidence. Tonight into Tuesday... CIGs/VSBYs deteriorating tonight with SN/+SN. Possible RA/SN mix or period of RA over CHH/ACK for a period of time. By 8z (4a) things will go downhill quick. MVFR to start towards 6z (2a), lowering to IFR-VLIFR from 06Z- 10Z and lasting for much of Tuesday. N/NE winds strongest with gusts up to 60 kts around Tuesday morning along east coastal MA. Blizzard conditions possible with snowfall rates of 1-3 inches per hour, requiring Airport Weather Warnings. Expect accumulation on all runways. Tuesday night...Light snow tapers off, MVFR/IFR CIGs gradually improve to VFR from S to N. KBOS Terminal...Snow will accumulate quickly on runways by about 9-10z (5-6a) as N winds increase. Near-blizzard conditions, white- out. Airport weather warnings will likely be issued for snowfall rates of 1-3"/hour. Impacts to Tuesday AM push definite. KBDL Terminal...Snow moving in closer to midnight. Light at first, picking up in intensity towards the early morning hours Tuesday. Moderate, heavy at times, looking at IFR-LIFR with accumulations closing in on 1"/hour at times. Accumulating immediately on runways. Impacts to Tuesday AM push definite. Outlook /Wednesday through Saturday/... Wednesday: Mainly VFR, with areas MVFR possible. Windy with gusts to 35 kt. Chance SHSN. Wednesday Night: Mainly VFR, with local MVFR possible. Windy with local gusts to 30 kt. Slight chance SHSN. Thursday through Thursday Night: VFR. Windy with local gusts to 30 kt. Friday: VFR. Breezy. Friday Night: VFR. Windy with local gusts to 30 kt. Saturday: VFR. Breezy. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Tuesday Night/...High confidence. A rapidly intensifying storm will pass just SE of the 40N/70W benchmark on Tuesday. This storm is expected to achieve a central pressure as low as 960-970 mb. We expect storm force winds over most of our waters with gusts as high as 60 kts over the SE outer waters. Waves will build to between 20 and 25 feet by late Tuesday morning and possibly to 25 to 30 feet east of Cape Cod and Nantucket. Snow along the near-shore waters will reduce visibility to well below 1 mile late tonight and much of Tuesday. Outlook /Wednesday through Saturday/...Moderate confidence. Wednesday: Low risk for gale force winds with gusts up to 35 kt. Rough seas up to 13 ft. Chance of snow showers, slight chance of rain showers. Wednesday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 11 ft. Slight chance of rain showers, slight chance of snow showers. Thursday: Moderate risk for Small Craft Advisory winds with areas of gusts up to 30 kt. Areas of rough seas. Thursday Night through Friday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Friday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Local rough seas. Saturday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft. && .TIDES/COASTAL FLOODING... The Tuesday morning high tide is the one of concern. Astronomical high tides are quite low for early this week, and there is fairly limited time to enable the build up of surge and waves by the time of high tide. Nevertheless, extremely rapid intensification of a coastal storm and associated rapid increase in surge and waves have raised concern for the Tuesday morning high tide cycle along east coastal Massachusetts. Latest computer model runs point to a very intense storm that will pass just southeast of the 40N/70W benchmark. The combination of slightly stronger conditions and concern for existing shoreline vulnerability have prompted us to upgrade the Coastal Flood Advisory along the Hull to Plymouth and Sandwich to Dennis stretch of coastline to a Coastal Flood Warning. A Coastal Flood Warning remains in effect for the ocean side of Cape Cod and Nantucket. Ocean Side Cape Cod and Nantucket... We are fairly confident now of coastal impacts reaching moderate levels. We anticipate the storm surge in this area to increase rapidly to near 3.5 feet about Nantucket and along the ocean side of Cape Cod from Truro to Chatham, including Wellfleet, Eastham, and Orleans. That surge combined with waves that may reach 25 to 30 feet just east of Cape Cod and Nantucket will produce areas of moderate coastal flooding and severe erosion. We anticipate impacts to be exacerbated by vulnerabilities from the prior two storms. Hull to Plymouth and Sandwich to Dennis... Along this stretch of coastline we anticipate minor to moderate coastal flooding and areas of significant erosion. We are forecasting a storm surge of near 3 feet except 3 to 3.5 feet along the Sandwich to Dennis coastline and 15 to 20 foot waves across Massachusetts Bay and Stellwagen Bank. Here too, vulnerabilities created from prior storms may exacerbate impacts. Ocean Exposed Coastline north of Boston to Salisbury... Along this reach of ocean exposed Massachusetts coastline, we anticipate areas of minor coastal flooding and splash over with a storm surge around 2.5 feet and waves around or a little over 15 feet east of Cape Ann by the time of the Tuesday morning high tide. As is the case along the rest of the Massachusetts ocean exposed east coast, impacts could be more significant due to the current vulnerability of the coastline. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...Winter Storm Warning from 11 PM this evening to 8 PM EDT Tuesday for CTZ002>004. MA...Winter Storm Warning from 11 PM this evening to 8 PM EDT Tuesday for MAZ002>006-008>017-020-024-026. Coastal Flood Warning from 8 AM to noon EDT Tuesday for MAZ019- 022-024. Blizzard Warning from 11 PM this evening to 8 PM EDT Tuesday for MAZ007-018-019-021>023. High Wind Warning from 2 AM to 8 PM EDT Tuesday for MAZ024. Coastal Flood Advisory from 8 AM to noon EDT Tuesday for MAZ007-023. RI...Winter Storm Warning from 11 PM this evening to 8 PM EDT Tuesday for RIZ001>008. MARINE...Storm Warning from 4 AM to 8 PM EDT Tuesday for ANZ231-232-250- 251. Storm Warning from 4 AM to 6 PM EDT Tuesday for ANZ233-234. Gale Warning from midnight tonight to 6 PM EDT Tuesday for ANZ230-236. Storm Warning from 1 AM to 6 PM EDT Tuesday for ANZ235-237. Storm Warning from 1 AM to 8 PM EDT Tuesday for ANZ254>256. && $$ SYNOPSIS...Sipprell/NMB NEAR TERM...Sipprell/NMB SHORT TERM...NMB LONG TERM...Sipprell AVIATION...Sipprell/NMB MARINE...Sipprell/Thompson TIDES/COASTAL FLOODING...WFO BOX Staff
Area Forecast Discussion
National Weather Service Caribou ME
727 PM EDT Mon Mar 12 2018 .SYNOPSIS... Low pressure will intensify as it moves northeast toward Nova Scotia overnight and Wednesday then slowly move north through the northern Canadian Maritimes Wednesday night and Thursday. && .NEAR TERM /THROUGH TUESDAY/... 722 PM Update... Sfc analysis showed inverted trof across western and northern areas. Radar showed some light returns were across the northern areas and the Mt. Katahdin region. Most of this was aloft as moisture was limited below 800mbs. Some llvl convergence in place to allow for some light snow showers. The latest RAP and HRRR were matching up well w/the radar and cloud scheme. The 12z GEM was close as well. Therefore, decided to add 20% pops for snow showers to the aforementioned areas. Activity dies out as the evening wears on. Hrly temps/dewpoints were adjusted to match the latest conditions. Stayed close to the daycrew`s fcst of going w/low to mid 20s w/upper 20s Downeast. Previous Discussion... The main concern in the near term, of course, will be the next Nor`easter that will affect the region beginning Tuesday morning. Low pressure developing along the Mid-Atlantic region will intensify and track northeast overnight. The low will then continue to intensify on Tuesday as it continues to track northeast toward southwest Nova Scotia by late Tuesday afternoon. After a mainly cloudy night tonight, expect snow to begin to develop across western portions of interior and coastal down east Maine shortly after daybreak on Tuesday. The snow will then continue to expand north across the central highlands and southern Aroostook by early afternoon Tuesday. The snow will become heavier and steadier by mid afternoon. As the low continues to intensify, northeast winds will increase and become gusty by early afternoon, resulting in some blowing and drifting snow, especially across down east areas. A Winter Storm Warning remains in effect for all of central and down east Maine beginning Tuesday morning. Across far northern Aroostook County, the snow will be slower to start, as low level dry air will be slow to give way with strong ridging in place near Labrador/New Foundland. In fact, some of the higher resolution models are suggesting that not much in the way of measurable snow makes it into far Northeast Aroostook County until very late afternoon, with drier flow of air downsloping off New Brunswick highlands to our east. A Winter Storm Warning has been issued for far Northern Aroostook County beginning Tuesday evening. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... Latest model trends over the last 6 hr cycles has been to track the intensifying secondary low a little further S thru the Gulf of ME. This will initially inhibit stronger sn banding from charging into Nrn ptns of the FA from Downeast and Cntrl ptns of the Rgn Tue ngt. On Wed, the sfc low will begin to become captured by the the upper low movg E from the great lks. This will allow for whats left of more enhanced sn banding to migrate nwrd into the NE hlf of the FA, resulting in better sn rates ovr this area attm. Snfl will begin tapering off from S to N beginning ovr Downeast areas by Wed aftn but not reaching far Nrn areas until late Wed ngt. For this reason, the final Nrn most wntr stm wrng begins latest (Tue eve) and ends latest (late Wed ngt. Intense snfl rates will end ovr Downeast and Cntrl areas during the ovrngt hrs Tue where the greatest stm total snfl is xpctd, with lesser but still quite sig accumulations ovr the N and E. Otherwise, mainly cldy skies and sct sn shwrs aftn rn/sn shwrs will cont Thu into Thu ngt as the upper low crosses and moves E of our FA with lgt additional accumulations. Temps will be near seasonal norms by day and cont sig abv norms at ngt. && .LONG TERM /FRIDAY THROUGH MONDAY/... Still xtnsv sc cld cvr and msly Nrn sn shwrs for our Rgn Fri as another s/wv trof from Cntrl Can crosses the Rgn. behind this system, the first - although modified - arctic air mass in at least 2 weeks will move into the Rgn for Fri ngt and Sat. Another s/wv for later Sun into Mon morn potentially could bring additional sn shwrs and colder temps from sig higher resident arctic air from Nrn Can. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... NEAR TERM: VFR conditions this evening will give way to developing MVFR ceilings after midnight, especially KBGR/KBHB. Flight conditions will deteriorate even further early Tuesday from south to north across the terminals. Expect snow to overspread KBGR/KBHB after 12Z Tuesday with IFR/LIFR conditions developing in snow, with areas of blowing snow expected by afternoon. Snow accumulations on untreated runway surfaces will likely range from 5 to 8 inches by late Tuesday afternoon at both KBGR/KBHB. The steadier snow is expected to reach KHUL by 18z Tuesday with conditions becoming IFR thereafter. The snow will be slower to reach the far northern terminals and is not expected to begin until after 20Z to 22Z or so, with conditions deteriorating to IFR. SHORT TO LONG TERM: All TAF sites will be IFR-VLIFR in sn Tue ngt after a brief start as MVFR erly Tue eve across Nrn most TAf sites. Cont`d IFR and VLIFR in sn Wed with conditions slowly improving to MVFR from S to N Wed ngt. All sites will be MVFR with clgs and vsbys in sn shwrs Thu, with Nrn TAF sites ocnly IFR attms. Conditions improve to VFR for Downeast sites Thu ngt but cont MVFR clgs and attms vsbys in sn shwrs for Nrn TAF sites into Fri, with all sites VFR Fri ngt and Sat...bringing cooler, spcly ngt tm temps, and a better possibility for day tm sunshine. && .MARINE... NEAR TERM: A Storm warning remains in effect beginning Tuesday morning and continuing through Tuesday evening. A Gale Warning is in effect for the intra-coastal zone from early Tuesday morning through Tuesday evening. Winds/seas will increase overnight and continue on Tuesday. Northeast wind gusts as high 55 kts will be possible across the outer waters along with seas building to 11 to 19 feet during Tuesday. Visibility will be lowering to 1 NM or less in developing snow early Tuesday morning and continue through Tuesday. SHORT TO LONG TERM: Storm wrngs over our outer MZs will need to be transformed into a interim gale wrngs into Tue ngt before dropping to SCA conditons for late Tue ngt and beyond. Went initially about 2 to 3 ft abv WW3/NWPS blended guidance for fcst wv hts Tue ngt then blended with guidance during the day Wed and cont`d with guidance for the rest of marine fcst pd. && .TIDES/COASTAL FLOODING... Tide cycles of greatest concern are Tuesday 12:50 AM and 9:25 PM. Due to the Lunar Cycle these astronomical tides will be 2-3 feet below the highest tides of the month. Expect the greatest storm surge and largest waves to occur mid afternoon Tuesday. Due to the lower astronomical tide and timing of surge and waves, coastal flooding appears unlikely at this time. Runup, splash over, and beach erosion are expected to be minimal. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...Winter Storm Warning from 6 PM Tuesday to 2 AM EDT Thursday for MEZ001-002. Winter Storm Warning from noon Tuesday to 8 PM EDT Wednesday for MEZ003>006-010. Winter Storm Warning from 8 AM Tuesday to 2 PM EDT Wednesday for MEZ011-015>017-029>032. MARINE...Gale Warning from 5 AM Tuesday to midnight EDT Tuesday night for ANZ052. Storm Warning from 11 AM to 8 PM EDT Tuesday for ANZ050-051. && $$ Near Term...Duda/Hewitt Short Term...VJN Long Term...VJN Aviation...Duda/Hewitt/VJN Marine...Duda/Hewitt/VJN Tides/Coastal Flooding...Mignone
Area Forecast Discussion
National Weather Service State College PA
1111 PM EDT Mon Mar 12 2018 .SYNOPSIS... A storm moving off the coast will clip the south and east with some light snow this evening and tonight. The storm will deepen as it moves into New England, turning our wind to the northwest as it does so. These northwest winds and a slow moving upper level trough swinging through over the next two days will create lake effect snows across northwest PA and the Laurel Highlands. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... 01Z MRMS RALA loop showing a band of light snow falling across the eastern portion of the forecast area from eastern Tioga County south through Adams County. Pooling of moisture along inverted surface trough, combined with large scale forcing ahead of upper low over the Grt Lks, will keep this area of light snow going into the late evening hours over the eastern portion of the forecast area. Visibilities running between 1-2sm under this band and webcams/observers indicate a coating to an inch has fallen in many locations of the Middle Susq Valley. A blend of latest HRRR and earlier NAM/HREFV2 support overnight accums of a coating to 3 inches along and east of the Susq River, with the greatest amounts over the high terrain of Sullivan County. Considered an advisory for Sullivan, but based on marginal amounts and coordination with BGM have decided not to issue. Expect the light snow to push east of the forecast area by dawn, as the inverted surface trough and associated ribbon of higher PWATS push east of the area. Further west, passage of upper trough axis, combined with orographic forcing, will produce scattered snow showers over the Allegheny Plateau and central mountains, producing a fresh coating overnight in many locations. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... Upper low crossing the lakes will be the star of the show for the short term. Tuesday seems like a typical NW flow SHSN day, with just a few SHSN making it past the Allegheny Front (roughly I-99). Although little activity is expected early in the day, coverage and intensity of diurnally-driven snow showers should peak during the afternoon, then begin to wane towards evening. Steep lower tropospheric lapse rates indicated in the model data across western Pa, indicating some locally heavy squalls are possible over the Alleghenies during the afternoon. However, the cellular nature of the convection will result in very brief episodes of heavier snow and model qpf only supports accums across the Allegheny Plateau of a coating to an inch Tuesday. NBM/Superblend indicating max temps Tuesday ranging from the low 30s over the Alleghenies, to the low 40s across the Lower Susq Valley. A tight pressure gradient west of intensifying low over New England will result in gusty winds, making it feel even colder. Bufkit soundings support gusts between 20-25kts, with the highest gusts in the southern half of the state. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... A large upper level low dropping south from the Great Lakes will keep periodic scattered SHSN over the western high terrain through mid-week. No period looks particularly worse than any other so not looking at any advisory necessary. The blustery persistent northwesterly flow will keep cold air advection moving into the region through mod week. This will allow for well below normal temperatures. Couple this with the gusty winds and wind chills every morning will be in the teens through mid week. Conditions will improve through the latter half of the week to around normal this weekend. Temperatures should begin to moderate by the upcoming weekend as upper-level ridging across the middle of the country builds eastward. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... A few adjustments to the TAFS at times this evening. Earlier discussion below. Some more last minute changes made to the 00Z TAF package. Sun came out here at the office just for a brief time...on back side of bands of snow just to the east. Bands of snow to the east now tightening up and getting into MDT. To the west...winds shifting to the northwest...and bands of snow showers becoming more widespread. Expect bands of snow with the coastal storm into the early morning hours across the east. To the west...bands of snow showers will likely persist into Wednesday...given a northwest flow of cold air off the Great Lakes. The intensity of the snow will likely taper at times during the day on Tuesday...given daytime heating...and the winds may back to the west some. Improving conditions for later in the week. Outlook... Tue-Wed PM...MVFR-IFR in snow showers wrn 1/3; mainly VFR with occasional MVFR possible in brief snow showers/flurries central and eastern 2/3. Thur-Sat...VFR. No sig wx. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Dangelo NEAR TERM...Fitzgerald SHORT TERM...Dangelo/Fitzgerald LONG TERM...Lambert/Ceru AVIATION...Martin
National Weather Service Eureka CA
303 PM PDT Mon Mar 12 2018 .SYNOPSIS...A cold front approaching the area is bringing breezy southerly winds and some light rain. Winds and rain will peak as the front moves through late tonight into early Tuesday. The remainder of the week will feature periods of rain and mountain snow. && .DISCUSSION...The frontal boundary is shown well on the water vapor and IR satellites. Winds have started to increase on the ridges with gusts of 35 to 50 mph as of 2pm. This evening winds will continue to increase peaking after midnight with the frontal passage. Winds over the ridges of the coastal counties are expected to peak around 40 to 50 mph. The wind advisory for Humboldt county at elevations above 1,000 feet looks on track. Some light rain is possible this afternoon and evening as a warm frontal boundary moves north across Mendocino county. The southerly winds will enhance the rain potential on the south slopes while the areas in the rain shadow to the north may only see a few sprinkles in the afternoon and evening. Tonight the cold front moves onshore. The HRRR modeled radar shows the heavy rain start to move onshore just after midnight. This is expected to spread across the area fairly quickly reaching eastern Trinity county by 4 or 5 am. Rainfall amounts are still expected to range from 0.75 inches to 1.5 inches in 4 to 8 hours. Minor street flooding and small stream flooding is possible. This is a very warm system and snow levels will be over 7,000 feet. The heavier rain will taper off at the coast around sunrise and the back edge will move east through the morning. A thunderstorm is possible with the frontal boundary. There does not appear to be enough instability so have left them out of the forecast. Behind the front on Tuesday another shortwave is expected to bring some rain showers to the area, but confidence is low on the coverage and location. There is some more instability with this shortwave as some colder air moves nearly overhead which brings a better chance for some thunderstorms. So have added these to the forecast. Tuesday night This boundary moves off to the east and showers start to diminish. Snow levels on Tuesday are expected to be around 4,000 feet dropping to nearly 3,000 feet Tuesday night. Snow amounts look to be less than 3 inches so will hold off on issuing a winter weather advisory. This will need to be watched as it gets closer. Wednesday there will be some showers lingering in the morning. In the afternoon there may be some showers over the interior. Confidence is low on this in general. Thursday and Thursday night the upper level low is still expected to bring an increase in showers to the area, however there is some model discrepancies on the location and timing of this low. The ECMWF is much slower in moving it down the coast and moves it inland quicker. This brings significantly more rain to Humboldt and Del Norte county, while the GFS solution keeps the precip farther south. Generally went with a blend of the models. Snow levels will be around 3,000 to 4,000 feet, but confidence is low on this due to the track of the low. Friday additional showers are expected, although the coverage is not expected to be particularly widespread. There will likely be an increase in coverage over the inland areas with the daytime heating. Saturday showers are expected to diminish before another systems brings some light precip to the area Sunday or Monday. MKK && .AVIATION...Increasing clouds and breezy-gusty southerly winds are in store for the main air terminals (ACV, CEC and UKI) today. These condition are ahead of an approaching cold front expected Tuesday morning. Gusty winds have been a tad bit slow to materialize along the Redwood Coast from ACV-CEC. However, Fortuna southward and much of Mendocino were reporting gusty winds through late morning. A large narrow swathe of stratus clouds developed from Eureka Humboldt Bay to CEC...dropping Cigs and Vis into IFR from late morning to early afternoon. Prefrontal light rain will begin by late afternoon into early evening...especially over Mendocino. The rain will intensify at air terminals tonight and overnight with Cigs and Vis sliding into mostly MVFR. LLWS potential threatens air terminals as "above surface winds" significantly increases. Post frontal weather activity will turn to showers. && .MARINE...Southerly winds are increasing across the waters ahead of an approaching cold front, particularly across the outer waters and near Cape Mendocino. While local buoys have not recorded Gale Force Winds quite yet, as of 2:50 PM buoys 14 and 22 are getting close with gusts reaching near 30 kt. Meanwhile, the Cape Mendocino waverider buoy (213) is beginning to indicate steepening seas, which is an indicator of strengthening local winds. These winds will continue to increase this evening, and this will drive building steep southerly seas through the night. Winds will quickly weaken to around 15 to 20 kt behind the cold frontal passage late in the overnight hours tonight, but will remain somewhat gusty and highly variable though Wednesday. Specifically, the passage of another cold front early Wednesday may yield some stronger westerly gusts. Overall, though, the weakening winds and variability in the wind direction will allow the steeper southerly seas to settle. However, a building longer period northwest swell will maintain elevated seas through at least early Wednesday. Conditions through the end of the week will improve, but will remain somewhat elevated with combined wave heights of around 5 to 8 feet. && .EKA WATCHES/WARNINGS/ADVISORIES... CA...Wind Advisory from 5 PM this afternoon to 1 AM PDT Tuesday for CAZ104>106. NORTHWEST CALIFORNIA COASTAL WATERS... Small Craft Advisory from 3 PM this afternoon to 9 AM PDT Wednesday for PZZ450-455. Gale Warning from 3 PM this afternoon to 4 AM PDT Tuesday for PZZ470-475. && $$ Visit us at Follow us on Facebook and Twitter at: For forecast zone information see the forecast zone map online:
Area Forecast Discussion
National Weather Service Hastings NE
634 PM CDT Mon Mar 12 2018 .SHORT TERM...(This evening through Tuesday) Issued at 337 PM CDT Mon Mar 12 2018 Hazardous Weather Potential: None. Aloft: RAP model initializations and upr-air data show highly- amplified NW flow over the CONUS. A shortwave trof over WY was moving thru the Wrn ridge. This trof will move thru this eve with NW flow contg into tomorrow. Height falls along the W coast will be nudging the ridge E. Surface: Strong high pres was over SA/MB but extended S to TX. This high will sag into the Dakotas tonight and to near FSD by 00Z/Wed. Rest of this afternoon: Increasing clouds from the W. Near normal chill. Enjoy the lack of wind. Tonight: M/cldy but clds will be decreasing from NW-SE late. Clds will probably hold temps up much of the night...but still went cold as this is a dry air mass (dwpts currently in the teens). Even a couple hrs of good radiating should allow temps to drop into the upr teens near sunrise. Tue: Almost an exact duplicate of today. Sunny with near normal chill. Highs 45-55F with about 49F in the Tri-Cities. .LONG TERM...(Tuesday night through Monday) Issued at 337 PM CDT Mon Mar 12 2018 Hazardous Weather Potential: - Near critical fire wx conds are likely Wed afternoon over N-cntrl KS - A few rumbles of thunder could occur over the far SE counties Thu night Aloft: NW flow will cont into Wed but the Wrn ridge will also cont pressing E as the E Pac longwave trof sets up along the W coast. The ridge will crest over the rgn Thu with svrl days of SW flow to follow. Spaghetti plots of models/ensembles show significant uncertainty develops Thu night-Fri with the 1st shortwave trof to arrive from the SW. The last 3 EC runs have been the most potent developing a 545 dm low in vicinity of GLD...and the 12Z GEM has joined it...while the last 2 GFS runs and its ensemble mean have a 564 dm ridge in the same location! Once that trof exits (if it actually occurs) then the next potent trof or low is slated to move thru Sun night and there is better model agreement on that. Surface: The high mentioned above will cont sinking S to the Gulf Coast Wed. NW flow will deliver a backdoor cool front that will cross the CWA and settle E-W across Nrn KS Thu as low pres begins to organize over CO. This low is fcst to head E across KS Fri and weaken. The GFS has it...but weaker and over OK. High pres in some shape or fashion will build in Sat-Sun...but no guarantees that the wx will be fabulous given that the CWA will still be on the cool side of the front. The another lee low should form and eject across the rgn Sun night with the rgn in the cold sector Mon. The uncertainty extends to temps/precip. If we aren`t confident in what will transpire with sfc/upr-lvl features...there`s no way we can be confident in the sensible wx either. Temps: Really only have high confidence Wed-Thu with much warmer temps...although the warmest temps will be shoved S Thu. Very uncertain Fri-Sun...but early next week is looking cooler. Precip: can`t be stated enough how uncertain the fcst is. If the EC runs are right...we`ll have some accumulating snow N of I-80 Thu night into Fri and Fri will much colder than we`re indicating. Can`t rule out a few rumbles of thunder over SE CWA Thu night. From Sat-Sun...we have svrl periods of 20% POPs. That is more due to model spread. POPs are very high Sun night due to the heavy QPF from the GFS/GEM...but the EC is not on board. It has a much weaker system and almost no QPF. Suffice to say...please give us some leeway on the fcst Fri-Mon. There will be changes and they could be substantial. Fire Wx: increased temps/winds Wed. That puts Rooks/Osborne/ Mitchell counties near RFW criteria. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday) Issued at 630 PM CDT Mon Mar 12 2018 Broken to overcast VFR ceilings are expected to continue into the overnight before breaking up a bit during the early morning of Tuesday. There is an outside chance at some patchy fog, but this appears unlikely given lingering cloud cover and northeasterly winds. Mostly clear skies are expected to prevail Tuesday. Winds will remain light through the TAF period. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ SHORT TERM...Kelley LONG TERM...Kelley AVIATION...Mangels
Area Forecast Discussion
National Weather Service Northern Indiana
950 PM EDT Mon Mar 12 2018 .SYNOPSIS... Issued at 751 PM EDT Mon Mar 12 2018 Lake effect snow showers will become more numerous later tonight into Tuesday with 1 to 3 inches of snow falling downwind of Lake Michigan by Tuesday morning and additional light accumulations into Tuesday night. Drier conditions are anticipated for the latter half of the week with moderating temperatures through the weekend. && .UPDATE... Issued at 945 PM EDT Mon Mar 12 2018 Added time to end of winter weather advisory for end time. Basic forecast thoughts to remain, however present lull in upstream snow showers and with HRRR bringing late am/midday mesovort into soutwest Lower MI/northwest IN suggests timing shift. Furthermore blend towards consshort with adjusted slr/highest ratios 12-18 UTC appear only slightly lowered. && .SHORT TERM...(This Evening through Tuesday Night) Issued at 306 PM EDT Mon Mar 12 2018 ...Lake effect snow showers to bring travel issues Tuesday morning... Cold front and associated short wave were rapidly pushing through the area, a few hours ahead of model depiction with widely sct to scattered snow showers in its wake. Upstream data shows there will be a break in the precip with some clearing likely to occur into early evening before next short wave drops through the area. radar already showing response to the strong wave with snow showers rapidly expanding in coverage and intensity across NW Wisconsin and the UP of Michigan. This looks to move in several hours ahead of previous forecasts and model runs, which considering handling of the forecast today (lagging model timing) seems reasonable. Growing concern for quick burst of accumulating snow in the 5 to 13Z window with several models showing between a tenth and quarter inch of QPF which would result in a fast 1 to 3 inches of snow, unfortunately impacting the Tues morning rush hour. Given all these factors have hoisted Winter Weather Advisory for Berrien, LaPorte and St Joseph Indiana counties where accumulations potential is highest. At this point will run through 13Z. Expansion of headlines could be needed through the day Tuesday, but signals show potential for Type III lake effect setup as advertised with one band continuing in the same area and another potentially in NE sections of the forecast area. To further complicate things, 0-2 km Theta E lapse rates go negative well inland, suggesting a expansion of snow showers across much of the area late morning into mid afternoon. Surface temps will be cooler than today, closer to freezing vs the mid 30s to near 40 currently being seen. This should help the snow stick more efficiently and could cause some localized travel issues for the afternoon commute. At this point keeping any snow amounts generally under an inch, but could end up higher in some areas with 1 or 2 models showing well over a half inch QPF for the entire event. Lake effect snow could linger into Tuesday night with yet another wave, but enough to worry about prior to that no significant changes made to previous forecast. && .LONG TERM...(Wednesday through Monday) Issued at 306 PM EDT Mon Mar 12 2018 Long term will end up rather quiet with the region sandwiched between trough to the NE and also well to the west. Several ripples come through to keep the warmest air generally west and south of us except for a few chances for a run at 50 Thursday and again Sun-Mon. More robust system looks to pass to our south over the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening) Issued at 750 PM EDT Mon Mar 12 2018 Difficult terminal forecast for northern Indiana this evening. Continuing a bit pessimistic, albeit lesser, with 00 UTC issuance. Slightly later adjustment per the latest HRRR signals/output. Continue into fueling/alternate criteria per 12-16 UTC group, though do not discount brief IFR visibilities at times within middle of lake effect snow band. Lesser MVFR at KFWA a bit earlier with lake effect focus shifting farther west/northwest IN thereafter, though uncertain with lake effect mesovort riding south along eastern Lake Michigan shoreline into southwest Lower Michigan/northwest Indiana per HRRR. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...Winter Weather Advisory until 9 AM EDT /8 AM CDT/ Tuesday for INZ003-004. MI...Winter Weather Advisory until 9 AM EDT Tuesday for MIZ077. OH...NONE. LM...Small Craft Advisory until 11 AM EDT Wednesday for LMZ043-046. && $$ UPDATE...Murphy SYNOPSIS...AGD SHORT TERM...Fisher LONG TERM...Fisher AVIATION...Murphy Visit us at Follow us on Facebook...Twitter...and YouTube at:
Area Forecast Discussion
National Weather Service Marquette MI
731 PM EDT Mon Mar 12 2018 .SHORT TERM...(This evening through Tuesday) Issued at 352 PM EDT MON MAR 12 2018 Water vapor imagery and RAP analysis show a weak shortwave moving across the western fcst area this afternoon. Another well-defined shortwave over nw Ontario is dropping south toward the Upper Great Lakes. Forcing from these shortwaves, particularly the one over nw Ontario will act to enhance lake effect snow tonight, especially into north central Upper Michigan, where advisories are posted into Tue afternoon for Marquette and Alger counties. Tonight, models indicate Ontario shortwave will drop down across the western fcst later this evening into the early overnight hours. Mid- level q-vector convergence field indicate best forcing for lake enhancement should occur this evening into the early overnight hours. This enhancement potential combined with continued cooling at 850mb should lead to expansion/intensification of shsn this evening. Then, thru the night, nocturnal cooling and 850mb temps falling to - 15 to -18C by 12z Tue will result in more traditional LES organizing in the n wind favored snow belts. Have some concerns about analysis of ice cover utilized in the mesoscale models and how it will affect the QPF generated and thus LES amounts. The ice on the lake has become more broken up in recent weeks and shouldn`t act as a solid sheet that inhibits heat/moisture fluxes. As a result, LES accumulations tonight could be greater than reflected by models, especially with deep cold air under troughing leading to lake induced equilibrium levels up to 8-10kft and DGZ well positioned in the convective layer. For now expect, greatest accumulations over the north central portions where upslope n wind and longer fetch should easily support decent coverage of 3-5in/12hr snow accumulations with locally higher amounts over higher terrain locations. Thus advisory still looks good for Marquette/Alger counties. To the w, n wind will favor the high terrain of Keweenaw County and Gogebic/Ontonagon Counties. Ice cover is more substantial off western Upper MI, but with the ice cover probably not as great as modeled and not inhibiting heat/moisture fluxes as much as models indicate, snow accumulations could be a surprise over the w tonight. Bumped up accumulations more solidly into the 2-4 inch range for starters with locally higher amounts up to 6 inches over the spine of the Keweenaw. Expect les to taper off by mid afternoon Tue as inversion heights lower near 3 kft with ridging/subsidence building in from north and west of Lake Superior. .LONG TERM...(Tuesday night through Monday) Issued at 247 PM EDT MON MAR 12 2018 Upper air pattern consists of a 500 mb trough on the west coast, closed low in the lower Great Lakes and a ridge over the Rockies 00z Wed. There is also a shortwave over northern Manitoba that drops southward Tue night and moves into the lower Great Lakes Wed night into Thu. In the extended, GFS and ECMWF show a 500 mb trough over New England and another over the western U.S. 12z Fri. The trough in the western U.S. moves little through Sun while the ern U.S. begins to get into some upper level ridging. Troughing moves into the Rockies on Mon. Temperatures remain near normal for this forecast period and will be fairly quiet. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 730 PM EDT MON MAR 12 2018 Lake effect snow showers will continue to impact KIWD/KCMX/KSAW intermittently overnight leading to MVFR to IFR conditions, especially at KIWD and KSAW. Conditions may occasionally dip to LIFR at KSAW between 0500-1200 UTC as heavier snow showers pass nearby, but confidence is a bit too low at this point in their placement to include in the TAF. Conditions will increase to MVFR and eventual VFR at all three airports from west to east tomorrow as winds back and snow showers are pushed into eastern Upper Michigan. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 352 PM EDT MON MAR 12 2018 Strongest winds across Lake Superior will be in the 20-30kt range this afternoon through Tue morning, strongest across the east half of the lake. Winds for the rest of the week will mostly be at or blo 20kt though a few periods of winds up to 25kt will occur. No gales are expected. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Winter Weather Advisory until 5 PM EDT Tuesday for MIZ005-006. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Voss LONG TERM...07 AVIATION...Borchardt MARINE...Voss