Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/04/19

National Weather Service Albany NY
1017 PM EST Sun Mar 3 2019 .SYNOPSIS... Low pressure will approach from the mid Atlantic States tonight, and will be southeast of southern New England by daybreak bringing snow to the region with moderate to heavy accumulations south of the Capital Region and across western New England. Cold and brisk conditions will continue during the afternoon into the evening. Some lake effect snow showers will impact the western Adirondacks and Mohawk Valley Monday night through Tuesday with colder than normal temperatures across the region. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Winter Storm Warning in effect for Litchfield County in NW CT and for southern Berkshire County MA for late this afternoon through Monday morning... Winter Weather Advisory in effect for the eastern Catskills, mid Hudson Valley, Taconics, southern VT and the northern Berkshires in western Massachusetts from late this afternoon into Monday morning... As of 1000 pm, snowfall has spread across the forecast area. There appears to be a more enhanced band stretching from central PA toward the I-88 corridor likely in association with some midlevel frontogenesis. This band has produced 2-4" amounts in the Binghamton area, and should result in snowfall intensity increasing along the I-88 corridor into the Capital District and southern Vermont as we head toward midnight. To the south, snowfall has been light but steady, with a few 1-2 inch reports over the Mid-Hudson Valley and Taconics. Heavier precipitation associated with stronger midlevel frontogenesis is working its way into central/northern NJ into the NYC area. The trajectory of this heavier precipitation is on track to brush Litchfield County through around 09Z. 00Z NAM and latest few runs of the HRRR have picked up on this, trending slightly wetter over our far southeastern zones (Dutchess and Litchfield Counties). Tweaked snowfall amounts slightly higher here, but zone average totals remain just below warning criteria in eastern Dutchess County, so no changes to the headlines are planned. Previous discussion... As of 420 PM EST...Some minor changes with the headlines, as we added Bennington County and eastern Rensselaer Counties to the Winter Weather Advisories, as snow totals are now in the 3-5" range. We also upgraded southern Berkshire County to a Winter Storm Warning with 4-8" expected which hits the 6" in 12-hr criteria based on a slight uptick in QPF from the guidance. We also trimmed back the end time for the NY zones in an advisory until 7 am and kept all the western New England headlines going until 10 am. The latest water vapor imagery shows a couple of potent southern stream short-waves moving across the Southeast and TN Valley associated with an active southern stream. The short-wave moving across the Southeast/Deep Southeast is causing some strong to severe thunderstorms with tornadoes. The area of low pressure and its associated inverted sfc trough will lift northeast from the lower-mid Atlantic States tonight. Meanwhile, a northern stream short-wave and cold front will be moving towards NY and New England from the Great Lakes Region. Gulf and some Atlantic moisture will stream northward and the forecast area will be near the right entrance region of a 250 hPa jet streak of 125-150 kts with strong upper level divergence. The low to mid level warm advection increases ahead of the warm front to initially two sfc waves moving towards the mid Atlantic Coast, we are expecting one to consolidate and form near the Delmarva Region by 06Z/MON. Moisture will continue to over run the warm front and be ahead of the cold front with the northern stream disturbance which will be over central/northern NY. The pcpn will increase in coverage between 5-7 pm south and west of the Capital Region due to the isentropic lift, and then spread northward quickly between 7-10 pm. Initially, rain will mix with snow, then change to snow as wet bulbing cools the column down in the mid Hudson Valley and south of the Capital District. The latest 12Z NAM has the best H850-700 FGEN over locations south of the Capital Region between 03Z-06Z, and then continuing into the early morning hours with snow rates on the 12Z HREFS getting into the 0.5-0.75"/hr range. Some locations in eastern Dutchess and Litchfield Counties may get into the 1"/hr range especially between midnight and 3 am, as their may be some bandlets. Further north, the NAM more so than the GFS has the H700-500 FGEN overspread the northern and central portions of the forecast area including the Capital Region/southern VT. The NAM was slightly heavier with the QPF in terms of the north and west extension, but still close to the latest 12Z ECMWF/WPC guidance. KALB should be around 0.25" for the event based on the deterministic, ensembles and ensemble plume guidance. Basically, we are expecting 0.30-0.60" in the advisory and warning areas, and a tenth to a quarter of an inch outside the advisory areas. Some of the 12Z NAM soundings show the strong upward vertical motion ahead of the wave intersecting the dendritic growth zone all the way north to the Capital Region/southern VT tonight, whereas the GFS with a slightly further south track has it more surpressed to the Mid-Hudson Valley, southern Berkshires and Taconics. This is a fast moving open wave and the snow should start to diminish and taper to scattered snow showers by 6 am. There could be some snow covered and slippery roads for the morning commute. Our heaviest snow amounts remain across Litchfield County CT, and the southern Berkshires where we believe 5-8" is likely. In the mid Hudson Valley, Taconics, eastern Catskills 3-6" is likely for moderate snow amounts with perhaps a few localized higher amounts in eastern Dutchess Co. Further north for southern VT, and the northern Berkshires 3-5" or 3-6" is likely and we have all these areas in the advisories. For the Capital Region/Mohawk Valley/Helderbergs/Schoharie Valley we have 2-4" forecasted, and further north in the southern Adirondacks, Lake George Saratoga Region we have 1-3" and their could be a sharp cutoff in the snowfall in the Adirondacks Park. Snow to liquid ratios of 12-15:1 were used for the majority of the event based on a blend of the guidance. The lower values were from the Capital District/Berkshires south and the higher values to the north. It will be average/climo snow to liquid ratio, and not as fluffy as Wednesday of last week, but not a heavy wet snowfall. Lows will be mainly in the 20s with mid and upper 20s from the Capital District/Upper Hudson River Valley south and east. Some mid teens to lower 20s will be possible over the southern Greens, and north and west, especially with the cold front moving through, and colder air being drawn into the system. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... Winter Storm Warning continues for Litchfield County in NW CT and the southern Berkshires until 10 AM EST Monday... Winter Weather Advisories continues for the eastern Catskills, mid Hudson Valley, and Taconics until 7 am EST Monday ... Winter Weather Advisories for the northern Berkshires and southern VT until 10 AM EST Monday... Tomorrow...Low pressure in the fast mid and upper level southwest flow exits quickly, as it passes about a 100 miles southeast of Long Island by 12Z/MON, and then pulls east to northeast of Cape Cod by 15Z/MON. The snow will end quickly in the morning with little additional accumulation (a coating to a few tenths). Mainly some upslope west to northwest snow showers will persist along the Taconics, southern Greens, and Berkshires. The low-level sfc pressure gradient will increase with the sfc cyclone deepening and intensifying to 985 hPa or so east of the Gulf of Maine. N/NW winds will increase to 10-20 mph with some gusts to 30 mph or so in the Capital District/northern and central Taconics, and the Berkshires. Low- level cold advection will continue during the day in the wake of the coastal low. H850 temps fall to -13C to -19C across the region. Highs Monday will be in the teens (southern Dacks) and 20s west of the Hudson River Valley, and upper 20s to mid 30s to the east. Max temps may occur in the late morning into the early afternoon. A few locations in the mid Hudson Valley may get into the upper 30s. Mon night...The eastern CONUS and the ALY forecast area will be under the influence of a broad longwave trough. Some lake effect snow may persists downstream of Lake Ontario in the western Adirondacks, western Mohawk Valley, and the northern Catskills with light snow accums of a few tenths or an inch or so. Sfc high pressure will attempt to build in from the Mid Atlantic States. H850 temps continue to run colder than normal with -16C to -19C values over the forecast area based on the latest GFS. Lows will feel more like January with single digits and lower teens with some below zero readings over the southern Adirondacks. Tue-Tue Night...The flow backs to the southwest ahead of the next piece of northern stream short-wave energy moving through the mid and upper level trough. A lake effect band may form but the downstream extension, and if any headlines are needed are still uncertain. This may also be a quick transitory lake band too based on the 3-km NAMnest. The short-wave will also disrupt the flow, as it will veer more to the west to northwest late Tue pm into Tue night. Some light snow amounts of a few inches have been placed in the forecast for the western Adirondacks into the western Mohawk Valley. The snow showers will likely be more widespread with the short-wave and reinforcing short of cold air. Also, a slight to low chance of snow showers was placed in the forecast area north and west of the mid Hudson Valley with the short-wave/sfc trough passage. Highs Tuesday will run at least 15 degrees below normal with 20s to near 30F in the valleys, and teens to lower 20s over the mtns. Lows Tuesday night will be in the single digits to lower teens with a few below zero readings over the Adirondack Park. Wind chills may be in the lower single digits to about 15 below zero in the southern Dacks. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... The main story in the long term will continue to be the unseasonably cold temperatures Wednesday and Thursday before some moderation occurs Friday into the weekend. H850 temps averaging -16 to -22C Wed/Thu are 1 to 2 SD below normal per the NAEFS. Forecast temperatures are expected to run some 15-20F below normal. While this will certainly be unseasonably cold, the forecast temperatures would not set any records. Some light snow showers are possible during this time, especially in the lake effect belts. Friday into the weekend, the airmass moderates while the midlevel flow becomes more zonal. Temperatures still appear cooler than normal, however. There are some signals among the deterministic and ensemble guidance for a quick shot of light snow Friday in association with a quick-moving embedded disturbance passing to our south, so will introduce chance PoPs for some southern zones. Otherwise, there has been a signal in the guidance for some time now in a stronger low pressure system developing over the upper Midwest during the weekend, with its associated warm advection pattern precipitation spreading into our forecast area on Sunday. It`s still a long way out, but enough model consensus exists at this time for high-end chance to low-end likely PoPs. Multiple precipitation types are possible given the cold antecedent airmass, the track of the low, and the warm advection pattern. It could turn out being a snow to mix or snow to rain type event. We will be ironing out the details this week. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... Light snow continues to spread into the terminals. As of 2340Z, it has begun at KPOU, is expected to begin shortly at KALB/KPSF, and by 01Z at KGFL. The snow will be relatively heaviest at KPSF/KPOU, where a period of prevailing LIFR conditions is likely 01-09Z (KPOU) and 03-10Z (KPSF), when snowfall rates of 0.5-1 inch per hour are likely. Vsby at KALB is expected to fall to IFR by around 01Z, and at KGFL around 03Z. KALB may see LIFR at times especially 04-08Z, when snowfall rates of around a half inch per hour are possible. The snowfall should end from west to east around 09-11Z. Total snowfall accumulation is expected to be in the 4-6 inch range at KPSF/KPOU, 2-4 inches for KALB, and 1-3 inches for KGFL. As the system pulls away Monday morning, cigs and vsby should improve rather quickly, with VFR conditions by 12-14Z (except MVFR may last to around 16Z at KPSF where some light snow and lower clouds may linger). Winds will be light and variable for the first part of the night, becoming northerly at around 5 to 10 kt late, then becoming northwesterly at around 10 to 15 kt with some gusts to 20 to 25 kt late Monday morning into the afternoon. Outlook... Monday Night: Low Operational Impact. Breezy NO SIG WX. Tuesday: Low Operational Impact. Slight Chance of SHSN. Tuesday Night: Moderate Operational Impact. Chance of SHSN. Wednesday: Low Operational Impact. Breezy Slight Chance of SHSN. Wednesday Night: No Operational Impact. NO SIG WX. Thursday: Low Operational Impact. Slight Chance of SHSN. Thursday Night: No Operational Impact. NO SIG WX. Friday: Low Operational Impact. Slight Chance of SHSN. && .HYDROLOGY... No hydrologic issues are anticipated through the next week, with below normal temperatures expected much of the period. A storm system will impact the region tonight into Monday morning with a moderate to heavy snowfall south and east of the Capital Region. Lighter amounts are expected from Albany north and west. Greatest accumulations will be for areas south and east of Albany. With the precipitation falling as snow, therefore this will not have an immediate hydrologic impact. Behind this system, mainly dry and cold weather is expected for much of next week, with some lake effect snow in favored areas. As a result, rivers and streams look to mainly hold steady well into next week. Temps will average below normal with ice thickening and strengthening on rivers, lakes and streams. The next widespread pcpn system may not be until late next weekend. 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...Winter Storm Warning until 10 AM EST Monday for CTZ001-013. NY...Winter Weather Advisory until 7 AM EST Monday for NYZ054- 058>061-063>066. MA...Winter Storm Warning until 10 AM EST Monday for MAZ025. Winter Weather Advisory until 10 AM EST Monday for MAZ001. VT...Winter Weather Advisory until 10 AM EST Monday for VTZ013>015. && $$ SYNOPSIS...Wasula NEAR TERM...Thompson/Wasula SHORT TERM...Wasula LONG TERM...Thompson AVIATION...Thompson HYDROLOGY...NAS/Wasula
Area Forecast Discussion
National Weather Service El Paso Tx/Santa Teresa NM
330 PM MST Sun Mar 3 2019 .SYNOPSIS... Continued west and mostly dry flow aloft will allow spring weather to continue across the area into the weekend. Warm temperatures will continue through Friday before a strong Pacific storm system moves in later Friday. This will bring strong winds and blowing dust to much of the region, along with some showers, mostly over the mountains. Temperatures may cool down to normal levels for the weekend. && .DISCUSSION... Big picture looks like we will remain mostly under the southern branch of a split flow jet for much of this forecast period. This will keep the area mainly dry, though considerable tap of higher level tropical moisture from low northeast of Hawaii will produce periods of high broken/overcast skies Monday night through Wednesday. In the short term, back door cold front and large area of stratus have been dammed up against our eastern terrain with just slight drift to the west. Both GFS and HRRR show frontal boundary making it to the Rio Grande Valley by around 12z, then retreating some on Monday as westerly surface winds redevelop. Did allow low clouds/fog to cover the eastern slopes of the Sacs, but did not bring it any further west. Will have to watch that tonight. Temperatures will cool some Monday, though still probably above normal. A bit stronger west push Tuesday bring the frontal boundary out to the Cont Divide or possibly Arizona border, for a couple more degrees of cooling. West winds kick in again Wednesday and Thursday, warming the area up to well above normal. The only significant weather feature in the forecast period is the strong Pacific frontal system moving in on Friday. Both GFS/ECMWF bring the system in over the Great Basin Friday afternoon, with attendant increase in clouds and winds over the CWA. Some mountain showers are possible with this initial push. Upper trough and front move in Friday night, with at least a brief shot of showers most places. Decent lee side cyclogenesis over SE Colorado, combined with strong core of low/mid level winds should translate to at least advisory level winds (if not warning level). Snow levels start out quite high, but fall to around 7000 feet late Friday night as the precip winds down. So a couple of inches are possible in the mountains, mainly above 8000 ft. System quickly exits Saturday morning with dry west flow resuming remainder of the weekend. && .AVIATION...Valid 04/00Z-05/00Z... VFR conditions are expected to continue thru the period as high clouds stream thru the area. Winds will be generally from the west around 5 to 10 kts, but in areas east of the Rio Grande winds are expected to shift to the south as a back door cold front approaches the region. The far eastern zones of Otero and Hudspeth counties will have a chance to observe a low stratus layer cloud associated to the cold front in the morning hours. && .FIRE WEATHER... Quiet weather is mostly expected for the first half of the week. Low moisture content (Min RH mid-lower teens) will be observed over the next few days, but 20-foot winds at or below 10 mph will avoid meeting any critical thresholds. A stalled back door cold front to the east will finally arrive late on Monday and into Tuesday. The cold air mass behind the front will be modified by then, so temperatures will drop only about 5 to 10 degrees from today`s values. As we remain under the influence of an upper ridge for most of the week , drier and warmer air will keep intruding into the Borderland. Temperatures will be well above normal by Thursday again. The approach of an upper level disturbance on Thursday will lead to breezy winds, and along with very dry air some areas may observe critical fire weather conditions. By Friday, an upper trough moves in bringing even stronger winds, but also more moisture with it, which will reduce the chances or reaching critical thresholds. For the weekend, the upper system may bring some precipitation chances across portions of the forecast area. Vent rates will be mostly above the good category, except on Tuesday. Then they increase into the excellent category as stronger 20-foot winds are expected over the second half of the week. && .PRELIMINARY POINT TEMPS/POPS... El Paso 47 70 41 68 / 0 0 0 0 Sierra Blanca 36 62 31 58 / 0 0 0 0 Las Cruces 43 68 38 67 / 0 0 0 0 Alamogordo 43 64 36 66 / 0 0 0 0 Cloudcroft 30 50 32 47 / 0 0 0 0 Truth or Consequences 42 67 37 68 / 0 0 0 0 Silver City 39 60 40 64 / 0 0 0 0 Deming 42 69 34 70 / 0 0 0 0 Lordsburg 42 68 37 72 / 0 0 0 0 West El Paso Metro 47 70 40 68 / 0 0 0 0 Dell City 32 62 30 60 / 0 0 0 0 Fort Hancock 44 72 36 69 / 0 0 0 0 Loma Linda 41 64 38 60 / 0 0 0 0 Fabens 44 71 39 69 / 0 0 0 0 Santa Teresa 43 69 37 67 / 0 0 0 0 White Sands HQ 44 68 40 67 / 0 0 0 0 Jornada Range 42 68 36 67 / 0 0 0 0 Hatch 43 70 36 68 / 0 0 0 0 Columbus 46 70 40 71 / 0 0 0 0 Orogrande 42 66 34 65 / 0 0 0 0 Mayhill 32 57 29 54 / 0 0 0 0 Mescalero 34 56 31 56 / 0 0 0 0 Timberon 32 55 30 52 / 0 0 0 0 Winston 35 62 32 65 / 0 0 0 0 Hillsboro 40 66 36 69 / 0 0 0 0 Spaceport 41 68 33 68 / 0 0 0 0 Lake Roberts 33 59 30 65 / 0 0 0 0 Hurley 40 62 39 66 / 0 0 0 0 Cliff 35 64 30 68 / 0 0 0 0 Mule Creek 34 61 29 66 / 0 0 0 0 Faywood 41 64 37 66 / 0 0 0 0 Animas 43 69 36 71 / 0 0 0 0 Hachita 43 68 37 70 / 0 0 0 0 Antelope Wells 45 70 38 73 / 0 0 0 0 Cloverdale 44 65 42 68 / 0 0 0 0 && .EPZ WATCHES/WARNINGS/ADVISORIES... NM...None. TX...None. && $$ Hefner/Crespo
Area Forecast Discussion
National Weather Service Sioux Falls SD
935 PM CST Sun Mar 3 2019 .SHORT TERM...(This evening through Monday) Issued at 350 PM CST Sun Mar 3 2019 Main concern in the short term are dangerous wind chills tonight and the blowing snow threat tomorrow afternoon. Current temperature are from just above zero in the Missouri Valley to around -5 in southwestern Minnesota. Sustained winds of 15 to 25 mph with gusts over 30 mph producing some blowing snow due to the deep snow pack across the region. The visibilities are 1 to 3 miles and webcams are showing finger drifting on major highways and would not be surprised if there are deeper drifts on a few less-traveled secondary roads with higher banks. Winds will drop off to 10 to 15 mph after sunset as the atmosphere stabilized and there neutral to weak warm advection aloft. Temperatures are expected to remain warmer than last night - from -5 to -12. With the winds around 10 mph and temperatures from -5 to -10 most of the night, wind chills will again be -25 to -35 so will continue the wind chill advisory through Monday morning. The surface pressure gradient remains strong through Monday. Both the GFS and the RUC have the winds from 30 to 35 kts at the top of the boundary during the afternoon - about 5 kts higher than today. There is every reason to expect these winds to mix down to the surface so should see some blowing snow and significant drifting where ditches are full. With west winds, the worst conditions will be on north-south roads. Where banks are above the road level in open areas, could see local reductions in visibility to a mile or less and significant drifting. Issued a winter weather advisory for areas where wind gusts will be over 30 mph and we have 18 or more inches of snow on the ground. It is more uncertain farther south given a little less snow cover and lower snow banks although there will certainly be some ground level drifting. If traveling late tomorrow morning into the afternoon, check road conditions and be aware less-traveled roads are likely to be worse than interstates and other major highways. Winds should begin dropping off toward sunset as the atmosphere stabilizes and a secondary front approaches. .LONG TERM...(Monday night through Sunday) Issued at 350 PM CST Sun Mar 3 2019 The main concern in the long term are chances for snow Wednesday night into Thursday and again on Saturday. Prior to the potential for accumulating snow, a strong upper level PV anomaly will drop southward across eastern plains Monday night. Moisture is really limited but with such cold temperatures will not be difficult to get ice introduced into clouds and produce light snow. Snowfall will certainly be less than an inch with the best chance of any accumulation from east central South Dakota into southwestern Minnesota. The best chance for snow will be in before midnight although a very light snow or flurries could linger after midnight. Tuesday will be a little warmer than Monday with highs from 10 to 20 degrees and a little less windy. It will be another well mixed day but this time winds at the top of the boundary layer are 20 to 25 kts. Cannot rule out ground level drifting but with little additional snowfall and lighter winds, not expecting any significant problems on Tuesday. On Tuesday night and Wednesday, the surface ridge will move east of the area allowing southerly flow to return. That will continue a slow warm up with highs from mid teens to lower 20s - still 20 degrees below normal but 20 degrees warmer than today. On Wednesday night a potent short wave will over top a long wave ridge expected to be across the area. There will also be one jet streak set up across central Minnesota and Wisconsin and a second moving across southern Nebraska. With the eastern plains in the entrance region of the northern jet streak, it will act to impede the northward progression of the mid-level frontal boundary. At the same time, the southern jet streak will result in strong ascent in the left exit region - in the vicinity of where the mid-level front is expected to set up. This is a good set up for banded snowfall. The trend in both deterministic models and GEFS has been for the front and snow band to shift south. While it is possible the snowband could extend as far north as I-90, the more likely solution is between the Missouri River and I-80. Since this is a mesoscale band of snow, the exact snowfall amounts and the location of the heaviest snow remain extremely uncertain. As has been the case all winter, adjustments in both the intensity of the snow and location can be expected over the next couple of days. The best that can be said now is that where snow does fall, there would be some impact to travel due to snow covered roads. After Thursday`s system, there will be a brief break and then a more significant system is expected to move into the eastern Plains for Friday night through Sunday morning. This is a full- latitude trough with a 500 mb low becoming negatively tilted and closing off as it moves into the Great Lakes. The other feature that is common between models is that the surface high will be over the eastern Great Lakes which will allow above freezing air to move north of I-80 - at least above the surface and perhaps even at the surface. What this means is the potential for a cornucopiaof precipitation types with snow, freezing rain, sleet and even a cold rain possible over portions of the area. The most likely area for remaining all snow is around Huron and Chamberlain with the lest likely area in northwestern Iowa. However, while most ensembles show a significant system, the details vary significantly amongst various member. At this point, it is best to say there could be a significant storm that could begin to affect the area beginning last Friday night. For now have either snow or rain/snow in the forecast but, as mentioned above, would expect this storm will also have sleet or freezing rain - although where that would be and how long any mixed precipitation would last is unknown. In addition to the precipitation, there could also be strong winds later on Saturday into Sunday. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) Issued at 935 PM CST Sun Mar 3 2019 VFR conditions are expected through tomorrow morning. Late tomorrow morning into tomorrow afternoon winds will increase with gusts as high as 35 to 40 mph. This may cause MVFR or IFR conditions in blowing and drifting snow. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...Wind Chill Advisory until noon CST Monday for SDZ038>040-050- 052>071. Winter Weather Advisory from noon to 6 PM CST Monday for SDZ038>040-052>056. MN...Wind Chill Advisory until noon CST Monday for MNZ071-072-080-081- 089-090-097-098. Winter Weather Advisory from noon to 6 PM CST Monday for MNZ071- 072-080-081-089-090-097. IA...Wind Chill Advisory until noon CST Monday for IAZ001>003-012>014- 020>022-031-032. NE...Wind Chill Advisory until noon CST Monday for NEZ013-014. && $$ SHORT TERM...Schumacher LONG TERM...Schumacher AVIATION...08
Area Forecast Discussion
National Weather Service New York NY
1025 PM EST Sun Mar 3 2019 .SYNOPSIS... Low pressure develops southwest of the region and will move southeast of Long Island tonight into Monday. The low then departs to the northeast into the Canadian Maritimes Monday into Monday night. Arctic high pressure slowly builds in through Thursday. Another low pressure system may impact the region Friday and Friday night. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... The fcst has been updated to include hvy snow wording, with radar indicating the main surge of pcpn now overspreading the cwa. Snowfall rates will increase thru midnight. Otherwise, the HRRR seems a bit too far south with the transition zone compared to the CC from KOKX radar. The alignment actually looks pretty good however when compared to the 18z GFS. As a result, the snowfall fcst, along with the most recent revisions, appear to be on track. Mixed p-type should remain confined to southern portions of Nassau county and NYC`s south boroughs, Suffolk County and extreme SE CT. This has impacted snow totals slightly with up to an inch more accumulation, mainly across SE CT. Otherwise, Winter Storm Warning remains in effect with a widespread 5 to 9 inch snowfall expected for the entire region, highest amounts over the western half of the forecast area between now and shortly after midnight, and the eastern half of the area during the second half of the night. Used raw 2 meter NAM temperatures with a slight decrease during times of heavier snow tonight. Relatively lower snow amounts expected along immediate coastlines. Some mixing with sleet and possibly freezing rain is expected especially towards the coastlines overnight with a warm nose at around 800mb making its way north. Forecast low passes near to just inside of 40N/70W benchmark. Main uncertainty is with the rain/snow line as models indicate heavy snow just north of it with trends farther north or south with this line making a difference with snowfall amounts. Trends farther north with the low and its warmth aloft will lead to a little less snowfall especially across the coasts whereas a trend farther south, keeps precipitation pretty much all snow with potential for slightly higher snow amounts. The jet stream exhibits phasing of polar and subtropical jets this afternoon into tonight. This is really key with the upcoming system. One feature that has good agreement with the models in the approach of the right rear quad of this jet tonight, particularly second half of this evening through midnight from Western Long Island and SW Connecticut to farther west. Thereafter that best forcing shifts towards SE Connecticut and Eastern Long Island for overnight through around 4am local time. The feature that is not too apparent is any coupled jet structure. The right rear quad is the more dominant jet structure without too large of a incoming left front quad farther south approaching. At 500mb, highest positive vorticity advection moves in late evening into the overnight period as shortwave moves from mid-Atlantic through coastal New England. At the surface, low pressure develops in the Southeast US early this evening. There will be a lot of convection down there and that convection allows for latent heat release which will cause subsequent downstream ridging and upstream troughing. The overall effect is to increase baroclinicity with noticeable decreasing wavelength in height patterns aloft. The low is set to deepen by late evening along the Carolina coast and then move northeast offshore of Long Island overnight, eventually settling to a point SE of Cape Cod by early Monday morning. The models deepen the low 10-15mb from 7pm tonight to 7am Monday morning. The 12Z NAM indicates a low track inside of 40N/70W but is also less with the deepening of the low. The result here allows more mid and low level warming for Eastern Long Island with even some rain possible whereas others keep Eastern Long Island colder with more sleet mix with snow as well as some freezing rain. Looking at mesoscale, 12Z HREF indicates a high likelihood of snowfall rates exceeding one inch per hour late this evening through the start of the overnight across the forecast region. This is about the same time the 850-700mb 2-D Frontogenesis maximizes across the whole region as well which is a forcing factor for lift. It shifts east of the region after 4am local time. Still some indications from models of some enhanced lift 4-7am for Southeast Connecticut and Eastern Long Island. Therefore, kept end time of 7am for the Winter Storm Warning. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... Snow tapers off with most forcing shifting northeast of the region Monday morning. Upper level low moves southward Monday through Monday night. Heights lower across the local region through the short term time period as a colder airmass settles in. At the surface, the low southeast of Cape Cod continues to move farther out into the Atlantic, moving into the vicinity of Nova Scotia by late in the day Monday while continuing to deepen. The low deepens a little more as it moves into the Canadian Maritimes Monday night. Meanwhile, high pressure will slowly build into the local region from the west Monday into Monday night. Dry weather will reestablish itself across the region Monday and with cold air advection occurring on a gusty NW flow. Went with consensus of raw data, keeping max temperatures in the mid to upper 30s for Monday. Cold air advection continues Monday night and with clearing skies but winds staying in the 5 to 15 mph range, min temperatures are expected to be in the teens, lower teens across the interior and upper teens for NYC and Long Island using a consensus of all model data. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Canadian high pres builds with an arctic airmass settling into the region through the middle of the week. This will result in mostly dry but unseasonably cold weather through Thu. There could be some flurries around at times Tue night and Wed. Wed/Wed night appear to be the coldest time periods with H85 temps around -20C. Highs Wed are expected to be in the mid to upper 20s and lows Wed night mainly in the teens, but some single digits in the normally colder spots. A weak WAA pattern then develops Thu, and becomes stronger Fri into Sat as a progressive mid level shortwave approaches from the central Plains. There is still a large degree of uncertainty between the global models in the H5 flow at the end of the week. 12z EC/CMC are similar with a flatter flow Fri morning while the GFS has a stronger shortwave tracking through the Ohio Valley. This is resulting in a weak sfc low moving across the area Fri night, while the EC/CMC are dry. Have maintained previous forecast with a low chc of pcpn Fri aftn/night, until this becomes better resolved. High pressure then builds across the area for the first half of the weekend, with a frontal system possibly impacting the area on Sun. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... Low pressure tracks east of Montauk early Monday morning, and up to Nova Scotia Mon aftn. Snow will continue to intensify thru 6z. The snow will be heavy at times, especially thru 9z. Snowfall rates could reach 1-2 inches per hour at times. The snow is expected to taper off around 10-12z Monday from W to E. Snow could mix with sleet, rain or freezing rain primarily along and east of a line from KLGA-KISP-KGON. LIFR and VLIFR is expected tonight, with improvement to VFR Monday morning. VFR then lasts thru the rest of the TAF period. NE winds back to the NW by Monday morning. Speeds increase after 06z tonight. Gusts 20-25 kt are expected late tonight through Monday morning, mainly along the coast. The gusty NW flow continues till about 1-4z Tue. Expected snowfall amounts for all terminals is 4-8 inches. .OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY... .Monday night...VFR with diminishing NW winds. .Tuesday-Wednesday...VFR. Flurries possible at times Tuesday night and Wednesday. W/NW winds with gusts up to 20 kt. .Thursday...VFR. W/NW winds with gusts up to 20 kt early. .Friday...Sub-VFR possible in snow Friday. && .MARINE... Sub-SCA conditions are expected for all waters through this evening. Then, pressure gradient increases ahead of an approaching low. Winds and seas will increase across the local waters tonight, with widespread SCA conditions for winds expected overnight into Monday morning. Ocean seas increase to 5 to 7 ft with increasing E-SE fetch overnight. Also for ocean waters, east of Fire Island Inlet, multiple models indicate winds gusting to gale force overnight into early Monday. Otherwise, mainly SCA conditions remain on the ocean Monday and Monday night with the Eastern Long Island Sound and Eastern Long Island Bays staying in SCA range for wind gusts Monday and Monday night. The other non-ocean waters go below SCA criteria Monday afternoon and Monday night. SCA level seas may linger into Tue morning east of Moriches Inlet, but a tightening pressure gradient will result in increasing winds and seas Tue evening, with SCA gusts spreading into eastern LI Sound and bays on Wed. Conds will gradually diminish Wed night, but may remain marginal on the ocean waters Thu. Tranquil conds are then expected through Fri. && .HYDROLOGY... Liquid equivalent precipitation of around 0.6 to 1 inch is expected from a coastal storm through early Monday morning. Most precipitation is expected to remain frozen with no hydrologic impacts expected. Otherwise, no significant pcpn is expected into next Fri. && .TIDES/COASTAL FLOODING... A few locations may approach minor coastal flooding benchmarks across the western south shore Bays of Long Island during Monday morning`s high tide. && .EQUIPMENT... NYC Central Park winds are out of service until further notice. Loss of data is due to a severed cable. Parts are on order. NYC NOAA Weather Radio Station KWO35 (162.55 MHz) will remain off the air for an extended period of time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...Winter Storm Warning until 7 AM EST Monday for CTZ005>012. NY...Winter Storm Warning until 7 AM EST Monday for NYZ067>075- 078>081-176>179. NJ...Winter Storm Warning until 7 AM EST Monday for NJZ002-004-006- 103>108. MARINE...Small Craft Advisory until noon EST Monday for ANZ335-338-345. Small Craft Advisory until 6 AM EST Tuesday for ANZ330-340-355. Gale Warning until noon EST Monday for ANZ350-353. && $$ SYNOPSIS...24/JM NEAR TERM...12/24/JM SHORT TERM...JM LONG TERM...24 AVIATION...12/PW MARINE...24/JM HYDROLOGY...24/JM TIDES/COASTAL FLOODING... EQUIPMENT...
Area Forecast Discussion
National Weather Service Mount Holly NJ
941 PM EST Sun Mar 3 2019 .SYNOPSIS... A winter storm will continue to affect the area through a good portion of the overnight hours,bringing what could potentially be the largest snowfall this season for some areas. High pressure builds into the region tomorrow as the low lifts off to the northeast. Quiet weather will persist through the remainder of the workweek, though highs will remain slightly below average. An area of low pressure looks to traverse the Southeast Friday, bringing the next chance for rain and snow for the region. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... 930 PM Update...Overall, forecast still in pretty good shape. Tricky area continues to be the I-95/I-295 corridor as detailed below. Given recent conditions and trends though, we`ve downgraded the Winter Storm Warning to a Winter Weather Advisory for Cecil Co. in MD, New Castle Co. in DE, and Salem Co. in New Jersey. These areas should see mainly a mix of sleet, rain, and snow with any additional accumulations of snow and sleet at most an inch or two. 815 PM Update...Snow/sleet/rain transition zone continuing to waver near the I-95 / I-295 corridor over SE PA and southern NJ into the northern Delmarva. As of 8pm, rain was falling at Wilmington International Airport with sleet at PHL and snow just to the north so sharply varying conditions over relatively short distances! This wavering zone looks to be the trend for at least the next couple hours until this zone may tend to shift northward. Winter Storm Warnings remain in place for the snow and mixed precipitation but we`ve now dropped all advisories except for Coastal Ocean County. 630 PM Update...Moderate to heavy precip ongoing as winter storm closes in on the area. As of early this evening, rain/snow transition zone doesn`t appear to be moving too much and looks to be located close to the I-95 corridor over the northern Delmarva eastward into southern New Jersey. With a change to rain having occurred through Queen Anne`s Co. MD into Kent Co. DE and points southward we`ve dropped advisories for these counties and also removed additional snow amounts here as well. Farther north, have increasing concerns that the transition zone may struggle to make it too much farther north...especially as it nears the Philly area. Also, latest HRRR runs suggesting sleet developing in this zone as well as the evening goes on. As a result, no real changes to forecast from around the Philly area and points northward. Please see previous discussion below for further details. Original Discussion (330 PM): Precipitation has begun to move into southern portions of the forecast area this afternoon and will continue to fill in from SW-NE this afternoon as isentropic lift increases ahead of a surface low currently centered over the SE US. This low will move eastward this afternoon into this evening and eventually part of it will redevelop off the DE/NJ coasts tonight. Initial precipitation over the area will be primarily rain over most of the area as surface temperatures are relatively warm and the precipitation intensity initially at least will be relatively light. With large dewpoint depressions it is possible some areas particularly in western portions of the forecast area may experience snow in the daylight hours due to wet- bulbing, however this will likely have difficulty accumulating on most surfaces. Around sunset a shortwave along and an associated jet streak will move towards the area. Dynamic lift associated with these upper level features combined with increasing 850-700 warm advection ahead of the approaching and deepening surface low will generate a period of fairly intense precipitation over much of the area early this evening. Given the diurnal timing (e.g. no sun) plus dynamic cooling, expect rain over much of the area to switch to snow in this period. This snow will accumulate fairly rapidly due to the high rates making travel hazardous. The exception will be central and southern Delmarva and coastal SE NJ where the precipitation will likely stay rain through the event. The main challenge with this event will be the advancing warm nose aloft overnight, as this feature will result in snow transitioning to sleet and/or rain wherever it crosses. There is naturally some spread in guidance over how fast this feature advances northwestward and also how far northwestward it gets (largely due to slight discrepancies of the surface low track). Current hi-res guidance brings this up to the I-95 corridor by late this evening and brings it around the I-195 corridor just before midnight. This is a bit further north than some earlier guidance was indicating and consequently reduced snow amounts somewhat in this corridor as sleet and rain show will potentially mix in later tonight reducing amounts. It must be emphasized there is still quite a bit of uncertainty in this area (the I-95 corridor) and slight changes in the surface low track and thermal profiles (and also dynamic effects which are often modeled poorly) may result in large changes in snow amounts. Also lowered amounts more significantly in SE NJ as most guidance has this area firmly in the rain/sleet zone for most of the event (outside of maybe the initial early evening burst). West of I- 95 and north of around I-78 precipitation should be snow the entire event and totals in the 5-8 inch range are expected with some favored areas potentially receiving a little more than 8 inches. The shortwave will have cleared the area by early Monday morning concurrent with the sfc. low moving north and east. Consequently precipitation will wane W-E once this occurs although some cooling aloft may allow for rain or sleet to briefly transition back to snow (although with light rates impacts from this will likely be limited). Finally precipitation will likely have cleared the area by daybreak as drier postfrontal northwesterly flow increases. && .SHORT TERM /6 AM MONDAY MORNING THROUGH 6 PM MONDAY/... Monday will be a transition day for the region. Low pressure will be quickly departing early in the day with any steady precip over by 6AM. Some lingering light rain or snow showers are possible to the northeast early, but the trend will be for drying and, by the afternoon, clearing. A large upper trough will be amplifying and digging in to our west, but the brunt of it will hold off for Monday. Still, decent CAA will be ongoing in the wake of the departing storm throughout the day, so temperature rises into the afternoon will be modest. We are fortunate, however, that temperatures should hold above freezing in most areas through the course of the day, with the exception of far northwest NJ and the Poconos. This will preclude a flash freeze Monday morning. Otherwise, a cool and blustery day but not bad weather for snow clean-up. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... The long term will be marked by an unseasonably cold midweek period followed by moderation and a potential return to unsettled weather late in the week. A robust longwave trough and associated closed upper low near the Hudson Bay will very gradually rotate eastward from Monday night through Thursday. This will bring with it an outbreak of unseasonably cold air for this time of year. The story on that has changed very little. We are still expecting both highs and lows from Monday night through Thursday night to be 10 to 20 degrees colder than normal. The exact magnitude of the cold is not certain, especially during the day. The strong March Sun argues for warmer daytime highs, but this tends not to be as effective during strong CAA, which will be occurring Tuesday and Wednesday. In addition, widespread snow cover will make it quite challenging to warm the air. And overnight, snow cover will certainly favor enhanced cold especially in areas of clear skies and light winds. So expecting it to be plenty cold days and nights. This looks like a dry stretch also. Several shortwaves passing near and over the region during this stretch, but all are moisture starved and nothing more than isolated snow showers are anticipated. One of these shortwaves will trigger cyclogenesis well offshore by Tuesday night, but this will not impact us beyond tightening the pressure gradient and bringing the winds up a little on Wednesday. By Thursday night and into Friday, the trough finally pulls away, though colder than normal air lingers into Friday. We then face a potential pattern change as cold air generally retreats away from our region. The large scale flow turns a little more zonal, and the upper air pattern becomes shortwave dominated, so this naturally lowers confidence. Will say that there do seem to be some similarities to the pattern we saw for much of February with troughing in the West and ridging in the East, but also cold air and high pressure not far north over eastern Canada. So an early hypothesis on the end of the week would feature something we`ve seen several times this winter: a leading wave sliding over or south of the region around Friday, with a larger storm behind it tracking to our west through the Great Lakes. A good deal of the latest guidance favors something like that. But at this early stage that this is still speculative, and it`s much too early for any details. Dailies... Monday night-Tuesday... Longwave trough overtakes the region with strong CAA. Am a little concerned about conditions for the Tuesday morning commute. We will do quite a bit of melting Monday, with many surfaces likely staying or becoming wet. Any standing water will freeze solid Monday night. So while a freeze-up is not much of a worry Monday morning, it could be a bigger issue on Tuesday morning. Tuesday night-Thursday night... Generally captured the idea here in the overview above. Reinforcing shot of cold air comes through Tuesday night with a shortwave passage, possibly accompanied by a few snow showers in the higher terrain. Wednesday looks a little breezy with tighter pressure gradient forced by developing offshore storm. Not concerned about any wind chill headlines this period. Sub- zero wind chills are likely in northern areas much of this period with single digits and low teens elsewhere, but it`s all below advisory criteria. Just anomalously and annoyingly cold for March. For the overnight periods, temperature values will be largely wind- dependent. Tuesday night may stay a little warmer than forecast if the winds ramp up sooner. Wednesday and Thursday nights have a better chance for more efficient radiational cooling, though the air mass starts to moderate by Thursday night. Regardless of exact values, it`ll be noticeably cold for March throughout this stretch. Friday-Saturday... Gradual moderation in temperatures as the trough pulls away. Looks like a Pacific shortwave may slide by the region per ideas above. Would mean a potential snow or mixed precip event around Friday, but does not look like a high impact event right now. If current timing consensus holds, Saturday would be favored as a dry day. Later in the weekend, broad troughing in the western and central US should favor ridging in the East which would support a storm tracking to our west with more wet weather outcomes as opposed to winter weather. But again, plenty of time to watch this and the general idea is just the chance for a return of unsettled weather by late week and the weekend. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... Tonight...Dual pol correlation coefficient product from the KDIX 88D indicates some wavering of the rain/snow/sleet line around the I95 corridor, which is having a direct impact on ptype and vsby at PHL, TTN, and ILG airports. Still expect widespread LIFR/IFR conditions at KRDG/KABE with moderate or heavy Snow much of the night tapering off by about 09Z. Mostly IFR/LIFR across the Delaware Valley with mostly SN but also PL and RA possible, tapering late, with some wavering due to changing location of the rain/snow line. KACY/KMIV will also have low CIGS, but VSBYS may not be too low with -SN and mostly RA. Primarily light NE winds early then N or NW winds around 10 knots towards dawn. Monday... Lingering MVFR ceilings expected for most areas in the morning. MVFR potentially lingering into the afternoon especially for RDG and ABE. Elsewhere, trending towards VFR but patchy areas of MVFR ceilings possible for most of the day. NW winds 10 to 15 kt gusting to 20 kt. Outlook... Monday night-Tuesday night... VFR. Westerly winds 5 to 10 kt. Wednesday-Wednesday night... VFR. WNW winds during the day Wednesday increase to 10 to 20 kt with gusts near to above 25 kt. Winds diminish to 5 to 10 kt Wednesday night. Thursday... VFR. Westerly winds around 10 kt with gusts up to 20 kt. Thursday night-Friday... Winds turn light and variable. Ceiling and visibility restrictions possible by Friday. && .MARINE... 9 PM Update...Winds have increased a bit sooner than expected so we moved up the small craft advisory so it`s now in effect. Previous Discussion...Onshore winds have developed today across the waters but remain well below advisory levels currently. Winds will become more northeasterly or even northerly with time tonight as they slowly approach advisory criteria. Seas on the Atlantic waters will also build slowly through the overnight hours, with 5+ ft seas likely being reached or exceeded by daybreak Monday. Winds and seas will peak on Monday morning, with north winds becoming northwest 15 to 25 kts with gusts to 30 kts and seas building up to 7 feet. Winds should diminish below advisory criteria on Delaware Bay Monday evening and on the Atlantic waters late Monday night. The small craft advisory was unchanged with this afternoon`s forecast. For Delaware Bay, it goes into effect at 1 am and lasts through 7 pm Monday. For the Atlantic waters, it goes into effect at 1 am and last through 1 am Tuesday. Rain is spreading over Delaware Bay and the Atlantic waters at this time, and will likely mix with some snow and/or sleet on the New Jersey Atlantic waters and upper portions of Delaware Bay this evening. Precipitation should taper off late tonight into Monday morning. Visibility restrictions should be expected during the precipitation, especially if any wintry mix occurs. Additionally, cannot rule out a lightning strike on Delaware Bay or the southern Atlantic waters this evening into the early overnight hours. Any embedded storm may produce erratic seas/gusts, as well. Outlook... Tuesday through Wednesday night: Sub-advisory winds/seas expected. Light freezing spray possible Tuesday night through Wednesday night. Thursday: Advisory-level northwest winds possible. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Winter Storm Warning until 7 AM EST Monday for PAZ054-055- 060>062-070-071-101>106. NJ...Winter Storm Warning until 7 AM EST Monday for NJZ001-007>010- 012>015-017>020-027. Winter Weather Advisory until 7 AM EST Monday for NJZ016-026. DE...Winter Weather Advisory until 7 AM EST Monday for DEZ001. MD...Winter Weather Advisory until 7 AM EST Monday for MDZ008. MARINE...Small Craft Advisory until 1 AM EST Tuesday for ANZ450>455. Small Craft Advisory until 7 PM EST Monday for ANZ430-431. && $$ Synopsis...Davis Near Term...Carr/Fitzsimmons Short Term...O`Brien Long Term...O`Brien Aviation...Miketta/O`Brien/O`Hara Marine...CMS/Fitzsimmons
Area Forecast Discussion
National Weather Service Reno NV
243 PM PST Sun Mar 3 2019 .SYNOPSIS... Light showers with areas of fog and low clouds will affect much of the region through early Monday morning, with intermittent snow impacts for Sierra passes. After a break Monday into much of Tuesday, the next storm brings heavy wet snows to the mountains, along with rain showers and gusty winds to the valleys Tuesday night through Thursday. A colder airmass Friday increases chances for snow showers all elevations but risk of heavy snows is low certainty this far out. && .DISCUSSION... THROUGH MONDAY... No major changes were made to this relatively quiet period of the forecast. * Remnant frontal boundary draped across the forecast area combined with waves zipping along aloft will keep showers going N of Hwy 50 into the nighttime hours. Some spots where banding sets up could pick up 0.25-0.5 inches rainfall, and Sierra passes will see occasional snow impacts tonight as temps drop. Interesting - snow levels dropped to valleys this afternoon near Janesville within convective band yielding a surprise 2" near Hwy 395. A few t-storms remain possible in areas that have cleared more - Mono- Mineral. HRRR showing 250-500 CAPE in these areas between 3-6 PM today. * Showers diminish from south to north by daybreak Monday as shortwave (very shortwave) ridging builds into the region. Should be a decent day, extending into most of Tuesday. With plenty of low level moisture and light winds, areas of fog and low clouds are possible again tonight into Monday AM. Best chances are along and north of Hwy 50 including Tahoe, Truckee to Reno and up towards Susanville. * Some concerns for refreeze of wet roads late tonight into Monday morning. Temps generally above freezing tonight but a few spots such as Lovelock, Carson Valley, Susanville, and outlying areas of Reno-Sparks could dip below freezing resulting in spots of ice. -Chris MIDWEEK STORM...Tuesday through early Thursday AM... * Increased south-southwest winds Tues PM into Wed for the Sierra ridges, Tahoe Basin and western Nevada. * Increased POPs & QPF for areas in NE California including Lassen and Plumas Counties. Decreased POPs & QPF for western Nevada due to precipitation shadowing potential. * Snow levels hover around 6000-6500 ft and then drop down to 5000- 5500 ft by early Thurs AM as the front moves through. Travel hazards likely in the Sierra for duration of event due to snow accumulation. The tranquil weather to start the work week will rapidly come to an end by Tuesday afternoon as cloud cover and south-southwest winds increase throughout the region ahead of our next storm system. During this time, a moderate low pressure system will move into the west coast impacting much of California and Nevada through Wednesday. Overall, winds do not look too impressive at this time as the associated jet looks to take more of a southerly trajectory aiming for areas just south of Mono County. Even with this potential set up, SSW winds will be gusty for Tuesday night along the Sierra crest and around the Tahoe Basin. By early Wednesday afternoon, gusty southerly winds will spread throughout western Nevada. Typical winter storm gusts of 30-40 mph are likely and as always will be higher for wind prone areas, such as exposed parts along Hwy 395, US 95 near Walker Lake, and the Sierra ridges with gusts around 60-80 mph. Precipitation starts to move into the Sierra and western Nevada region by Tuesday afternoon with the bulk of it concentrated for southern Mono County, coinciding with the sub-tropical jet. As we progress into early Wednesday morning, model guidance shows the jet becoming splitty forcing a slug of sub-tropical moisture into NE California, including Lassen and Plumas counties. With the recent heavy rains that impacted this area last week along with the potential for another round this week, flooding concerns are increasing and will continue to be monitored, especially along the Feather River. As for the western Nevada valleys, after an initial round of spillover Tuesday afternoon forecaster confidence is growing in the fact that this region will become "shadowed out" from precipitation Tuesday night into Wednesday. This is mainly due to the more southerly flow aloft which tends to inhibit moisture from spilling over the Sierra. By Wednesday evening, the flow aloft shifts more westerly which would allow for more spillover into western Nevada as the storm`s associated cold front pushes through the region, but overall moisture will be limited at this point. So, we know that a storm is on the horizon with the possibility for a significant amount of precipitation for the Tahoe Basin and Mono, Lassen, & Plumas counties, but how much in terms of snowfall accumulation? Snow levels look to start out on Tuesday evening at around 6000-6500 ft for the Tahoe Basin and Mono County, hover around these levels through Wednesday, and then finally drop to 5000- 5500 ft by early Thursday morning with the passage of the cold front. For much of the high Sierra, 1-3 feet of snow will be possible, with the highest totals focused into the southern portion of Mono County and into Inyo County. As for around the Tahoe Basin northward, 6-10 inches is probable for areas above 5500 ft with mainly rain for lower elevations by Thursday morning. Travel during this time over any of the Sierra passes is likely to be hazardous with chain controls expected. The active weather then continues into the end of the week with possible snowfall down to valley floors. -LaGuardia THURSDAY ONWARD... No large changes as precip chances wind down from the Tuesday/ Wednesday system through Thursday afternoon. There is another wave expected to approach the region late Thursday/Friday with some additional snow expected for mainly Sierra locations. Have trended the forecast towards the deterministic ECMWF/GFS runs which favor a more southerly trajectory of the wave; increased chances of precip and liquid totals mainly south of Highway 50. Models are still at odds on how far south the main low will go, so there is a lot of wiggle room for changes over the next couple of days. Still, system speed should preclude heavy snow/rain totals. Otherwise, winds will likely be brisk Friday with snow levels at all valley floors. Snow showers are expected linger into the weekend as troughing digs off the Pacific Coast with the potential for another system late in the weekend or early next week. Boyd && .AVIATION... For RNO, CXP, TVL, TRK: Bands of showers moving through have yielded an unusual fog and low clouds scenario over much of the region today. Following the latest HRRR we expect on and off showers, mainly rain, through about 3-6z/Mon. Could mix with SN at TRK and TVL but no accumulation. Plentiful moisture and light winds is likely to keep lower clouds and fog potential through Monday morning. Trended TAFs in these directions which is supported by statistical guidance. Fog and low clouds Monday AM could be more considerable than shown but not confident enough to hit things that hard. Some turbulence aloft is likely given observed ridgetop winds gusting SW30G50. GFS shows these winds persisting until Monday daybreak. For MMH: Totally different story here with brilliant sunshine much of today, being south of main frontal boundary forcing for showers. Mainly VFR conditions with light WNW breezes. Lee-side turbulence expected aloft through tonight with Mammoth Mountain summit gusting SSW40G60. -Chris && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$ For more information from the National Weather Service visit...