Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/05/23

Area Forecast Discussion
National Weather Service Burlington VT
941 PM EST Sat Feb 4 2023 .SYNOPSIS... Bitterly cold conditions this afternoon and evening will give way to a warming trend on Sunday as surface high pressure shifts east of New England. The next chance of precipitation, which should fall mainly as snow, arrives Sunday night with a weak cold frontal passage. More precipitation, this time mainly rain, is expected by mid week. && .NEAR TERM /THROUGH SUNDAY NIGHT/... As of 931 PM EST Saturday...Temperatures continue to rise slowly but surely tonight with warm air advection riding winds from the south and southwest. Blended in some HRRR to both hourly temperatures and dew points, as our forecast was trending a bit too high on dews for observations, and the HRRR seemed to have the best idea on T and Td for the next several hours. Lowered some of the winds ever so slightly, as conditions are a bit calmer than expected under the ridge. Skies are now overcast for most locations across the forecast area, but this could fluctuate as lapse rates steepen throughout the day tomorrow and mixing occurs. Some light snow showers or flurries are possible across northern New York and potentially into Vermont tonight with the passage of a warm front, included slight PoPs for that in this update. Previous discussion below: Previous discussion...Southwest flow will increase this evening on the backside of the ridge and ahead of weak low pressure lifting up west of the St Lawrence Valley. This will allow a weak warm front to cross our area overnight, so the gradual warming trend will continue tonight right into Sunday. Areas east of the Greens will likely cool down a few degrees after sunset since they`re the furthest removed from the warm front, but even those areas should see climbing temperatures after midnight. Therefore, lows will mainly occur early in the overnight period, ranging from 5 to 10 below in the Northeast Kingdom to around 10 above in the southern St Lawrence Valley. A few light snow showers can`t be ruled out as the warm front lifts through, but the vast majority of the region will remain dry through Sunday morning. South winds increase through the morning as well, especially in the Champlain Valley owing to channeling, and temperatures will warm into the lower to mid 30s areawide in response. The weak parent low will slowly move by to our north late Sunday into Sunday night, and precipitation chances will increase as its associated cold front approaches from the west. The precipitation should start as rain as it moves into the St Lawrence Valley late in the afternoon, but the loss of daytime heating along with evaporational cooling should allow the bulk of the precipitation to fall as snow as the front gradually shifts east overnight. The snow will focus along the western slopes of the Adirondacks and the northern Greens, with an inch or two of accumulation expected. Elsewhere, snowfall will be less than an inch, with much of the Champlain Valley and central and southern VT to remain dry. Overnight lows will be in the mid 20s to around 30. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... As of 315 PM EST Saturday...Snow showers linger Monday morning across the Adirondacks and northeast Vermont associated with the aforementioned upper trough passage, but will quickly end by midday as high pressure builds eastward from the Great Lakes over the Northeast. Northerly winds on the front-side of the high will provide a non-diurnal temp trend with morning temperatures in the mid 20s west to mid 30s east gradually falling through the afternoon to the teens and 20s by the evening. Under the center of the surface and upper level ridge axis, lows Monday night will tail off into the single digits and teens above zero under partly cloudy skies. After a brief break of high pressure Monday night into Tuesday morning, active weather returns again heading into Tuesday afternoon/night as another lows looks to pass north/northwest of the region. Boundary layers temps ahead of the system will be warmer than the previous one with widespread mid/upper 30s and some 40s Tuesday afternoon, offering a valley rain and mountain snow mix Tuesday evening/night with the best chances for accumulating snow being across eastern Vermont where light accumulations are possible. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 315 PM EST Saturday...An impactful period of weather remains ahead for the middle to end of the work week and into the weekend with a very convoluted upper level pattern evolving. Driest period will be Wednesday and Wednesday night with high pressure briefly building back into the region, but by Thursday morning the first in a series of potent shortwaves embedded in a broad longwave trough digging into the central US will advance through the Great Lakes and northwest of the forecast area Thursday afternoon. Strong warm advection associated with a southwesterly 50-60kt 850mb jet will support temperatures once again rising above freezing with rain as the dominate ptype through Thursday night outside of the highest elevations where snow is likely. There also are indications of a brief period of a wintry mix of sleet or freezing rain as well at the onset, but given the poor resolution of guidance out this far have kept the ptype rain/snow for now. As this system exits the region Friday, attention will turn to the next 2 shortwaves over the Great Lakes and southern states and if/when they phase moving into the Friday night Saturday period. Too early to tell what will evolve, but there is some agreement among deterministic and ensemble guidance that the North Country will be impacted somehow. Whether it`s more rain, mixed precipitation, or perhaps a significant snow storm remains to be seen, but it`s something to watch closely heading into midweek. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... Through 18Z Sunday...Main threat to aviators will be LLWS with a low level jet moving over the region 00-06Z. The shear layer should be around 2000ft out of the southwest around 40kts. SFC winds will be light and south for most terminals except MSS which is keeping a NE wind due to channeled flow down the St Lawrence Valley. South winds increase after 14Z with gusts to 20kts; this may limit LLWS somewhat as speeds begin to phase, but expect some turbulence to remain. Otherwise, conditions will remain VFR through 20Z with CIGs lowering west to east 20-06Z as a cold front moves into the North County. Outlook... Sunday Night: Mainly VFR, with local IFR possible. Chance SHSN. Monday: Mainly VFR, with local IFR possible. Slight chance SHSN. Monday Night: VFR. NO SIG WX. Tuesday: VFR. Windy with gusts to 30 kt. Likely SHRA, Slight chance SHSN. Tuesday Night: Mainly VFR, with areas MVFR possible. Likely SHRA, Slight chance SHSN. Wednesday: Mainly VFR, with areas MVFR possible. NO SIG WX. Wednesday Night: VFR. NO SIG WX. Thursday: Mainly VFR, with local MVFR possible. Chance SHRA, Chance SHSN. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Hastings NEAR TERM...Hastings SHORT TERM...Lahiff/Storm LONG TERM...Lahiff AVIATION...Boyd/Hastings
Area Forecast Discussion
National Weather Service Medford OR
429 PM PST Sat Feb 4 2023 Updated AVIATION Section .SHORT TERM...KMAX-88D this afternoon revealing light returns streaming south to north along the coast region and into Northern California. A few mtn RAWS have measured a click (.01") in the past few hours, but things are generally still quite dry. A deep upper trough off the Oregon coast will gradually make its way inland through the remainder of the weekend. Tonight a strong short wave moving through the base of the trough will move onshore into northern California helping to enhance upslope precipitation there. Also, a strong surface low being advertised in the high-res models is expected to move into the coastal waters and move onshore around Reedsport near 12z. There is uncertainty in the track of the low and we`ve generally been following HRRR guidance and are expecting Gales. Winds on the coast will likely get quite gusty in the overnight but we feel the event will remain below warning gusts. Wind Advisory will remain for the Shasta Valley, and local gusts may bump around advisory levels nea summer Lake but we`ve also held off on a headline there. Also looking for 15 gust 25-type winds in the Aslhand to Medford region tonight. Meanwhile inland, moderate snow rates should begin this evening in the Mount Shasta region and last into early Sunday. A Winter Weather Advisory is in effect there above 5000 feet. We considered extending that Winter Weather Advisory across the South Oregon Cascades and Siskiyous but no given period seems to threaten substantial rates, and the heaviest accumulations will be above above the most traveled routes. Hence no Cascades/Siskiyous headlines for snow, but it will snow tonight through Sunday with snow levels beginning near 5000 feet, falling to 4000 overnight, then to near 3500 feet Sunday with totals of 5-10 inches looking common. Stavish .LONG TERM...(Monday through Saturday)...Upper ridging will result in dry weather for Monday. The upper ridge will flatten out Tuesday afternoon as the next upper trough approaches from the west. Precipitation ahead of a cold front will move into the marine waters and coastal counties Tuesday morning, then spreading inland west of the Cascades Tuesday afternoon. However the Rogue Valley could remain dry into Tuesday afternoon due to the westerly component of the upper flow which typically results in downsloping. The front will move through the area Tuesday night, followed by an upper trough with scattered showers that will become more isolated as the upper trough axis shifts east during the overnight hours. The upper trough moves east of the area Wednesday afternoon with upper ridging building in Wednesday night, and lasting into next Saturday with dry weather expected. This is being supported by all members of the GFS ensemble members and the majority of the ECMWF ensemble members. One thing to note: There`s good agreement an upper trough will move east near 140W Thursday evening, with a split flow developing Friday into Saturday with a cutoff low Saturday. However the location of the low is well enough offshore to keep the best chance of precipitation well south of our forecast area. -Petrucelli && .AVIATION...05/00Z TAFs...Southeast winds have surfaced this afternoon at Medford where gusts recently reached ~30kt and at Klamath Falls where a gust of ~40kt was recently reported. An airport weather warning is in effect for Klamath Falls until midnight for gusts greater than 35kt. Low-level wind shear is expected where winds aren`t reaching the surface (at Roseburg). Low pressure is expected to form along a front offshore this evening, and then move onshore overnight. This could result in a period of gusty winds at North Bend around 7-10z as offshore east or southeast winds turn onshore from the SW or west. VFR ceilings will continue this evening, but MVFR ceilings will become more widespread overnight as the front and associated precipitation moves into the area. The exception will be Medford where VFR ceilings should continue through tonight due to downsloping. However partial obscuration is possible later tonight in the higher elevations surrounding Medford. Post-frontal showers will continue with breezy conditions and a mix of VFR/MVFR on Sunday. -Spilde && .MARINE...Updated 200 PM PST Saturday, February 4, 2023...An offshore front will continue to bring strong SSE winds to the offshore waters this afternoon averaging 20-30 kt with gusts to 40 kt. Steep to very steep seas can be expected due to the combination of building wind waves and west swell. A surface low pressure center is expected to form along the front tonight and move quickly through the waters from southwest to northeast between 7 pm (03z) and 4 am (12z) PST. Recent hi-res model guidance is showing this low center having a brief period of strong winds associated with it along with a sharp wind shift from SSE to W (or even NW). For this reason, we have expanded the gales to include the inner waters during this time period. Then, the front will move onshore after 4 am PST (12z). Post- frontal winds should ease to 15-25 kt (gusts to 30kt) from the WNW. Fresh WSW swell will then combine with incoming long period W swell to create steep, hazardous seas Sunday. Seas will build to around 14- 16 ft at 13 seconds Sunday evening, then will gradually subside below 10 feet by Monday afternoon. Calmer conditions will last into Monday night before another front and high and steep west swell builds in late Monday night into Tuesday. -Spilde && .MFR WATCHES/WARNINGS/ADVISORIES... OR...CA...Winter Weather Advisory until 10 AM PST Sunday above 5000 feet for CAZ080-082-083. Wind Advisory until 7 PM PST this evening for CAZ081. PACIFIC COASTAL WATERS...Hazardous Seas Warning until 7 PM PST this evening for PZZ350-356. Gale Warning from 7 PM this evening to 4 AM PST Sunday for PZZ350-356. Gale Warning until 4 AM PST Sunday for PZZ370-376. && $$