Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/26/17

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
320 PM AKST Sat Nov 25 2017 .SHORT TERM...Tonight through Monday...According to water vapor satellite imagery, a weakening upper level trough extends over the eastern gulf, and a deepening ridge extends over the western gulf, with a strengthening shortwave digging east through the Aleutian Islands. A strong jet can also be seen wrapping around the trough over the eastern gulf, advecting moisture aloft from south of the Haida Gwaii area. In addition, weak surface lows can be seen rotating around each other in the associated upper level low, and a strong high remains over British Columbia and extends into the Yukon Territories. Due to this synoptic setup, outflow winds will persist throughout most of the northern inner channels. We upgraded Lynn Canal to Storm Warning this afternoon, as current observations indicated as such. We expect the winds to remain this strong through this evening and diminish through tonight. We also have some lingering showers being reported across the panhandle. This is due to the TROWAL associated with one of the lingering surface lows lifting north that is supported by divergence aloft from the left exit region of the jet that was mentioned previously. The main story for tonight and continuing into tomorrow is the winds, as precipitation should be drying out through most locations tonight. A shortwave will swing northeast into the southern panhandle beginning tonight and lift northeast into British Columbia tomorrow. This feature will help to tighten the pressure gradient between the high that`s already over Canada. We`ve been monitoring high resolution model guidance, in addition to current observations, for our wind analysis. These models have been struggling with wind values through the inner channels, so most of the local effects for wind throughout the inside waters have been added manually. The Storm Warning will remain for Lynn Canal through early this evening, but expect winds to diminish overnight. High res models and mountain wave guidance also hinted at a strong wind event for the downtown Juneau and Douglas area. Forecast soundings for Juneau, mainly the GFS, also indicated possible favorable conditions, so we opted to follow HRRR guidance for timing and strength of the wind downtown; we`re expecting winds out of the northeast at 25 to 30 mph tonight and continuing into tomorrow morning, with wind gusts to 45 mph. On Monday, a weather front associated with a surface low developing over the western gulf will lift northeast, increasing winds along the offshore and eastern gulf marine zones. PoPs will also increase along this front and bring more snow to the northern two-thirds of the panhandle and rain over the far south once it lifts north early Monday. We opted to use a blend of GFS and EC for pressure adjustments and opted for high res models and hand analysis for the winds over the gulf and throughout the inner channels. A combination of the NAM, GFS, and SREF was used for PoP updates. Overall, forecast confidence in the short range is average, trending below average due to model disagreement. .LONG TERM...Rather different weather pattern for the Gulf of Alaska and SE Alaska for the long range period compared to what we have seen over the last few weeks. Mean 500 mb trough axis is forecast to shift westward to be more over western Alaska and the Bering Sea opening the door for warmer and wetter SW flow through much of next week. Several shortwaves are embedded in the SW flow pattern and promise to bring rather unsettled conditions through late week at least. Several new trends are apparent in the long range forecast today. First off, the scenario of a weak low that was forecast yesterday to advance on Cross Sound from the SW on Tue has been abandon in favor of a stronger low crossing over Haida Gwaii late Mon night. This has stabilized wind forecasts for the NE gulf and gulf coast Tue with more general SW winds expected now, but has dropped confidence on wind forecasts for the extreme southern panhandle Mon night (due to some indications that guidance wants to put the low even further SE and a wide spread on low strength). Used Nam and some ECMWF to represent it as both had a decent track and strength. Second forecast trend is for a general increase in winds in many areas Tue night into Wed. Several models are now suggesting a rather vigorous front will travel east across the gulf at that time with 20 kt (Canadian) to 35 kt (GFS) winds accompanying it. Ended up increasing wind in the forecast with a wide area of 25 to 30 kt winds across the gulf. Winds also increased in the inner channels to 15 to 25 kt especially for the southern panhandle. Final trend is the general southerly flow and warm air advection that will affect just about the entire panhandle. Warmest temperatures appear mid week with many areas threatening to rise above freezing by Wed. With these warmer temps snow level will be rising above sea level and snow will be changing to rain for many areas. Main changes to the forecast were from Mon night through Wed with changes in low position and strengthening fronts changing around the wind forecast a bit. Main guidance was Nam with some ECMWF followed by WPC guidance for later periods. && .AJK Watches/Warnings/Advisories... PUBLIC...Strong Wind from 9 PM AKST this evening through Sunday morning for AKZ018-025. MARINE...Heavy Freezing Spray Warning for PKZ012. Storm Warning for PKZ012-013. Gale Warning for PKZ022-032-035-043-051-052. Small Craft Advisory for PKZ011-021-031-034-041-042-053. && $$ Voveris/PRB Visit us at
Area Forecast Discussion
National Weather Service Burlington VT
717 PM EST Sat Nov 25 2017 .SYNOPSIS... A cold front will sweep across the North Country this evening, allowing rain to end as a period of snow showers across the mountains. Temperatures will trend colder for Sunday with highs only in the upper 20s to mid 30s with northwest winds. Skies will remain mostly cloudy, and another weak upper level disturbance approaching from the northern Great Lakes region will bring additional snow showers to most areas during Sunday Night. Should see temperatures trend milder on Tuesday and through the remainder of next week. && .NEAR TERM /THROUGH SUNDAY NIGHT/... As of 717 PM EST Saturday...The forecast remains largely on track this evening as surface cold front, currently entering the Adirondacks makes steady progress eastward. Did opt to adjust precipitation chances slightly based off the latest BTV 4km WRF and HRRR hourly output into the overnight hours which are capturing current radar trends quite nicely. The overall theme remains the same however, as scattered to numerous rain showers, most focused across the northern high terrain, transition to snow showers over time as front clears east and cold thermal advective processes commence on northwesterly flow. Have a great evening. Prior discussion... Overcast conditions prevail across the North Country this afternoon in SW flow regime. Briefly reached 52F at BTV and 57F at RUT during the late morning hrs, but pre-frontal trough and associated -SHRA has generally cooled readings into the 40s, and locally into the upper 30s in the nrn Adirondacks. Lingering showers across central/nrn VT will result in <0.10" additional rainfall thru mid-late aftn. Otherwise, just looking at cloudy conditions with SW winds generally 5-10 mph thru early this evening. Trailing cold front across the Ottawa Valley at 19Z will bring a northwesterly wind shift as it moves across northern NY and VT between 00-06Z late this evening. Anticipate FROPA at BTV around 03Z. Cooling low-level thermodynamic profiles will begin to support snow around 01Z in the nrn Adirondacks and by 04Z or so in the northern Green Mountains. So, will have some upslope/orographic snow showers during the overnight hrs with up to 1-2" across the higher summits, and a general coating to 1" possible across the nrn Adirondacks region and central/nrn VT in general by 12Z Sunday. Generally cloudy in valley locations with a brief flurry or two. Daybreak lows will range from the low-mid 20s across the nrn Adirondacks and St. Lawrence Valley, to the uppr 20s to lower 30s across central/nrn VT where low-level CAA arrives a bit later. Highest PoPs (70-80%) confined to the higher summit locations, with just 20-30% in the lower valleys. Will see NW winds 10-15 mph with some gusts to 25 mph with steep lapse rates (and downsloping in the CT River Valley) thru Sunday morning, before sfc ridge axis briefly shifts into the region with lighter winds expected late in the day. Any lingering snow showers should end across the mtns during the morning hrs before upslope winds diminish. Not looking for much sunshine with trapped moisture and low- level inversion -- maybe a few breaks in the afternoon before clouds advance ahead of next shortwave trough from the nrn Great Lakes. Highs on Sunday mainly 28-35F, warmest at BTV. 700mb shortwave trough in NW flow and weak sfc reflection move in for Sunday night from the northern Great Lakes region. Limited moisture with PW values 0.2-0.3" but sufficient synoptic ascent and upslope enhancement for some light snow or snow shower activity, especially 03-09Z. Went with high PoPs (70-90%) for a low QPF event...liquid equiv. 0.05-0.15", highest in the mtns. Everyone should see at least a light period of snow, with 1-3" in the mtns, and a dusting to an inch possible in valley locations by 12Z Monday. Sunday night lows generally 22-28F. && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... As of 315 PM EST Saturday...Monday will start out with a NW flow at all levels, cold advection, and some leftover upslope snow showers or flurries. As weak high pressure and rising heights/temps aloft move in any snow showers will be winding down some breaks of sun may develop from southwest to northeast. and 925mb temps will range from -10 near KMSS to -4 at VSF in downslope flow resulting in highs ranging from upper 20s north to upper 30s south. A ridge of high pressure will crest over the region Monday night but warm advection aloft in advance of a warm front in the Great Lakes will bring increasing high clouds overnight. Low temps expected in the teens and 20s, but should level out after midnight. Coolest readings in the northeast kingdom of VT. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 315 PM EST Saturday...The long term feature of interest will continue to be the progressive, near zonal synoptic flow pattern across the northern tier of the nation. This west to east flow will result in a roller coaster of temperatures, but generally on the milder and drier side of average for this time of year. Confidence is about average with models in general agreement, though details get fuzzier toward the end of the week. Tuesday is looking milder as a strong WSW flow of air (>50 kt at 850mb) returns with high temps pushing into the 40s to around 50 warmest west of the Greens, cooler east as 925mb temps rise to about 5-8 degC and 1000-500 thickness to about 552dm. The next potential round of light precipitation still looks to occur on Tuesday night, exiting during Wed morning. Most of that looks to be of the light rain shower variety as it stays fairly mild in the 30s to around 40 but could be a little mix in the cool spots. The rest of Wed into Thu look to be dry as high pressure and ridging aloft builds into the area. Max temps will continue on the mild side with highs in the 40s while lows will be closer to average in the 20s. GFS has joined the EC with the forecast of a more significant weather maker late in the week as a trof digs and cuts off near the mid-Atlantic coast along with it`s surface low nearby. However, there is really no cold air in place in advance of the low so right now looks to be more wet than white but it`s way too early to get too caught up in the details. Raw model temp guidance is much warmer than the statistical but have trended toward that warmer solution for now with a mild SE flow of air into New England, but stay tuned. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... Through 00Z Monday...It appears ceilings will generally trend downward into the MVFR category after 00Z with HIR TRRN OBSCD and localized IFR at KSLK. Will see some upslope/mountain snow showers overnight, mainly affecting KSLK with occasional flurries or light snow showers during the overnight hrs. Will see an increase in NW winds on Sunday, with gusts 18-22kts. Will maintain mix of MVFR/VFR ceilings, mainly 2000-4000ft across the region Sunday 12-18Z. Outlook... Sunday Night: Mainly VFR, with areas MVFR possible. Chance SHSN. Monday: Mainly VFR, with local MVFR possible. Chance SHSN. Monday Night: VFR. NO SIG WX. Tuesday: VFR. NO SIG WX. Tuesday Night: Mainly VFR, with local MVFR possible. Chance SHRA, Chance SHSN. Wednesday: Mainly VFR, with local MVFR possible. Slight chance SHRA, Slight chance SHSN. Wednesday Night: VFR. NO SIG WX. Thursday: VFR. Slight chance SHRA, Slight chance SHSN. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...None. NY...None. && $$ SYNOPSIS...Banacos NEAR TERM...JMG/Banacos SHORT TERM...Sisson LONG TERM...Sisson AVIATION...Verasamy/Banacos
Area Forecast Discussion
National Weather Service Wilmington NC
927 PM EST Sat Nov 25 2017 .SYNOPSIS... A dry cold front will cross the coast late tonight, followed by dry and cool high pressure early next week. A gradual warming trend will come by Wednesday as the area of high pressure moves offshore. Another cold front should bring a few showers Friday, with a cooling trend into next weekend. && .NEAR TERM /THROUGH SUNDAY/... As of 930 PM Saturday...A 500 mb shortwave is moving across the eastern Carolinas now, outlined by a region of 600-300 mb moisture and clouds. This cloud cover will clear off the coast in just a few more hours with clear skies developing across the area late tonight into Sunday. A surface cold front extending from the upstate of South Carolina into the western Piedmont of North Carolina will move eastward and approach I-95 between midnight and 1 AM. The front should reach the coast a couple hours later, with northerly winds developing behind the boundary. Most models with the exception of the NAM and HRRR are running a little fast with their depiction of the front, but there should be little real impact on sensible weather across the area. Forecast lows range from around 40 in the Lumberton area to the mid 40s at the coast. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... As of 248 PM Saturday...The forecast will remain only a temperature one as a mostly zonal flow aloft prevails through the period. The pattern does shift a little by early Tuesday setting the stage for a decent warmup by the middle of the week. At the surface, high pressure will move slowly from the Tennessee Valley basically overhead by the end of the period. Temperatures will be below normal through the period with lower to middle 30s for lows (a little warmer Tuesday morning) and highs mostly in the lower to middle 60s Monday afternoon. && .LONG TERM /TUESDAY THROUGH SATURDAY/... As of 248 PM Saturday...Pleasant late Autumn weather on tap this period with temperatures and sunshine minutes both poised to run above normal. Phasing of a dampening southern stream short-wave and a progressive, northern stream upper trough, will bring an air mass change to more `expected` seasonal temperature levels for very early December, Friday into the weekend. GFS/Ecmwf both resolve this upper feature in relative good agreement for days 6/7, and the high amplification of the upper trough will support a chance of showers or a TSTM Thursday night or early Friday. Low-level winds appear moderately strong ahead of the upper trough and a spike in column moisture, may allow a `non- zero` chance of a brief line of severe storms late week. We will see if models hold onto to the high trough amplification, or not, in future runs. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... As of 00 UTC...A weak cold front moving across the Appalachians will cross the TAF sites later tonight and shift off the coast around 06 utc. VFR conditions are expected with only mid and high level clouds ahead of the front. Winds will be light overnight and a windshift from the west-southwest to the north will occur through the period. Wind speeds will increase to 8 to 10 knots by Sunday afternoon as high pressure builds in from the north. Extended Outlook...VFR. && .MARINE... NEAR TERM /THROUGH SUNDAY/... As of 930 PM Saturday...Westerly winds currently range from 10 knots at the beaches to 15-17 knots out at 20 miles distance from shore. A cold front still across the western portions of North and South Carolina should reach the beaches and will move offshore late tonight, shifting wind direction northerly with an increase to 15-20 knots. Gusts, especially across the waters north of Myrtle Beach, could reach 25 knots after 4-5 AM. This is very close to our previous forecast and no substantial changes have been made to wind speed/direction forecasts. Currently wave heights range from 2 to 2.5 feet nearshore to 3.5 feet out at Frying Pan Shoals. This necessitates another decrease to wave height forecasts, but only for the next several hours as waves should begin to increase late tonight behind the cold front. SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... As of 248 PM Saturday...Surface high pressure to the west will move slowly eastward through the period. Winds will be from the north through most of the period at ten knots or less. By late Monday into early Tuesday the flow will turn more northeast with similar wind speeds. Significant seas will be 2-3 feet. LONG TERM /TUESDAY THROUGH THURSDAY/... As of 248 PM Saturday...This appears to be a favorable marine period shaping up as high pressure over the waters migrates slowly offshore, resulting in a light veering wind Tuesday. A weak cold front will bring a wind shift to the north on Wednesday, but speeds to remain well below advisory levels. Light N-NE winds Thursday, will veer to south in the afternoon as high pressure releases its grip, and low pressure moves into the Ohio Valley. Light wind chop, and weak ESE swell will describes seas this period, and no TSTMS expected on the 0-20 NM waters through mid-week. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...MJC NEAR TERM...TRA SHORT TERM...SHK LONG TERM...MJC AVIATION...DRH