Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/25/19

Area Forecast Discussion...UPDATED
National Weather Service Lubbock TX
529 PM CST Sun Nov 24 2019 .AVIATION... VFR conditions to continue through this period. May be a brief period of LLWS tonight at LBB as winds aloft increase to about 35kts with a 30 degree difference from surface winds. Due to the marginal nature did not include it within the TAF. /WCI && .PREV DISCUSSION... /issued 317 PM CST Sun Nov 24 2019/ DISCUSSION... BLUF: Wind on Tuesday follow by messy weather for the Thanksgiving Holiday...some potential for frozen precipitation. This afternoon, we have a fetch of Pacific moisture streaming into the region thanks to an upper low well west of the Baja. In advance of an approaching shortwave, high-level clouds have developed across much of the forecast area. A weak cold front was sagging south through the Central Plains. We`ll see the shortwave pass over our area overnight, clearing skies and pulling the front closer to our forecast area. By midday Monday, it should advance through the northeast third to half of the FA before washing out, so we don`t expect a major impact on highs tomorrow. RAP IR analysis this afternoon shows the first ripple in the flow across the Pac-NW of what will become our wind-maker for Tuesday. As this deepens into an open low over the Rockies by Tuesday morning, it will start to become somewhat negatively tilted, closing off as it moves into KS by midday. The GFS and Euro have come into much better agreement on the track and strength of this feature, with the NAM being somewhat of an outlier. Soundings show mixing may not be as deep as previously advertised, keeping us from tapping the higher winds at H7; however, the gradient at lower levels will be tight enough to keep winds likely at advisory or higher for much of the area Tuesday afternoon. We have ramped up our advertising of this event, and we`ll be evaluating the need for an advisory or watch in the next shift or two. Then we come to the messy Thanksgiving Holiday. As our wind machine pulls away, a cold air will be pushed in behind it overnight Tuesday. All the while, a large upper low will be deepening over northern CA, pushing Pacific moisture back into our area during the day on Wednesday. We`ll be looking at a chance for precip starting late Wednesday through Friday night. This is a tricky forecast for the first 24 hours of precip, though. Current thinking keeps most of the area all liquid Wednesday afternoon, save for the southwestern TX Panhandle, where a rain/snow mix may develop without accumulation. Wednesday night, temperatures are debatable. With profiles nearing saturation, cloud cover to consider and flow starting to turn more out of the south, temperatures could have a difficult time cooling...which could negate the frozen precip all together. The likely scenario with this setup still leans towards a rain/freezing rain mix for much of the FA, with only very light snow mixed in. As the flow turns more southerly and southwesterly Thursday, pulling in warm moisture, a transition back to all rain and staying rain is expected. We`ll then be focusing on the arrival of the famous dry slot, which models currently introduce early Friday evening. From there on out, dry and breezy will be prevalent before the next front late weekend. So, we are able to better hone in on the time period for precip, but the exact precip type is still to be foreseen. && .LUB WATCHES/WARNINGS/ADVISORIES... None. && $$ 58/99/99
Area Forecast Discussion
National Weather Service Marquette MI
639 PM EST Sun Nov 24 2019 .SHORT TERM...(This evening through Monday) Issued at 420 PM EST SUN NOV 24 2019 WV imagery and RAP analysis indicated quasi-zonal mid/upper level flow across the northern CONUS. The next significant upstream shortwave trough was moving into western North Dakota. At the surface, gusty westerly winds prevailed between a ridge through the Upper Mississippi Valley and 991 mb low pressure near James Bay. Vis loop indicated mostly sunny skies across Upper Michigan in the relatively dry airmass. Mid and high clouds were increasing across MN with the developing WAA pattern ahead of the shrtwv. Tonight, short range models suggest that light snow will develop over northern MN and expand eastward into western Upper Michigan this evening as 285k-295k increases. However, little or no accumulation is expected given the relatively modest dynamics and dry low levels. Thickening cloud cover will also help keep min temps mainly in the upper 20s inland to around 30 along the Great Lakes. Monday, moderate to strong 700-300 vector conv associated with the shrtwv should be able to squeeze out additional light pcpn mainly over the north. With temps climbing through the 30s, any light snow early will change over to rain. Rain chances will increase over the west late as the sfc trough approaches and the deeper moisture and with the shrtwv moves in. .LONG TERM...(Monday night through Sunday) Issued at 454 PM EST SUN NOV 24 2019 ...Accumulating wet, heavy snow becoming likely late Tuesday night into Wednesday... Models suggest a building ridge over the N Pacific will drive a trough downstream across the western CONUS on Monday. By Tuesday, this ridge will begin to amplify as an area of low pressure develops on the leeside of the Rockies Tuesday evening. This low pressure is progged to lift northeast, reaching Lake Michigan by Wednesday morning as a shield of precipitation will accompany it. This will be the main focus of the period as it brings a chance for widespread 6 to 12 inches of system snow. Models solutions have come closer over the last 24 hours, but the impacts from Colorado Lows are still highly sensitive to the exact track of the low. A strong ridge of high pressure moves in behind this low on Thursday that should keep the UP dry through Friday as models suggest the development of another low pressure system across the Central Plains into the weekend. Starting off on Monday night, models show a shortwave trough exiting Upper Michigan to the east with scattered mixed precip coming to an end. Some models suggest lake-effect precip to continue in the WNW wind belts, however 850mb temps will only range from -4C to -6C. Model soundings show inversion heights near 4-5kft, but limited moisture throughout the DGZ. This would limit precip to be -SHSN, or perhaps some -DZ/FZDZ. Tuesday, brief ridging will help winds relax ahead of the next wave of precipitation. Models have come into a good agreement for the last 24 hours worth of runs. This low pressure system is expected to deepen as it moves through Lower Michigan at roughly 988mb. Winds were increased late Tuesday into Wednesday as NBM seemed to be too low over land and marine. This increase in winds will bring an increased chance at lakeshore flooding and erosion concerns for areas affected by NE winds. It will also be blustery across Upper Michigan with NE winds gusting up to 35 mph at times, especially along Lake Superior which will bring some concerns for blowing snow. As far as snow totals go, models are in decent agreement for QPF, leading to increased confidence in snow totals at or above 6 inches across the majority of the UP. This confidence in increased as SREF, GEFS, and various deterministic models show mean snow totals at or above 6 inches across portions of Upper Michigan. Snow totals in these situations are highly sensitive to the exact track of the low, so expect some shifting as we get closer to Tuesday night into Wednesday. As it stands, have increased QPF slightly along the NE winds lake-effect belts due to some lake-enhancement concerns as 850mb temps fall to -7C to -10C by Wednesday afternoon. This brings the chance at up to a foot of snow across the higher terrain of Marquette County. Of course, slight changes in low track and wind direction will change the expected totals. Lowest snow totals are expected along Lake Michigan as higher temperatures will create some rain early on Wednesday as the warm sector of the low pressure grazes Upper Michigan. If the low tracks further north, expect some decrease in snow totals as rain coverage increases across Upper Michigan. Behind this system, troughing along the Pacific Coast will create a period of ridging across the central CONUS. This ridging should cut off any residual lake-effect early on Thursday as models suggest another shortwave moving across the Rockies on Friday morning. This shortwave is then progged to develop into another leeside low pressure system. The GFS and EC have this low taking a similar path across Lower Michigan which would bring another round of widespread snow across Upper Michigan Saturday night into Sunday. The GEM shows a similar solution to the GFS and EC, however, the GEM is roughly 24 hours behind with the low passing to the south on Monday. Overall, the potential is there for another shot at widespread snow this weekend, but additional details still need to be worked out as we get through this first blast of snow Tuesday night into Wednesday. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 639 PM EST SUN NOV 24 2019 Snow showers moving in from the west later this evening into the overnight hours will bring MVFR ceilings and possible visibility restrictions to KIWD/KCMX. KSAW will see VFR ceilings prevail tonight. Low pressure moving across northern parts of Lake Michigan will push a cold front across the region during the day tomorrow, leading to veering winds at all TAF sites and the return of MVFR ceilings area-wide. A few models show the potential for ceilings to get even lower, but for now have opted to maintain MVFR ceilings. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 420 PM EST SUN NOV 24 2019 Westerly winds to 30 knots across Lake Superior will diminish tonight. Wind then increase back to 20-30 kts on Monday with broad low pressure moving through Ontario and clipping Lake Superior. A strong low pressure system will approach the area on Tue and will bring northeast gales to 40-45 knots on Wed. The track of this low is still uncertain and will have an impact on the wind speeds. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...JAW AVIATION...Ritzman MARINE...JLB
Area Forecast Discussion
National Weather Service Seattle WA
222 PM PST Sun Nov 24 2019 .SYNOPSIS...Colder air will continue to filter into the region for much of this week. Lingering showers will continue through Tuesday before diminishing Wednesday. Snow levels may drop low enough for some isolated snow or a rain-snow mix in some of the lowland areas Monday night through Tuesday night. Conditions will dry out Wednesday through late this week. The next chance for any precipitation looks to be during the second half of next weekend. && .SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...A few showers have developed this afternoon as expected. However, a PSCZ that earlier was progged to develop during the early afternoon has yet to form. However, short range guidance does still indicate the potential for enhanced convection with this feature (also of note is that the HRRR has trended a bit further north with this feature now placing it along I-90). We will continue to monitor this potential. Shower activity is expected to increase somewhat overnight then gradually diminish Monday through Tuesday night. Snow levels in the central Cascades/central Puget Sound will drop below 3000 feet late this afternoon or early evening, reaching around 2000 feet Monday morning, around 1000 feet Monday night, and hovering between sea level and 1000 feet Tuesday and beyond. Note that areas to the north may see snow levels ~500 feet lower and areas to the north ~500 feet higher. Some of the headlines: * Widespread, significant snow accumulation is NOT expected in the lowlands - in fact most areas will likely see no snow. * However, we cannot rule out that any Puget Sound lowland area could see a rain/snow mix or even a brief, light snow accumulation (generally less than 1 inch) by the end of this event. * Pinpointing exactly where and when those accumulations will occur is extremely difficult due to the hit/miss nature of the showers. However, the best odds will be Monday afternoon through Tuesday morning across the north Interior (Island, Skagit, Snohomish, southern Whatcom, northern King, northern Jefferson, and northern Clallam counties) where precipitation may be enhanced by convergence at times, leading to temporarily lowered snow levels and very isolated accumulations of 1-3 inches. * The mountain passes will also see hit/miss snow showers through Tuesday night - leading to quick bursts of snow accumulation followed by periods of no snow. The best estimates place total additional accumulation in the 4-8 inch range between now through Tuesday night - though again convergence zones could lead to significantly higher totals over narrow areas. Obviously, with the lowering snow levels, temperatures are also expected to fall over the next few days with lowland high temperatures around 50 today, in the mid-40s Monday, and the low 40`s Tuesday. Overnight lows will fall to below freezing in most lowland locations by Wednesday morning - so any residual moisture on the roadways may turn to ice. -Wolcott- .LONG TERM /WEDNESDAY THROUGH SATURDAY/...Synoptically, a strong mid level closed low will barrel down from Canada into the Pacific NW Tuesday night into Wednesday. Current track of deep layer moisture spares Washington and takes aim at southern OR and northern CA. This leads ultimately to a dry forecast for the area, however, could see a few wrap-around snow showers across the Cascades during the first half of the day. Little additional accumulation is expected. Still worth keeping an eye on the track and progress of the closed low in case wrap-around lingers longer than expected. Thursday still looks mostly dry and cold for the Thanksgiving holiday. High temps now looking to stay in the mid-upper 30s with lows Thursday night in the low-mid 20s. An omega block tries to develop across the eastern north Pacific & west coast Thursday into Friday, keeping the cold dry pattern in place through the end of the week and into the weekend. The next chance for precipitation looks to hold off until late Saturday or Sunday and even that is unclear at this time. With cold air in place, cannot rule out precipitation starting as snow or a rain/snow mix in the lowlands then turning to rain as snow levels rise with an incoming system. We will continue to monitor that potential this week. Kovacik/Wolcott && .AVIATION...Onshore flow will prevail tonight with NW winds aloft. The air mass remains moist and slightly unstable for scatted showers across the region. Ceilings are a mixed bag but MVFR conditions are possible with showers. Most areas will see IFR to MVFR conditions overnight. 33 KSEA...Expect showers in the vicinity tonight with possible MVFR conditions. S winds at the surface to 10 kt. 33 && .MARINE...Onshore flow will continue tonight. Meanwhile, seas will remain within 10 to 14 feet. A second system will drop down from the northwest tonight and Monday for Small Craft Advisory winds. Strong offshore flow will develop on Tuesday and continue through Thursday. 33 && .HYDROLOGY...Snow levels will drop this week and significant QPF accumulation is not expected, therefore, river flooding is not expected during the next 7 days. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory until 10 PM PST Monday for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm-Coastal Waters From James Island To Point Grenville 10 To 60 Nm- Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm. Small Craft Advisory for rough bar until 4 AM PST Tuesday for Grays Harbor Bar. Small Craft Advisory until 4 AM PST Monday for Coastal Waters From Cape Flattery To James Island Out 10 Nm-Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm. Small Craft Advisory until midnight PST tonight for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca. Small Craft Advisory for hazardous seas until 4 PM PST Monday for West Entrance U.S. Waters Strait Of Juan De Fuca. && $$