Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/26/18

National Weather Service Kansas City/Pleasant Hill MO
525 PM CST Sun Nov 25 2018 .Discussion... Issued at 244 PM CST SUN NOV 25 2018 Extremely powerful storm system will continue to produce whiteout conditions with periods of heavy snow and wind gusts up to 55 mph. When comparing the drying on water vapor imagery with the 1.5 PV pressure surface, broader scale models have underestimated the intensity/ how far south the upper level features of the system dug. The higher resolution models and CAMs seem to have done a better job with the intensity, particularly the winds. Leading up to today, we`ve had to adjust the winds upward above the most aggressive model with every forecast. With the surface low tracking along and just north of I-44, a nearly perfect scenario for a classic winter storm for this forecast area. The surface low, which at 20Z was near Jefferson City, will continue to deepen and move to the northeast as the upper system pushes east of the area, leaving a deformation band of heavy snow that will shift east through the late afternoon and evening hours. As the whole systems shifts east, the pressure gradient will begin to weaken and winds will begin to decrease. But with a pressure gradient magnitude of greater than 60 ubars/km on the northwest side of the surface low, sustained winds in the 25 to 35 mph range will continue for another few hours in eastern KS and western MO, and through this evening in central and northeastern MO. The HRRR and the RAP depict a secondary deformation band in our eastern zones and have increased QPF to account for this. This then increased snow amounts several inches from in our eastern zones. With this forecast issuance, will keep the blizzard warnings going. But a clearing of the warnings from west to east will occur through the evening hours. For the rest of the forecast, it looks like quiet weather can be expected through Thursday or Friday. It looks like another active weather pattern will develop in the area next weekend. The GFS has several storm systems moving through with temperatures supportive of wintry weather late in the weekend or early next week. && .Aviation...(For the 00Z TAFS through 00Z Monday Evening) Issued at 524 PM CST SUN NOV 25 2018 Terminals along the Kansas-Missouri border will continue to bear the brunt of a significant blizzard for another hour or two before CIGs, VIS, and wind improve on the back side of the system. CIGs are starting the hedge up, with upstream observations indicating that VIS will start to follow soon. However, expect the strong and gusty winds to persist through the night, though the gusts should ease up a bit late tonight. Anticipate lots of amendments at KMCI and KMKC as conditions will be changing as the storm moves out. However, there will be no amendments for KIXD and KSTJ terminals, due to the failure of the ground observation equipment at those sites. It is unknown at this time when those two sites will return to normal service. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...Blizzard Warning until 9 PM CST this evening for KSZ025-057-060- 102>105. MO...Blizzard Warning until midnight CST tonight for MOZ007-008-016- 017-023>025-031>033-039-040-045-046. Blizzard Warning until 9 PM CST this evening for MOZ001>006- 011>015-020>022-028>030-037-038-043-044-053-054. && $$ Discussion...CDB Aviation...Cutter
Area Forecast Discussion
National Weather Service Pendleton OR
806 PM PST Sun Nov 25 2018 .UPDATE...The upper level ridge is flattening and shifting eastward. By sunrise on Monday, the axis of the ridge will be along the WA/OR/ID border. The upper level flow is backing to the southwest, allowing mid and high level clouds to spread east of the Cascades. Precipitation is increasing on the backside of the ridge from the Puget Sound area south to Eugene. The band of precipitation will gradually approach the WA Cascades by early Monday morning. Although warmer air will cause snow levels to rise to around 4000 feet along the east slopes of the central and southern WA Cascades, cold air will remain trapped in the valleys. There is a potential for light freezing rain in this area late tonight and Monday morning. NWS Spokane and Seattle have winter weather advisories for freezing rain and understandably so based on the amount of QPF expected overnight and Monday morning. Looking at the HRRR for the Cascade east slopes in Kittitas, Yakima, and Klickitat Counties, only a trace to a 0.03" of QPF are expected before 8 AM Monday. After 8 AM, temperatures could warm above freezing with precipitation primarily as rain. Will hold off on any advisories, but forecasters will be keeping a close eye on radar if precipitation spreads faster than models advertise. Only minor updates were made to the forecast. Temperatures along the east slopes were lowered a few degrees for tonight. Patchy freezing fog was added to the Kittitas Valley. Wister && .PREV DISCUSSION... /issued 215 PM PST Sun Nov 25 2018/ SHORT TERM...Tonight through Wednesday...A ridge of high pressure over the region will keep a cold front positioned off the Pacific Northwest coast overnight. The ridge will be slow to move eastward Monday but as it does some precipitation will begin to spread into the Washington Cascades. This means there is a slight chance of some freezing rain early Monday from the Kittitas valley up to Snoqualmie Pass. Temperatures will be right around freezing so the efficiency of ice forming will not be good so decided not to issue any advisory for this. That said, the NWS Seattle office has issued a freezing rain advisory for the west side of the Cascades which includes the Snoqualmie Pass region. The cold front will not make a push eastward until late Monday night and Tuesday with a frontal passage occurring by Tuesday afternoon and evening. The front will bring precipitation across the forecast area mainly in the form of rain with high snow levels then turn to showers Tuesday night and Wednesday. Snow levels will lower Tuesday night and Wednesday to around 4000 to 5000 feet. There will be some accumulating snow during these periods above 4000 feet but not expecting enough to warrant issuing any type of headlines. LONG TERM...Wednesday night through Sunday...An unsettled pattern is expected to persist through the weekend with the best widespread precipitation chances Thursday night into Friday morning. Wednesday night an occluded front will move across WA and OR. While precipitation may be heavy at times in the Cascades most of the precipitation will remain on the west side. Model consistency becomes rather poor beyond Thursday with significant spread in the ensemble solutions. Another occluded front will move through Thursday night. Models show that the second occlusions will retain its structure better so it should produce more rain. Rain will taper off behind the front Friday. Another occlusion will move across WA and OR Saturday night. The GFS has the triple point over south central OR so there may be some stronger winds mixing to the surface over high elevations in OR. The ECMWF has the triple point over central OR and a massive surface low with strong winds in western WA. I leaned toward the GFS since ensemble spread does not favor strong solution. Snow levels generally 4500 to 5000 ft slowly trending down to 1500 to 2500 by Sunday. Coonfield AVIATION...00Z TAFs...TAF sites expected to remain VFR for next 24 hours. Increasing mid/upper level cloudiness tonight. Light winds. 76 && .PRELIMINARY POINT TEMPS/POPS... PDT 29 46 41 46 / 0 0 20 80 ALW 30 47 43 46 / 0 0 20 80 PSC 29 38 33 46 / 0 10 50 80 YKM 29 38 32 44 / 10 30 70 80 HRI 31 41 34 47 / 0 0 40 80 ELN 28 39 32 44 / 10 50 80 80 RDM 28 54 44 51 / 0 0 30 80 LGD 29 46 38 45 / 0 0 20 90 GCD 28 49 38 47 / 0 0 20 90 DLS 34 45 38 50 / 10 10 60 90 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ 85/85
Area Forecast Discussion
National Weather Service Tallahassee FL
756 PM EST Sun Nov 25 2018 .UPDATE... Made some adjustments to PoPs based on latest radar trends and expected timing. Otherwise no major changes. A marginal risk of severe weather remains in place for mainly the Florida panhandle and western big bend overnight. Latest 00z KTAE sounding has quite a bit of work to do to support surface based convection with a low level inversion in place. However, the airmass is expected to quickly change from west to east overnight as a more unstable airmass to the west advects into the area. && .PREV DISCUSSION [639 PM EST]... .NEAR TERM [Through Tonight]... A Marginal Risk for severe thunderstorms tonight from Dothan to Tallahassee and points southwest, with the primary threats isolated damaging wind and a brief tornado, beginning as soon as 9 PM this evening in the far Western FL Panhandle and Southeast Alabama and translating eastward into the Tallahassee area in the 5 AM to 8 AM time frame. The 18Z Surface Analysis indicated a 997 hPa low over Missouri with a southward extending cold front entering the Mississippi Valley, and a warm front over southeast Louisiana advancing northeastward. Thunderstorms were developing along this warm front as of late this afternoon with some supercells already noted on the LIX WSR-88D. The warm front will advance northward across the area overnight, followed quickly by a strong cold frontal passage. There is broad agreement amongst the model guidance for a northeast-southwest oriented line of convection along or just ahead of the cold front, reaching the Ben Hill-Colquitt-Leon-Gulf County area in the 5 AM to 8 AM time frame. The threat will hinge on just how much instability can work inland, with model disagreement between the robust NAM/RAP and conservative GFS. Nonetheless, there is broad agreement for an axis of higher instability just ahead of the cold front, with a rather narrow area juxtaposed with higher shear (0-1 km) in association with the warm front, supporting the brief tornado threat. In addition, minimal Convective Inhibition (CIN) is noted in some of the NAM and RAP runs, especially near and south of I-10. The wind field is also robust, with Bulk Shear in excess of 50 kt, and even 850 hPa winds approaching 40 kt, supporting the isolated damaging wind threat. If parcels can become surface based, e.g., weaker CIN, then the isolated damaging wind and brief tornado threat could materialize. The greatest chance of this would be in the marginal risk area closer to the coast. Also, steeper lapse rates in the hail growth zone could favor marginally severe hail, but this appears to be a lesser of the threats. With the warm/cold frontal passage, a mild night is in store as temperatures will only bottom out in the mid-50s to mid-60s for lows, in some cases warmer than Saturday`s high temperatures! .SHORT TERM [Monday Through Tuesday Night]... The previously mentioned cold front looks to be right down the middle of our CWA and right over Tallahassee at 7AM Monday and it will continue to move southeast through the day. There should be ongoing widespread rain showers with the front which will also overspread to the southeast. For now, we only have isolated thunderstorms in the forecast for Monday. It looks like the line weakens as it moves east with the bulk of the lift well to the north and any jet influences weakening as it moves east. There could be a brief period right before the frontal passage for these storms but the severe threat looks low. Temperatures will be quite tricky as the temps will generally cool with the front. However, parts of SE AL where the front will already be through by 7AM will likely warm a few degrees. Meanwhile, other parts of the area may see their highs overnight/before noon on Monday. This means there will be plenty of room for temps to fall with temps Mon night near freezing in the north and upper 30s in the south. The base of the upper trough will still be to the west on Tuesday and will continue to push through Tuesday night. Surface high pressure will slowly build in from the west with dry weather returning. Tue highs will only be in the lower to upper 50s with lows a deg or two cooler than Mon night. This could end up being our first freeze for SE AL and SW GA and possibly into the FL Panhandle. Right now lows for those areas are around 31-33 deg. .LONG TERM [Wednesday Through Sunday]... The mid level ridge will start to build in from the west Wednesday and continue to build through Friday. The surface high pressure will move directly overhead Wed night into Thursday. This all leads to dry weather continuing through Friday night. The building ridge will lead to a slight warming trend. Highs Wed will be in the mid 50s, rising to the mid 60s Thu, lower 70s Friday and even the mid 70s Sat/Sun. Lows will warm from the mid 30s Wed night into mid to upper 50s by Saturday night. A deep upper low will be digging into the midwest states on Saturday with a strong surface low to its southeast. A cold front will be moving east and will overspread rain across our region Saturday and Sunday. The timing is still a bit off and the overall strength of any storms can`t be determined at this time. Either way, it will probably be a stormy weekend and something to keep an eye on. .AVIATION... [Through 00Z Tuesday] Showers and thunderstorms are beginning to overspread the region ahead of the next low pressure system. Started rain a little earlier than previous TAFs but kept mostly the same after that. TSRA will be possible later this evening as the dynamics get closer. IFR/LIFR in TSRA appear likely in the overnight hours. A front will swing through from west to east overnight into Monday morning ending rainfall and flt conds improve beginning Monday afternoon. .MARINE... Winds increase tonight to close to 20 knots with occasional seas to 6 feet. For now, have held off on a Small Craft Advisory with any 20 knot wind or 6 feet seas being too occasional to warrant one. The winds will stay elevated for the next few days with the far western waters having the highest chance for near advisory criteria conditions. Widespread rain showers across the waters are likely tonight into Monday afternoon with dry weather expected Monday night through Friday night. .FIRE WEATHER... Red flag conditions are not expected for the next several days. .HYDROLOGY... Half an inch to an inch of rain is possible tonight but should not cause any flash flooding or river flooding issues. Additional rainfall is expected for the weekend but it`s too far out for exact rainfall amounts. .SPOTTER INFORMATION STATEMENT... Spotter activation is not requested. However, spotters are always encouraged to safely report significant weather conditions when they occur by calling the office or tweeting us @NWSTallahassee. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 61 68 37 55 33 / 80 70 10 0 0 Panama City 59 63 40 55 38 / 80 60 0 0 0 Dothan 52 55 33 51 32 / 60 30 0 0 0 Albany 56 61 35 52 32 / 80 50 0 0 0 Valdosta 59 67 37 54 32 / 80 80 10 0 0 Cross City 61 72 41 58 35 / 20 70 30 0 0 Apalachicola 64 68 40 57 38 / 80 70 10 0 0 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...High Rip Current Risk until 10 PM CST this evening for South Walton. GA...None. AL...None. GM...None. && $$ UPDATE...DVD NEAR TERM...LF SHORT TERM...LN LONG TERM...LN AVIATION...Scholl MARINE...LN FIRE WEATHER...DVD HYDROLOGY...LN