Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/29/20

Area Forecast Discussion
National Weather Service Dodge City KS
800 PM CST Sat Nov 28 2020 .UPDATE... Issued at 800 PM CST Sat Nov 28 2020 Based on radar trends (moderate rain in northern Clark county moving north) and latest HRRR trends, increased and expanded pop grids for the next several hours. Several short term high resolution models show light rain reaching the US 50 corridor by midnight. After midnight, the rain will dwindle and shrink southeastward as the closed low pulls away. && .SHORT TERM...(This evening through Sunday) Issued at 348 PM CST Sat Nov 28 2020 During the mid afternoon hours, an upper low continued to move slowly east into the western Texas Panhandle. This system was quite small and rather moisture-starved, but was still formidable enough to produce light rain and even some snow across portions of the Texas Panhandle today. This system was also cold-air starved, so pretty much all the snow was confined to higher elevation areas of the western Texas Panhandle and adjacent northeastern New Mexico right near the cold-core center of the upper low itself. As the upper low moves east tonight, it will continue to move across lower elevation, and thus the preponderance of precipitation should stay a cold rain this evening and overnight. The question is how far north this precipitation will reach. Some of the latest short term, high-resolution models suggest some very light measurable cold rain may make it as far north as Highway 50 before dissolving. We will carry some 50-60 POPs mainly in the Red Hills region nearest Oklahoma border through the night. Precipitation amounts up to a tenth to perhaps fifteen hundredths is about all that can be expected tonight. As this upper low pulls away early Sunday, the active northern branch of the polar jet will have a strong wave of its own, moving southeast from the Dakotas across the Midwest region. A strong surface cold front will push quickly south Sunday morning. The going forecast already had north winds behind the front handled fairly well, and our latest forecast is simply a continuation of what we had going -- sustained 25 to 35 mph much of the day with gusts 40 to 45 mph. A couple of 50 mph gusts will also be possible, particularly mid to late morning tied to the highest pressure rises immediately behind the front. The airmass behind the front will not be bitterly cold, but the strong winds will certainly create a bit to the air as temperatures struggle to reach mid to upper 40s. .LONG TERM...(Sunday night through Saturday) Issued at 348 PM CST Sat Nov 28 2020 Interesting potential weather in the Long Term. There are some changes that have started to show up in the global models this morning that the latest NBM have not yet caught up to. The Canadian GDPS and ECMWF models are now showing a potent jet digging south across the Rockies, carving out an impressive upper low across the Central Plains mid-week -- insomuch that both these models are showing 0.25 to perhaps 0.50 of storm total QPF across portions of southwest/central Kansas centered on Wednesday and Wednesday Night. This is quite a drastic change in global models showing this westward shift in upper level low formation. The thermodynamic profiles would certainly support snow if this indeed pans out. It should be noted that the official forecast going out this afternoon has ZERO mention of any precipitation -- as there is not quite the appetite yet to alter the NBM starting point -- as the morning NBM has 12-hr POPs around 5 to 10 percent with no weather mention. The GFS remains farther east with no precipitation, so until all the major global models start lining up, blended solutions (i.e. NBM) will be slow to show anything formidable with respect to precipitation. It is something that will have to be watched closely, however, and the end user should be cognizant of the fact that the mid-week forecast may change quite a bit given how chaotic the large scale hemispheric pattern is right now. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 435 PM CST Sat Nov 28 2020 Radar indicates areas of light to moderate rain near LBL as of 2230z. Included a TEMPO group for -RA for LBL through 01z Sun, after which time rain in the vicinity of LBL is expected to diminish. MVFR ceilings currently at LBL are expected to persist much of the night, as a closed low drifts from near AMA at 00z Sun to western Oklahoma at 12z Sun. Elsewhere, VFR will continue tonight, with broken mid level cloud as far north as GCK/DDC and light west winds. A strong cold front is expected to sweep through the airports around, or just after, 12z Sun. After 15z Sun, strong north winds will impact aviation operations at all terminals with gusts of 35-40 kts. The strongest winds are expected during the late morning/midday hours, before gradually relaxing late Sunday afternoon. Very dry air will promote VFR/SKC Sunday and Sunday night. && .PRELIMINARY POINT TEMPS/POPS... DDC 32 46 19 49 / 30 0 0 0 GCK 30 45 16 49 / 20 0 0 0 EHA 28 46 19 53 / 30 0 0 0 LBL 28 47 17 51 / 60 0 0 0 HYS 31 45 17 47 / 0 0 0 0 P28 38 49 23 47 / 50 20 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Turner SHORT TERM...Umscheid LONG TERM...Umscheid AVIATION...Turner
Area Forecast Discussion
National Weather Service Des Moines IA
530 PM CST Sat Nov 28 2020 .DISCUSSION.../Tonight through Saturday/ Issued at 212 PM CST Sat Nov 28 2020 High pressure centered over southern Missouri has allowed for clear skies today. In fact, the nearest clouds on GOES-East satellite are several hundred miles away in Oklahoma/southern Kansas or North Dakota. Abundant sunshine and southwest winds into the area allowed temperatures to climb into the mid to upper 50s by 2 pm for most locations. Big changes are on the way, however, as a cold font draped across the northern plains will dive south and across Iowa Sunday morning. Southwesterly winds will shift to northwesterly with temperatures dropping rather substantially. Highs for Sunday will will have a hard time cracking 40 degrees with most places topping out in the mid 30s. This will be accompanied by gusty northwest winds behind the front thanks to a tightening pressure gradient with decent cold air advection and subsidence into the area. Model soundings indicate winds at the top of the mixed layer of 30-36 knots depending on model or location with sustained winds at 18-23 kts. Hi-res models such as the hrrr and href suggest better gusts will occur in the southern Nebraska/northern Kansas vicinity. Thus, have opted not to issue a wind advisory as the area remains a few knots shy of criteria. Regardless, it will be a cold and blustery day exacerbated by the relatively mild conditions seen Saturday. Temperatures will continue to drop Sunday evening and with brisk winds continuing overnight Monday morning wind chills will be rather the single digits. The forecast for the upcoming week is rather quiet with no precipitation chances in the current forecast at all. While the area will be moisture starved, this does not mean that the pattern is quiet. In fact, the atmospheric pattern over the upcoming week is quite complicated with a number of deep closed lows moving across the country with embedded shortwaves. At certain points the evolution of the systems resembles somewhat of a fujiwhara effect before lifting east. The split flow cuts off moisture to the area but the complicated pattern yields high uncertainty in the temperature forecast for the upcoming week as these systems drop out of Canada. Placement of these systems could result in fairly substantial differences in temperatures. && .AVIATION.../For the 00Z TAFS through 00Z Sunday evening/ Issued at 530 PM CST Sat Nov 28 2020 Quiet aviation weather is expected overnight prior to a cold front arriving toward daybreak. Widespread VFR conditions are forecast along with southwest surface winds. The front is forecast to pass through the state on Sunday morning with very strong northwest winds on the backside. Have increased wind speeds and gusts during the day on Sunday and also have added additional cloudiness as climatologically very favorable for status development on backside of frontal passages this time of year. Have kept any ceilings VFR at this time given only limited support for status in guidance. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...Hagenhoff AVIATION...Cogil
National Weather Service Hastings NE
648 PM CST Sat Nov 28 2020 ...Short Term and Aviation Update... .UPDATE... Issued at 647 PM CST Sat Nov 28 2020 Some thoughts on wind speed potential Sunday: As already outlined by previous forecast in main afternoon discussion below, strong north winds are the main feature on Sunday. However, after perusing various model soundings and leaning a bit more toward the latest RAP13, have slightly- increased mainly gust potential in our official forecast, with worded products now calling for more in the way of 40-45 MPH than 35-40 MPH. In turn, have refreshed our Hazardous Weather Outlook (HWOGID) to hit winds a bit harder as well. Even so, am a little concerned that we still may not be hitting max gust potential quite hard enough, as the more aggressive solutions (not only the RAP but also the HREF mean) suggest that especially the 8-11 AM time frame could feature sporadic gusts to around 50 MPH, as this time frame features the greatest overlap between the onset of diurnal mixing and the strongest winds a few thousand feet off the deck (before they weaken somewhat heading into afternoon). Fortunately, do not think we will see gusts quite as high as Warning criteria. && .DISCUSSION...(This evening through Saturday) Issued at 229 PM CST Sat Nov 28 2020 The biggest issue for this forecast will be wind for Sunday. An upper level trough will swing through within progressive flow tomorrow with an associated cold front pushing through overnight tonight. Surface pressure rises near 5 mb/3 hours will give us 30-35 mph wind gusts overnight, with wind gusts likely subsiding in the early morning, before increasing as low-level mixing occurs and brings momentum transfer to the surface near 40 mph wind gusts. This will be a dry frontal passage with bone dry air and plenty of subsidence behind the front. Temperatures should stay cool enough to avoid critical fire weather criteria, although it still looks like we could get into the near-critical range in our southwest, and with wind gusts near 40 mph with such dry conditions, I would not be surprised about a random grass fire or two for Sunday. Wind speeds should be on the decrease during the afternoon as relative humidity bottoms out, so we would at least have that going for us, although still gusty. Mid and long term models indicate some ridging at the beginning of the work week until a sort of dumbbell-looking feature toward mid- week. Although we will lack deep level moisture, there could be enough lift to squeeze out some non-measurable precip. Temperatures will be largely seasonable, although could be a bit on the cool side during mid-week if a dumbbell upper low passes overhead and brings in cooler air and more sky cover. Still, a dry forecast for the next seven days outside of the mid-week shot at some non-measurable precip that would not be out of the question. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday) Issued at 647 PM CST Sat Nov 28 2020 High confidence in VFR ceiling/visibility and dry weather through the period, with only some passing mid-high level clouds anticipated. That leaves strong winds as the paramount concern both at the surface and slightly aloft, as the early morning hours Sunday are likely to feature some fairly strong northerly low level wind shear (LLWS). More wind-specific details follow. Surface winds: By far the lightest winds of the period will focus these first 8 hours or so, as speeds average under 10KT as direction gradually shifts from southwesterly to westerly. Then a passing cold front will arrive between 8-10Z, bringing increasing north-northwest speeds with gusts around 20KT possible initially. The overall- strongest winds of the period will focus during the daytime Sunday, with several hours of sustained speeds 20-25KT/gusts 30-35KT. Although not officially included in current TAFS, gusts could briefly reach 40KT mainly during the 14-17Z time frame. LLWS: Have introduced a period of fairly strong northerly low level wind shear 08-14Z, as although surface winds will be on the increase through this time, winds no more than 1-1.5K ft. above the surface will be quite intense at around 50KT, resulting in a solid 35-40+ KT of shear magnitude between the surface and this level. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...Pfannkuch DISCUSSION...Heinlein AVIATION...Pfannkuch
Area Forecast Discussion...UPDATED
National Weather Service Miami FL
802 PM EST Sat Nov 28 2020 .Update... High pressure over the Western Atlantic waters will move slowly southward tonight into the Bahamas, as low pressure develops over the Northwest Gulf of Mexico. This will allow for the steering flow over South Florida to become more south/southeast but light and allow for some low level moisture to work into the region from the south. Therefore, the weather will remain mostly dry tonight over South Florida with only an isolated shower over the east coast metro areas and the adjacent Atlantic coastal waters. Light winds and low level moisture over South Florida will allow for some fog to develop over the interior and west coast metro areas especially west of Lake Okeechobee late tonight into early Sunday morning. Therefore, Fog has been expanded to include rest of the interior and the west coast metro areas with even areas of fog west of Lake Okeechobee for late tonight into early Sunday morning. Rest of the forecast looks good at this time and no other changes are planned. && .Prev Discussion... /issued 622 PM EST Sat Nov 28 2020/ Aviation... The winds will remain light and variable over all of the TAF sites tonight along with mostly dry conditions. Patchy fog should develop over the interior areas of South Florida late tonight, but remain away from most of the TAF sites. The only exception is for APF taf site where the vis and ceiling could fall down into MVFR conditions between 08Z and 11Z due to fog. && Prev Discussion... /issued 303 PM EST Sat Nov 28 2020/ Short Term (Rest of today through Sunday)... Rest of today... A broad area of weak low-level high pressure is evident across the region via the latest RAP analysis and GOES-16 water vapor imagery loops. This is supporting very weak low/mid-level flow across southern Florida. The MFL 12Z RAOB captured this weak low- level flow pattern quite well -- depicting a cloud-layer mean wind of 9 knots from the WNW. Aloft, a swath of enhanced mid/upper- level southern steam flow is evident across northern Florida. While there may be some weak upper-level divergence associated with this area of enhanced flow, large-scale forcing for ascent remains nearly negligible across the South Florida CWA. The large-scale pattern discussed above is supporting a strong 750- mb subsidence inversion -- below which a relatively moist layer is evident via this previously mentioned MFL RAOB (characterized by low- level RH near 80%). This shallow moisture combined with a north- south oriented mesoscale coastal boundary across the Atlantic waters is supporting shallow convective showers with very little in the way of motion. In fact, most of these showers appear to be anchored along the western periphery of the Gulf stream, where localized heat/moisture fluxes are supporting higher theta-e marine boundary layer air. Considering the relatively rich low-level moisture below the above mentioned inversion and fairly dense cloud coverage/debris over the Atlantic coastal waters, the coastal boundary layer has remained somewhat sheltered from diurnally-driven inland vertical mixing. This has preserved the surface moisture -- supporting a small uptick in weak surface-based buoyancy along the southeast coast (nearing 500 J/kg this afternoon). Further west, nearly clear skies is supporting efficient surface heating, which has generally mixed out the above mentioned rich low-level moisture and actually stabilized these areas to an extent. That being said, areas over western Miami- Dade County/inland South Florida could see isolated showers develop, owing to the interface of deeper inland boundary-layer mixing and the above mentioned moist/sheltered coastal boundary layer. Therefore, isolated mesoscale driven convective showers remain possible along the immediate Atlantic coastline of Miami-Dade and Broward Counties, with lower chances extending inland. Any showers that do manage to develop over land areas today will be shallow in depth -- owing to warm/dry mid-level air and associated strong convective inhibition (SBCINH near -150 J/kg). A lack of any appreciable large-scale forcing for ascent will inhibit parcels from reaching their LFCs within this fairly hostile thermodynamic environment. That said, the very slow/non- existent storm motions and slow propagation vectors will support some light rainfall accumulations across metro Miami-Dade County. The relatively light nature of these showers should greatly limit the threat of urban/street flooding, but if any shower becomes locally enhanced and moves slowly over a particular coastal area, ponding of water could occur, though unlikely. Sunday... Weak high pressure will remain in place across the region, supporting very similar conditions to that of today. Isolated coastal showers will be possible, but coverage and intensity should be low. Temperatures will remain seasonable for this time of year. Winds begin to transition to a southerly direction, but remain light overall. Long Term (Monday Through Saturday)... The extended period opens up with high pressure retreating into the Atlantic as a complex low over the Gulf Coast states begins to traverse northeastward, pushing a frontal boundary down the peninsula and across South Florida mid Monday into early Tuesday. Current model solutions, albeit still showing minor differences in timing, depict the low quickly progressing up the eastern Seaboard along with the best upper level dynamics. Therefore, showers with perhaps a few thunderstorms are possible with the front`s passage. Behind the front, high pressure builds back across the peninsula, with northwesterly to northerly flow advecting a colder and drier airmass into the region. The coldest temperatures should be felt Wednesday morning with overnight lows dipping into the upper 40s to lower 50s across coastal metro areas and mid to lower 40s over the interior and western Lake Region. This will be somewhat short- lived as high pressure slides further eastward, veering the flow out of the northeast then east, essentially inciting a warming and slight moistening trend as the airmass modifies by late week. Guidance then hints at the potential for cyclogenesis in our vicinity, along with a second frontal boundary by the tail end of the week and into next weekend. Unsurprisingly, agreement this far out is poor in regards to timing, location, trajectory, and overall impacts to South Florida. This will be something that will be monitored with each model run and as we get closer in time. Marine... A weak area of high pressure over the region will continue to support light winds and generally benign marine conditions across the local waters through this weekend. Early next week, a cold front will approach the area and bring an increase in winds and associated hazardous marine conditions, which will persist until late next week. Aviation (18Z TAFs)... Primarily VFR throughout the period, with weak high pressure and light/variable wind flow in place. Shallow moisture continues to support VFR cigs along the southeastern portions of S FL this afternoon, as well as brief passing SHRA. Convective coverage is too minimal to mention in the TAFs, but brief MVFR cigs/vis could accompany this activity along the eastern terminals. && .Preliminary Point Temps/PoPs... West Palm Beach 68 82 70 84 / 10 10 10 30 Fort Lauderdale 70 83 70 84 / 10 10 10 20 Miami 69 83 71 84 / 10 10 10 20 Naples 67 83 70 81 / 0 10 10 70 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. GM...None. && Update...54/BNB Marine...55/CWC Aviation...54/BNB Short Term...55/CWC Long Term...11/HVN