Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/28/22

See below for an aviation forecast discussion for the 00Z TAFs.

&& .SHORT TERM...(This Evening through Wednesday Night) Issued at 224 PM CST Tue Dec 27 2022 Overall, fairly quiet tonight and Wednesday before a system skirts part of the CWA Thursday, bringing a chance of precipitation. The warmer temps today have been welcoming after the frigid conditons we have been experiencing for the past week. The main challenge in the short term will be how low the temps drop tonight and how warm the temps get on Wednesday due to cloud cover expected and snow covered ground. During the morning hours, we saw temperatures rise in the western part of the state as a warm front passed through the area. However, in the James River Valley area, it does not look like we will reach our high of 32 at ABR so I did lower them as the snow depth/cloud cover have played a part in keeping the temps a little cooler than what NBM suggested. The warm front continues to push east across the CWA, ushering in the warm air advection behind it. We have downsloping winds continuing on the eastern slopes of the Sisseton Hills and the Coteau with an SPS issued until 6PM, due to blowing snow reports in this area. The downsloping winds should diminish through the evening into tonight. I used the ECAM for winds and gusts in this area to show for this. RAP/GEFS at 500mb indicates a ridging pattern over much of the Northern Plains becoming more flattened as it pushes east, giving us more of a zonal pattern by this evening. Winds will turn more southwesterly through the overnight as an upper level trough is positioned out west. This trough will move east through the midweek, but overall flow will remain southwesterly. 700mb indicates a shortwave pushing in from the west this evening through the overnight with a low skirting across Canada/MT bringing the increase in clouds. This low will continue to push east HREF/RAP/ECMWF Ensemble keeps the area dry with this system tonight through Wednesday. NBM/RAP at ABR does indicate the possibility of patchy fog (with the Rap sounding showing this as well at the surface) so added that into the forecast, something to watch for during the overnight. Our attention then turns to a 1003mb low that will push across the central parts of the midwest starting early Thursday. The latest ECMWF/GEFS ensembles keep the precip chances mostly in our eastern/southeastern coverage area, which is positioned in the northern/northwest side of the low. We could start seeing mixed precip/snow chances (15-20%)in this area early in the morning (between midnight-6 AM) on Thursday, however, the ECMWF sounding at Watertown indicates a dry layer between 900-700mb during this time with saturation near the surface (as possible freezing drizzle/rain). The sounding clearly indicates a warm nose between 900-800mb with temps in the warm nose around +8C and the surface temps hovering around 0C early Thursday. The entire column does becomes saturated through the day and becomes colder. I left in a slight chance of pops given by NBM during this time frame. 925 temperatures at 12Z Wednesday will hover around 0-2C with surface winds out of the west/southwest. I did decrease our temps a few degrees for tonight due to the impact of the snow. Lows are forecasted to be in the 20s-30s. Highs for Wednesday should be fairly similar (Again, I lowered the highs a few degrees from the NBM). Winds will be out of the west/northwest, however, cloud cover still expected. Highs should range in the 30s to the lower 40s with warmest in south central SD. .LONG TERM...(Thursday through Tuesday) Issued at 224 PM CST Tue Dec 27 2022 Latest round of deterministic/ensemble data concerning Thursday`s system has pushed things further east and weaker compared to 24 hours ago. In fact, there are a number of ensemble members that show barely any precip with this system. That said, the ensemble mean approach would still bring light QPF/snow amounts to the southeast CWA Thursday into Thursday evening, with perhaps some mixed precip issues. Focus then shifts to the potential storm system early next week. GEFS/EC/CMC ensemble probs for 24-hour snowfall 3"+ at 12Z Tues shows fairly high (50%-70%) chances across the area, although the EC is displaced further south. Still some evidence of mixed precip potential as well closer to wherever the warmer air sets up in our region. As for temperatures, it doesn`t appear we`re in line for any arctic- type air intrusions anytime soon, with ensemble data supporting continued high temps in the 20s and 30s mostly throughout the period. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening) Issued at 516 PM CST Tue Dec 27 2022 Terminals KABR,KATY,KPIR,KMBG VFR/Mostly cloudy (high cirrus) skies should persist well into tonight, before potentially clearing off Wednesday. Short term guidance continues indicate a chance for either some fog or low stratus development overnight/early Wednesday morning in/around KABR as winds go light. Additional sub-VFR cigs/visbies will be possible in/around KATY by Wednesday afternoon. KPIR/KMBG will remain VFR through forecast period, although some low level wind shear potential will exist at KPIR for a few hours into this evening. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...Dorn SHORT TERM...MMM LONG TERM...TMT AVIATION...Dorn
Area Forecast Discussion
National Weather Service Corpus Christi TX
905 PM CST Tue Dec 27 2022 ...New UPDATE... .UPDATE... Issued at 826 PM CST Tue Dec 27 2022 Boundary layer moisture is beginning to increase along the coast as a trough develops in the lee of the Rockies. Temperatures have fallen pretty quickly under ideal radiational cooling conditions with light southeast winds and clear skies. Lowered temps a few degrees for tonight as temperatures have already fallen below forecast lows at a number of locations. Next forecast challenge for tonight is the extent and density of fog. Surface winds have decoupled from the low level flow and dwpts are rising and expected to result in 100% RHs overnight. This will likely result in patchy to areas of fog formation. SREF probabilities indicate >40% probability of visibilities below 1 mile developing late tonight across much of the brush country and coastal plains. NBM probs are near 30%. Thus cannot rule out patchy dense fog overnight, but it should not become widespread or prevailing. Will continue to monitor. && .SHORT TERM... (Tonight through Wednesday night) Issued at 209 PM CST Tue Dec 27 2022 Key Messages: - Warming trend continues - Fog begins to return late tonight A pleasant day is unfolding as high pressure passes by the region. Temperatures have warmed into the low to mid 60s so far today under mostly sunny skies. Winds will gradually shift around to the southeast this evening as surface high pressure moves towards the SE CONUS. The return of low level moisture will lead to a foggy night across the region as winds become light overnight. Maintained the mention of patchy fog only at this point as guidance continues to indicate the development of a 25-30 knot LLJ which may help to fight off any dense fog development. A warmer day is expected tomorrow with temps topping out in the mid to upper 70s for most of the region. Onshore flow will strengthen through the day as low pressure deepens over the Plains. As a result, warm and moist air will begin to flow over the cooler shelf waters. This will likely lead to the start of a prolonged period of sea fog through the remainder of the work week. Currently expect sea fog to develop during the late afternoon hours Wednesday with radiational fog develop inland as we head into Thursday morning. In addition to the fog, it`s possible we see a few showers over the Gulf waters Thursday morning as deeper moisture becomes embedded in the LLJ && .LONG TERM... (Thursday through next Monday) Issued at 209 PM CST Tue Dec 27 2022 Key Messages: - Warming trend with fog through Thursday - Shower and thunderstorm chances (20-40%) Thursday ahead of and along a weak dry front - Cold front early next week with isolated to scattered showers and thunderstorms Thursday a mid-level trough and attendant frontal boundary will approach South Texas. This dry boundary still may result in a few showers and thunderstorms, mainly east where more moisture aloft combine with upper level dynamics and isentropic lift. Our next front comes in early next week as another trough digs in from the Desert Southwest. Currently, dynamics look more conducive for thunder with higher CAPE values > 1,000 J/kg and minimal CIN according to the GEFS Plumes. Again any storms that develop will favor eastern portions of the CWA and the Gulf waters. Onshore flow should increase low level moisture sufficiently for radiation fog with light winds and dewpoint depressions around three degrees or less Thursday morning, possibly late Thursday night and again Sunday morning. Have also included sea fog along the coastal waters for the same time period as warm surface temperatures and dewpoints in the 60s override cooler sea surface temperatures. Fog looks less likely after the front Friday and Saturday as dewpoint depressions spread further apart making it more difficult for the waters to cool the air above it down to the dewpoint temperature. Temperatures during the daytime will range in the mid to upper 70s along the coast and up to the mid 80s around the Coastal Plains and Brush Country. After FROPA, things will cool slightly by about 5-10 degrees. Overnight lows will generally range in the 50s except Sunday with mid 60s across much of the region. && .AVIATION... (00Z TAFS) Issued at 531 PM CST Tue Dec 27 2022 Skies will be mostly clear through midnight with light southeast winds. This will bring higher surface moisture back into the region and set up for a fog event overnight. There is considerable uncertainty on how low visibilities may get with the GFS showing little to no fog and the NAM12 and HRRR showing a potential for dense fog. For now have included visibilities in IFR range across inland terminals. But will reassess as 00z models come in for the 06z TAFs. Fog should dissipate by mid Wednesday morning with increasing southerly winds gusting to 20 knots across the coastal plains with VFR ceilings east and mostly clear skies out west. && .MARINE... Issued at 209 PM CST Tue Dec 27 2022 A moderate to occasionally onshore flow will return tonight across the Middle Texas coast. Winds will increase through the day tomorrow with Small Craft Advisory conditions possible tomorrow night. Sea fog will return tonight with another round of sea fog expected Wednesday night into Thursday morning. Small Craft Advisory conditions continue Thursday in response to moderate to strong onshore flow. Then, moderate flow will switch around to the northeast after a frontal boundary moves offshore Friday morning and becomes weak. Saturday, moderate flow will become variable before returning to onshore in the evening. Sufficient low level moisture combined with the frontal boundary will result in isolated showers and thunderstorms through early Saturday. Warm humid air overriding cooler waters may result in sea fog Thursday morning but should lift by the afternoon. && .PRELIMINARY POINT TEMPS/POPS... Corpus Christi 44 76 64 77 / 0 0 10 10 Victoria 41 75 63 76 / 0 0 10 40 Laredo 48 73 55 74 / 0 0 10 0 Alice 43 78 61 79 / 0 0 10 0 Rockport 50 70 63 73 / 0 0 20 30 Cotulla 44 76 54 73 / 0 0 0 0 Kingsville 46 78 63 79 / 0 0 10 0 Navy Corpus 53 71 65 72 / 0 0 10 20 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ SHORT TERM...JM/75 LONG TERM....BF/80 AVIATION...JM
Area Forecast Discussion
National Weather Service Goodland KS
155 PM MST Tue Dec 27 2022 .SHORT TERM...(This evening through Friday) Issued at 145 PM MST Tue Dec 27 2022 Tonight...broken to overcast high cloud cover will move across the area tonight ahead of an approaching upper level trough. South to southwest winds of 5 to 15 mph this evening will veer to the northwest at 5 to 10 mph after midnight. Low temperatures are expected to range from the middle 20s to around 30 in the Republican river valley as well as the McCook, Norton and Hill City areas to the lower 30s elsewhere. Wednesday-Wednesday night...high cloud cover will remain over most of the area during the day. An area of more favorable moisture (850- 500mb) for precipitation moves into parts of far eastern Colorado from the northwest late in the afternoon. With a 120kt jet moving overhead and some lift lower down current forecast of slight chance and low chance pops look good. High temperatures are forecast to range from the upper 40s in Yuma to around 60 from Hill City to Leoti. For the overnight hours, the upper trough axis reaches the Continental Divide. The area of favorable moisture in the 850-500mb layer splits up after about midnight with one batch of moisture moving east of the area and another hugging the Palmer Divide and points south (per GFS) with drier air aloft moving in. The NAM shows a similar scenario with much less moisture while the ECMWF shows much more moisture and widespread precip from McCook to Burlington and Cheyenne Wells west. The current QPF forecast after midnight mimics the ECMWF and lesser extent HRRR solutions. Given the dry air even at the boundary layer from the GFS and NAM solutions I`m not sure how we`ll get any freezing precipitation. Low temperatures are generally going to be in the 20s. Currently, we`re advertising snowfall amounts of a trace to inch or so from Trenton to Cheyenne Wells west. Thursday-Thursday night...broad upper level troughing is over the area with high pressure over the eastern US and southwest US. Current pop forecast mimics the more moist ECMWF with the precipitation chances decreasing from southwest to northeast during the day and dry conditions overnight. The NAM and GFS solutions are much drier with much less QPF during the day. Any additional snowfall appears to be 1/2 inch or less. High temperatures are forecast to be in the upper 30s to upper 40s. Low temperatures drop into the lower teens to lower 20s. upper level trough axis extends from the northern plains south through the Tri-State area into west Texas. Dry conditions are expected with high temperatures in the lower 40s to lower 50s. .LONG TERM...(Friday night through Tuesday) Issued at 1223 PM MST Tue Dec 27 2022 Above-normal temperatures continue through the first half of the long term period. A larger trough moving into the area Sunday night into Monday will drop temperatures for the start of the work week and bring a chance for wintry precipitation. Extent and amount of precipitation remains uncertain at present; however, there are some indications portions of the area could see significant snowfall - as such, will need to continue to closely monitor. At the start of the long term period 00Z Saturday, an upper-level shortwave trough axis is moving into the Tri-State Area with a surface low over northeastern New Mexico/southeastern Colorado. Any precipitation associated with the weak system as it progresses east- northeastward is expected to be outside of our area. Saturday evening into the first part of Sunday, we`ll see some brief upper- level ridging as the next upper-level low comes ashore the west coast and surface low pressure develops in the lee of the Rockies. Focus will turn towards the low center`s approach and arrival in our area and how it tracks Sunday night into Monday. Continued variability in GFS and ECMWF solutions results in low confidence in impacts, particularly in the precipitation forecast for this time period. By 12Z Monday, the latest GFS places the ~540dam low center over our eastern CO counties, having a brief shot of precipitation mainly confined to eastern CO/parts of southwestern Nebraska while the latest ECMWF has the low center positioned more over southeastern CO, northeastern New Mexico, and the Texas/Oklahoma Panhandles, allowing for more widespread, wrap-around precipitation into our CWA. Regardless, models agree that some precipitation is possible for at least portions of our forecast area; uncertainty is in magnitude and extent of precipitation chances. Will need to continue to monitor closely as at least the ECMWF solution and its trends indicate potential for significant snowfall for the area. Monday into Tuesday, the low center moves off towards the north- northeast and any precipitation chances will gradually come to an end. High temperatures are again forecast to be in the 40s and 50s for the weekend, dropping into the 30s and 40s Monday and Tuesday. Morning lows will be in the upper-teens to low-20s through Monday morning, dropping into the low-teens to low-20s by Tuesday morning. Wind gusts reaching into the 30mph range are possible Monday afternoon. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 145 PM MST Tue Dec 27 2022 KGLD...VFR conditions are expected through the period. A south wind around 12kts at taf issuance will subside below 11kts by 01z or so, veering to the southwest then northwest overnight at speeds under 10kts. Winds become northerly around 18z, gusting to 20kts or so from 18z-22z. KMCK...VFR conditions are expected through the period. A light and variable wind is expected from taf issuance through 15z. From 16z-19z, a light northwest wind is expected. From 20z through the rest of the taf period, northwest winds increase with gusts to 25kts expected. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...99 LONG TERM...CC AVIATION...99
Area Forecast Discussion
National Weather Service North Platte NE
518 PM CST Tue Dec 27 2022 ...AVIATION UPDATE... .SYNOPSIS... Issued at 318 PM CST Tue Dec 27 2022 974 mb sfc low pressure near the coast of Washington state will fill as it moves east tonight through Wednesday night tracking along the Canadian border. The models show warm air advection peaking near 15C at h850mb late this afternoon followed by a steady decline in temperatures. The weakest of Pacific cold fronts will drift through wrn and ncntl Nebraska tonight with very modest cold air advection continuing through Wednesday night. Key Messages: -Confidence in the rain snow forecast Wednesday night and Thursday is very low. Some models are dry. -Confidence has increased in the prospect of a winter storm affecting wrn and ncntl Nebraska Sunday and Monday. && .SHORT TERM...(This evening through Wednesday night) Issued at 318 PM CST Tue Dec 27 2022 The system coming ashore across the Pacific Northwest continues to produce significant model differences across wrn and ncntl Nebraska. The dispute among the models revolves are how much of the energy moves through WY. The GEM and ECM show the system becoming stronger and more developed across Nebraska than the NAM and GFS. The models appear to be focusing the best forcing across swrn and ncntl Nebraska and the prospect of snow across nwrn Nebraska has diminished. The ensembles of the GFS, GEM and ECM continue to show light precipitation developing Wednesday night-after midnight. The GFS and NAM have gone dry except for isolated showers which the GEM and ECM continue to be bullish with the amount of forcing producing higher QPF. Light rain mixed with freezing rain changing to snow is the operative ptype and QPF is light, generally 1/10th of an inch or less. The p-type leans on the RAP model which shows temperatures at h850mb hanging above freezing most of the night. There is reasonably good support for ice accumulation in areas where the ground sfc remains below freezing and the frost depth is currently a foot or more across much of wrn and ncntl Nebraska. The temperature forecast uses the short term model blend, the RAP and HRRR models. This forecast is based on the expected cold air advection pattern tonight and beyond which all models show. .LONG TERM...(Thursday through Tuesday) Issued at 318 PM CST Tue Dec 27 2022 WPC suggested a blend of the dry GFS/NAM with the wet ECM/GEM models for QPF which actually resembles the ensembles of each of those four models. Snow and rain is possible but not likely Thursday morning and chance pops are in place for a highly uncertain forecast. The forecast is for around an inch of snow and a few hundreths of an inch of ice. The snowfall prediction is close to WPC. The ice accumulation is somewhat speculative- WPC suggested none. This system should lift northeast through swrn and ncntl Nebraska Thursday with dry weather Thursday night through Saturday. There is little change in the storm system predicted to affect wrn and ncntl Nebraska Sunday and Monday except to say confidence is increasing and WPC suggested medium confidence in significant snowfall across most of wrn and ncntl Nebraska. Their winter weather outlook lines up fairly well with the GEM, ECM, GFS ensembles and, the deterministic German Icosahedral model. It is worth noting the operational GFS, GEM and ECM show a spread of about 200 miles with the stripe heavy snow predicted across the cntl/nrn Plains and this storm is currently circulating off the coast of nrn Japan. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 518 PM CST Tue Dec 27 2022 VFR is expected through Wednesday afternoon for western and north central Nebraska terminals. Most cloud cover should be high level (20kft agl) with ceilings gradually lowering toward 28/18z. Wind is the main concern as low level shear conditions are present through the overnight. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CDC SHORT TERM...CDC LONG TERM...CDC AVIATION...Snively