Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/05/22

Area Forecast Discussion
National Weather Service Dodge City KS
435 PM CST Sun Dec 4 2022 ...Updated Aviation... .SHORT TERM...(This afternoon through Monday evening) Issued at 1232 PM CST Sun Dec 4 2022 Recent water vapor satellite imagery and RAP upper air analysis indicates upper level zonal flow continues over the central plains between a strong cut-off ridge over central Mexico and a strong cut-off low over Canada. As these features remain fixed in place through the short term, little to no change is expected to the upper level pattern. At the surface, high pressure will depart for greener pastures during the day Sunday, and a weak lee cyclone will develop in eastern CO in its wake. Winds will trend towards southerly as a result, but not exceed 10 mph given a mostly inconsequential surface pressure field. Moisture plume embedded within the upper level westerlies will keep skies cloudy through Sunday afternoon, only supporting highs in the low/mid 50s. Overnight will be equally quiet, with light winds and clearing skies as lows drop into the mid 20s to mid 30s. Monday morning, the influence of the powerful upper level low in Canada will spread southward as a cold front is forced through our area. However, weak post-frontal CAA will only halt the warming trend for the far northern zones with afternoon highs ranging from the upper 40s north to low 60s along the KS/OK border. Cold air finally pushes equatorward into southwest KS Monday evening as winds weaken and trend northeasterly, allowing low temperatures to drop into the upper teens to upper 20s. .LONG TERM...(Tuesday through Sunday) Issued at 121 PM CST Sun Dec 4 2022 Upper level zonal flow will begin to turn south-westerly at the beginning of the long term period as a shortwave trough moves onshore over the California coast. Progress for this feature will be slow at first, and Tuesday will be another quiet day for southwest KS with light winds, partly cloudy skies, and highs in the mid/upper 40s to low 50s. On Wednesday, the upper level impulse will push forward, inducing lee cyclogenesis somewhere in southeast CO or adjacent northeast NM. Mass response will result in winds increasing out of the southeast, and allowing afternoon temperatures to increase as well despite abundant cloud cover with highs in the upper 40s northeast to upper 50s southwest. Wednesday night into Thursday morning, the upper level shortwave trough will begin ejecting into the central plains, however medium range guidance disagrees on how quickly this will occur, with the ECMWF showing the much slower solution. This also throws into question how much precipitation southwest KS can squeeze out of this system, as a slower wave ejection would translate to more QPF. Given the deterministic ECMWF has trended slower with the wave today, and the continued strong EPS support, confidence is growing precipitation might be a little more widespread than initially thought. While uncertainty still persists, latest NBM pops approaching the likely category (55-74%) over the eastern zones with slight chance pops (15-24%) extending to the KS/CO border were accepted. That said, QPF totals will still assuredly be paltry, with maybe a tenth of an inch or two the most likely scenario for most locations. Daytime Thursday, northwest winds will increase briefly on the northwest periphery of the deepening surface low, but relax fairly quickly as it pulls away. This latest shot of cold air will not amount to much, as afternoon highs on Thursday will still reach the mid 40s/low 50s. Surface high pressure will build into the central plains Thursday night into Friday morning in the wake of the upper level shortwave trough, fostering ideal radiational cooling conditions and supporting lows in the teens to 20s. Friday through the end of the period, medium range guidance begins to diverge regarding key synoptic features, rendering predictability low. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 435 PM CST Sun Dec 4 2022 VFR will continue through this TAF cycle, with variable amounts of cirrus. Current cirrus overcast is expected to thin out during the day Monday. Short term models suggest some stratus near P28 overnight, but expectation is for any stratus to remain southeast of the airports. Light wind less than 10 kts are expected through 12z Mon. After 18z Mon, a weak dry backdoor cold front will bring a NEly wind shift, with NE winds gusting modestly 20-23 kts. && .PRELIMINARY POINT TEMPS/POPS... DDC 31 55 23 47 / 0 0 0 0 GCK 30 55 23 46 / 0 0 0 0 EHA 37 63 26 53 / 0 0 0 0 LBL 32 62 23 50 / 0 0 0 0 HYS 26 47 19 43 / 0 0 0 0 P28 34 57 28 47 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Springer LONG TERM...Springer AVIATION...Turner
Area Forecast Discussion
National Weather Service Pocatello ID
829 PM MST Sun Dec 4 2022 .UPDATE... Updated forecast to include a chance of freezing rain around Malad, Preston and Bear Lake regions. Received a report of freezing rain earlier this evening around Logan. HRRR soundings at LGU showed the presence of an elevated warm layer and surface obs showed temps in the valleys near or slightly below freezing. The biggest threat appears to be through 06z although the HRRR does not show that elevated warm layer completely eroding away until later in the night. Also included patchy fog for the Snake Plain as the HRRR shows visibilities tanking overnight after our evening precipitation pulls away. Concerned about coverage given cloud cover and wind may stay up just enough to keep near-surface layer mixed. 13 && .PREV DISCUSSION... /issued 209 PM MST Sun Dec 4 2022/ SHORT TERM... This morning`s Winter Weather Advisory for the lower Snake, Magic Valley and zones to the south was allowed to expire at noon today as the threat for freezing rain has ended. Forecast did pan out nicely as FZRA was observed in many spots across the area including here at the Pocatello airport, although very briefly. A few area webcams into the Magic Valley appeared glazed over so the forecast worked out quite nicely given the uncertainty around this morning. Things are a bit clearer now for the remainder of this event. Mountain snow will continue especially around the Island Park region, the Big Holes and down into the Bear Lake range where Winter Weather Advisories continue through tomorrow morning. Outside of these areas, additional accumulations will be light, generally an inch or so. A second round of precip will move through the region later this afternoon and into the evening hours. Winds have become southerly and temps have begun to warm above freezing so rain will be the most likely precip type from Pocatello south and west into the Magic Valley. Into the upper Snake, forecasting a brief period of rain/snow mix but after sunset, when temps begin to cool again, precip type will trend towards snow again. This is true for the lower Snake and Magic Valley as well but by the time this occurs, most of the precip will likely be east of the area. Things begin to taper off through the overnight and certainly for the day on Monday. Only lingering snow chances will be along the Wyoming border with very light accumulations. McKaughan LONG TERM (Tuesday through Sunday)... Not much change in the extended forecast. With northwest flow in place, light snow looks to continue to fall in the Upper Snake Plain and Eastern Highlands on and off through Tuesday with little accumulation expected. POPs drop on Wednesday, so it is looking drier. The closed low that ECMWF and GFS were showing yesterday is more of a trough now and does not dig quite as far southward, though the difference brings little change to the forecast so far. As southwest flow begins on Thursday, that should dry out any of the light snow still falling. Our next trough moves in from the west late Thursday night into early Friday morning to bring more snow to much of the area. Zonal flow Friday into the weekend looks to bring a couple of rounds of snow through the weekend with the more active pattern continuing into next week. As for temperatures in the extended forecast, look for highs in the upper 20s and low 30s Tuesday. It`ll be colder after Tuesday, generally in the 20s for Wednesday through Saturday, which is about 5-10 degrees below normal for this time of the year. Morning temperatures will be in the single digits and teens. Winds will be a bit breezy in the extended with afternoon gusts 15-25kts. AMM AVIATION... We are seeing a short break in precipitation at BYI, PIH, and IDA this afternoon as snow continues on and off at SUN and DIJ. This will allow for some VFR conditions with VCSH at BYI, PIH, and IDA for a while with SUN and DIJ at MVFR to IFR conditions. Our next push of moisture looks to arrive around 23-01Z from the southwest. This brings flight conditions to generally MVFR and IFR with low CIGs and VIS thanks to falling rain and snow at BYI and PIH and snow at the rest of the sites. This round could drop conditions to below airport minimums at DIJ in some of the heavier bursts of snow as VIS drops briefly below 1SM. Snow wraps up around 06-07Z Monday at SUN, BYI, PIH, and IDA, but light snow will continue at DIJ. AMM && .PIH WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 8 AM MST Monday for IDZ060-064-066. && $$