Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/23/20

Area Forecast Discussion
National Weather Service La Crosse WI
554 PM CST Sat Feb 22 2020 .SHORT TERM...(Tonight through Sunday) Issued at 1140 AM CST Sat Feb 22 2020 Tranquil and pleasant late winter weather looks to persist for the remainder of the weekend as above normal temperatures continue. Nearly zonal flow exists across the northern tier of states with subtle short waves tracking in flow. A few weak impulses will be moving through region by tonight but lack of forcing and relatively dry airmass is really only leading to area of high cloudiness and some breezy winds. Only items to keep an eye on tonight will be possibility of more fog development, especially north of I94 in deeper snow pack. HREF fields continue to peg this. Also how cold temperatures could drop in favored cold spots. Both of these items highly dependent on wind speeds. Even last night with winds staying up it managed to decouple in parts of western Wisconsin leading to lows just above zero. Given these trends, lowered temperatures in favored areas and introduced some patchy fog far north. Confidence in how widespread fog may be is low. On Sunday another short wave trough will straddle the International Border and approach western Great Lakes. While a stronger wave, still not expecting much in the way of weather except for increase in cloud cover. Another warm day on tap as well. .LONG TERM...(Sunday night through Saturday) Issued at 144 PM CST Sat Feb 22 2020 Zonal flow aloft sticks around for the start of the long term period, keeping mild temperatures present into the early portions of the new week. Surface high pressure slides east across the region Sunday night into Monday as a southern stream shortwave trough ejects northeastward into the Middle Mississippi River Valley from the Southern Plains. This low pressure system is expected to stay just south of the local forecast area during the day on Monday, with only some mid to high clouds spreading north as a result. Although we will remain unscathed from this first shortwave during the day on Monday, a northern stream shortwave trough will dive southeast from the northern Rockies Monday night into Wednesday and likely merge with the southern stream wave, bringing with it snow/rain chances. There is still quite a bit of spread and uncertainty due to a lot of moving parts, but it is at least becoming more evident that we could see accumulating snow across portions of the area where the deformation zone of the low sets up. Confidence remains low on the exact location and snow amounts due to differences in solutions, but will continue to closely monitor and refine details as confidence increases. Milder conditions will be replaced by colder air Wednesday through the end of the week as northwest flow sets up aloft. Surface high pressure should keep things mostly dry during this time, but there may be some quick, light precipitation chances by the end of the week as a few shortwave troughs ripple through the overall flow. Temperatures look to stable out some by next weekend as upper ridging builds over the central CONUS. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 554 PM CST Sat Feb 22 2020 VFR conditions expected through the period with a rather dry airmass overhead and no significant forcing moving through the region. LSE will be on the northern periphery of a low level jet developing this evening, resulting in marginal low level wind shear through about 07-08Z per latest RAP trends. Stronger surface winds at RST will prevent LLWS from being an issue there. Southerly winds will shift to the southwest late tonight, increasing and veering to the northwest Sunday afternoon as a weak cold front sweeps through the area. SKC expected for most of the period, though some guidance hints at possible post-frontal low stratocu developing Sunday afternoon. Some models also hint at fog potential in some areas tonight, mainly north of both TAF sites. Not expecting any aviation impacts from either scenario given dry low level air and a decent pressure gradient in place, but confidence in either scenario is rather low. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...Shea LONG TERM...NMB AVIATION...Kurz
National Weather Service Hastings NE
600 PM CST Sat Feb 22 2020 .SHORT TERM...(This evening through Sunday) Issued at 241 PM CST Sat Feb 22 2020 Aloft: It`s the same story as has been the case almost this entire winter. Fairly low-amplitude zonal flow is over the CONUS. RAP tropopause analyses and aircraft wind obs revealed a broad ridge over the Cntrl/Srn Plns. A wk shrtwv trof was over the Dakota`s and was of no consequence here. Elsewhere...another wk shrtwv trof was over SW Canada...and a low was over Srn CA. The SW Canada trof will head E thru Srn Canada. The CA low will move to the 4-corners by 12Z/Sun and to the OK panhandle by 00Z/Mon. The ridge will move downstream as a result...with SW flow developing over NEB/KS. Surface: 1032 mb high pres was over the Gulf Coast states. That high will slowly slide into the Atlc thru tomorrow. Meanwhile... low pres will form and move E thru Srn Canada. A sfc trof will form to its S with its tail end crossing the CWA late tonight. High pres will form over the Nrn Rckys behind this trof and low and will slide into the Nrn Plns tomorrow. Low pres will also be forming over the Srn Plns. Rest of this afternoon: Temps have certainly overachieved...with widespread 60s. Areas W of Hwy 183 over S-cntrl NEB have been flirting with near critical fire wx conds. 5-min obs indicate that the gustiness near 25 mph is just occasional and not continuous. So decided not to include mention in the HWO. Tonight: Cirrostratus will cont to stream into the CWA from the SW mainly S of I-80...but it should overtake the entire CWA after 06Z. So bottom line is incrsg clds. Low temps are not easy...offsetting incrsg clds with winds becoming lgt/vrbl in a very dry which will support temps plummeting after sunset. Am concerned fcst lows may not be cold enough from I-80 N. Sun: Partly-mostly cldy forenoon. Becoming cldy after 18Z. It will take time...but some -RA should move into N-cntrl KS after 18Z. It will be fighting very dry air in place...and dry low-lvl air continuing to advect in from the NE. Have POPs as far N as Hwy 6...just in case some sprinkles occur...but don`t bet on it. Am surprised how warm temp guidance is given the thick cld cover fcst to be overhead. Highs are fcst in the low-mid 50s...but would not be surprised to see temps fall short of that...espcly S of Hwy 6 where cld cover will be thickest. .LONG TERM...(Sunday night through Saturday) Issued at 241 PM CST Sat Feb 22 2020 Aloft: The longwaves are fcst to amplify next week and spaghetti plots of the last 2 runs of the GFS-FV3/EC/CMC/UKMET at 500 mb show indicate exceptionally good agreement all the way thru Fri Feb 28th. A shrtwv trof currently over the GlfAK will strengthen and dig into the Nrn Rckys Sun night and cont digging into the Nrn/Cntrl Plns response to upstream amplification over the N Pac. This will result in a low forming and moving into NEB Mon night. It will move downstream into the MS Vly Tue-Wed along with the longwave trof...and into the Ern USA Thu-Fri. Cyclonic NW flow will be over NEB/KS Wed-Fri...with the upstream ridge over Wrn USA/Can. The EC ensemble mean suggests the flow will deamplify Sat with the dampening Wrn ridge approaching the CWA. Surface: The Srn Plns low will move E into the mid MS Vly Mon. The next low coming in from the Pac will reform over the Nrn Rckys Sun with its associated cool front crossing the CWA Mon night. Strengthening chilly high pres will slide SE out of Canada Tue and cross the CWA Wed. A warm front is then fcst to form Thu from cntrl Canada into the Cntrl Plns and become stationary as it will be parallel to the flow aloft. Temps: Warmer than normal Mon...then turning cooler than normal Tue-Wed with widespread highs in the 30s. A warming trend will dvlp Thu-Sat...and temps could be creeping into the 50s/60s by Fri-Sat. Precip: The chance of -RA will cont Sun night...mainly over N-cntrl KS. But we do have POPs as far N as Hwy 6 just in case. As the temp profile cools Sun night... what -RA is falling could mix with or change to snow before ending Mon morning. The upr low moving in Mon night into Tue will increase instability a bit. That will result in shwry wx...starting with rain shwr potential Mon afternoon N and W of the Tri-Cities...then expanding to the entire CWA during the evening and transitioning to snow shwrs Mon night into Tue. Pcpn amts are fcst to be light. So little or no accum is currently expected. Winds: neglected to mention with the 2016Z update to this product that winds were incrsd above NBM for Mon and Tue. Mon is looking breezy. Tue is looking windy. Both the GFS and EC have 40 kt at 850 mb. If that remains the case over the coming couple days... winds will need to be incrsd further in the fcst...and this will need to be added to the HWO. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Monday) Issued at 538 PM CST Sat Feb 22 2020 VFR conditions will continue throughout the TAF valid period through at least 00Z Monday. Clear skies will give way to high clouds as we head through the late night hours. Mid to high level clouds are expected throughout the day on Sunday. The wind will gradually shift from west northwest this evening, to northerly Sunday morning, and eventually northeasterly by Sunday afternoon. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...Kelley LONG TERM...Kelley AVIATION...Wesely
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
541 PM CST Sat Feb 22 2020 .SHORT TERM... (Through Late Tonight) Issued at 247 PM CST Sat Feb 22 2020 Quiet weather is expected tonight. Overnight lows should be around 10 degrees warmer than they were last night due to the combination of WAA from persistent southwesterly winds along with increasing mid/high clouds which will interfere with radiational cooling processes. Overnight lows are expected to be in the low/mid-30s, which is around 5-15 degrees warmer than normal for this time of year. Kanofsky .LONG TERM... (Sunday through Next Saturday) Issued at 247 PM CST Sat Feb 22 2020 Early afternoon water vapor imagery and the RAP 1.5 PVU analysis fields depicted a strong PV anomaly located over southern California. A pronounced warm conveyor belt associated with this feature stretched from well southwest of Baja California through the desert southwest and into the central/southern plains. Model guidance is in excellent agreement that the closed upper low will reach the Four Corners region by 12z Sunday and continue progressing eastward towards the central CONUS. This feature will bring widespread rain to the area from tomorrow afternoon through Monday evening. That said, many areas will be dry for most of the day on Sunday because the rain will spread from southwest to northeast. Some parts of east-central MO and southwest IL might even stay dry until late afternoon or early evening. Model forecasts of PW values are slightly higher than they were 24 hours ago, but still at +2 SD for this part of the country at this time of year. This suggests that there could be periods of moderate rainfall at times even though the total rainfall amounts are only around 1-2" for the event. Models are also showing a narrow axis of instability which extends into the southern part of the LSX CWA, therefore thunderstorms have been added to the grids in this area. This makes sense conceptually given that the forecast surface low track is expected to be farther north compared to previous guidance. Meanwhile, a separate low pressure system was lurking south of the Gulf of Alaska this afternoon. This feature is expected to be located along the Pacific Northwest coast at 12z Sunday, which means that it might not be adequately sampled by RAOBs until 00z Monday. This feature is expected to dive into the central CONUS during the early part of the week and eventually bring another period of active weather to the region during the middle of the week before it progresses eastward. However, adequate sampling of this feature while it`s still back over the Pacific Northwest is very important for Monday`s weather forecast in MO/IL because slight variations in its location and speed could affect how much interaction occurs between it and the aforementioned low pressure system which will still be affecting MO/IL on Monday. Specifically, the latest model runs are showing more interaction between these two features compared to 24 hours ago, and this interaction has altered the forecast track of the Sun/Mon system. As discussed yesterday, the Sun/Mon system will have barely cleared the area before precipitation chances increase again ahead of the much larger low pressure system over the central CONUS as it continues progressing eastward and eventually carves out a deep trough over the eastern CONUS. Temperatures will be cold enough for snow during at least part of the time that this system will be affecting the area. Compared to 24 hours ago, the latest GEFS plumes no longer show such a pronounced timing split, but there are now more members with snowfall amounts greater than 1". This variability leads to greater uncertainty regarding snowfall amounts for the middle of the week. Temperatures will be slightly cooler on Mon due to widespread rainfall and extensive cloudiness, and modest cold air advection in the wake of the departing low pressure system should keep highs a few degrees cooler for Tue compared to Mon. Highs on Mon/Tue should be in the 40s to low 50s for most areas. Temperatures will turn much colder by the middle and end of the week with highs in the 30s and lows in the teens/20s for Wed/Thu. Model guidance depicts a few vorticity lobes rotating around the deep trough centered over the eastern CONUS, and this could bring precipitation chances to the region during the end of the week or over next weekend. Kanofsky && .AVIATION... (For the 00z TAFs through 00z Sunday Evening) Issued at 530 PM CST Sat Feb 22 2020 LLWS is expected at KUIN overnight into early Sunday morning as a southwesterly LLJ sets up over northeast Missouri and west Illinois overnight. There is some uncertainty as to how far south and east the LLJ will exert its influence. At the moment have decided to keep LLWS out of KCOU, but will continue to monitor conditions through the evening. Otherwise, VFR conditions will prevail for one more day ahead of the approaching rain Sunday afternoon into Monday. Present thinking rain will hold off at terminals until after 00Z. MVFR ceilings will move into KSTL late in the TAF period as the main rain shield moves northeast into the area. MRM && .LSX WATCHES/WARNINGS/ADVISORIES... MO...None. IL...None. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
646 PM EST Sat Feb 22 2020 .SHORT TERM...(This evening through Sunday) Issued at 426 PM EST SAT FEB 22 2020 Water vapor imagery and RAP analysis show zonal flow along the U.S./Canada border. A shortwave is noted over the eastern Dakotas. However, due to a dry air mass as sampled by 12z raobs, only some high clouds are associated with the wave from central MN to ne IA. Farther upstream, another shortwave is over Alberta. This wave will affect the weather here on Sun. Closer to home, under sunny skies, it`s another warm Feb aftn across the fcst area. Of course, downwind of Lake MI, conditions are cooler with temps around freezing toward the shore. Elsewhere, temps have rise into the 40s, with some locations topping 50F. Main fcst concerns tonight revolve around fog/stratus potential. Some fog/stratus developed across northern WI last night. Since there was some development last night and we`re undergoing another day of snowmelt across the Upper Mississippi Valley, will probably see an increase in coverage of fog/stratus late tonight compared to what happened early this morning. Fcst soundings for tonight certainly do have a stronger shallow saturation look than yesterday`s fcst soundings had for last night. Low-level winds slacken late tonight, so that should be when fog and stratus really start to develop. Lows tonight will be in the 20s. Some of the traditional cold spots may slip into the teens. Shortwave currently over Alberta will reach Lake Superior Sun aftn. Wave will be strengthening as it approaches, and 12hr height falls upwards of 160m are indicated at 500mb over northern Lake Superior. Best forcing will pass n of the area, and with deep dry mid-levels persisting per fcst soundings, pcpn should not be a concern here. However, as low-level moisture is swept up by the associated cold front, it`s possible there may be a little post frontal upslope -dz on the Keweenaw for a time Sun aftn. With the rather vigorous wave passing and the fcst area becoming situated in the jet surge area of the wave, post frontal wnw winds will increase and become gusty, especially over the Keweenaw under the ideal wind direction. While caa is not particularly strong (roughly 6C in 6hr at 850mb), it will support increased mixing with fcst soundings suggesting the potential to mix to winds of 40-45kt. With a favorable orientation to the gradient wind, the isallobaric wind will provide additional support for stronger winds as a modest pres rise/fall couplet of +2 to +3mb/-2 to -3mb per 3hr is indicated. Expect post frontal wind gusts over the Keweenaw to reach 40-45mph Sun aftn and 30-35mph over the rest of the w half of Upper MI. Depending on the extent of fog/stratus early Sun, it should be another mild day with temps pushing into at least the lower 40s F across the central and interior w. If stratus becomes widespread and doesn`t break before fropa, temps will be held back to the low/mid 30s. .LONG TERM...(Sunday night through Saturday) Issued at 346 PM EST SAT FEB 22 2020 The long-term period picks up with a mid-level short wave lifting off to the northeast. On its southern periphery a 35-40 kt LLJ will persist atop a PBL remaining well-mixed through most of the night owing to modest CAA. Therefore expecting winds and temps to verify on the breezier and warmer side of the guidance envelope, respectively, with gusts initially in the 15-30 mph range before midnight (higher over the Keweenaw) diminishing after midnight, and lows in the mid 20s for most with perhaps a few low 20s near the Wisconsin line. The air mass will be marginally cold enough to kick off a few light lake-effect rain or snow showers on Monday, but with the flow becoming W, that will all stay out over Lake Superior. Quiet weather is expected Tuesday before attention turns to the next developing storm system. This system develops as a northern stream short wave digs into the Central Plains and phases with a southern stream wave ejecting out of the SW U.S. The idea of some sort of significant storm has been well advertised for several days now in the models, but with run-to-run inconsistency in exact track, which is not unusual when dealing with a SW U.S. wave and the associated uncertainty in how quickly it ejects. The trend the past 24 hours or so has been back NW and closer to home for the U.P. This is not to say any sort of significant snow is a done deal; right now the GFS is the only deterministic model showing decent accumulations (although the NAM extrapolated would probably support it as well). Further complicating things is that the GEFS are largely supportive of the deterministic GFS solution with high probabilities of exceeding 0.10" of QPF for at least the eastern half of the CWA, so it can`t be written off as an outlier. And the EC has ticked back NW as well. Given this set-up with a prolonged NE wind and cold air wrapping into a deepening cyclone, even if the synoptic precip shield ends up missing to the east some NE flow lake-effect or lake-enhanced upslope snow is likely. Even the EC, although initially drier in the low levels, saturates enough that by Wednesday evening there would be steady snow in the NE wind LES belts. Since this kind of precip isn`t well captured in the coarser ensembles that feed into the NBM, have increased POPs significantly in the NE wind LES belts Wed, N wind LES belts Wed night, and then NW wind belts Thursday. Have kept everything likely or below for now, however. Several inches of snow is a distinct possibility Wednesday into Thursday for the aforementioned areas, and odds are increasing overall even away from Superior over the eastern and south-central U.P. The mid-week time frame certainly bears watching. Seasonably cold air returns Friday but otherwise the end of the week into next weekend once again looks tranquil. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 636 PM EST SAT FEB 22 2020 VFR conditions/clear skies may give way to the development of some fog/low stratus later tonight as added moisture from melting snow will allow saturation in the boundary layer. MVFR vis in BR should develop overnight at KCMX/KSAW with the potential of LIFR cigs and/or vis Sun morning. At KIWD, slight downslope component to the wind may be just enough to prevent conditions from falling out of VFR. As a cold front moves through Sun afternoon winds shifting from sw to upslope westerly flow will allow for MVFR to possibly IFR cigs in stratus to develop. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 426 PM EST SAT FEB 22 2020 Expect sw winds mostly aob 20kt on Lake Superior tonight. Winds will increase Sun into Sun night as a cold front approaches and passes across Lake Superior. With passage of the front, w to nw gales of 35- 40kt will develop across western Lake Superior by Sun aftn and will reach far eastern Lake Superior early Sun evening. Winds will then diminish to blo gale force from w to e Sun night. Winds will diminish further to blo 20kt on Mon. As low pres slowly lifts across the Ohio Valley, the Lower Great Lakes and into Quebec Tue thru Thu, n to ne winds will increase to up to 30kt. Not out of the question that there could be some gale force gusts over central and eastern Lake Superior late Wed into Thu. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Gale Warning from 7 PM Sunday to 4 AM EST Monday for LSZ251-267. Gale Warning from 1 PM Sunday to 4 AM EST Monday for LSZ243>250- 264>266. Gale Warning from 11 AM EST /10 AM CST/ Sunday to midnight EST /11 PM CST/ Sunday night for LSZ162-240>242-263. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...RJC AVIATION...Voss MARINE...Rolfson
Area Forecast Discussion
National Weather Service Phoenix AZ
832 PM MST Sat Feb 22 2020 .SYNOPSIS... Showers and isolated thunderstorms will linger overnight as a low pressure system moves eastward through Arizona. In the wake of the storm, below normal temperatures are expected Sunday along with isolated showers across the higher terrain north and east of Phoenix. A return to near normal temperatures is likely early next week, followed by a warming trend later in the week as high pressure builds across the intermountain West. && .DISCUSSION... Shower activity has continued to decrease across the forecast area. Though there will continue to be some showers (and a few thunderstorms) overnight, the threat for flash flooding has diminished quite a bit. Therefore, and in coordination with WFOs Tucson and Flagstaff, the Flash Flood Watch is cancelled for the remainder of the evening. Please see our Twitter feed for rainfall statistics from this event. && .PREVIOUS DISCUSSION... The long fetch of deep moisture is clearly evident on water vapor imagery and extends southwestward well into the tropical east Pacific. This atmospheric river has pushed east of the Phoenix, exposing the lower clouds lifting cyclonically towards the surface low located near the CA/NV/AZ triple-point. Rain totals so far today have been significant, with Sky Harbor Airport more than doubling the previous daily precipitation record set over 100 years ago. Elsewhere, much of the Valley received between three quarters of an inch and one inch of rain, and as much as one to two inches was observed across the higher terrain of Maricopa and Gila Counties. Operational GFS continues to trend slower with regard to the upper low as it weakens and translates eastward through northern Arizona. Wrap-around shower activity will likely linger past midnight as depicted by the HRRR and PoPs have been increased accordingly. In the wake of the low pressure system Sunday, low clouds and isolated showers will persist, particularly from Phoenix north and eastward. Latest NBM is a bit cooler as well with high temperatures below normal in the lower to mid 60s across central Arizona. However, further west away from the influence of the low pressure system, temperatures will still manage to climb into the mid to upper 70s. && .AVIATION...Updated at 0050Z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Some lingering effects of the storm system will continue to effect the TAF sites through mid to late Sunday morning. Showers in the vicinity will taper off very early in the period. Although late tonight around 08Z, and again on mid morning Sunday around 16Z showers could move into the vicinity associated with the passage of the upper level cold core, and later an area of wrap-around moisture. Expect variable low cloud BKN CIGs from 5-8kft through late morning to early to mid afternoon on Sunday. Wind speeds will also taper off this evening to around 5-8kt and favor the southwest to southeast before favoring the east for several hours beginning around 11Z. However, confidence on wind directions is currently fairly low due to the lingering showers that are forecast to move through the area. Southeast California/Southwest Arizona including KIPL and KBLH: Lingering showers in the vicinity of KBLH will taper off this evening. Winds will be the bigger impact during the period, with speeds up to 15-20 kts and westerly gusts to 25-33kt at KIPL and from the southwest at KBLH early this evening. Surface winds should gradually subside during the overnight hours at both locations. FEW-SCT mid and high clouds should prevail through most of the period. By mid morning moderate northwesterly winds should prevail at KBLH. && .FIRE WEATHER... Monday through Friday: No significant changes to the extended outlook...Conditions will continue to dry with minimum RH values dropping into the 10-25% range by midweek and declining overnight recoveries. Winds will behave more typical for the week with directions favoring terrain/diurnal trends. Speeds will also remain fairly light outside of occasional afternoon breezes. && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...Wind Advisory until 10 PM PST this evening for CAZ562. && $$ DISCUSSION...Iniguez/Hirsch AVIATION...Sawtelle/Percha FIRE WEATHER...Deems