Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/21/21

Area Forecast Discussion
National Weather Service Goodland KS
949 PM MDT Wed Oct 20 2021 .SHORT TERM...(This evening through Friday night) Issued at 256 PM MDT Wed Oct 20 2021 Across the region this afternoon, skies are sunny as the remnants of morning cloud cover north from exiting low pressure system have moved away from southwest Nebraska locales. Winds are still gusting up into the 25 to 35 mph range, with temps ranging from the mid 50s to around 60F. Forecast concerns in the short term revolve around the potential for frost over the CWA with a drop in temps as surface ridge traverses the area. As mentioned from previous forecast, the concern for increasing cloud potential could hamper overnight lows. This continues to hold as the latest HRRR guidance shows increasing clouds late in the overnight period towards morning. This combined with a switch to warm southerly flow will keep the majority of the Freeze Watch above hard freeze numbers. As a result have changed the Watch to a Frost Advisory with same timeframe as the current one(14z Thursday ending). Some isolated spots along/north of Highway 34 could see upper 20s, but the areal coverage not enough to warrant Freeze Warning at this time. The passage of the surface ridge to the east, combined with approaching upper ridge from the west, will afford the CWA an upward trend in temps with decent WAA on southerly flow at the surface and west-northwest flow aloft. While temps at night will afford some more mention of frost, the areal coverage will be much lower than tonight. Dry wx conditions expected thru Friday night as a result. These dry conditions will allow for fire wx concerns to crop up yet again, especially on Friday when upper teens for good portion of area along/west of Highway 27 expected. Gusts below criteria. For temps, an upward trend is expected in the short term period with high pressure building over the region. Thursday`s high will range from the mid 60s to around 70F. On Friday, lower to mid 70s. Overnight lows will see a warming trend as well with lower and mid 30s to start off tonight. A few isolated spots along/north of Highway 34 could see upper 20s. By Thursday night, mainly mid 30s. Going into Friday night, upper 30s west and north, to the lower and mid 40s for southern and eastern locales. With the expected overnight lows tonight, and expected winds, the area will see wind chill readings drop into the mid 20s to lower 30s. Coldest readings will occur mainly in northeast Colorado and southwest Nebraska. .LONG TERM...(Saturday through Wednesday) Issued at 246 PM MDT Wed Oct 20 2021 The main concern for the extended forecast is the potential for some fire weather concerns, a slight chance of precipitation and frost issues. The extended forecast begins with a deamplifying ridge coming over the Tri-State area with near-zonal flow becoming southwest as a trough treks across the Four Corners region. Through the day and into the overnight hours, the trough lifts to the northeast, reaching the forecast area by Sunday morning. A few rain showers may develop in the morning, particularly for areas along and east of a line from Benkelman to Oberlin. Temperatures will be slightly cooler Sunday afternoon than the previous day, ranging from the mid- 60s to low 70s. Lows will fall into the mid-30s to mid-40s. Any chances for frost will be limited to eastern Colorado and will be dependent on cloud cover. Clouds are expected to increase through the night, which could eliminate the chances for frost in the western portions of Cheyenne, Kit Carson and Yuma counties. An amplifying ridge comes over the High Plains and Central High Plains. Southerly winds will help bringing in the warmer air and felt that model guidance was forecasting afternoon temperatures a little on the cool side. Brought temperatures up a few degrees to account for this, particularly in the western CWA. Expected highs will range from the low to mid-70s across the region. Tuesday, the ridge pushes to the east and a trough is expected to enter the region. Temperatures are expected to reach into the 70s in the afternoon with breezy conditions. Minimum relative humidity values will fall into the mid-teens to low 20s along and west of a line from Leoti to Atwood to Palisade. Wind gusts are expected to reach into the low to mid-20s, particularly in eastern Colorado. Elevated to near critical fire weather conditions are expected. Those with fire interests will want to continue to monitor the forecast over the coming days, particularly as there is potential for a cold front to move through during the day. With the FROPA potential, this could limit the amount of time where our stronger winds and lowest RH values coincide with one another. Tuesday evening a few rain showers are expected to develop and move into the region. Right now, the best chance for any showers remains limited to areas along and north of the Kansas-Nebraska border. Areas in eastern Colorado will dip into the mid to upper 30s while most our Kansas and Nebraska areas are expected to stay in the 40s overnight. Conditions remain dry on Wednesday with cooler temperatures expected as the trough moves out. Afternoon highs will range from the mid- 60s to low 70s. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 949 PM MDT Wed Oct 20 2021 The 06Z TAF period features VFR conditions for KMCK and KGLD. Winds look to be light from the NNW before switching to the SSW just after 06Z at KGLD; whereas for KMCK winds will be light and variable through the majority of the night before being from the SSW mid morning Thursday. Mid to high clouds are expected to move west to east across the area tonight and throughout the day Thursday as conditions are expected to remain at VFR. Between 10Z-13Z there may be a brief period of low stratus and/or patchy fog around the KMCK terminal hinted at by some guidance and forecast soundings moving in from the Nebraska Sand Hills where the greatest potential for visibility restricting fog/stratus looks to develop due to a warm front draped over the area. At this time low chance for MVFR conditions but confidence is to low at this time to be mentioned in the TAF but will be monitored overnight for any potential amendments. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...Frost Advisory from 3 AM MDT /4 AM CDT/ to 8 AM MDT /9 AM CDT/ Thursday for KSZ001>004-013>016-027>029-042. CO...Frost Advisory from 3 AM to 8 AM MDT Thursday for COZ090. NE...Frost Advisory from 3 AM MDT /4 AM CDT/ to 8 AM MDT /9 AM CDT/ Thursday for NEZ079>081. && $$ SHORT TERM...JN LONG TERM...AW AVIATION...TT
Area Forecast Discussion
National Weather Service Marquette MI
826 PM EDT Wed Oct 20 2021 .SHORT TERM...(This evening through Thursday) Issued at 457 PM EDT WED OCT 20 2021 Water vapor imagery and RAP analysis show split flow continuing across much of N America. In the southern stream, the well-defined shortwave that was over the central Rockies 24hrs ago is now centered near Sioux Falls, SD. Wave that was in the northern stream over western Hudson Bay 24hrs ago has separated out from that flow and is now a well-defined mid-level low centered over far sw Hudson Bay. Cold front associated with the latter wave swept s across the fcst area last night/early this morning, and it is now running from southern Quebec across northern Lower MI to low pres (associated with the former wave) over far s central MN. In the wake of the front, low-level moisture/upslope flow has led to considerable low cloudiness across much of the fcst area today. Air within that shallow moist layer has cooled sufficiently for an added lake moisture component as well. Result has been some -dz closer to Lake Superior, especially earlier today in the higher terrain favored by upsloping n to ne winds. In the confluent flow btwn the 2 waves, the resulting upper jet streak has led to right entrance upper diffluence over the area today. Along with some increase in low-mid level fgen and modest isentropic ascent, -shra are spreading into south central Upper MI with more notable development to the wsw across northern WI into central MN. Shortwave near Sioux Falls will weaken as it moves to Lower MI by Thu aftn then to the Lower Lakes Thu evening. Associated sfc low will track e across northern Lower MI Thu morning. Upper diffluence/modest isentropic ascent and broad low-mid level fgen should support upstream -shra spreading across the fcst area this evening, except for the Keweenaw. MUCAPE of a few hundred j/kg in the 1-3km layer will skirt s central Upper MI, and with some lightning noted this aftn in the pcpn across WI, will include a mention of thunder in Menominee County. Shra will end far w late tonight then quickly from w to e across the rest of the fcst area during Thu morning. The one exception will be across n central Upper MI due to potential lake effect. 850mb temps across Lake Superior roughly around 0C at 12z Thu will fall to -4 to -5C by late aftn. Sfc water temp of Lake Superior is roughly around 12C with higher values present. With the increasing overwater instability, inversions at around 3kft Thu morning do increase to 5-6kft in the aftn. Across western Lake Superior subcloud layer remains quite dry (inverted-v). This is quite reasonable given the early season/still relative high sun angle which leads to well-mixed boundary layer air advecting over the lake, a notable negative for lake effect pcpn. As a result, do not expect any lake effect shra to develop off western Lake Superior on Thu. Across eastern Lake Superior, conditions should be different. Lake effect clouds are evident off Lake Nipigon today under 850mb temps around 0C. On Thu, 850mb temps will be around -7C across Lake Nipigon. As low- level flow realigns, this preconditioned air will stream across Lake Superior to Marquette/Alger counties in the aftn. Combined with the cooling air mass and rising inversion, low chc pops appear warranted by late aftn in that area. Leaned toward some of the cooler guidance for max temps on Thu under caa and with expectation of considerable stratocu development. Expect highs from the lwr 40s to around 50F, warmest s central. .LONG TERM...(Thursday night through Wednesday) Issued at 344 PM EDT WED OCT 20 2021 An active weather pattern will continue for the start of the extended forecast. The departing shortwave on Thursday evening will continue to trek to the New England coast, while an ULL at 500mb will remain nearly stationary for a majority of Friday through Sunday near the James Bay region. This ULL will have numerous ripples of shortwave energy embedded within the flow as jet energy treks from west to east across the Northern CONUS/Hemisphere. The ULL maintaining its stationary presence over the James Bay region will result in north to northwest flow aloft across the Great Lakes. The north to northwest steering flow and colder air aloft will mix down to the surface, and result in cooler temperatures at the surface, and lake effect precipitation. At this time, it looks to remain as a cold rain shower activity over the area from Friday through most of Sunday. Overnight lows going below freezing are plausible, so a rain/snow mix at times will be possible also. Another shortwave will approach the UP by Monday, but this time it will be from the south. Deterministic output at this time shows the weak shortwave remaining to our south, with a slight chance of showers over the south central tier of Upper Michigan. The remainder of the week will teeter totter from above average temperatures back to near normal temperatures as the progressive weather regime returns to the CONUS. Upper level ridging on Monday through early Wednesday will cause above average temperatures and mainly dry conditions. Wednesday into Thursday will bring the next wave through the area, with precipitation and cooler temperatures. Lake effect rain showers could also return to the area. Overall, autumn conditions will become more present across Upper Michigan, with precipitation opportunities on the rise as well. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 820 PM EDT WED OCT 20 2021 LL stratus deck remains fixed in place across Upper Michigan with some hints that it attempts to break up in the vicinity of KIWD and KCMX as Thursday progresses. However, no such luck at KSAW through this TAF period as the wind shift from NNE to NNW becomes favorable for an enhanced moisture feed to set up across Lake Superior right into the KSAW vicinity, with an additional connection to Lake Nipigon in Ontario. Winds will also be on the increase tonight into early tomorrow as the pressure gradient tightens overhead. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 457 PM EDT WED OCT 20 2021 NE winds gusting up to 30kt over far western Lake Superior should diminish to 20-25kt during the night. Otherwise, gusts in the 15- 25kt range should be the rule tonight on Lake Superior. While wind gusts will fall back to 15-20kt over western Lake Superior on Thu, wind gusts will tick back up to 20-30kt over the e as increasingly colder air moves over the lake. Winds will then diminish Thu night, and for Fri/Sat, expect gusts mostly under 20kt as high pres ridge moves closer to the lake. High pres will then settle over northern Ontario Sun and Mon. Winds will increase a bit into Mon, depending on the strength of low pres tracking e to the Ohio Valley. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...BW AVIATION...lg MARINE...Rolfson
Area Forecast Discussion
National Weather Service Phoenix AZ
439 PM MST Wed Oct 20 2021 .UPDATE... Updated Aviation discussion. && .SYNOPSIS... Dry tranquil conditions are expected over the next several days with temperatures warming to around normal starting Thursday and lasting through the weekend. A slight cool down and breezy to possibly windy conditions will be likely early next week as a strong low pressure system tracks mostly to the north of our region. This system may also bring a chance of precipitation to the region at some point early next week, but chances may be limited to higher terrain areas. && .DISCUSSION... Weak quasi-zonal flow is in place across the area with passing high clouds. Aircraft and RAP soundings show a few degrees of warming below 700 mb from this time yesterday, which should result in afternoon highs a few degrees warmer than yesterday. Height rises over the region, as ridging amplifies downstream of an active trough pattern in the northeast Pacific, should yield another few degrees of warming through Thursday. NBM MaxTs for both Thursday and Friday are in the upper-80s across the lower deserts with 20-40% chance of reaching 90 degrees each day most places. Conditions will also remain dry with light winds through the end of this week as well. Around midday Friday the first of a couple of strong and dynamic troughs will move inland in the PacNW. While this first wave will remain well north of the local area, heights will be suppressed slightly which should lead to a few degrees of cooling heading into the weekend, along with some breezier conditions. NBM forecast MaxTs for this weekend are in the mid-80s across the lower deserts both days. The second, more prolific trough will take shape late this weekend and begin pushing inland in the northwest CONUS late-Sunday into Monday. Greatest impacts from this trough are still expected in the coastal states through early next week. WPC cluster analysis still shows moderate variance among global members mostly in terms of how far south the trough will dig and timing. Models continue to support a strong atmospheric river with this trough, so the amplitude of the trough will certainly have an influence on precipitation chances for the local area. It is still too early to say with confidence what the chances are, but latest NBM still has a 10-20% chance for rain in south-central AZ, favoring high terrain, around Tuesday. In addition to the rain chances, this trough will also likely result in breezy conditions across the region. There is still uncertainty in magnitudes, but the ECMWF EFI is showing the potential for unseasonably high winds Monday into Tuesday mainly north of the local area. Lastly, much cooler temperatures will be possible with the magnitude of cooling again dependent on the evolution of the trough. && .AVIATION...Updated at 2339z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT; and Southeast California/Southwest Arizona including KIPL and KBLH: Light winds surface and aloft (favoring westerly directions above Fl120 and south/southeasterly below that) will continua through Thursday except for some modest strengthening above FL210. Surface winds will be light and follow familiar diurnal patterns overall. But, there may be a period this evening over the Phoenix area with light northerly directions during the transition between early evening westerly and late evening onset of downvalley/drainage winds (favoring easterly directions). Skies will be mostly clear tonight followed by another batch of cirrus during the day Thursday. && .FIRE WEATHER... Friday through Tuesday: High pressure in place early in the period will shift to broad troughing early next week as a strong low pressure system impacts most of the Western U.S. Moisture levels are likely to increase modestly late in the weekend into early next week with the weather system, but precipitation chances are likely to be very limited for the lower deserts to slightly better over the high terrain. Near normal temperatures are expected for the bulk of the period with light winds on Friday becoming breezy during the daytime hours over the weekend. Even stronger winds will be likely for Monday when widespread gusts of 20-30 mph will be possible. Min afternoon RH values will improve through the period starting out in the teens on Friday, rising to 20-30% for Sunday-Tuesday. Overnight recoveries will mostly reach between 35-60% through the period. && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Benedict AVIATION...17 FIRE WEATHER...Kuhlman