Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/21/21

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
529 AM CST Sat Nov 20 2021 .UPDATE... Issued at 527 AM CST Sat Nov 20 2021 Aviation discussion updated below for the 12Z TAFs. && .SHORT TERM...(Today through Sunday Afternoon) Issued at 323 AM CST Sat Nov 20 2021 Radar echoes are increasing across northwest SD as the weak mid- level wave moves into the region. Have not noticed precip on obs recently, nor do web cams show any noticeable evidence of rain or snow across northwest SD. Miles City, MT did report -RA for a short time last evening while this activity was further upstream. Still appears to be a rather lackluster system and will maintain low chances with very minimal precip amounts in the forecast. Interesting to note though that a handful of models try to pain a narrower area of higher POPs/QPF over portions of central/north central SD, so will monitor trends and adjust as necessary. But still, we`re talking small precip amounts and a very minor system. With temps still in the mid to upper 30s out west, may be more of a rain precip type as we progress through the morning hours. Latest HRRR trends suggesting this as well as it`s showing mainly rain for precip type as this system moves through, whereas last evening, it was showing a period of snow now through mid/late morning. Focus will then turn to the potent cold front moving through late tonight into early Sunday morning. By 12Z Sunday, it should already be through a good portion of the CWA. At 06Z Sunday, 850mb temps are around 0C, but by 18Z Sunday temps drop to around -10C to -15C. Once again sided towards the 90th percentile for wind speeds on Sunday given the strong cold air advection and pressure rises. .LONG TERM...(Sunday Evening through Friday) Issued at 323 AM CST Sat Nov 20 2021 The extended forecast continues to look dry at this time. High pressure will settle in over the region Sunday night, with fairly cold lows expected. The high gets pushed eastward on Monday ahead of a trough digging down the lee of the Rockies. A decent pressure gradient develops between these two systems, so could see some breezy to windy conditions Monday afternoon into the day Tuesday. The southerly winds will aid in bringing warmer air into the region, with above normal highs Tuesday afternoon. The low pressure system and its associated front will track across the CWA Tuesday night, bringing a return to cooler temperatures. Wednesday could again be a bit breezy before high pressure drops back over the area Wednesday night and Thursday. Another low and associated frontal boundary look to track across the area on Friday. High temperatures on Monday will range from the mid 30s across west central Minnesota, to the upper 40s to lower 50s west of the Missouri River, and from the upper 40s east to the lower 60s southwest on Tuesday. Cooler air then returns with highs in the mid 30s to mid 40s Wednesday, in the 30s Thursday, and in the mid 30s east to the upper 40s southwest Friday. Overnight lows will be mainly in the teens, with some lower 20s west of the Missouri River Sunday night. Lows will be in the 20s to the lower 30s Monday night and Tuesday night, the mainly in the teens Wednesday night and Thursday night. && .AVIATION...(For the 12Z TAFS through 12Z Sunday Morning) Issued at 527 AM CST Sat Nov 20 2021 Terminals KABR,KATY,KPIR,KMBG VFR conditions are forecast through the TAF period. Mid level clouds will stream across the region today as a weak system passes through. A brief -RA or -SN shower is possible at KPIR this morning, but conditions are expected to remain VFR. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...TMT SHORT TERM...TMT LONG TERM...Parkin AVIATION...TMT
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
600 PM EST Sat Nov 20 2021 .AVIATION... Lots of mid clouds around 10 kft this evening in the wake of the upper level disturbance. Could be a few breaks in the mid clouds after 04z-06z, especially for the northern sites. Those breaks may be enough to get a little stratus layer to develop across MBS and FNT. Will just have scattered coverage for now but will have to watch if the stratocu expands from CAD and RQB. Light southerly winds generally overnight increase to around 10 knots for Sunday. Better moisture will arrive on Sunday, providing greater potential for some lower ceiling heights within an increasing coverage of showers for Sunday afternoon. Highest confidence in DTW/YIP/DET seeing rainfall resulting in cigs/vsby dipping into MVFR. .DTW THRESHOLD PROBABILITIES... * Moderate confidence in cigs aob 5000 Sunday afternoon * High confidence in precip type as rain Sunday afternoon && .PREV DISCUSSION... Issued at 358 PM EST Sat Nov 20 2021 DISCUSSION... The plume of mid level moisture and elevated instability proved worthy of the challenge posed by a formidable layer of dry air in the low levels. This resulted in pockets of light rain and brief flurries after impressive work was done from the starting point shown in the 12Z DTX sounding. The mid level moisture axis now moves eastward this evening. Low level dry air is reinforced by westerly flow from the IA/MO/IL vicinity tonight while mid and high clouds thin enough for partly cloudy conditions at times. A late return of thicker high clouds, along with light but persistent south wind, helps keep temperatures above freezing through sunrise Sunday. High clouds late tonight precede the next low pressure system that remains set to bring a stronger surge of moisture for rain during Sunday. Forcing for vertical motion is mainly tied to the southern stream shortwave initially which backs and strengthens the wind field below 700 mb. Moisture transport that was lacking closer to the surface today becomes strong enough to better saturate the low levels by Sunday afternoon, especially from the Ohio border through metro Detroit where likely/numerous POPs remain warranted. A trend to monitor is from longer projections of hi-res runs like the RAP and ARW which suggest light rain mostly misses SE MI. These solutions do not back the wind as much in the low to mid levels apparently due to earlier influence from the northern stream trough digging in from central Canada by afternoon. This weakens and deflects isentropic lift/moisture transport eastward before saturation in SE MI. The plan is to buy another forecast cycle and look for additional support of these hi-res runs from the remainder of the model suite. In the meantime, a higher POP/low QPF scenario is maintained with entry level likely POPs near the Ohio border tapering to chance toward the Tri Cities and northern Thumb through Sunday afternoon. All rain precipitation type is favored by a comfortable margin in QPF- producing solutions. The northern stream 500 mb trough takes over Sunday night beginning with the strong cold front that it whips through Lower MI during the evening. The frontal passage immediately transitions any remaining precip to snow, although with coverage being surprisingly low given the strength of cold advection over the Great Lakes. Model RH plan views and soundings show the dry slot around the south flank of the trough overwhelming any potential for significant lake effect snow showers this far SE during Sunday night. The primary impact becomes the surge of colder air driven in on initial wind NW gusts of 30 to 40 mph. The peak gusts diminish toward midnight while colder air continues to arrive with temperatures down into the 20s and wind chill into the teens by sunrise Monday. The low level thermal trough becomes entrenched for Monday and limits temperatures to a struggle for mid 30s across Lower MI, which feels more like mid 20s when factoring in 20 mph NW wind gusts for much of the day. Model boundary layer RH fields remain dry and a 300 wind direction less favorable for extension of lake effect snow showers this far east. Some flurries from higher based diurnal stratocu is about all the potential supported during the day and then just stratocu Monday night as the wind backs with the passage of high pressure through the Ohio valley. Ridge will slide through the area Tuesday and Wednesday keeping the weather fairly quiet with a slight warm up as winds turn back to the SW. There is a weak shortwave lifting NE ahead of the next trough which could drum up a few light showers Wednesday. Otherwise, next chances of showers will come later in the week Thursday and Friday as the next longwave trough passes east through the Great Lakes. MARINE... Moderate southwest flow will temporarily slacken the remainder of the day and through tonight as the pressure gradient briefly weakens across the central Great Lakes. Existing Small Craft Advisories along portions of the Lake Huron nearshore waters and outer Saginaw Bay will thus be allowed to expire. Southwest winds will then quickly ramp up again Sunday afternoon and especially Sunday night and into early Monday morning as low pressure developing over the upper Midwest rapidly deepens and tracks northeast towards the northern Great Lakes. This system will pull a strong cold front across the region flipping winds to the northwest along with a surge of cold air. Winds to gale force across the Lake Huron basin will be likely during this time, and Gale Warnings have been issued for all of the Lake Huron waters. The potential will exist for a few gusts to strong gales Sunday night across the northern Lake Huron waters. Small Craft Advisories will also be in effect during this time for Lake St. Clair and western Lake Erie, where it is anticipated that gusts will remain just below gale force. Moderate northwest flow remains in place through the middle of next week as high pressure slides eastward across the Ohio Valley. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...Gale Warning from 7 PM Sunday to 10 AM EST Monday for LHZ421-422- 441>443-462>464. Gale Warning from 4 PM Sunday to 10 AM EST Monday for LHZ361>363. Lake St Clair...Small Craft Advisory from 7 PM Sunday to 10 AM EST Monday for LCZ460. Michigan waters of Lake Erie...Small Craft Advisory from 7 PM Sunday to 10 AM EST Monday for LEZ444. && $$ AVIATION.....RBP DISCUSSION...BT MARINE.......IRL You can obtain your latest National Weather Service forecasts online at
Area Forecast Discussion
National Weather Service Marquette MI
632 AM EST Sat Nov 20 2021 .SHORT TERM...(Today and tonight) Issued at 335 AM EST SAT NOV 20 2021 Water vapor imagery and RAP analysis reveal generally zonal flow from the Pac NW into the Great Lakes region. Several shortwaves are noted in this flow to the W Coast. The shortwave moving from Saskatchewan into Manitoba and responding waa regime ahead of it have resulted in spotty mid-high clouds across the Upper Great Lakes early this morning. Temps currently range from the mid 20s over the western interior to the 30s near the Great Lakes. Gusty south winds at the sfc have not really panned out overnight as previously fcst by last night`s models which is a bit surprising given the 40+ kt LLJ translating across the area. As a result, have decided to back off a bit on downsloping wind gusts along the Lake Superior shore through this morning (more in the 20-25 mph range). Today, the shortwave now moving into Manitoba will lift into northern Ontario later this morning/afternoon and push a sfc trof into western Upper MI late morning/early aftn and into the e late aftn/early evening. Given the lack of column moisture, no pcpn is expected. Also, removed lake effect pops over se Luce County in the morning as fcst soundings indicate shallow moisture layer will be warmer than -10C. With no ice in cloud, most likely ptype would be drizzle but lowest levels off fcst sounding look too dry for this to occur. Under a mix of clouds and sunshine, expect highs in the upper 30s and lower 40s. Breezy south winds in the morning, mainly east half will become lighter and westerly when the trough passes late afternoon. Brisk s to sw winds up Lake MI tonight into Sat morning will build larger waves that may cause some minor lakeshore flooding/beach erosion on the east side of the Garden Peninsula and e of Manistique. Tonight, A sfc ridge moves in behind the trough and eventually becomes centered over the U.P. this evening into the early overnight. With models forecasting near calm winds and PWAT values around .1 inch, anticipate nearly ideal radiational cooling conditions with only some patchy high cloud cover expected. Went on the lower end of model temp guidance, blending 25th percentile NBM guidance with the bias-corrected Canadian. Expect teens over much of the interior with maybe lower 20s east and over the Keweenaw. Near the Great Lakes shores, expect min temps in the mid to upper 20s. .LONG TERM...(Sunday through Friday) Issued at 244 AM EST SAT NOV 20 2021 500mb height GEFS spaghetti plots show little variance in the upcoming pattern through at least Thursday next week. Overall this suggests decent model agreement among the GEFS members for the upcoming clipper system, lake effect event, and a third event that may impact Thanksgiving travel or post Thanksgiving shopping. On Sunday, all eyes are just upstream to an amplifying shortwave dropping out of Manitoba. This clipper system is expected to phase with a southern energy stream over the Upper Great Lakes. The result will be a deepening surface low just northeast of Lake Superior. Guidance has trended the low just slightly north. Overall, this doesn`t change much in terms of sensible weather across the region. Rain showers will be possible in the east half as moisture convergence and favorable dynamics support the developing cyclone. There are some differences in this shower activity among the models though and its entirely possible the east half may remain dry through early afternoon when the upstream cold front and colder airmass begins filtering in. In the west, ptype along the frontal boundary looks to be a mix of rain and snow. As the low develops and more cold air pours into the region, 850mb temps dropping to around - 12 to -15C will support another lake effect event downwind of Lake Superior. Ptype will quickly change over to snow as northwesterly winds increase due to the tightening pressure gradient. There may also be a slight isallobaric component to the winds that would further amplify them. These winds and moderate lake effect will result in not only accumulating snow, but areas of blowing snow across the northwest wind belts Sunday night and Monday. Additionally, the strong winds will support large waves on Lake Superior, which may prompt lakeshore flooding and beach erosion concerns, particularly east of Marquette. Winter headlines during this event look likely into Monday. Lake effect looks to end from west to east during the day Monday as the next ridge axis builds in. The east may continue to see shower activity into Monday night though. Monday highs will struggle to reach 30 in the east and may only top out in the mid 20s in the west. A chillier night is expected Monday night. Some single digits look possible in the interior west with teens in the east and near 20 by Lake Superior. Return flow and dry conditions are expected on Tuesday. Overall it looks to be a warmer day with highs in the 30s to near 40. A tight pressure gradient and downsloping may support some breezier winds. Attention then turns to another system progged to eject out of the Northern Plains. While there`s still some differences among the deterministic guidance, ensembles support increasing confidence of a low moving into the Upper Great Lakes late Wednesday. Current positioning of the low suggests warm air over the region would support rain initially, with a mix developing overnight. This system is expected to slowly progress through the region, with another shot of cold air on its western flank. This colder air would support another lake effect event downwind of Lake Superior beginning potentially on Thanksgiving. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) Issued at 630 AM EST SAT NOV 20 2021 VFR conditions will prevail thru this fcst period at IWD/CMX/SAW. LLWS will remain at SAW until 14Z this morning. Expect west winds to gust near 25 knots at CMX this afternoon as a sfc trough passes through the region. && .MARINE...(For the 4 AM Lake Superior forecast issuance) Issued at 335 AM EST SAT NOV 20 2021 Tight pres gradient btwn departing high pres ridge and approaching low pres trof from Plains will continue to result in s to sw winds up to 30kt this morning, especially east half. May even see a few gale gusts at higher platform locations over the open waters of the east half. Expect winds to diminish to 20kt or less from w to e in the afternoon as the weakening low pres trof moves across Lake Superior. Winds will remain under 20kt tonight. A sharp cold front will then sweep across Lake Superior on Sun with a low pres developing along the front e of the lake Sun night. With the passage of the front, expect an abrupt wind shift to nw gales of 40-45kt, continuing thru Sun night. The strongest winds will occur over central and eastern Lake Superior. Winds will diminish to blo gale force across the w early Mon morning and across the e by Mon afternoon. Passing high pres ridge late Mon night/Tue morning will bring a short period of winds blo 20kt. With the passage of the ridge, southerly winds will increase, likely gusting back to around 30kt, at least across the e half of Lake Superior, late Tue aftn into Wed. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Gale Watch from Sunday afternoon through Monday afternoon for LSZ264>267. Gale Watch from Sunday afternoon through Monday morning for LSZ162-263. Lake Michigan... Gale Watch from Sunday afternoon through Monday morning for LMZ221-248-250. && $$ SHORT TERM...Voss LONG TERM...JP AVIATION...Voss MARINE...Voss