Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/14/20


Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1151 PM EDT Tue Oct 13 2020 .AVIATION... Light west-northwest flow will develop behind a weak cold front overnight. Mainly clear skies will be replaced by increasing mid level clouds on Wednesday as a warm front lifts into the area. Winds will become south/southeast with the passage of this front as well. .DTW THRESHOLD PROBABILITIES... * None. && .PREV DISCUSSION... Issued at 359 PM EDT Tue Oct 13 2020 Anticyclonically bifurcated flow with sfc-850 high pressure center will move east of Southeast Michigan during the mid to late afternoon hours. Ribbon of modest 925-675mb thetae is poised to track into the forecast area as moisture transport increases behind the departing anticyclone. Satellite trends have been very bullish with altocumulus-altostratus in advance of weak shortwave within favorable corridor of system relative isentropic ascent. The clouds will march across the area through roughly 02Z. With regards to precipitation potential, consensus of model solutions keeps saturation above 10.0 kft agl through this evening. The RAP soundings do suggest that some moisture aoa 6000 ft agl will be able to provide for some convective instability and free lift mainly 00- 02Z for the Saginaw Valley and Saginaw Bay region. Upstream observations are lacking with any midlevel moisture/clouds. Will not be introducing PoPs this forecast package. Deep potential vorticity reservior with strong left exit region dynamics will result in low pressure across the Northern Great Lakes Wednesday. Thermal ridge amplification downstream of the wave will lead to organizing elevated warm front/warm advection beginning midday Wednesday. A strong signal exists in veil of high cloud overspreading the area by 18Z. High confidence in dry air mass sub 10.0 kft agl for southeast Michigan with bulk of lead wing isentropic lift occurring north of the forecast area. Dry environment brings some question for surface wind gusts potential during the daylight hours. Current messaging supports 15 to 25 mph during the afternoon with residual subsidence inversion at a fairly low 4.5 kft agl limiting mixing heights. Main baroclinic zone/composite cold front will push into Lower Michigan late Wednesday night and for the daytime Thursday. Main forecast item to watch for will be enhanced/deep moisture that is expected to eject northeastward out of MO/Mid Mississippi River Valley and ride along the cold front as a frontal wave. Deep fgen response is being forecasted under change in upper level jet dynamics due to jet streak. Both cloud cover, development/coverage of stratiform precipitation, and frontal timing will impact temperatures Thursday as surface cold front will be east of the area. Current high temperatures forecast is likely for 12Z timing with holding/falling temperatures during the day. A considerable amount of uncertainty exists with the magnitude of isentropic ascent aloft, some solutions are very lean on precipitation. Late afteroon boundary layer destabilization with cold air/instability showers may end up being the greatest precipatation potential after 18Z. Deep cold air aloft will be firmly entrenched across Southeast Michigan Friday. Automated guidance is likely too optimistic, highs will likely struggle to climb above 50 degrees. Persistent cool weather is being advertised for next weekend with highs in the lower 50s. MARINE... Passage of a cold front late tonight will increase instability slightly over the lakes and will result in a brief period of elevated winds between 20-25 knots. Diminishing winds then expected late Wednesday morning as the northern periphery of a high pressure system slides into the Great Lakes. Lighter winds will be short- lived as low pressure travels from Minnesota into Ontario late Wednesday into early Thursday which will increase the pressure gradient over the Great Lakes as a strong low-level wind field develops aloft. This will result in the likely issuance of Small Craft Advisories for the nearshore zones. Some brief gales will be possible across Lake Huron, specifically around central and southern Lake Huron, but will preclude the issuance of a Gale Watch as the duration of potential gales will be to or below the three hour threshold. Otherwise, a moderate pressure gradient will hold over the Great Lakes through Thursday which will result in continued elevated winds and waves. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...Small Craft Advisory from 4 PM Wednesday to 4 PM EDT Thursday for LHZ421-422-441>443. Lake St Clair...Small Craft Advisory from 4 PM Wednesday to 4 PM EDT Thursday for LCZ460. Michigan waters of Lake Erie...Small Craft Advisory from 4 PM Wednesday to 4 PM EDT Thursday for LEZ444. && $$ AVIATION.....DG DISCUSSION...CB MARINE.......AM You can obtain your latest National Weather Service forecasts online at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Goodland KS
916 PM MDT Tue Oct 13 2020 .UPDATE... Issued at 904 PM MDT Tue Oct 13 2020 Update the forecast mainly for the area of possible frost early Thursday morning and Thursday night into Friday morning. Strong winds during the day on Wednesday ahead and behind of a cold front will subside Wednesday night from north to south across the area. The far northern sections of the forecast area extending eastward along US Hwy 34 from northern Yuma county in far northeast Colorado through far southwest Nebraska to the McCook area could see temperatures around freezing along with light winds and partly cloudy skies that will have diminishing sky cover, all of which increase the possibility of frost across that area. Thursday night into Friday morning, much of the forecast area will see temperatures below freezing as another surge of colder air moves into the region. && .SHORT TERM...(This evening through Wednesday) Issued at 205 PM MDT Tue Oct 13 2020 500 mb RAP analysis and water vapor imagery showed northwest flow over the region today, with an upper trough entering the Pacific Northwest. Skies were sunny to mostly sunny across the area, as east winds shifted to the south at 10 to 15 mph. At 1:30 PM MT, temperatures ranged in the upper 60s and low 70s. Temperatures fall into the upper 30s to upper 40s tonight as dry weather prevails. A surface trough moves across the region, shifting winds from south to west. Meanwhile, the Pacific Northwest disturbance pushes further onto the northern and central Rockies. On Wednesday, a cold front is expected to push through the High Plains, entering the northern portion of the region by the early afternoon. As a result, high temperatures range from the upper 70s to low 90s from northwest to southeast. Gusty north winds will push through the region from north to south behind the front during the afternoon and early evening. Current thinking is gusts up to 50 mph will be possible, but this will need to be monitored. With relative humidity values of 10 to 15 percent throughout the majority of the region, have issued a Red Flag Warning in effect from 11 AM MT to 8 PM MT. In addition to fire weather concerns, there is also a potential for blowing dust which could reduce visibilities. The cold front continues across the southern portion of the area Wednesday evening where winds will continue to be gusty. Temperatures fall into the low 30s to low 40s with the coldest temperatures in eastern Colorado. A frost/freeze highlight will likely be needed. .LONG TERM...(Thursday through Monday) Issued at 316 PM MDT Tue Oct 13 2020 At the start of the forecast period, model guidance shows the CWA underneath the back part of the base of the trough associated with a Hudson Bay low giving a west-northwesterly flow aloft on Thursday. Going into Friday, the flow over the CWA changes more northwesterly as the back part of the trough moves over the CWA. Starting Friday going into Saturday, the trough begins to move eastward away from the CWA causing a transition to a more zonal westerly flow aloft. Models continue to diverge with their solutions beginning late Saturday. The GFS shows a trough developing as the Hudson Bay low moves southward placing the CWA under the base of the trough by Sunday and staying there into Monday. The ECMWF shows the Hudson Bay low remaining stationary developing a trough with a base in the Northern Plains area keeping the westerly flow over the CWA on Sunday and Monday. This situation will be monitored to see if future models come into better agreement. At the surface, the Tri-State area expects to see temperatures getting colder along with possible chances for precipitation starting over the weekend. The CWA may see a hard freeze overnight Thursday into Friday morning for areas along and west of a line from Tribune, KS to McCook, NE. Saturday sees potential for possible fire weather west of KS-25 with area RH values forecasted below 20%. However forecasted wind gusts below 25 mph for these areas do not support fire weather at this time. A cold front is expected to pass through the CWA late Saturday giving the very northern parts of the CWA a slight chance for rain transitioning to snow into Sunday morning. Areas north of I-70 may also see a chance of rain on Sunday evening that will transition to snow in the early Monday morning hours. The Tri-State area expects to have high temperatures in the lower to upper 50s on Thursday with Friday`s highs reaching the lower to middle 60s. High temperatures on Saturday increase to the middle to upper 70s followed by highs dropping to the lower 50s on Sunday and Monday. Tri-State overnight lows for Thursday and Saturday expect to drop to the middle 20s to lower 30s. Overnight lows on Friday are forecasted to range from the upper 30s in the western portion of the CWA to the lower 40s in the eastern portion. Overnight lows in the middle 20s are expected across the Tri-State area for the remainder of the forecast period. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 541 PM MDT Tue Oct 13 2020 Conditions will remain VFR at MCK and GLD through the 00Z TAF period. Mostly clear skies are expected with a few high clouds. LLWS is also expected at MCK between 04-10Z with southwest winds above the night time surface inversion at around 40kts. Light south surface winds at both locations will turn southwest after 08Z and then northwest following the passage of a cold front around 18Z. Northwest to North winds will continue to increase with the following the passage of the front with wind speeds of 20-25kts gusting to 35kts. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...Red Flag Warning from 11 AM MDT /noon CDT/ to 8 PM MDT /9 PM CDT/ Wednesday for KSZ001>004-013>016-027>029-041-042. CO...Red Flag Warning from 11 AM to 8 PM MDT Wednesday for COZ252>254. NE...Red Flag Warning from 11 AM MDT /noon CDT/ to 8 PM MDT /9 PM CDT/ Wednesday for NEZ079>081. && $$ UPDATE...LOCKHART SHORT TERM...JBH LONG TERM...076 AVIATION...LOCKHART
Area Forecast Discussion
National Weather Service North Platte NE
648 PM CDT Tue Oct 13 2020 .SHORT TERM...(This evening through Wednesday night) Issued at 330 PM CDT Tue Oct 13 2020 The main concern in the short term will the strong winds Wednesday afternoon and fire weather concerns Wednesday afternoon as well. Winds are expected to be strong Wednesday, with the strongest wind gust in the afternoon. Forecaster confidence is moderate to high in the wind forecast, the one concern is that winds will be even higher than anticipated. Increased winds higher than most of the forecast models to better handle stronger winds aloft and deeper mixing level. Looking at bufkit soundings there will be very strong winds aloft that will mix down and some soundings suggest wind gust as much as 50 to 55 mph but was not confident enough to put wind gust above 50 mph at this time, as that looks to be mostly sporadic, mainly across the northwest CWA. As for fire weather concerns, recovery overnight will be poor with RH ranging from 35 to 65 percent, with the lowest RH across southwest Nebraska. A poor recovery in combination with strong gusty northwest winds has led to a concern in elevated to near critical conditions across much of the Sandhills and near critical to critical conditions across portions of southwest and north central Nebraska. Did trend dewpoints tomorrow towards the RAP as this model did fairly well with this afternoons dewpoints, however this was a lower trending model for dewpoints. The main concern, thus creating low to moderate confidence in min RH for Wednesday afternoon will be cloud coverage. Models have suggested cloud coverage during a majority of the day across portions of north central Nebraska and the Sandhills. If we remain cloudy during the day this could have an impact on temperatures and min RH would be higher than anticipated. Across southwest Nebraska confidence is a little better and can moderately expect min RH around 20 percent, possibly lower, as the likelihood of cloud coverage is much less. The main driving force for issuance of the fire weather watch is the continue dry conditions, anticipated warmer temperatures and near critical humidity in combination with very strong northwest winds. Will continue to monitor and will likely upgrade the fire weather watch. .LONG TERM...(Thursday through Tuesday) Issued at 330 PM CDT Tue Oct 13 2020 With the passage of the cold front Wednesday temperatures will be below normal Thursday and Friday with highs in the upper 40s to low 60s. Temperatures then rebound back into the 70s across the southern CWA which could cause elevated fire weather concerns. Then another cold front will push through Saturday night bringing colder temperatures for Sunday with highs only in the 40s. There will also be a possibility of precipitation in the form of rain, rain/snow mix or possibly snow showers with the cold front passage Saturday night, however at this time precipitation amounts look to be low. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 648 PM CDT Tue Oct 13 2020 Skies will be mostly clear over the next 18 hours with some scattered high clouds expected overnight. Some mid level cloudiness will impact the KVTN terminal Wednesday afternoon. Low level wind shear is expected overnight tonight at both terminals with speeds of 45 to 50 KTS expected. Wind shear levels will range from 1000 to 1500 FT AGL. On Wednesday afternoon, a strong cold front will pass through the area. this will lead to gusty northwesterly winds which may reach 30 to 40 KTS late Wednesday afternoon. && .LBF WATCHES/WARNINGS/ADVISORIES... Fire Weather Watch from Wednesday afternoon through Wednesday evening for NEZ209-210-219. && $$ SHORT TERM...Gomez LONG TERM...Gomez AVIATION...Buttler
Area Forecast Discussion
National Weather Service Marquette MI
821 PM EDT Tue Oct 13 2020 .SHORT TERM...(This evening through Wednesday) Issued at 355 PM EDT TUE OCT 13 2020 Latest RAP analysis and Hi-res guidance is showing a broader shortwave that will track over the northern part of Lake Superior throughout the day. This shortwave is part of a mid to upper-level low seen at 500mb, that is located near the James Bay and will likely stay in place through this forecast period. This low has a negative tilt to it and will be responsible for this shortwave and another shortwave that will come Wednesday with a good rush of caa moving into Upper Michigan, beginning of a cooling trend. Both shortwaves will bring more chances of showers and windy conditions but better rain chances and breezy winds will come with the Wednesday shortwave. With this shortwave moving through the cwa today, some showers have developed with a little bit fgen as a forcing mechanism ahead of the cold front. Latest runs did show LI values as low as -4 and some decent bulk shear of up to 50 kts, which has triggered a few isolated thunderstorms, mainly over the east half. Have tweaked PoPs and PoTthunder to reflect this change since previous runs did not catch this. Even if a thunderstorm occurs, will not be a washout like yesterday with most areas that see rain, only receiving up to 0.05" QPF. Once front passes on through, conditions will dry out and skies will turn mostly clear to start before the next shortwave moves in Wednesday morning. There will be better fgen forcing and dynamics will be better than today`s shortwave, which means widespread rain is likely again. Rainfall totals will be between 0.5-1.0" in most spots. Best chances of seeing heavier rain will be over the north and less to the south. With this fall pattern, continue to count on breezy conditions through the rest of the afternoon and early evening. Did decide not to issue a wind advisory for the Keweenaw Peninsula, even though there have been a few gusts near the 45mph range but still think this won`t last all afternoon. Like last night, winds will subside again tonight and then increase again with decent mixed layer just above the surface. Temperatures this afternoon should reach the mid to upper 50s with those southerly winds, aiding in waa ahead of cold front. Once front passes, caa will start to work in and with clear skies to start, lows should drop in the 30s in most spots with a few upper 20s in the more favorable cool spots over the interior west. Went with the 25th percentile for highs Wednesday as this will begin the stretch of some strong caa taking hold over the cwa. .LONG TERM...(Wednesday night through Tuesday) Issued at 427 PM EDT TUE OCT 13 2020 The extended fcst for much of the next week will be generally highlighted by below normal temperatures as models and ensembles advertise an amplified blocking pattern setting up and a broad, cool and persistent trough enveloping much of central North America. Models indicate positive 5H height anomalies developing over the eastern Pacific into the Gulf of Alaska and over the North Atlantic into Greenland by late week into early next week. The 500 mb height anomalies become abnormally strong this weekend over the North Atlantic into Greenland where heights become more than 3 standard deviations higher than normal. These amplified ridges will force a broad and amplified mid-upper level trough to develop and persist across central North America through the period, including the Upper Great Lakes region. The result will mean much blo normal temperatures beginning by Thu and continuing for the most part into the early part of next week with fairly peristent lake effect rain and snow showers for the w-nw wind belts downwind of Lake Superior. Beginning Wed night into early Thu, as a sfc low lifts e-ne across north central and eastern Lake Superior into Ontario Wed night, the dry slot associated with the low will move into sw and central sections of the U.P. with mostly dry conditions there. There could be some scattered evening showers along the cold front over the eastern counties, but then mostly dry conditions after that. The best coverage for showers will be over the western counties where wraparound moisture, cyclonic upslope nw flow and some lingering enhancement at least into the evening (with lake delta-t around 10C) will aid with some lake enhanced/lake effect showers. With web bulb zero heights most places staying at or above 2 kft, expect pcpn mostly as rain. KIWD NAM sounding does however show WB zero heights lowering near 1 kft just before sunrise as CAA increases, so maybe some light snow showers/flurries could mix in with rain far west just before sunrise into late Thu morning. Tightening of the pres gradient on the backside of the system and 5-6 mb/3hr pres rises with ensuing CAA will likely result in a period of 35-40 knots nw gales over central and eastern Lake Superior late Wed night into Thu morning. A brief period of advisory criteria gusts to 45 mph may also be possible along the eastern Lake Superior shore from Munising to Whitefish Point early Thu morning. Otherwise, expect breezy conditions elsewhere during the day on Thu. By late Thu into early Sat, this looks like it will be the start of a sharp cool down where 850 mb temps drop to around -7 to -9 C by Thu afternoon and remain in that range into Sat morning. Light lake effect rain and snow showers generated by the cold flow across Lake Superior will be mostly over the nw wind lake effect belts of Lake Superior on Thu and then should be mostly confined to the Keweenaw Peninsula Fri. Models do indicate a shortwave moving across the area on Fri which could aid isolated diurnal shower development for the rest of Upper Michigan, and perhaps provide enhancement to lake showers over the Keweenaw. Late Sat-Sat night, models now in agreement that a Pac NW Coast shortwave and deepening storm system will track southeast through the Northern Plains on Sat then round the base of the long wave trough and track northeast through the Upper Great Lakes Sat night/early Sun. Models still differ somewhat on the strength and track of the storm system, although a blend of the 12Z GFS and UKMET and 00z ECMWF would appear to converge on a track of the storm through the Dakotas and southern MN and then tracking northeast through northwest WI into western Upper Mi. This sfc low track solution would be too far north for any notable wintry pcpn, with the most likely 850 mb low track going across the Apostle Islands and then western and north central Lake Superior. Still, it`s not impossible that some of the WAA precip Saturday evening at the onset could end up as light snow or a light rain/snow mix as temps on Saturday are only expected to make it into the low 40s before the precip arrives. Expect gusty southerly winds, perhaps gale or near gale force over northern Lake Mi and the east half of Lake Superior late Sat into Sat evening. Might also be some lakeshore flood issues along Lake Michigan during this period. I`m discounting the latest 12Z ECMWF solution as an outlier at this point as it tracks the storm system on an IMT-MQT path through the U.P. Obviously this will be something to watch though, as this scenario would probably yield a few inches of accumulating snow for the western cwa Sat night. Sunday, as the low departs expect another round of blustery NW winds, CAA, and lake-effect rain/snow chances in the west and west- northwest wind lake-effect belts. Models bringing 850 mb temps right back down to around -5 or -8 C for Sunday means another day with highs ranging from the mid 30s west to mid 40s east. If the deeper 00Z ECMWF solution verifies then advisory wind criteria would be likely over at least the nw U.P. with nw gales over much of Lake Superior. Monday into Tuesday, model solutions become a bit more muddy out beyond Sunday. The ECMWF shows a baroclinic zone setting up just se of the Upper Mi for early next week where the se fcst area could get brushed with light mixed pcpn during the period. Meanwhile, the GFS and CMC show no evidence of this boundary, just spawling high pressure from the mid-Mississippi Valley into the Lower Great Lakes as our region maintains a cool nw to w flow with light lake effect pcpn downwind of Lake Superior. Since ensembles show less support for the ECMWF, will lean more toward the GFS and CMC at this time and maintain chc pops for nw-w flow lake effect rain and snow showers downwind of Lake Superior along with cooler than normal temps. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 821 PM EDT TUE OCT 13 2020 VFR conditions tonight into Wednesday morning will give way to deteriorating conditions as a low pressure system moves into the region. The increased low level moisture inflow along with rainfall will drop cigs to MVFR during the afternoon. There may also be period of IFR vsby with any heavier showers. Southerly winds will increase and become gusty during the afternoon. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 355 PM EDT TUE OCT 13 2020(For the 4 PM Lake Superior forecast issuance) Issued at 406 PM EDT MON OCT 12 2020 Well, the active weather pattern is here to stay, at least through this forecast period. Current gales will linger over the east half of the lake through this evening while dropping over the west half. duration will be shortest over western Lake Superior. Winds will briefly drop under 20 kts overnight tonight before ramping back to 20-30 kts from the southeast ahead of next shortwave approaching from the Dakotas. Would not be surprised at all if there were some gale force gusts to 35 kts, especially over the east half. Behind the shortwave, winds will turn to the north and northwest with winds increasing to gales to 35 kts across the lake early Thursday. Could have some high-end gales to 45 kts, especially over the central and eastern parts of the lake. Winds finally diminish to under 20 kts by late Thursday into Friday. Winds will increase again Saturday ahead of next system. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Gale Warning until 10 PM EDT this evening for LSZ250-251-265>267. Lake Michigan... None. && $$ SHORT TERM...JH LONG TERM...Voss AVIATION...JLB MARINE...JH