Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/01/20

Area Forecast Discussion
National Weather Service Grand Rapids MI
1156 PM EDT Sat Oct 31 2020 LATEST UPDATE... Aviation .SYNOPSIS... Issued at 258 PM EDT Sat Oct 31 2020 - High winds and snow showers Sunday and Sunday night - Cold early week, moderating by mid-week && .UPDATE... Issued at 705 PM EDT Sat Oct 31 2020 For the most part our ongoing forecast looks fine. I did fine tune the precipitation to show a break between the showers ahead of the cold front and the wrap around snow showers behind the front. There is enough cold air with this system to bring the freezing level to the ground or very near to the ground by early afternoon so I could see grassy surfaces down wind of the better fetch snow showers getting and inch or so Sunday. The higher terrain areas north of Grand Rapids would see the most. There seems to be a preferred area of snow accumulations near US-131 just south of Grand Raids. In that area we have good lift in the DGZ and cloud tops look to be near 9000 ft, so these could be decent snow showers. The gusty winds look very much on track too. The latest HRRR is still showing gusts in the 40 to 45 mph, the ECMWF has gusts in the 45 to 50 mph range. && .DISCUSSION...(This evening through next Saturday) Issued at 258 PM EDT Sat Oct 31 2020 - High winds and snow showers Sunday and Sunday night Forecast wind profiles continue to show 40 to 45 knots in the mixing layer for Sunday afternoon and evening so we expect the potential for wind gusts over 45 mph. We have expanded the wind advisory across the entire CWA. Sharp thermal trough with 850 mb temps plunging to minus 10C or lower Sunday afternoon and evening. Strong CAA will mean temperatures actually falling through the 30s during the day and surfaces should be cold enough for any snow to stick, with accumulations an inch or two possible across the northern interior zones. Model soundings show inversion heights generally above the DGZ with cyclonic flow and lake-generated instability helping create some decent updrafts, although strong winds will tend to disrupt stronger bands from forming. Some rain will mix in near the shore because of the warmer lake temps. The trough axis moves east with drying early Monday. - Cold early week, moderating by mid-week Trough moves out early next week with rising heights and moderating temperatures by mid-week. 850 mb temps go from about 0C on Monday to about 14C on Wednesday. No precip expected through the end of the week as western CONUS trough amplifies keeping ridging across the east. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1156 PM EDT Sat Oct 31 2020 The primary story with this system coming through is strong winds. The GRR VAD wind profiler shows 50 knots at 2000 ft AGL. Many locations near the Lake Michigan shore are getting gusts to 35 to 45 mph already. We are expecting the strongest surface winds behind the cold front Sunday. I am thinking surface wind gusts in any open location like an airport could see gusts to 40 mph with no problem at all a good part of the day. Winds will diminish by mid evening Sunday. The area of showers is starting to develop now and will become widespread by 06z and last until around 10z. It is questionable now how much MVFR there will be with these showers as there is a lot of dry air at low levels ahead of the front. Still it is possible we could locally see some heavier rain and MVFR cigs/vsby for a time. There will be about a 3 to 6 hour break between the frontal rain band and the lake enhanced snow showers that will follow Sunday during the day. These snow showers will be light mostly but in the 15z to 21z time frame locations near and inland of US-131 could see some local IFR in snow showers. These conditions would be brief. After 21z enough dry air comes in to end the snow showers and bring VFR cigs. Skies may clear by 06z Monday. && .MARINE... Issued at 258 PM EDT Sat Oct 31 2020 Gale Warning and Lakeshore Flood Warning in effect and are unchanged from previous forecast. South gales to 40 knots are expected tonight then going west and northwest on Sunday and increasing to 45 knots during the afternoon and evening. A few gusts to Storm force are possible north of Pentwater. Waves are expected to build over 10 feet tonight and up to 14 feet on Sunday. This will cause some erosion of dunes and flooding of areas adjacent to the lake. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Lakeshore Flood Warning until 1 AM EST Monday for MIZ037-043-050- 056-064-071. Wind Advisory until 7 PM EST Sunday for MIZ037-043-050-056-064- 071. Wind Advisory from 9 AM to 7 PM EST Sunday for MIZ038>040- 044>046-051-052-057>059-065>067-072>074. LM...Gale Warning until 1 AM EST Monday for LMZ844>849. && $$ UPDATE...WDM SYNOPSIS...Ostuno DISCUSSION...Ostuno AVIATION...WDM MARINE...Ostuno
Area Forecast Discussion
National Weather Service Lincoln IL
852 PM CDT Sat Oct 31 2020 .SYNOPSIS... Issued at 240 PM CDT Sat Oct 31 2020 A cold front will move across Illinois tonight bringing gusty northwest winds and much cooler temperatures for Sunday. The chill will be short-lived however, as temperatures are expected to make it back into the 60s for highs by midweek. Weather is expected to remain dry through the week. && .UPDATE... Issued at 852 PM CDT Sat Oct 31 2020 Cold front is still on track to move into the CWA late this evening and move across the state overnight. Winds may be on the lighter side as the front moves through, but strong gusty northwest winds are expected a couple of hours after FROPA and as colder air advects into the region. HiRes model guidance suggests sustained winds around 25 mph with gusts of 35-40 mph and possibly 45 mph. So, forecast winds will be just below wind advisory criteria for this CWA. Therefore will continue the current SPS...but adjust to have winds slightly stronger at times during the morning hours. Update for stronger winds is necessary for late tonight into tomorrow morning and will be out shortly. && .SHORT TERM...(This evening through Sunday) ISSUED AT 240 PM CDT Sat Oct 31 2020 Breezy conditions should subside somewhat this evening ahead of an approaching cold front currently over southeast Minnesota into western Iowa. The front is associated with a strong northern stream wave digging into the eastern U.S. Models are in good agreement in bringing the front through between 04z and 09z. With strong cold advection and height rises behind the front and enhance subsidence on the backside of the wave, winds should come up before sunrise west of I-55 and by mid-morning elsewhere. Extended HRRR and SREF suggest wind speeds just below advisory levels. By middle afternoon, the gradient is already exiting the state and heights are rising so expect winds to gradually decrease. Strong cold advection behind the front, should keep temps from rising much on Sunday. 850 temperatures are progged to fall into the -5C to -10C by range by Sunday evening. This should keep temps in the 40s despite abundant sunshine. .LONG TERM...(Sunday night through Saturday) ISSUED AT 240 PM CDT Sat Oct 31 2020 Clear skies, cold Canadian air mass, and diminishing winds should set up the region for low temperatures in the 20s Sunday Night. However heights start to rise quickly in the wake of the departing shortwave and 850 temps respond increasing some 20C by Tuesday evening. Temperatures are expected to be around 10 degrees above normal for an extended period. Models are in unusually good agreement in building a broad ridge across much of the U.S. next week. A weakness in the ridge does move across the Midwest midweek, but the Gulf of Mexico remains cutoff and the weak wave should have little impact on our weather. Next significant system amplifies over the western U.S. toward the end of the week, but is not expected to bring any chances of precip until after the valid period of this forecast. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 612 PM CDT Sat Oct 31 2020 VFR conditions will prevail at all TAF sites next 24hrs. Mid and high clouds are advecting into the area and will bring broken cigs around 8kft to PIA and BMI this evening, but this should scatter out around midnight. SPI/DEC/CMI will just see scattered cloud later this evening and overnight. Skies will then become clear early morning and continue through rest of TAF period. Winds will be out of the south-southwest this evening, but as a front moves into and through the area, wind direction will shift to westerly around or just after midnight with gusts up to 22kts. After the front moves through overnight, wind direction will become northwest and wind gusts will increase to 25kts...then increase to over 30kts during the early morning hours. This will continue into the afternoon. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Auten SYNOPSIS...Auten SHORT TERM...Barker LONG TERM...Barker AVIATION...Auten
...Updated Aviation Forecast Discussion...

.DISCUSSION... Issued at 315 PM CDT Sat Oct 31 2020 Mild temperatures, gusty winds and decreasing relative humidity values have bumped the fire danger up into the very high category for much of the local area this afternoon. That should continue until near sunset. Otherwise temperatures are the main forecast concern for the next several days. Precipitation chances from now through next Saturday are very low. Upper air maps from this morning showed the following features of interest. At 850 mb and 700 mb, thermal ridges were in place from KS and NE through MN and the eastern parts of the Dakotas. Colder air was starting to push in from the northwest though with 850 mb temps colder than 5 C from northern MT and western ND northward. Strong 12 hour height falls of up to 150 meters were noted in southern Manitoba, associated with a shortwave trough. Water vapor satellite imagery, in combination with recent RUC model initializations indicated that the trough stretched from Manitoba down to the TX panhandle. Some variable mid and high level clouds should move through the area over the next 12 hours. Winds will gradually decrease tonight as the atmosphere decouples and high pressure builds east across the northern and central parts of the Plains. Ridge axis should stretch from central ND to the TX panhandle by sunrise Sunday. That ridge will build east/southeast over our area during the day Sunday, with much lighter winds than today. So poor mixing will help keep temperatures down. We expect highs to range from 46 to 49 in southwest IA and 47 to 52 in eastern NE. Winds will turn to the south or southeast in eastern NE by early evening. Winds will not be from the south the whole week, but from Monday through Friday they should mainly have a southerly component. A weak cold front pushing through could turn winds to the northwest on Thursday. We look for a warming trend Monday into Tuesday, and then a pretty mild rest of the week with highs in the mid 60s to lower 70s. Tuesday will probably be the warmest day, with highs from 67 to 70 in southwest IA and 70 to 75 in eastern NE. The warmest readings Tuesday should be west of a line from Beatrice to Albion. Fire danger could be high or very high that day, so will have to monitor that with later forecasts. Gusty south winds are forecast for Friday afternoon, and even moreso on Saturday, as low pressure deepens over the High Plains in response to the digging mid level trough over the Rockies. There is fairly good model agreement with the large scale pattern until Sunday, then differences increase dramatically with pretty big spreads shown in both the high and low temperature forecasts from the National Blend of Models (NBM). For the 8 to 14 day period, it looks like there will be some precipitation chances with temperatures trending cooler than normal. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 628 PM CDT Sat Oct 31 2020 LLWS threat will persist through tonight at all terminals. Otherwise, VFR conditions will prevail. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Miller AVIATION...DEE