Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 11/22/22

See below for an aviation forecast discussion for the 00Z TAFs.

&& .SHORT TERM...(This Evening through Tuesday Night) Issued at 304 PM CST Mon Nov 21 2022 As of 20Z, a surface cold front bisects the CWA, with northerly winds and a batch of low stratus to the north, and light winds, warmer temps to the south. The low stratus is approaching KABR, which would impact aviation. The HREF, along with the HRRR suggests the low clouds will drift southward some before shifting eastward overnight as an upper level shortwave slides across North Dakota. The shortwave may produce light snow, mainly in ND and northern MN, with dry conditions expected in this CWA. Weak downslope winds will be possible on the eastern side of Prairie Coteau between 10 to 15Z Tuesday. Thankfully, blowing snow should not be an issue. Warmer temperatures will move into the CWA behind the trough, surface warm front on Tuesday with highs likely reaching the lower 30s, in northeastern SD, to the upper 40s, in south central SD. Temperatures should remain mild Tuesday night due to increasing southerly winds and weak ridging aloft. .LONG TERM...(Wednesday through Monday) Issued at 304 PM CST Mon Nov 21 2022 First time range of interest in the extended period revolves around the weak shortwave energy that crosses the Dakotas Wednesday night into Thursday. Have slight chance POPs in the forecast now as there is only limited support for precip within individual ensemble members and in various precip probability output. Soundings are also supportive of at least mentioning a slight chance. But again, a minor system this looks to be, with little if any precipitation. Main highlight throughout the extended forecast is the turn to warmer temperatures, especially Wednesday, then again Friday and Saturday. Rather mild air aloft overspreads the region Friday into Friday evening, and NAEFS/EC ENS 850mb temps are still showing up at the 90th percentile. There`s even some 97th percentile sneaking in on the EC ENS Friday evening. All that said, this equates to periods of highs in the 40s and 50s for many locations, especially where snow cover is minimal or non-existent. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday Evening) Issued at 514 PM CST Mon Nov 21 2022 Terminals KABR,KATY,KPIR,KMBG While prevailing VFR conditions are expected through the valid TAF period at KPIR and KMBG, low stratus (MVFR) will impact the KABR terminal, and possibly the KATY terminal, for a while this evening. Guidance suggests conditions will improve by late tonight (at or after 06Z) at KABR. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...Dorn SHORT TERM...SD LONG TERM...TMT AVIATION...Dorn
Area Forecast Discussion
National Weather Service Grand Rapids MI
850 PM EST Mon Nov 21 2022 LATEST UPDATE... Update .UPDATE... Issued at 849 PM EST Mon Nov 21 2022 I am in agreement with the daytime forecaster that dense freezing fog is likely tonight. My typical way to decide this has changed some recently when I realized that when the RAP model, HRRR model and NAMNEST all show dense fog at the same time in the same place it just about always happens (over the past year anyway and there have been numerous events for this). Actually every run of the HRRR, RAP for the past 6 hours shows the dense fog in the same place at the same time, this is from around 2 am till around 10 am on Tuesday. So here is the glitch, we have an area of low clouds dropping south behind the backdoor cold front (which is now south of I-96). The clouds are forecast to break up during the night. The models keep forecasting this run after run. My problem is it is hard to see a reason to believe that will really happen. So, for now, I will leave the forecast as is. If the low clouds do not get down to GRR (I-96) or if they do but break up quickly early Tuesday morning we will very likely have dense freezing fog. I am just not sure enough to issue a dense fog advisory. So, be sure to allow extra time if you have to travel to work during the morning commute Tuesday, you just may have some travel delays from icy bridges. overpasses and locally dense freezing fog. && .DISCUSSION...(This evening through next Monday) Issued at 310 PM EST Mon Nov 21 2022 - Risk for fog/icy spots tonight Clouds will be dropping down from the north this afternoon and evening...but are forecast to diminish overnight. The winds will decrease steadily this evening eventually going calm. The melting snow this afternoon will add some moisture to the low levels. For the past couple of runs...the HRRR has been showing an area of denser fog developing between Grand Rapids and Lansing later temperatures drop through the teens and potentially in the single digits. If this happens...there could be some icy spots on the roadways for the morning commute Tuesday. If the cloud cover holds on longer or the wind stays up...the risk for any impacts will be diminished. For now we did add some fog to the forecast and mentioned the potential hazard in the hazardous weather outlook/social media posts. - Weak system to bring showers to the area Thu night into Friday night A cold front is shown to track through the CWA during this time frame. Moisture will advect in from the south ahead of the front with PWAT values shown to make a run towards an inch. There will be some mid level lift along the frontal zone as it tracks through Thursday night and this will support a potential for scattered showers. Forecast thermal profiles suggest these will be mainly rain showers...which is what we will go with for most locations. Around Big Rapids and Harrison...some snowflakes could mix in given as 925/850 mb temps are shown to drop to near freezing later at night. The southern end of the cold front stalls out over northern IL and perhaps southern MI Friday before lifting as a warm front Friday night. Very little lift is seen along this frontal zone. The DGZ is shown to be unsaturated...thus if there is any precipitation along this should be in the form of light rain or drizzle. We will hold onto a very low POP for this period. - Increased potential for precipitation Sat night into Sunday AM Over the weekend the models are in relative agreement in showing a mid level low lifting out of the southern Rockies..up into the OH Valley. This track puts the CWA on the cold side of the system....which raises some concern for a wintry mix of precipitation. We currently have low temperatures near or below freezing for Saturday night. Thus there is some potential for a wintry mix at some point Saturday night. Accompanying this system will be stronger mid level lift and abundant moisture from the the precipitation should be widespread. The latest ensemble forecasts are also trending up with the 24 hr qpf...but at this time most suggest values remaining under a half inch. Stay tuned for later updates though as this system is still a ways off and much can change concerning the track and timing. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 700 PM EST Mon Nov 21 2022 The primary threat tonight is dense freezing fog from around 3 am till around 10 am (ish). A weak or more so, a shallow cold front is moving due south across lower Michigan as I write this at 645 pm. The clouds, with MVFR cigs are just north of a line from near MKG to near MBS. That is about 30 miles behind the surface cold front. Based on wind directions and thermal profiles, seems the cold air is forecast to be about 2000 ft deep as it moves over the I-96 area of Lower Michigan while more like 3000 ft in depth near Route 10 by 3 AM. Seems the clouds will not get much farther south than I-96 and then quickly mix out leaving mostly clear skies in the 06z to 12z time frame. Winds will be light and variable near the surface at that time over our TAF sites. Add the moisture from the melting snow and it would seem reasonable to believe dense freezing fog is likely overnight. Most of our HI res models show this scenario. MVFR cigs move in then mix out, shortly after that dense fog forms within say, 30 miles of US-131 and does not mix out until mid morning Tuesday. So, I did not put dense fog for MKG , LAN or JXN but did at the other TAF sites. Being November, it may take awhile to mix out the fog but skies should clear by noon (17z). && .MARINE... Issued at 310 PM EST Mon Nov 21 2022 The winds remain at or above small craft advisory criteria along the lakeshore...but they are diminishing quickly. We will still hold onto the current headline...but it might be able to be cancelled early if this trend continues. The current expiration is set for 04z tonight. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...Small Craft Advisory until 11 PM EST this evening for LMZ844>849. && $$ UPDATE...WDM DISCUSSION...MJS AVIATION...WDM MARINE...MJS
Area Forecast Discussion
National Weather Service Reno NV
145 PM PST Mon Nov 21 2022 .SYNOPSIS... Strong inversions will continue into Tuesday with haze and patchy fog in valleys. A dry cold front will bring an increase in mountain winds Tuesday night into Wednesday. High pressure then builds in for the Thanksgiving holiday yielding quiet and mild weather. Potential remains for rain, snow, and wind next week, starting as early as Sunday, though forecast confidence is below normal. && .SHORT TERM... Another round of strong inversions today with plenty of valley haze and light winds. One of the more notable inversions was around Mono Lake where dense fog and pogonip were observed. AM temps in Lee Vining were near 20 at 6700` while just a few miles to the west it was 41 on Lee Vining Hill at 8900`. Guidance favors more of the same tonight into Tuesday morning. Intermittent high clouds into this evening but models showing clearing overnight which would help haze/fog formation in sheltered lower valleys especially around Mono Lake again and possibly Crowley Lake. Fog at Mono Lake was slow to erode today, with patchy low clouds even right now, so we could see a rather quick increase in fog again tonight. Elsewhere, dry airmass with limited humidity recoveries will help keep fog from being too extensive. Brush by (and dry) cold front will help increase NW winds aloft Tuesday afternoon and evening, with some of that surfacing in the Surprise Valley per the HRRR otherwise most valley areas remaining light & variable. After the front sweeps through, we`re looking to see a turn of the winds to more NE on the Sierra crest ridges after midnight Tuesday evening into Wednesday. Not a major event for the east side, and even the HRRR doesn`t show that flow surfacing into normally prone areas like west shores of Lake Tahoe. -Chris .LONG TERM... The warming trend will continue through Friday as a ridge amplifies over the western US. Warmest temperatures of the week are expected on Thanksgiving Day and Friday, with high temperatures around 5 degrees above seasonal normals across the region. High pressure associated with this ridge will also allow valley inversions to continue, with continued degradation in air quality and hazy skies. Some improvement in mixing is possible on Wednesday as a shortwave trough passes to our north and brings an uptick in ridgetop winds. However, this system will not be strong enough to completely mix out the inversion. It looks more promising for active weather as we move into the holiday weekend. A trough will start to deepen off the Pacific Northwest coast on Saturday night. Gusty southwest ridgetop winds in excess of 60 mph are expected to begin Sunday afternoon. Winds look to remain elevated at ridge level overnight and into Monday afternoon. Valleys will see breezy winds Sunday and Monday afternoons. This system is expected to push a cold front through the region on Monday morning, with temperatures diving well below normal again for the first half of next week. Exact details on precipitation associated with this system, especially precipitation type and amount, remain on the lower confidence side for now. However, blended guidance suggests good chances for at least a trace of snow along the Sierra crest on Sunday night. Bottom line, it will be a good idea to keep an eye on the forecast if you have travel plans Sunday night into early next week. -Whitlam && .AVIATION... Robust inversions will yield light winds and valley haze through Tuesday morning. Continued fog and low clouds near Mono Lake today, will likely return again tonight and Tuesday morning. Can`t rule out patchy fog near TRK but less confidence there with passing high clouds and dry airmass. HRRR guidance not showing signals for widespread fog. Approaching cold front will starting kicking up the winds aloft Tuesday afternoon and night with 700mb flow 20-25 knots out of the NW. While not a favorable direction for mountain waves, some low level wind shear is possible for mountain locations Tuesday evening into early Wednesday morning. -Chris && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$