Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/23/23

Area Forecast Discussion
National Weather Service Denver/Boulder CO
832 PM MST Wed Feb 22 2023 .UPDATE... Issued at 824 PM MST Wed Feb 22 2023 Water vapor imagery showing the lead upper wave lifting out across the far northeast plains of Colorado this evening where the heaviest snowfall has departed Colorado. Radar imagery is still showing several last bands of snow which will be working their way across the plains through the rest of the evening with drying conditions westward over the Front Range and plains. Have allowed many of the winter storm warnings and advisories to expire this evening. Have also cancelled the winter storm warnings for zones 31 and 33 as any significant snowfall will be further southward across Summit county. Wind chill advisories/warnings will continue over the plains until 9 am Thursday morning with temperatures now below zero at most locales and winds at 8-15kt across the plains. && .SHORT TERM...(This evening through Thursday) Issued at 247 PM MST Wed Feb 22 2023 Radar has blossomed across much of the Foothills and portions of the I-25 corridor over the past hour or two. While this next round of snow may not nearly deliver the snowfall that the HRRR promised, it still looks like most locations across the I-25 corridor should see another half inch to as much as two inches this evening. Some lucky spots of the foothills may see a bit more than that through midnight tonight. Snow showers across the mountains will make travel difficult across the high country... especially west of the divide where winds are stronger and blowing snow has become an issue. As the snow comes to an end... the main story will shift to the bitter cold temperatures. Temperatures across the area will remain in the single digits to as low as the -10s overnight. Wind chill values across the northeastern plains have already fallen into the -10 to -20F range, and thus we`ve started the Wind Chill Advisory now rather than waiting until later this evening. The cold/breezy conditions across the far northeast corner is enough to justify a Wind Chill Warning there. The Wind Chill Advisory for the Denver metro is still on track to start at midnight, as it will take some time for these zones to consistently meet thresholds until later tonight. Tomorrow should be quieter but still quite chilly across the area. High temperatures will likely remain between 10 and 20 degrees across the majority of the CWA. The exception may be the Palmer Divide and parts of the Southern Foothills that may be able to break out of the surface inversion. Scattered snow showers are also expected to continue across the mountains under a moist/west-southwesterly flow aloft, but snowfall amounts won`t be particularly noteworthy. .LONG TERM...(Thursday night through Wednesday) Issued at 247 PM MST Wed Feb 22 2023 Strong southwesterly flow aloft will be in place from Thursday evening through Sunday morning with increasing heights and temperatures aloft. During Sunday evening, a shortwave trough will move through the area. Then, flow will turn westerly aloft again Monday through the middle of next week. With the majority of the period seeing westerly flow aloft, there will be a chance of snow in the mountains nearly every day. The only exception will be on Saturday when there is a lack of moisture and conditions will be dry. Most days, the mountains will see light snowfall with maybe an inch or two of accumulation falling in the locations favored during southwesterly orographic flow, like the Park Range. When the shortwave trough moves across on Sunday, there may be just enough lift and moisture to allow for moderate snow in the mountains. However, it is possible that amounts remain light if the shortwave moves to the south of our forecast area. Otherwise, high temperatures will be above normal across the plains Saturday through the beginning of next week. Wind gusts will be strong in the mountains on Friday with gusts up to 55 mph. Winds may be on the stronger side on Sunday as the shortwave moves across. Besides the minor travel impacts in the mountains due to snow, there are no major weather concerns during the long term period. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 457 PM MST Wed Feb 22 2023 Last band of moderate to heavy snow will be moving across the terminals between 00-01z with a quick 1/2-1 inch of snow with the band. Should see some improvement in visibilities/ceilings behind the band but can`t rule out some lingering light snow flurries for a few more hours. Lower confidence on how long the low clouds actually hang around tonight but expect low clouds to redevelop Thursday afternoon as cyclone drags more low clouds into the terminals during the afternoon hours. Could also see more snow showers from late afternoon through evening hours. && .BOU WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 5 AM MST Thursday for COZ034. Wind Chill Advisory until 9 AM MST Thursday for COZ038-042>044- 048-049. Wind Chill Advisory from midnight tonight to 9 AM MST Thursday for COZ039-040-045-046. Wind Chill Warning until 9 AM MST Thursday for COZ050-051. && $$ UPDATE...Entrekin SHORT TERM...Hiris LONG TERM...Danielson AVIATION...Entrekin
Area Forecast Discussion
National Weather Service Boston/Norton MA
1016 PM EST Wed Feb 22 2023 .SYNOPSIS... Weak high pressure moves out this evening ahead of our next storm system. A warm front brings a wintry mix of precipitation, beginning late this afternoon and evening, continuing into Thursday night. The greatest impacts will be across western and central Massachusetts. Bitter cold then arrives Friday afternoon into early Saturday. Very cold Saturday, but moderating Sunday. Scattered snow showers are possible both days. Another round of a wintry mix of precipitation is possible early next week. && .NEAR TERM /THROUGH THURSDAY/... Update: 1015 PM The change from snow to sleet/freezing rain continues, received a report of one inch in Chesterfield, MA as of 10 PM, the newest surface obs indicate the change over is occurring just north of the Mass Pike. As of this hour, KBOS continues to report light snow, but anticipate that change over in the next hour as KOWD now reports rain and surface temp of 35F. Wind at KBOS are still NE and are anticipated to become east as the low pushes through. Given the current weak gradient there is a low chance the winds become north due to the cold air draining from the north, will need to watch this closely. Otherwise, minor adjustments to the forecast this evening to reflect observed trends. Previous Discussion... 7pm Update: Latest run of the NBM looked to have a good handle on the steadier precipitation per regional radars. That was the basis for this update. Timing the precipitation type changes remains a challenge. Have high confidence that there will be some sleet and freezing rain mixing in, especially after midnight. More likely to remain all rain towards the south coast of New England. Also brought temperatures back in line with observed trends. 4pm Update: High pressure continues its exit to the east this afternoon and the arrival of low pressure to our west is heralded by ever increasing mid and high clouds. These will continue to thicken and lower through the afternoon and evening as a warm front lifts north through southern New England this evening. The disturbance responsible for this upcoming winter storm will ride up the mid level ridge from the midwest into New England, flattening the ridge as it does and generating a strengthening surface low pressure over NY/PA tonight. Along the frontal boundary of this low, a secondary low will then develop/strengthen off the mid Atlantic coast, passing to our south and helping to pull in colder air from the north later on. Confidence is high that this storm system will occur and high that it will be a messy, mixed precipitation, overrunning event. While confidence has increased since yesterday, it is still only moderate in the exact timing of precipitation types and the timing of the changeover. Most guidance has come into better agreement with the arrival time of the warm nose (Temps > 0C around 800 mb) lifting through the region; however some hi- res guidance like the HRRR is slower. At this point, though, the forecast is honed in on a brief heavy, wet snow to sleet/freezing rain to rain transition with the warm advection precipitation in the lower elevations. For locations above 1,000 ft it is more likely to be a heavy, wet snow to sleet/ freezing rain system, as the low level cold air holds on throughout the event. This will amount to generally 1 to 2 inches of snow north of the MA Pike with 2-4 inches possible in far northern MA. Ice accumulations of a few hundredths of an inch in the low elevations and 0.1 to 0.25"+ in the higher elevations of the Berkshires and Worcester Hills are likely. This will cause a difficult Thursday morning commute, especially for the higher elevations. A Winter Weather Advisory is in effect for these locations through Thursday afternoon. After 12z (7am) on Thursday a dry slot begins to move in above 850 mb, which will act to cut off the widespread steady precipitation. However, given the position of the low to our southeast, low level flow will be out of the northeast while flow above 850 mb is warmer, from the west. This creates an inversion with plenty of low level moisture trapped below it so don`t expect to see a nice, clearing skies on Thursday. Besides continued low clouds BUFKIT guidance indicates sounding profiles favorable for rain/drizzle and, more concerning, potential for freezing rain/drizzle thanks to very cold air that funnels down from northern New England through the day Thursday. Confidence in freezing drizzle coming to pass, though, is only moderate, since some guidance shows the warm nose aloft cooling/shrinking enough so that precip could fall as light snow and/or sleet. Some locations could certainly see a disruption to the Thursday evening commute with slick roads given the lingering moisture and dropping temperatures. Temperatures will be down into the 20s generally northwest of the I-95 corridor by Thursday evening. && .SHORT TERM /THURSDAY NIGHT/... By Thursday night, we`re gearing up for yet another round of wintry mix precip as a subsequent frontal wave moves through. Given the previously mentioned northerly cold advection any precipitation that is produced will be in an environment with sub freezing surface temperatures outside of the south coast and coastal plain; rain is more likely for southern RI and far southeast MA. Given the potential for light icing as far south as northern RI into the Boston metro and parts of the coastal plain, the Winter Weather Advisory has been expanded south and east, and extended through 4AM Friday. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Highlights... * Brief cold blast Friday afternoon into Saturday, with wind chills near to below zero Friday night * Well below normal temps Saturday, moderating Sunday. Scattered snow showers possible both days * Another wintry mix precip event possible late Monday into Tuesday This portion of the forecast will begin with a significant cooldown, as a large high pressure approaches from central Canada. This will mean significantly colder air precedes this high pressure. Expecting high temperatures Friday to be early, then falling through the afternoon. Most areas will be in the single digits and teens by Saturday morning, with wind chill values near to below zero. This weekend is looking to be mostly dry, and definitely colder than we have been. A slight warming trend expected Sunday. There does remain a chance for some light precipitation with the passage of a couple of mid level shortwaves, but not looking like either would be a significant event. The window for any precipitation looks to be late Saturday into Sunday night, but not during this entire time. Exact timing will be important, with snow more likely, but some rainfall could develop towards the south coast of New England during the daytime. The most significant weather-maker during this portion of the forecast should still be sometime early next week. Still looks to be a progressive system. Guidance hinting at the development of a secondary low pressure somewhere across southern New England. Exactly where this sets up, it at all, will determine how much snow stays in the forecast. At this time, went with a rain/snow mix, again favoring snowfall at night, and across the higher terrain of central and western MA. Near normal temperatures expected early next week, with the possibility of slightly above normal temperatures Tuesday. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Tonight...Moderate confidence, mainly due to timing issues with the precipitation type changes. Slowed the arrival of the lower cloud bases by a couple of hours, especially across the eastern half of MA. High confidence in trends, but the timing remains a challenge. Confidence on precip type is low to moderate, but for interior terminals a SN to PL/FZRA, to RA transition is likely between 00Z and 12Z. Light winds out of the south become easterly overnight. Thursday...Moderate confidence. IFR/LIFR becoming MVFR by early afternoon. Mixed precipitation comes to and end from west to east, areas of IP/FZRA still possible through early afternoon. NE wind 10/15 kt gust to 20. Thursday night...moderate confidence. IFR cigs return with another round of precipitation. For terminals on the south coast of RI and in southeast MA will be -RA with -FZRA/IP elsewhere. Precip comes to an end after midnight. KBOS Terminal...High confidence in trends. Moderate confidence in timing. There remains a high degree of uncertainty as to the precip type from midnight through Thursday morning. Guidance indicates a potential for snow to change to PL much of the morning, or to mix with/switch back and forth from PL to RA. Currently leaning toward a more PL than RA forecast through the morning push. KBDL Terminal...High confidence in trends. Moderate confidence in timing. Highest degree of uncertainly is in precipitation type, PL or RA, between around 02Z and 06Z. Thinking right now is PL quickly changing to RA, but that change could be delayed. Outlook /Friday through Monday/... Friday: VFR. Strong winds with gusts up to 50 kt. Friday Night: VFR. Windy with areas of gusts up to 30 kt. Saturday: VFR. Breezy. Slight chance SN. Saturday Night: Mainly VFR, with local MVFR possible. Slight chance SN. Sunday: Mainly VFR, with areas MVFR possible. Breezy. Chance SN, chance RA. Sunday Night: VFR. Windy with gusts up to 30 kt. Slight chance SN. Monday: VFR. Breezy. Chance RA, chance SN. && .MARINE... Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Tonight...High confidence. Winds becoming SE and increasing to 15 to 20 kts gusting 20 to 25 kts by sunrise. Seas increasing to 2 to 4 ft. Thursday...High confidence. Winds becoming NE and increasing 15 to 20 kts gusting 25 to 30 kts. Seas buildings 5 to 7 ft. Outlook /Friday through Monday/... Friday: Strong winds with gusts up to 35 kt. Rough seas up to 9 ft. Slight chance of snow. Friday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Freezing spray, slight chance of snow. Saturday: Winds less than 25 kt. Local rough seas. Slight chance of snow. Saturday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of snow. Sunday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas locally approaching 5 ft. Chance of rain, chance of snow. Sunday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Seas up to 5 ft. Chance of rain, slight chance of snow. Monday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain, slight chance of snow. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...Winter Weather Advisory until 4 AM EST Friday for CTZ002>004. MA...Winter Weather Advisory until 4 AM EST Friday for MAZ002>012- 014-026. Winter Weather Advisory from 4 PM Thursday to 4 AM EST Friday for MAZ013-015>019. RI...Winter Weather Advisory until 4 AM EST Friday for RIZ001. Winter Weather Advisory from 4 PM Thursday to 4 AM EST Friday for RIZ002>005. MARINE...None. && $$ SYNOPSIS...Belk/BW NEAR TERM...Belk/BW/Gaucher SHORT TERM...BW LONG TERM...Belk AVIATION...Belk/BW MARINE...Belk/BW
hasn`t changed much from the previous forecast discussion where
deterministic and ensemble guidance continue to be in good agreement
showing a closed upper low originating on the Pacific coast Saturday afternoon, lifting northeast through the central CONUS Sunday and up through the Great Lakes on Monday. One big difference in the 12Z NWP was the development of a stronger secondary low along the Mid- Atlantic coast Monday night which acts to help keep a colder northerly flow across the forecast area. This favors snow as the dominant ptype as compared to previous runs where some wintry mix was introduced into southern Vermont. Given the event is over 5 days away, and the system is yet to be sampled by the upper air network, the forecast bears watching over the weekend. Seasonably cool and drier conditions are favored to follow for Wednesday. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... 2340z UPDATE... No major changes to the 00z TAFs except to insert some marginal 35 kt LLWS at 2000 ft for KMSS and KRUT based on the latest forecast soundings and to tighten up the window of the heaviest snow and blowing snow. Expect the heaviest snow and 1/4 mi vsby for KBTV between 05z and 09z. Cigs and vsby improve to MVFR to even low VFR after 12z as the brunt of the storm exits. PREVIOUS DISCUSSION... Through 18Z Thursday...VFR conditions will prevail through 00Z. Thereafter, a winter storm will produce significant impacts across the region with moderate to locally heavy snowfall expected through much of the remainder of the TAF period. Conditions quickly deteriorate after 00Z with ceilings lowering from VFR to MVFR and snow arriving between 01-04Z from south to north. Snow becomes heavy at times with visibility as low as 1/4SM through around 12Z. Snow will mix with sleet at KRUT at times, which should improve visibility toward IFR/MVFR. Additionally, developing northeasterly wind gusts of 25-35 knots will create near zero visibility at times at KMSS from 06-12Z. Conditions improve to MVFR by 15Z with snow ending, but low clouds persisting into the afternoon. Outlook... Thursday Night: Mainly MVFR, with local IFR possible. Likely SN, Chance SHSN. Friday: Mainly VFR, with local MVFR possible. Slight chance SHSN. Friday Night: VFR. NO SIG WX. Saturday: VFR. Chance SHSN. Saturday Night: Mainly VFR, with local MVFR possible. Chance SHSN. Sunday: Mainly MVFR, with local VFR possible. Chance SHSN. Sunday Night: Mainly VFR, with local MVFR possible. NO SIG WX. Monday: VFR. Slight chance SN. && .EQUIPMENT... A communications error is preventing information from exiting the KMPV AWOS. Technicians are looking into this issue; "AMD NOT SKED" will be appended until data is flowing again. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...Winter Storm Warning until 1 PM EST Thursday for VTZ001>011- 016>021. NY...Winter Storm Warning until 1 PM EST Thursday for NYZ026>031- 034-035-087. && $$ SYNOPSIS...Chai NEAR TERM...Boyd/Chai SHORT TERM...Lahiff LONG TERM...Lahiff AVIATION...Chai/Lahiff EQUIPMENT...WFO BTV
National Weather Service Hastings NE
510 PM CST Wed Feb 22 2023 ...AVIATION UPDATE... .DISCUSSION...(This evening through Wednesday) Issued at 450 PM CST Wed Feb 22 2023 -- Up front note: with various very short term (first 12-18 hours) concerns regarding wintry precip/dangerous wind chills dominating forecast efforts on this shift, this will be a very "short term heavy" discussion (versus the usual), with honestly minimal focus directed on the longer term (especially Days 3-7). -- KEY MESSAGES FOR THE ENTIRE 7-DAY FORECAST: * A combo of Winter Weather Advisories/Wind Chill Advisories will clearly remain the main story over the next 12-18 hours, although it should be noted that actual falling/accumulating snow should largely end within our coverage area (CWA) no later than 3-4 AM. * Although not expected to be a "major deal" at this point, another "sneaky" round of light snow could occur already Thursday night-Fri AM, which IF it materializes has the potential to catch some folks off guard. * Temperature-wise, it may seem hard to believe right now, but we are still looking at a rather abrupt warm-up this weekend (highs well into the 40s-50s and even some 60s south!), with slightly above-normal highs in the 40s-50s then persisting through mid- week. * Going hand in hand with the warm-up, a northward surge of seasonably-high dewpoints/low level moisture into our area Sunday COULD set the stage for a round of late-winter thunderstorms in at least parts of the CWA particularly Sunday evening. Although FAR from a sure thing at this Day 4-5 range, a few strong to marginally-severe storms (probably with mainly a hail threat) cannot be completely ruled out, and our southern CWA is already included in a rare February Day 5 severe risk area by SPC. -- More details/further information building upon the Key Messages above: 1) Changes worth noting from previous forecast (along with greatest uncertainties): - In the very short term, and based in part on freezing drizzle occurrence mainly earlier in the day, the official Winter Weather Advisory was expanded to include our ENTIRE Nebraska CWA (considered KS zones as well but with overall less potential for travel impacts there held off). - However, the Wind Chill Advisory for late tonight-Thurs AM (which already included our entire Neb CWA) WAS expanded to include 4 of our 6 KS counties where values as low as -15 to 20 appeared most likely (in collab with neighbors, left Osborne/Mitchell out for now, but still plenty cold there with chills of -10 to -15). - Although models vary in likelihood of occurrence, chances for at least light accumulating snow (PoPs) have been raised/expanded for Thurs night-early Fri AM. If snow does occur, a "sneaky" half inch or so could greet folks for the Fri AM commute (and potentially catch them off guard given this was largely a snow- free forecast period up until now. - Per final Key Message above, have officially introduced the Sunday evening thunderstorm chances to our Hazardous Weather Outlook (HWOGID). Although am not "sold" on a severe threat yet in our CWA (the main threat should focus off to our south), this system does bear watching for at least "elevated hailers"...especially in our east-southeast zones. Plenty of time for this to come into better focus before it arrives. 2) Basic precip overview: In addition to our ongoing wintry precip expected to wrap up late tonight, we also have the aforementioned "sneaky" snow chance for Thurs night-Fri AM and then the chance of rain/possible thunderstorms for Sunday afternoon-Mon AM. Beyond that, our forecast currently remains dry Mon afternoon-Wed, although the GFS would suggest perhaps a minor system moving through around Wed (high uncertainty). 3) Basic temp overview: Needless to say, we`ll see an abrupt swing from fairly brutal mid- winter cold to above normal, early-spring-like readings just over the course of the next 4-5 days! See short-term specific paragraphs below for more on the next couple days, but in short: very cold lows a few degrees either side of zero tonight, continued seasonably-cold highs Thurs mainly 10-25, one more very cold night Thurs night with lows again a few degrees either side of zero (but with less wind than tonight). Then the very beginning stages of a warm-up Friday (highs mainly 20-30) before a much more pronounced/legitimate warm-up commences over the weekend (widespread 40s to around 50 Sat/widespread 50s Sun with 60s mainly in KS). A slightly above normal regime then looks to continue Mon-Wed with highs a mix of 40s-50s. -- SHORTER TERM DETAILS FOCUSED SOLELY ON THE NEXT 36 HOURS/3 FORECAST PERIODS: - CURRENT/RECENT WEATHER SO FAR TODAY: Admittedly, today`s conditions have been a bit worse overall than expected. Although actual snow totals so far today have been less than a half inch in most places, many places also observed at least a brief period of freezing drizzle that put a very light glaze on some area roads. Preceding overnight forecaster had pulled the threat of freezing drizzle with expectation that it would be slightly too cold to maintain liquid/non-frozen droplets, but as it turned out it stayed JUST warm enough in the low levels (temps slightly above -10 C or roughly 14 F) to allow at least limited freezing drizzle. To be fair, most places only saw a light icing/glaze, but in combo with the fairly persistent light snow that either mixed with or occurred after the drizzle, we`ve had several reports of at least modestly-slick roads as supported by NDOT 511 page. Given increasing odds for a slick evening commute for a good chunk of our CWA, expanded the Winter Weather Advisory to include all of our Neb counties. Considered extending into at least our top row of KS counties as well, but with overall-less travel impacts and less potential for accumulating snow there later tonight, opted against it for now. Briefly touching on the ACTUAL meteorology, in the mid-upper levels water vapor satellite and short term model data confirm very active, southwesterly flow, with one shortwave trough passing off to our east (responsible for earlier/ongoing precip) and the next/primary disturbance steadily approaching from eastern CO (responsible for the "main round" later this evening). At the surface, temps have steadily fallen today (as expected) with current readings ranging from around 7 far north/west-central to as "warm" as low-mid 30s far southeast. North winds were also every bit as strong as expected, with widespread gusts at least 30-35 MPH earlier in the day. Fortunately, speeds have decreased slightly this afternoon, but still averaging sustained around 20 MPH/gusts 25-30. - THIS EVENING-OVERNIGHT: Officially, have no mention of freezing drizzle going beyond 00Z/6 PM, as the continued invasion of increasingly-cold low level air should keep "forcing" precip type over to snow. While many areas will see a multiple hour "lull" in snowfall late this afternoon/early evening, want to make it very clear that the MAIN ROUND of accumulating snow will not occur until the 8 PM-Midnight time frame, during which time the aforementioned eastern CO disturbance will send a quick-hitting band of steady light to briefly- moderate snow across mainly the northwest 2/3rds of our CWA. As noted by previous forecaster, this round of snow could be a bit "convective" in nature...not necessarily true thunder snow but with perhaps a few narrow bands of heavier snow with lesser amounts in between them. Officially, made minimal change to our storm total snow forecast, still calling for most areas south/east of the Tri Cities to only receive around one-half inch or less, ramping up into the 1-2" range farther north/west (perhaps including G.I/.Kearney) and then the overall highest amounts of 2-3" mainly targeting our far north (Valley/Greeley/Sherman). Again though, any enhanced banding could lead to some places even south/east of the Tri Cities to slightly over-achieve. Fortunately, this later evening round of snow will be fairly brief, but travel could be dicey for a time given that northwest winds will actually increase a bit overnight (gusts into the 25-35 MPH range), resulting in areas of blowing/modest drifting. Leaning on higher-res models such as HRRR, actual falling snow should completely vacate our far north-northeast zones by around 3-4 AM, but for now will allow official Winter Wx Advisory to run through 6 AM to account for residual blowing snow. As for the Wind Chill Advisory, opted to expand southward to include 4 of our 6 KS counties, as they will be "close enough" to our official Advisory criteria of -20 to justify. We will actually come very close to flirting with Wind Chill Warning criteria (-30) in a few counties north/west of the Tri Cities, but with the vast majority of the CWA looking to remain just "warmer" than this, decided to continue a "high end" Advisory. Actual low temps tonight are aimed from around -4 far north/west central, to around +8 far southeast (Beloit KS area). - THURSDAY DAYTIME: Right off the bat, the Wind Chill Advisory officially continues until Noon, so that`s the main concern. Any falling snow will be long over by sunrise, so confidence remains high in a dry/snow- free day with skies actually averaging mostly sunny a good chunk of the time. Although the day starts plenty breezy/windy (sustained 15-25/gusts 25-35 MPH), fortunately speeds will decline as the day wears on, with speeds by mid afternoon down to 10-20 MPH sustained/gusts 15-25 at worst. Although the sunshine and gradually decreasing winds will make it feel better than today, it will still be quite cold by late-Feb standards with highs only ranging from around 10 far north, teens central to low- mid 20s in KS zones. - THURSDAY NIGHT: The million dollar question (by far) is whether we get a "sneaky" round of light snow, especially late in the night but perhaps starting already in the evening. Some models (GFS) hit this potential harder than others (NAM), but even the latest ECMWF has come around to it more than the previous run. Forcing-wise, in short, this would be sparked by a low amplitude mid level wave inducing broad/weak mid level warm air advection. Even "worst case scenario" at this point suggests no more than 1" of snow, but again this was a dry forecast period only 24 hours ago so this bears watching! Officially, our forecast calls for up to around one-half inch of snow, but PoPs have been kept pretty modest (but higher than before) at 20-30 percent most areas. Temp-wise, increasing clouds could prove our low temp forecast to be too warm, but will call for most areas a few degrees either side of zero. Fortunately, much lighter winds than tonight (generally 5-15 MPH out of the northeast) should keep Wind Chills from reaching Advisory levels, but still plenty cold bottoming out near -20 far north to around -10 far south. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Friday) Issued at 459 PM CST Wed Feb 22 2023 Light snow is expected to fall over the TAF sites to around midnight tonight. Late this evening a heavier snow band is being forecast by the HRRR and RAP which should lower vis back down to IFR. Looking at surrounding obs this afternoon expect vis to bounce between IFR and VFR until the snow band moves. IFR visibility is expected with the snow band. The winds will remain gusty overnight into the AM before tapering off in the afternoon. && .GID WATCHES/WARNINGS/ADVISORIES... NE...Wind Chill Advisory from midnight tonight to noon CST Thursday for NEZ039>041-046>049-060>064-072>077-082>087. Winter Weather Advisory until 6 AM CST Thursday for NEZ039>041- 046>049-060>064-072>077-082>087. KS...Wind Chill Advisory from midnight tonight to noon CST Thursday for KSZ005>007-017. && $$ DISCUSSION...Pfannkuch AVIATION...Beda
Area Forecast Discussion
National Weather Service Grand Rapids MI
923 PM EST Wed Feb 22 2023 LATEST UPDATE... Update .UPDATE... Issued at 913 PM EST Wed Feb 22 2023 Impactful storm continues for the region. Power outages have been climbing rapidly into the evening hours with the bulk of the outages south of a South Haven to Lansing line. Radar trends indicate that the precipitation will continue for another 2 to 3 hours. The temperature has climbed up to 34 around Kalamazoo and South Haven...but it has stalled its climb further north and east and in some cases its falling. As a result we delayed any transition to rain for places like Battle Creek and Jackson where impacts were growing. Further north...for Grand Rapids and Lansing...the thickness of the ice has been increasing steadily. With another couple of hours of freezing rain...we should see a steady increase in the power outages for those locations as well. Moderate to heavy snow has been falling near and north of Big Rapids to near Mount Pleasant line. This is the region where we have the highest snow amounts predicted. After midnight a steady decrease in the precipitation intensity is expected as the main lift pushes east of the region. && .DISCUSSION...(This evening through next Wednesday) Issued at 347 PM EST Wed Feb 22 2023 --Warnings continue into early Thursday-- So far the impacts from this storm have not been too overwhelming, especially along the I-94 corridor where MDOT website still shows traffic moving along at normal speeds. This is probably related to marginal sfc/road temps right around 32 as well as late Feb insolation. Travel speeds however do look lower north of the I-94 corridor due to slightly colder temps. Still several reports of sleet along I-96 per MPing and mostly snow to the north of I-96. Will hang on to all existing headlines as is since the heaviest precipitation rates are still to come. Regional radar shows convective precip approaching from the southwest and a band of tstms from cntl Il into nrn IN which may eventually impact the I-94 corridor. Those heavier rates along with approach of dark should cool the boundary layer back down and increase the impacts, even near the I-94 corridor. Axis of highest QPF has shifted slightly more south in 12Z HREF, with amounts over 1.5" clipping JXN then trailing off northward to around 1" at GRR and 0.50" at LDM. Freezing rain algorithms which account for precip rates, web bulb temps and winds continue to highlight the ice storm warning area with a half inch or more of ice accretion, especially over eastern sections of the warning where heaviest QPF is expected. Short range guidance still shows the warm wedge aloft pushing north and becoming more pronounced with time as we move into the evening hours. This will spread the sleet threat farther north and possibly result in more of the way of freezing rain vs sleet up to the I-96 corridor. From an Bourgouin/energy p-type method standpoint however, RAP shows sufficient negative cape/energy down low to maintain a prevalence of sleet in the I-96 corridor. Those favorable capes in lowest 4K ft actually appear to sag slightly southward again from after 00Z, implying that the sleet threat could even expand back southward before the heavier precip exits after 10 PM. Expect to see a transition to mainly freezing drizzle after 10 PM as the mid level dry slot arrives from the southwest. Snow and blowing snow has been fairly impactful over the nrn CWA today and we`ve heard reports of 4" in Big Rapids already. Another 3-6" possible up north before tapering off after midnight. The arrival of the warm wedge/sleet may begin to hold down snow amounts by 00Z especially near and south of M-20. Still looking at some impactful wind gusts up to 45 mph on Thursday as west-southwest winds pick up quickly over the southern half of the area toward Noon. This will coincide with temps briefly warming into the 40s over the same area, but temps crash back into the teens thursday night. Winds relax later Thursday night into Friday but some lake effect flurries may persist. --Relatively quiet weekend weather-- After a weak shortwave in zonal flow aloft brings a chance of light snow Friday night, a large sfc high slides across the region over the weekend. This should provide relatively benign weather with highs in the mid to upr 30s. --Another storm Monday-- Medium range guidance is in good agreement in sending another system our way around next Monday. Upper low moves from srn CA to the 4 corners then ejects northeast. Still spread in sfc low track/position but ensemble mean has it over srn Lwr MI 00Z Tue. Current thermal profiles suggest mostly rain, although a mix is possible north of I-96. Another deep system is suggested in guidance later next week which may be colder with a better chance of mainly snow vs rain or a mix. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 636 PM EST Wed Feb 22 2023 The main surge of precipitation was pivoting through the TAF sites at this time with most sites reporting freezing rain mixing with sleet/snow. There were even a few lightning strikes near KJXN over the past 2 hrs. The surface temperatures have been holding steady early this evening which has resulted in the freezing rain persisting around KAZO...KBTL and KJXN. Based on those trends...along with an east northeast wind...we did prolong the mention of freezing rain in those TAF sites. Further north the wintry mix will continue through the heaviest precipitation part of the storm. While we will see a diminishing trend to the intensity of the precipitation near and after midnight...we will see freezing drizzle persisting into Thursday morning. The southern TAF sites of KAZO...KBTL and KJXN may see the temperatures climb a few degrees above freezing which will diminish the freezing drizzle. IFR and lower conditions will likely prevail through the night. On Thursday the wind shifts and become westerly as the storm pulls east of the TAF sites. The temperature will climb above freezing. However...IFR will likely persist into the afternoon. && .MARINE... Issued at 347 PM EST Wed Feb 22 2023 Gale warning has been issued south of Whitehall for Thursday afternoon and evening as winds crank up abruptly on back side of departing winter storm. Otherwise SCA continues in brisk east flow. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...Winter Storm Warning until 1 PM EST Thursday for MIZ037>040- 043>046. Winter Storm Warning until 4 AM EST Thursday for MIZ050>052- 056>059. Ice Storm Warning until 4 AM EST Thursday for MIZ064>067-071>074. LM...Small Craft Advisory until 11 AM EST Thursday for LMZ844>847. Gale Warning from 11 AM to 10 PM EST Thursday for LMZ844>847. Small Craft Advisory until 10 PM EST Thursday for LMZ848-849. && $$ UPDATE...MJS DISCUSSION...Meade AVIATION...MJS MARINE...Meade
National Weather Service Jackson KY
907 PM EST Wed Feb 22 2023 .UPDATE... Issued at 907 PM EST WED FEB 22 2023 Valley winds have died down considerably, while ridges and open terrain remain stronger. The Wayne County mesonet site is marginally meeting Lake Wind Advisory criteria, and the advisory is left in place for the time being. && .SHORT TERM...(This evening through Thursday night) Issued at 512 PM EST WED FEB 22 2023 Aloft, the region remains under a west-southwest flow regime. Our next upstream shortwave will move out of the Plains overnight and into the Upper Midwest and Great Lakes through the day tomorrow. At the surface, a trough will pass through the Commonwealth overnight, kicking off some showers and laying out a third to half inch of rainfall across the area. Winds have begun to decrease across the area through the mid to late afternoon. It appears we had an isolated gust or two to around 40 mph earlier today but overall it seems the Lake Wind Advisory may have represented actual conditions better than a full advisory. SPC`s HREF does show H850 mean winds (65-70 kts) increasing across mainly the northern half of the forecast area this evening. However, models (12Z & 18Z runs) continue to suggest enough decoupling of the boundary layer will occur to keep those highest wind gusts off the surface. There does appear to be a temporary (01Z-04Z) weakening of the nocturnal inversion just as the core of highest winds transit the area. Thus can not totally rule out some additional higher wind gusts mixing to the surface at times, especially with the aid of some of the shower activity should it move into eastern Kentucky sooner than expected. The latest runs of the HRRR suggest this could be a possibility. Therefore allowed the current Lake Wind Advisory to continue. After digging a bit, Thursday appears more interesting than anticipated. After near record highs today, it begs the question of whether we see even warmer temperatures Thursday. Skies clear (at least partially) through the morning behind the exiting disturbance. Record high temperatures will basically boil down to how much sun light we see versus cloud cover. This will have other implications as well. The more sunlight we realize, the warmer temperatures will get, the deeper the mixing that takes place across the area. This would allow a considerable amount of drier air to mix to the surface and allow for a better mixing of higher wind gusts to the surface as well. This would increase the possibility of reaching critical fire weather conditions. For now trended lower with minimum afternoon RH values and will see what comes in with the next runs. Showers are expected to produce between a third and half inch of rainfall overnight. This one positive would definitely help with fuel moistures, and improve conditions. .LONG TERM...(Friday through Wednesday) Issued at 318 PM EST WED FEB 22 2023 In the extended, we will see alternating periods of dry and quiet and weather and wet and very active weather. The period will start off dry and quiet on Friday, as a ridge of high pressure temporarily settles over the region. Cloud cover will be slow to decrease, as another weather system will be moving across the Tennessee Valley Friday night into Saturday. This first system will bring scattered to numerous rain showers to eastern Kentucky going into the weekend, as an area of low pressure moves eastward along a slow moving frontal boundary to our south. As this first round of rain moves through, another much strong weather system will be taking shape over the central Plains. This second system will begin moving our way Sunday night, with a warm front bring scattered rain showers to the area to end the weekend. As the low moves closer on Monday, the rain will become widespread, and could be heavy at times late in the day. The rain will continue to move to the east Monday night and will quickly taper off, with the precip likely exiting the area by early Tuesday morning. The other aspect of this second weather system will be wind. The last model data has winds of 35 to 50 mph accompanying the second low as it moves through Monday through Tuesday. Sustained south to southwest flow of 15 to 25 mph, with gusts of up to 40 mph, or perhaps higher, will not be out of the question Monday and Monday evening. The winds should gradually die down Tuesday afternoon and evening. High pressure should bring dry and pleasant weather to our area Tuesday through Wednesday, along with lighter winds and mostly clear to partly cloudy skies. Temperatures through out the extended will generally be above normal. Highs on Friday and Saturday should rise into the low to mid 50s across eastern Kentucky. After that, we should see much warmer daytime readings ranging from the upper 50s to lower 60s. Monday may see the mercury max out in the upper 60s to lower 70s as the strong southerly winds kick in. Nightly lows will follow suit, with the coolest nights averaging out in the upper 30s, with the warmest night only falling into the 40s for most of the area. Sunday night we may even see lows only falling into the upper 40s to lower 50s south of I-64. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) ISSUED AT 907 PM EST WED FEB 22 2023 VFR conditions prevailed at the start of the period, but mid level ceilings in the 10-15K ft range were beginning to make their way into the area from the northwest. Winds were still brisk over ridges and open terrain, gusting 20-30 kts, but had died down quite a bit in valleys. Showers were over central KY, about to enter the area. As the area of showers progresses southeast across the area between about 03-09Z tonight, ceilings will lower, eventually settling to MVFR in most places. The showers will taper off from northwest to southeast overnight and early Thursday morning, but MVFR ceilings are expected to linger a short time after the rain. Clearing will take place during the morning and early afternoon, with VFR conditions then lasting until evening. Winds will diminish overnight, with gusts subsiding to generally less than 20 kts. However, they will pick up again during the day Thursday, especially after clouds break up, with gusts above 20 kts in the afternoon. && .JKL WATCHES/WARNINGS/ADVISORIES... Lake Wind Advisory until 1 AM EST Thursday for KYZ051-052-060- 079-080-083>085-106. && $$ UPDATE...HAL SHORT TERM...RAY LONG TERM...AR AVIATION...HAL
Area Forecast Discussion
National Weather Service Melbourne FL
944 PM EST Wed Feb 22 2023 ...New UPDATE, MARINE, AVIATION, PREV DISCUSSION... .UPDATE... Issued at 944 PM EST Wed Feb 22 2023 As has been the case the last few nights, skies rapidly cleared out around sunset, with much less this cirrus overhead due to the upper ridge having shifted east over the peninsula. Surface and low level winds are more backed, which is expected to keep both coverage and density of late night/early fog much lower than last night. To wit, the afternoon/evening HRRR runs have been steadfast in showing nil in the way of visibility reductions, even with its propensity to sometimes overdo fog events (kudos to the model for being pretty much right on the money for this morning`s event). Given that the surface ridge has shifted northward into central Florida, still expect at least patchy, mainly shallow fog to form overnight, mainly inland from I-95. Current forecast looks fine with slightly warmer mins in the L60s. && .MARINE... Issued at 944 PM EST Wed Feb 22 2023 Overnight...Based on current NOAA Buoy 41009 ob showing sustained south winds of 18kt, plan to keep the Cautionary Statement going for the outer Volusia/Brevard into the overnight hours. Both winds and 3-4ft seas should subside late. && .AVIATION... (00Z TAFS) Issued at 944 PM EST Wed Feb 22 2023 Generally prevailing VMC. Patches of MVFR to possibly IFR VSBYs 1-2SM BR) in mist/fog 09Z-13Z, possibly accompanied by LCL IFR to LIFR ST CIGs. However, with the model guidance unanimously unenthused with the prospects of dense fog, have maintained the current idea of fog being mainly shallow, with limited spatial coverage/temporal extent. && .PREVIOUS DISCUSSION... Issued at 345 PM EST Wed Feb 22 2023 Thursday...Conditions will improve quickly by mid morning, giving way to quickly warming temperatures. Record highs may be in jeopardy at several sites, especially across the interior on Thursday, as temperatures reach the mid 80s to near 90 degrees. Friday-next Wednesday...Strong mid-level ridge will remain in place over the Florida peninsula through the weekend before shifting slightly southward early next week. This ridge will assist in keeping temperatures warm, conditions mostly dry, and winds will remain around 10 mph. Sea breeze development is also likely thanks to the temperature gradient between the peninsula and local waters. On Tuesday of next week, there is some indication of a very weak frontal passage as the mid-level ridge shifts southward, but this front will provide very little relief in the way of temperatures. Some isolated showers may be possible across the northern portions of Volusia and Lake counties and across the adjacent Atlantic waters in association with the weak front, but confidence isn`t high this far out. Temperatures will continue to be the highlight of the long term forecast, with afternoon highs generally in the mid 80s along the coast and the upper 80s to near 90 across the interior west of I-95. This is around 10 to 15 degrees above normal for this time of year, with many interior sites potentially breaking record highs over the next several days. Should highs reach 90 degrees or even low 90s, this will not only break daily record highs but also threaten record highs for the month and Winter Season (see climate section below for values). Overnight lows will be about 5 to 10 degrees above normal, ranging from the upper 50s to mid 60s across east central Florida. These temperatures will be close to the forecast dewpoints, and with mostly clear skies and lighter winds during the overnight hours, patchy to areas of fog development will be possible most nights through the early morning during the period. && .MARINE... Issued at 345 PM EST Wed Feb 22 2023 Thursday...High pressure continues to prevail over the local waters. Southerly decrease to around 10 kts, with seas subsiding to 2-3 ft. Friday-Monday...High pressure over the Florida peninsula will keep conditions dry through the period. Generally favorable boating conditions Friday through Saturday as southerly winds between 5 to 10 knots keep seas right around 1 to 2 feet. Sunday, winds veer to out of the west and increase to 10 to 15 knots across the local offshore Atlantic waters, causing seas to build to 3 to 4 feet in the Gulf Stream. Monday, winds become southerly again at 10 to 15 knots and seas remain around 2 to 3 feet. && .FIRE WEATHER... Issued at 345 PM EST Wed Feb 22 2023 Thursday-Sunday...High pressure over the west Atlantic slides westward across the area late this week into the weekend, keeping unseasonably hot and dry conditions in place through the period. Highs will continue to be near record values over the interior for the next several days. The east coast sea breeze will be able to form each afternoon and move inland, keeping RH values at the coast above critical levels. Over the interior, Min RH values during the afternoon are forecast to fall as low as the mid 30s to low 40s. Wind speeds, however, look to remain around 10 mph or less, so Red Flag Warnings are not expected. Still, very warm and continued dry conditions will lead to more fire sensitive conditions. Additionally, fog development, as well as settling of smoke near or immediately downwind of prescribed burns or any new brush fires, will be a continued concern during the late night and early morning hours. && .CLIMATE... Issued at 345 PM EST Wed Feb 22 2023 Near record highs are expected over the next several days, mainly across the interior. Highs near the 90 degree mark are possible across the interior, especially on Thu, which could tie or potentially break record highs for the month and even the Winter Season! Daily Record Highs For the Next 5 Days (Through 2/27): 23RD 24TH 25TH 26TH 27TH LOC HI-MAX HI-MAX HI-MAX HI-MAX HI-MAX DAB 87 2013 88 2012 87 2022 89 1939 87 1971 LEE 87 2019 87 2012 88 2022 87 2018 86 2021 SFB 88 2019 89 2012 89 1962 89 1971 89 1962 MCO 89 2013 90 1962 90 1962 89 1971 89 1962 MLB 90 1961 92 1962 87 2013 91 1939 87 1977 VRB 89 2008 90 2019 87 2020 87 2018 87 2007 FPR 89 1932 90 2012 87 2020 90 1928 90 2007 Record Highs for the Month of February and for the Winter Season (Dec-Jan-Feb) and Last Occurrence: LOC FEB HI-MAX WINTER HI-MAX DAB 89 02/01/1985 89 02/01/1985 LEE 89 02/22/1991 89 02/22/1991 SFB 89 02/24/2012 89 12/18/2016 MCO 90 02/25/1962 90 12/07/1978 MLB 92 02/24/1962 92 02/24/1962 VRB 90 02/24/2019 90 02/24/2019 FPR 90 02/24/2012 90 02/24/2012 && .PRELIMINARY POINT TEMPS/POPS... DAB 84 63 87 62 / 0 0 0 0 MCO 88 64 90 64 / 0 0 0 0 MLB 84 64 86 63 / 0 0 0 0 VRB 85 64 87 62 / 0 0 0 0 LEE 87 64 89 64 / 0 0 0 0 SFB 88 64 89 63 / 0 0 0 0 ORL 88 65 90 65 / 0 0 0 0 FPR 84 64 86 62 / 0 0 0 0 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...None. AM...None. && $$ SHORT TERM...Cristaldi LONG TERM....Pendergrast AVIATION...Cristaldi
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
936 PM CST Wed Feb 22 2023 .UPDATE... Issued at 907 PM CST Wed Feb 22 2023 We have not made significant changes to the pop/snow forecast for the rest of tonight. We`ll see multiple bursts of snow, with short lulls in between the rest of the night. The heaviest band of snow is expected to impact the area with the wave currently moving across Nebraska. This shortwave will come in just before sunrise and is the one that will have the potential to see a 3 or 4 hour period where snowfall rates are pushing over 1" an hour. So the final burst will be the strongest one as well. The one area of the forecast we have changed are the wind speeds and gusts. In both cases, we have knocked them down from what we had going. Simply put, observations have been coming in quite a bit lower than forecast, with the latest update keeping sustained winds more 25 to 30 mph, with gusts of 35 to 40mph. From looking at our 00z sounding, we have a huge hook in the low level hodograph, which means we have rapidly changing wind directions with height. To be efficient with mixing stronger winds down to the surface, you want a deep layer of relatively uniform wind directions and this is not what we have tonight. We didn`t make any changes to the headlines, but with this decrease in wind speeds, we may be able to start dropping the blizzard headline as the burst of heavy snow in the morning moves out. && .SHORT TERM...(This evening through Thursday night) Issued at 318 PM CST Wed Feb 22 2023 KEY MESSAGES: - Travel will become increasingly difficult this evening, and nearly impossible tonight as winds increase and snow intensifies. No changes to warnings or advisories. - Overall snowfall amounts have trended a bit less, but significant snow is still expected area-wide. Not too much has changed from the previous forecast regarding the current winter storm. Snow over southern MN will continue pushing northward as the first shortwave (of two) passes thru IA and into WI this evening. Snow and increasing winds have already caused widespread visibilities to fall below 1 mile in southern MN. The entire area will see snowfall with this first wave, but the heaviest snow should remain across southeastern MN into our eastern WI counties. Here, another 4-6" is expected into midnight. Areas north will generally see another 2-4" from lighter snowfall rates this evening. Northeasterly winds should also increase from the tightening surface pressure gradient along with gusts due to the deepening of the boundary layer. Sustained winds will range from 20- 25 knots area-wide and up to 30 knots in west-central MN. With gusts of 30-35 knots (approaching 40 knots in west-central MN), the snowfall, and fresh snowpack, blizzard conditions will develop across much of western, central, and southern MN by this evening. Travel within the Blizzard Warning will be nearly impossible so it is highly advised people stay off of the roads and remain inside. Meanwhile, a second, stronger shortwave will approach from the southwest late this evening. A stronger jetstreak and sharper trough axis make this wave much more impressive than the first. As this feature tracks through MN and WI, strong dynamical lift will reinforce and expand the existing precipitation, with enhancement focused from western MN east-northeast into central MN. Heaviest snow will begin in our west this evening, translating ahead of the wave through the overnight hours. While PWATs are not too high (around 0.5"), forecast soundings across most of our MN CWA show potential for a very deep DGZ (due to cooling thermal profiles) amid the very strong lift. In fact, RAP and HRRR soundings in central MN show multiple hours of +10kft DGZs (with even some double DGZ layers) from midnight into Thursday morning. HREF shows additional support with a multi-hour period 1-1.5" per hour snowfall rates translating northeast through south-central MN. These heavy snowfall rates and ongoing winds will deteriorate already poor conditions within the Blizzard Warning that will last through the Thursday morning commute. Large drifting, impassible roads, and next to no visibility is expected for western, central, and southern MN. Conditions won`t be much better for the Twin Cities and areas east as significant snowfall and gusty winds will lead to near blizzard conditions. The overnight snow will quickly accumulate resulting in 10-14" total (with locally higher amounts possible) for western and central MN, much of the Twin Cities metro, and portions of western WI through Thursday morning. Elsewhere, snow totals from the event should range from 5-9". Snow should taper off as we progress on Thursday as the shortwave moves away. However, light snow/snow showers could last quite late into Thursday afternoon judging from forecast soundings as cold air moves in behind the system. Winds will also turn northwesterly and slow during Thursday. Clouds should begin to break up Thursday evening as temperatures plummet with the incoming cold air mass Thursday night. Lows by Friday morning are expected to be in the negative single digits in our east to upper negative teens in our west. Combined with the still breezy winds, wind chill values will range from -20 to -30 across the western half of MN. .LONG TERM...(Friday through Wednesday) Issued at 318 PM CST Wed Feb 22 2023 KEY MESSAGES: - Another system could bring wintry precipitation early next week. Our adventures with split flow look to continue as we move into the latter portion of the forecast period. A southwest US upper low will be reloading as we head into the weekend, with periodic shortwaves embedded in northwest flow moving through our area from Friday into the first part of the week. The western upper low looks to eject out into the Plains by Sunday night, before lifting northeast toward the lower Great Lakes by Monday night. We continue to be on the northwest edge of the precipitation shield associated with this upper feature and associated surface low. However, there is a fair bit of spread in the ensemble guidance beyond Saturday, so it doesnt appear to be a situation to stray much from the NBM consensus guidance. We might see some flurries or very light snow across the area Friday night as we start to get into the return flow of the surface high, but it may not be worth mentioning in the forecast given the light nature and low probability of occurrence. More robust warm advection commences on Saturday, but the airmass will be quite dry, so no precipitation is expected. A weak shortwave trough and surface reflection will move through Saturday night, but at this point it appears that any precipitation will stay to our north. Eyes then turn to the system lifting out of the southwest US and southern plains. Lee side cyclogenesis looks to occur late Sunday, with the surface low then tracking generally through the southern Plains Sunday night and into the lower Great Lakes by Monday night. We warm up over the weekend, and given its a southern stream wave, there looks to be a fair amount of warm air associated with it, so precipitation-type will be a concern as it moves up into our area. As mentioned, there is still quite a bit of spread in the guidance with respect to the track, timing, and intensity of the upper trough and surface low, with the 12Z GFS being a more northwest solution than much of the other guidance (although the ensemble envelope certainly includes similar solutions). Although forecast soundings suggest an elevated warm layer, which could result in an area of freezing rain, surface temperatures may be near or above freezing where that elevated warm layer is sufficiently warm to melt hydrometeors Sunday night into Monday night. At this point, will keep things simple and stick to a mention of rain/snow in the forecast and avoid additional precipitation types. As things get nearer in time we should have a better handle on the details of the thermal profile and can refine more specific locations where sleet and/or freezing rain could also occur. Once the Sunday/Monday system departs a ridge of high pressure will briefly build across the area, with dry weather expected Tuesday into early Wednesday. An upper trough embedded in westerly flow will move through the region on Wednesday, along with what should be a weak attendant surface low. There wont be too much moisture return ahead of this feature, but there appears to be sufficient forcing and moisture to include a mention of chance PoPs with perhaps a rain/snow mix (mainly in the south) once again. With the exception to the cold start of the period on Friday, we`ll generally see temperatures near or above normal through the period. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 611 PM CST Wed Feb 22 2023 Not much flying will be happening in and out of local airports tonight, with snow expected to continue into much of the morning. The snow will come in pulses, with visibilities bouncing around quite a bit for much of the night, but did focus the worst conditions to when the wave currently coming out of Denver gets here. This wave is expected to bring more persistent and widespread 1/4sm or less vis in snow for about a 2 or 3 hour window. Timed this heavy burst in with the HRRR/RAP. Behind this wave, snow should end pretty quick and we may see cigs start to break up as well, but for now, kept MVFR cigs in place until we get a better feel of how cigs will act in the wake of the snow. Only noticeable change from the previous forecast is we did back down on the winds some as wind observations have not been getting up to what we`ve been forecasting. KMSP...The snow tonight looks pulsy, but it`s the window from 10z to 13z when the wave from Denver gets here that looks to feature the worst conditions, with 1/4sm or less visibilities likely. Behind that, snow intensity will diminish quickly, with snow expected to basically be done around 18z. For the end of the TAF, confidence is lower with what any post storm stratus field will look like, but clearing is expected at some point Thursday afternoon into the evening. /OUTLOOK FOR KMSP/ Fri...VFR. Chc IFR/-SN in evening. Wind WNW 5 kts bcmg S. Sat...VFR. Wind SW 10-15 kts. Sun...VFR. Wind SE 5-10 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...Blizzard Warning until noon CST Thursday for Blue Earth-Brown- Carver-Chippewa-Douglas-Faribault-Freeborn-Kandiyohi-Lac Qui Parle-Le Sueur-Martin-McLeod-Meeker-Nicollet-Pope-Redwood- Renville-Rice-Scott-Sibley-Stearns-Steele-Stevens-Swift-Waseca- Watonwan-Wright-Yellow Medicine. Winter Storm Warning until noon CST Thursday for Anoka-Benton- Chisago-Dakota-Goodhue-Hennepin-Isanti-Kanabec-Mille Lacs- Morrison-Ramsey-Sherburne-Todd-Washington. WI...Winter Storm Warning until noon CST Thursday for Barron-Chippewa- Dunn-Eau Claire-Pepin-Pierce-Polk-Rusk-St. Croix. && $$ UPDATE...MPG SHORT TERM...CTG LONG TERM...WFO MPX AVIATION...MPG
Area Forecast Discussion
National Weather Service Pendleton OR
334 PM PST Wed Feb 22 2023 .Updated Aviation Discussion. .SHORT TERM...Tonight through Friday night...A large upper low pressure system is currently centered over the Pacific Northwest. Shortwave troughs are rotating around this parent upper low. The most recent shortwave trough moved over the forecast area this morning, in combination with an arctic cold front, which is bringing in much colder temperatures. An area of snow developed over the Foothills of the Northern Blue Mountains this morning, and produced a quick 2-3 inches over these northern Foothills. The HRRR model has done the best in forecasting this area of snow, both with timing and position of where the snow was at. The snow is tapering off now, as was forecast by the HRRR to do so by this time. The HREF also did well in forecasting this area of snow. A Winter Weather Advisory is currently in effect for the northern Foothills and the Blue Mountains until 4 PM PST. This may be able to end sooner if the dissipating trend continues. There is also a Winter Storm Warning in effect until 4 PM PST for the east slopes of the OR Cascades. Current radar imagery is still showing snow moving over the Cascade crest onto the east slopes, mostly over northern OR. This warning may be able to continue until its expiration time at 4 PM PST. The large parent upper low pressure system is forecast by all of the deterministic and ensemble models to persist over the PacNW through Thursday. Then the center of the low is forecast to retrograde south-southwest to a position off the northern CA coast by Friday morning. It will break off the parent upper trough leaving the forecast area between it and a weaker upper trough over northeast WA. This will allow more drying to take place on Friday into the extended period on Saturday. Very cold air will continue to move into the CWA tonight and persist through Friday night. Record low temperature will be possible over a good portion of the forecast area, mainly from central OR north and northeast across the Lower Columbia Basin, the Blue Mountain Foothills and the Yakima/Kittitas Valleys. The cold air will be the primary concern over the next couple of days. High temperatures are expected to be only in the 20s over the lower elevations and in the teens over the mountains on Thursday. Then temperatures will moderate a couple degrees on Friday with highs in the mid 20s to lower 30s lower elevations, and mostly in the 20s in the mountains. Night time lows will be in the teens lower elevations and single digits in the mountains tonight. Then Thursday night`s lows are forecast to be in the lower to mid teens lower elevations, and single digits in the mountains, with possibly a few single digits below zero in high elevation meadows such as Bear Valley. Friday night`s lows are expected to be in the teens over most of the CWA, with some single digits and teens in the Ochoco-John Day Highlands. Areas that received fresh snow last night and this morning could be colder if skies clear out and winds remain light, due to strong radiational cooling. These temperatures are well advertised by the HREF and the NBM 1D Viewer. Temperatures will continue to moderate going into the extended forecast period on Saturday. The GFS ensemble is showing temperature anomalies to be 20 to 30 degrees below normal across most of the forecast area tonight through Friday night. The exception is in areas east of the Blue Mountains which will be mostly 5 to 10 degrees below normal. The ECMWF and Canadian ensembles are showing temperatures anomalies to be about 10 degrees warmer than the GFS ensemble. Due to these differences, will lean to the NBM temperature forecast guidance, which is between the GFS vs the ECMWF and Canadian ensembles. Some areas of the Lower Columbia Basin, the Yakima/Kittitas Valleys, and the ridges between the Yakima/Kittitas Valleys and the Lower Columbia Basin are expected to remain breezy to windy tonight. As a result, wind chill temperatures will be very low, with values between zero to -10 in the valleys, and -10 to -20 on the ridge tops where the winds will be strongest. Most of the populated areas will be in the zero to -10 range tonight, and then about 5 to 10 degrees warmer Thursday night due to lighter winds. In any case, this scenario will be watched in case wind chill highlights become needed. 88. .LONG TERM......SATURDAY THROUGH WEDNESDAY...The extended period is characterized by an active weather pattern through the beginning of next week as a shortwave and associated upper level low pressure system drives through the Pacific Northwest. This will allow for mountain snow chances to return to the forecast Sunday onward, with the potential for a dusting of snow along the Blue Mountain Foothills and east slopes of the Cascades each day. The other weather concern resides with breezy conditions early in the week, with wind gusts of up to 35 mph possible both Sunday and Monday afternoon. Otherwise, temperatures will be increasing through the period, with highs increasing from the mid to upper 30s Saturday into the upper 40s to low 50s on Wednesday for the lower elevations of the Basin - which is only 1 to 3 degrees cooler than normal for this time of year. A transient, weak upper level ridge will quickly travel across our area Saturday as a cut-off low spins off the Southern California coast before driving inland along the US-Mexico border Saturday evening. Mostly clear skies overnight into Saturday morning will allow morning temperatures to drop into the low to mid teens for lower elevations and single digits for mountain zones. Flow aloft will turn more westerly as mostly sunny skies will attribute to the beginning of a warming trend that will last through the week, with highs on Saturday being about 10 degrees warmer than on Friday. Flow aloft will incur a more southwesterly component through the afternoon and evening as the ridge continues east and an upper level shortwave approaches the coast. Winds will be picking up through the Grande Ronde Valley as pressure gradients tighten through the afternoon, with gusts of 20 to 30 mph possible out of the south. The shortwave will push onshore overnight into early Sunday morning as snow chances materialize along the Cascades and Northern Blue Mountains. Snow chances become more widespread through the morning and afternoon hours, encompassing areas of the Lower Columbia Basin, Blue Mountain Foothills, Eastern Gorge, and Central Oregon. 4 to 8 inches of snowfall is anticipated through the Cascades and Northern Blue Mountains above 4000 feet on Sunday, with up to an inch of snow along the Blue Mountain Foothills. Confidence in these snow amounts are moderate (60%), as the NBMv4.1 highlights an 80-90% chance of 4 inches along the Cascades and a 50-60% chance of 4 inches over the Northern Blue Mountains. Snow levels will be increasing into Sunday, with values between 500 and 1500 feet for Central-Southern Washington and 1500 to 2000 feet for North-Central Oregon. Winds will also be increasing through the morning, peaking in intensity during the afternoon and evening timeframe with widespread gusts of 25 to 30 mph possible. The shortwave passes through the Pacific Northwest and exits east by Sunday evening, but a much stronger upper level system will be following close behind and approaching the coast late Sunday into Monday morning. This will keep southwesterly flow aloft occurring and allowing snow levels to continue to rise into the 1000 to 1800 feet range through South- Central Washington and 1800 to 2400 feet through North-Central Oregon north-to-south. After a brief break overnight, showers will again return along the Cascades and Northern Blue Mountains early Monday morning before becoming widespread through the afternoon and evening. Snow amounts of 1 to 3 inches are likely over the Cascades and Northern Blue mountains above 4000 feet, with .10 to .20 inch along the Northern Blue Mountain foothills. Snow levels drop around 1000 feet overnight into Tuesday, allowing for a brief period of snow possible along the foothills and eastern slopes of the Cascades through Tuesday morning. The low pressure system continues to slowly dig along the Oregon and Northern California coasts before driving inland into Central/Southern California Wednesday. This will allow for a strong upper level ridge over the Eastern Pacific to infiltrate into our area, which should begin to dry conditions out late Tuesday and extend through the day on Wednesday. Guidance is in good agreement with the overall pattern of a weak shortwave followed by a stronger upper level system that provides the potential for lower elevation snowfall on Sunday, but differences do arise regarding the shortwave`s speed and the larger system`s progression through the week. The GFS is quicker with the passing of the initial shortwave, which relates to a stronger resulting system on Monday as it drives through Northern California Tuesday instead of dropping south along the coast before moving inland through Southern California late Wednesday as with the ECMWF. This results in a slightly windier, drier, and warmer outcome with the GFS versus the ECMWF. These timing differences are highlighted by the 500mb EOF Patterns, as a dipole is represented for both the shortwave on Sunday and the stronger system into Monday. Cluster phase space shows the variability within ensembles and the deterministic product, with slightly more confidence in the ECMWF outcome as ensemble members are in better agreement with one another. 75 && .AVIATION...00Z TAFS...Variable conditions across all sites with VFR conditions at RDM/BDN/YKM/PSC, MVFR at DLS/PDT, and IFR at ALW due to reduced visibilities of 2SM and low ceilings of BKN007 as light snow continues to fall. Light snow chances will be migrating south later today, impacting RDM/BDN this evening before turning to more moderate snowfall after 08Z and extending through the remainder of the period. Breezy winds of 20 to 30 kts out of the northwest will be possible for PSC and YKM through the period, with 20 to 25 kts gusts possible for RDM/BDN after 22Z. 75 && .PRELIMINARY POINT TEMPS/POPS... PDT 15 24 10 26 / 20 20 20 0 ALW 17 29 12 30 / 20 20 20 0 PSC 17 29 14 32 / 0 0 0 0 YKM 10 24 8 30 / 10 10 0 0 HRI 16 28 13 30 / 10 10 10 0 ELN 10 21 7 28 / 10 10 0 0 RDM 11 20 4 25 / 20 30 20 0 LGD 16 29 12 35 / 10 50 40 0 GCD 16 31 9 38 / 20 60 20 0 DLS 18 27 16 32 / 20 20 10 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...Winter Weather Advisory until 4 PM PST this afternoon for ORZ502- 507. Winter Storm Warning until 4 PM PST this afternoon for ORZ509. WA...Winter Weather Advisory until 4 PM PST this afternoon for WAZ029- 030. && $$ SHORT TERM...88 LONG TERM....75 AVIATION...75