Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/27/21

National Weather Service Albany NY
933 PM EST Fri Feb 26 2021 .SYNOPSIS... High pressure will shift off the New England Coast tonight. A low pressure system moving across the Great Lakes Region and a warm front will bring some snow and light mixed precipitation transitioning to rain on Saturday. Milder weather is expected on the weekend, as another disturbance will bring some light precipitation back into the region to close the weekend. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... As of 933 PM EST....IR satellite imagery and surface observations show high clouds have most of the area. There has even been some breaks (especially for the western Adirondacks and Mohawk Valley) at times as well. With the fairly thin high cloud cover and light/calm winds, temps have been falling rather quickly this evening. Most of the region has already fallen below freezing, with only the mid Hudson valley still remaining in the 30s. Temps have already fallen into the teens for parts of the Adirondacks thanks to the breaks in the clouds as well. Temps will continue to fall over the next few hours, as clouds remain thin and winds stay light. All areas will be falling below freezing, with mins ranging from the mid teens to the upper 20s. Clouds will start increasing in thickness and coverage after about 2 or 3 AM. Although most of the overnight should be precip free, 3km HRRR suggest some light steady snow should reach most areas by daybreak with some dustings possible in the Mohawk and Hudson Valleys to Berkshires and NW CT. Up to an inch is possible across the higher terrain of the southern Adirondacks, eastern Catskills and southern Green Mountains. While the main batch of precip looks to continue up from the south towards the Catskills, Mid Hudson Valley and Taconics, there should be another area of precip that lifts towards the Mohawk Valley and Adirondacks from central NY. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... Precipitation transitions to rain through Saturday morning but an additional inch or two of snow is possible along with a brief mix with sleet in the southern Adirondacks before changing to rain there. Strong warm advection and isentropic lift will bring widespread rain to the region, exiting later Saturday afternoon. Highs Saturday in the 40s with around 40 southern Adirondacks and southern Green Mountains. Cold advection quite weak behind the system and the next upper energy will begin its approach from the west southwest later Saturday night. There should be considerable cloud cover through the night but some breaks in the clouds are possible at times, not enough to help temperatures fall much. Although, temperatures should fall to around or below freezing by Sunday morning. The next upper impulse and shot of enhanced warm advection and isentropic lift arrives after daybreak Sunday with mixed precipitation in the eastern Catskills, Schoharie Valley and southern Adirondacks. Once again, any mixed precipitation changes to rain as rain expands over the entire region. Highs in the 40s with around 40 higher terrain. Precipitation decreases in coverage to just showers Sunday night, then a strong northern stream upper impulse tracks east and southeast brushing northern parts of the region and northern New England. Rapid cooling aloft ahead of a strong low level thermal gradient along a low level cold front will result in some convective instability. There could be some snow shower/squall activity as the snow squall parameter in sources of guidance suggests that possibility. Highs Monday in the lower to mid 40s but 30s in higher terrain. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Potent upper level shortwave will be moving across Upstate New York and into New England on Monday evening. A band of snow showers and embedded squalls are expected with the passage of this Arctic boundary, especially for areas north of the Mohawk Valley and I-90. Best chance will be during the evening hours, with skies expected to clear out after midnight. Behind this strong cold front, much colder air will work into the region, along with gusty northwest winds. Temps will fall into the single digits and teens for Monday night and only rise into the 20s for Tuesday. With the gusty winds over 30 mph at times, this will result in low wind chills, especially for the higher elevations, where wind chills around -5 to -15 are possible. Otherwise, it should be dry with a mostly sunny sky for Tuesday, although the gusty winds will mitigate any benefit of the early March sunshine. The winds should start to diminish for Tuesday night into Wednesday as high pressure builds towards the area. Some models do show a southern stream storm around the mid-week, but most guidance shows this storm (if at all) remaining south of the region. As a result, it should be dry for the mid to latter portion of the week, with daytime temps in the mid 30s to mid 40s and overnight lows in the teens and 20s along with a partly cloudy sky. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... Flying conditions are currently VFR with light/calm winds and bkn-ovc high level clouds in place. These high clouds will be in place for most of the night, with ceilings finally lowering for the late night hours (after 3 AM). Some light snow will start to spread south to north across the area around daybreak, although snow should be brief (only a few hours in duration), as a strong southerly flow will allow precip to mix with and changeover to plain rain as temps rise above freezing. Within snowfall, flying conditions should be IFR for visibility, but will improve to MVFR as precip mix with and changes over to rain. Although winds should be light for the overnight, southerly winds will pick up around sunrise and be 10 to 15 kts through the morning hours, with a few higher gusts possible. LLWS will be possible, as 2 kft winds will be around 40 kts from a southeasterly direction for the morning hours. After precip changes to plain rain, it will start to taper off for the early afternoon hours from south to north. However, lingering low level moisture will keep MVFR cigs in place for most of the day. Southerly winds may start to become more w-sw by late in the day, but will continue to generally be around 10 kts for all sites. Outlook... Saturday Night: No Operational Impact. NO SIG WX. Sunday: Moderate Operational Impact. Chance of RA. Sunday Night: Moderate Operational Impact. Chance of RA. Monday: Low Operational Impact. Slight Chance of SHRA. Monday Night: Moderate Operational Impact. Windy With Gusts To 33 kts. Chance of SHSN. Tuesday: Low Operational Impact. Breezy. NO SIG WX. Tuesday Night: No Operational Impact. NO SIG WX. Wednesday: Low Operational Impact. Slight Chance of SHRA...SHSN. && .HYDROLOGY... No major hydrologic issues are foreseen through the middle of next week. Some melting and sublimation of the snowpack in the valleys is expected during the day time over the next several days. NERFC forecasts show minor up and down changes in river flows due to the diurnal freeze/thaw cycle. River ice is not expected to break up over the next several days. Mainly light snow showers are expected this morning across the southern Adirondacks and the western Mohawk Valley. Additional light snow and rain is possible Saturday with temperatures rising above normal to close the weekend. Some snow melt and ripening of the snow pack is possible. Total QPF from the Saturday system will range from a tenth to third of an inch with some locally higher amounts over the southern Adirondacks, eastern Catskills, and the western New England higher terrain. Another system will bring light precipitation to close the weekend mainly in the form of rain. A strong cold front with snow showers is expected to move through on Mon-Mon night with below normal temperatures possible Tuesday before rising to near normal levels for the mid week. For details on specific area rivers and lakes, including observed and forecast river stages and lake elevations, please visit the Advanced Hydrologic Prediction Service /AHPS/ graphs on our website. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...NAS NEAR TERM...Frugis/NAS SHORT TERM...NAS LONG TERM...Frugis AVIATION...Frugis HYDROLOGY...NAS
Area Forecast Discussion
National Weather Service Binghamton NY
958 PM EST Fri Feb 26 2021 .SYNOPSIS... An area of low pressure will track through the region tomorrow bringing a mix of rain and snow showers. Another system follows on it`s heels Sunday with another chance for precipitation. Cooler with high pressure building in early next week. && .NEAR TERM /THROUGH SATURDAY NIGHT/... 955 PM Update... Added the mention of freezing rain as it is looking a little more likely based on latest RAP forecast soundings. Will still hold off on an advisory for now, but there is some concern that a short fuse winter weather advisory may be needed for a few hours tomorrow morning until temperatures climb above freezing. Dew points are still well into the mid teens across the area, so some evaporational cooling should occur at the onset of precipitation. Also, road surface temperatures are just below freezing, and if some light snow is to occur first, as is currently forecast, the freezing rain will have less of an impact on road conditions. Will add mention into the HWO for now about the possibility of slick travel conditions for tomorrow morning. Previous Discussion... Low pressure moves into our area overnight. Enough moisture and lift look present to develop some precipitation. However, the most abundant QPF over 1/10th of an inch looks to be confined to the higher elevations in the western Catskills, Wyoming valley and northern Oneida county where the terrain can enhance precipitation. In these locations snow of an inch or two is possible. Soundings look fairly uniform throughout warming fairly quickly through the morning hours Saturday. So while precipitation should start as snow showers or light snow a transition to rain should occur. Some sleet may mix in during the transition but this or any freezing rain looks rather brief at this time. Temperatures look to fall to around or just below freezing but rise into the 40`s tomorrow. Once the low pressure system passes to the east most of the rain showers should come to an end in the afternoon hours. Our region will be in between low pressure systems so while a break in the precipitation is expected clouds will linger. Temperatures only fall back to around 30 due to the cloud cover. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... Main concerns in the short term are focused on the potential for a wintry mix Sunday morning then rain in the afternoon through Sunday night before the cold air sweeps back in on Monday with more scattered snow showers through the day. Upper level ridge across much of the Northeast US will allow for early morning quiet weather on Sunday, but a passing upper low in the Great Lakes moving to the e/ne will combine with a weak surface inflection over the Appalachians moving newd into the mid Atlantic region through most of the day Sunday. These two features will usher in a broad area of large scale lift over the region amidst an initially dry air mass, which may allow the precipitation to take a little bit longer to reach the ground. However, a faint ribbon of deep moisture will advect in later in the day and act to increase the potential for precipitation in the afternoon. The type of precipitation will be a challenge early in the day Sunday with surface temperatures initially below freezing but quickly warming into the mid to upper 30s by the late morning hours. There will likely be some light snow mixing with sleet around or just after sunrise moving in from south to north, but amounts should be limited to less than a half inch. The precipitation will change to all rain before noon, and the rain showers will likely persist through the afternoon. Rainfall amounts will likely be limited to a third of an inch or less in ne PA, the souther tier of NY and into the Catskills. Even lesser amounts are expected further north into the Finger Lakes. As the upper low and surface feature to the south lift off to the northeast, they slowly phase together and a colder air mass wraps around the back side of the system, eventually pushing into wrn NY by late Sunday night into Monday morning. Most of the guidance is hinting at an initial cold front moving through Monday morning which will be quite dry and relatively mild with the thermal gradient. This may kick off a few snow showers through the morning, but the secondary cold front...of an Arctic nature...winds up and starts to push from the central Great Lakes into wrn NY/ern Great Lakes by late Monday afternoon. There is expected to be a short wave associated with this very cold air mass, and may generate some snow squalls and eventually a period of lake effect showers downstream of Lake Ontario. The axis of the coldest air will not arrive until later Monday night, but the effects will begin to be felt just before sunset. && .LONG TERM /TUESDAY THROUGH FRIDAY/... There is expected to be a period of very cold air and potentially significant lake effect snow Monday night through Tuesday afternoon. The LES will get kick started by a short wave embedded within a very cold air mass, with 850mb temperatures -18 to -14 deg C. A fairly steady northwest flow and favorable temperatures, along with an open Lake Ontario will allow for the potential of lake effect snow southeast of Lake Ontario into central NY Monday evening through Tuesday morning. The 850mb ridge axis will shift through the area Tuesday afternoon and should allow the winds to back to the w/sw and bring any lingering lake snow showers to an end. A few days/nights of cold temperatures are expected early this week with morning lows in the single digits and teens Monday and Tuesday and afternoon highs in the 20s to near 30 on Tuesday. Ridge of high pressure builds in briefly Tuesday night into Wed morning, which will allow for a period of quiet but cold conditions. However, this ridge will also advect in a slightly warmer air mass on Wednesday with highs topping out in the upper 30s and lower 40s. The pattern becomes a little more quiet and temperatures are more seasonal into the latter half of the week with highs in the 30s near 40 and overnight lows in the 20s. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... VFR through the evening. However, ceilings and visibilities drop around overnight with the arrival of light snow/rain and possibly some brief freezing rain. The steadier precipitation arrives during the early morning and could see some IFR restrictions toward sunrise at most TAF sites. Exact timing of when and how fast the restrictions move in are still somewhat uncertain. High probability of LLWS forming overnight as well at all terminals and persisting until at least late Saturday morning. Temperatures warm tomorrow afternoon and the warm/moist airmass over the snow on the ground may lead to fog and and drizzle with further restrictions into the evening possible. Outlook... Saturday night... Lingering restrictions possible. Sunday...Occasional restrictions possible in scattered rain showers. Monday...Restrictions possible in rain and snow showers, especially the Central NY terminals. Tuesday and Wednesday... Brief restrictions can`t be ruled out with a few rain and snow showers. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...None. NY...None. && $$ SYNOPSIS...MWG NEAR TERM...MPK/MWG SHORT TERM...BJT LONG TERM...BJT AVIATION...MPK
Area Forecast Discussion
National Weather Service Green Bay WI
511 PM CST Fri Feb 26 2021 Updated aviation portion for 00Z TAF issuance .SHORT TERM...Tonight and Saturday Issued at 238 PM CST Fri Feb 26 2021 The latest RAP analysis and satellite/radar imagery show high pressure centered off the east coast of the U.S., and a cold front positioned over the eastern Dakotas early this afternoon. The cold front is tracking east with cloud bases mostly above 9kft and little to no precip along it. 12z soundings from MPX and GRB tell the story, with very dry air through large portions of the column. Pwats range from near normal at MPX and around the 10 percentile at GRB. Richer Gulf moisture is heading north but still a ways away over southern Illinois and Indiana. Forecast concerns mostly revolve around the potential for light wintry precip tonight. Tonight...Clouds will be on the increase tonight as a period of ascent arrives ahead of shortwave energy and the weak cold front. Forecast soundings indicate that most of the ascent goes towards saturating the atmosphere, and ascent exits before the column has a chance to fully saturate. As a result, have backed off precip chances significantly across north-central WI, but left a slight chance in case spotty light snow develops. Chances are a little higher over east-central WI around or shortly after midnight where the northwest fringe of the deeper Gulf moisture grazes part of the area. Temps look warm enough for spotty rain/freezing rain/light snow but can`t see much in the way of accumulations. Stayed on the warmer side of guidance compared to the national blend, with lows ranging from the middle 20s to low 30s. Saturday...Trailing shortwave energy will pass overhead during the morning, but moisture looks even less than overnight and no additional precip chances are expected. But clouds will likely hang around for part of the morning before an influx of dry air and subsidence leads to clearing skies for the afternoon. Temps will remain warm and range from the lower to middle 40s. .LONG TERM...Saturday Night Through Friday Issued at 238 PM CST Fri Feb 26 2021 The main focus for the extended forecast will be the fast moving shortwave trough accompanied by a fairly vigorous surface low Sunday morning. Saturday night through Sunday...A fairly robust and fast moving system remains set to pass through the region late Saturday night through Sunday morning. P-type will vary across the area with this system. For the north, temperatures at the surface and aloft should suffice to keep all precipitation as snow. Further south and east, a wintry mix becomes possible as surface temps dip below freezing but the 925-850mb layers remain just above freezing. How much icing and sleet develop in these areas will vary depending on if we can keep ice crystals in the clouds aloft. the mixed and icing areas will likely be fairly narrow between the areas of snow and rain. Some areas near the Fox Valley and lakeshore may also just see rain with this system. As far as snow goes, most areas will still have a shot of seeing some snow, but accumulations across the north may be heavier as the shortwave provides a good amount of lift through the dendritic growth zone. Brought up amounts to around 2-4 inches for this forecast period for the heaviest band of snow. In short, we`re set for a fairly sharp gradient of snowfall from heavy to light to none across our area, with a small window in there for some wintry mix and light icing. Much will depend on the exact track of the system in the next couple days. Behind this, winds will pick up Sunday afternoon, but given the wet nature of the snow that morning, it`s unlikely we`ll see any blowing/drifting snow concerns. Rest of the forecast...There will be another shot at some light snow for the far north as another shortwave comes southwards from Canada early on Monday. Intensity will likely be somewhat limited, as winds will not be conducive to much lake enhancement. Still, there will be a window to accumulate up to an inch of snow with this system. Winds will remain gusty during this period, which may create a few areas of drifting snow on Monday. behind this, a fairly broad but shallow upper ridge will move in to the region, keeping us dry through the midweek. Another vigorous system is possible towards the end of next week, but is currently projected to pass south of the area. Temperatures will dip briefly after the weekend, as CAA behind the surface low on Sunday drops highs back into the upper teens to upper 20s. Temperatures then recover for the middle of next week, with highs pushing back into the lower to middle 40s as Pacific air arrives from the west. && .AVIATION...for 00Z TAF Issuance Issued at 511 PM CST Fri Feb 26 2021 An upper level disturbance will move across the area tonight and produce middle clouds and maybe some sprinkles or snow flurries at MTW and SBM. VFR conditions will continue Saturday. A low pressure system will bring increasing clouds and some snow or rain to the region late Saturday night into Sunday. Several inches of wet snow and IFR conditions are likely north of a AUW to AIG to IMT line. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......Uhlmann AVIATION.......RDM
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
558 PM CST Fri Feb 26 2021 .UPDATE... Issued at 534 PM CST Fri Feb 26 2021 Updated to include 00z aviation discussion below. && .SHORT TERM...(This evening through Sunday) Issued at 253 PM CST Fri Feb 26 2021 Primary concern is the system which will move through the region Saturday night into Sunday, bringing a band of accumulating snow through as it does so. Until then things look fairly benign and mild. There is the possibility of a few sprinkles with the surface and upper level shortwave trough currently moving across the area. Otherwise, look for decreasing clouds later tonight with winds decreasing from now through that time frame. Saturday looks to be mild across the area, with some increase in clouds during the afternoon. Things get much more interesting Saturday night as a quick moving shortwave trough and upper level jet streak move northeast from the central Plains across our area. Guidance is in good agreement on the development of a narrow axis of moderate to strong frontogenesis beneath an area of upper level divergence with this feature. Cross sections suggest that the frontogenesis will be steeply tilted, which underscores why the axis of heavier precipitation will be quite narrow (on the order of a county or two). Above the frontogenesis zone the theta-e lapse rates look to be near zero with an area of negative EPV (suggesting that although there may not be upright instability some symmetric instability will be present). The reduced stability will significantly enhance vertical motion, helping to squeeze out as much precipitation as will be possible in the 3-6 hour window of good forcing. The guidance continues to show some differences in exactly where the frontogenesis will setup, making it tough to forecast explicit snowfall amounts. The HRRR extensions from 12Z and 18Z are farther north with things than most of the other guidance (including the GEFS and EPS ensemble systems), and have more precipitation (max at around 1" QPF) than other guidance. However, as more CAMs become available, it will certainly be worth watching how they handle this system. At this point the forecast is likely less than what will eventually be the maximum values, and instead has somewhat lower values spread over a larger area to account for the uncertainty. Subsequent forecasts should be able to better refine the maximum amounts and tighten the forecast gradients to the north and south of that. The southern gradient in snowfall looks to be particularly tight due to both lower precipitation amounts and some rain mixing in with the snow for a longer period (for most locations, any initial rain should change to snow fairly quickly). The northern gradient in snowfall will be a bit more baggy with some frontogenesis higher up (600-500 mb) extending farther to the north/west (but the stability will be greater there and the precipitation will be less, hence lower totals). .LONG TERM...(Sunday night through Friday) Issued at 253 PM CST Fri Feb 26 2021 During Sunday night, a second cold frontal passage is expected as a northwesterly upper-level jetstreak moves from the Canadian Prairie to the Northern Plains. This feature will be embedded within the backside of the trough that brought precipitation earlier this weekend. Guidance squeezes out enough QPF along the front (from the marginal post-trough moisture) that a dusting to an inch of snow is possible across northern MN into northwest WI. Lift and low-level saturation decrease to the south, however some snowflakes cannot be ruled out across our northern to eastern CWA. Thus, have introduced slight chance PoPs in these regions Sunday night. Temperatures Sunday night into Monday night will also decrease as a brief shot of cold, arctic air follows the cold front. How cold temperatures get is another question. The ECMWF and EPS mean show lows Monday morning around 10 near Brainerd to mid teens south. Meanwhile, the GFS is much colder (well below the 25th percentile of the EPS) with single digits for most of the CWA and below zero temperatures in western MN. Regarding Mondays highs, spread within the guidance only increases. Overall, highs have been trending colder with the ECMWF, EPS, and GEFS showing MSP only reaching the mid-20s. Meanwhile, the GFS has been a steady cold outlier with single digits to mid-teens forecast. It seems less likely that we get as cold as the GFS suggests, however, it is concerning that other models are trending that direction. Have opted to keep current NBM highs and lows Sunday night through Monday night, as current forecast temperatures are between the 25th and 50th percentile of the ensemble guidance. This combined with model trends supports that leaning towards colder temperatures are likely a safer bet. A split, zonal flow regime will take over the CONUS after Monday, resulting in dry conditions for the MPX CWA the rest of the period. On Tuesday morning, enhanced, southwesterly 850 mb flow shifts eastward into the Northern Plains. This will allow for strong WAA, building slight ridging over the central US. Highs Tuesday are forecast in the low 40s, with upper 40s possible in southwest MN. Winds Tuesday afternoon could also be breezy from the enhanced low-level flow. Thus, have increased sustained winds and gusts Tuesday to highlight this possibility. The upper-level ridging will shift east Tuesday night but the warmer air remains. Temperatures are forecast to slowly climb into the mid 40s area wide (with slightly warmer temperatures on the Buffalo Ridge) by Thursday. Looking ahead, it appears even warmer weather is possible by late next week, as the Climate Prediction Center highlights a good chance of above normal temperatures across the central US in their 6-10 and 8-14 Day Outlooks. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 534 PM CST Fri Feb 26 2021 Winds will settle down this evening, dropping to under 10kt by roughly 03z-04z. Winds will then remain under 10kt throughout this TAF set but undergo a directional change, eventually ending up N to NE 24 hours from this time. VFR ceilings to start, generally in the 070-120 range, overnight through much of tomorrow. Lower ceilings into the MVFR range will start to be a problem late afternoon into the evening for sites along and north of I-94. No precipitation expected through this TAF duration, but chances for -SN in southern MN increase after 28/00z. KMSP...No weather concerns through Saturday afternoon. Going into Saturday evening, ceilings are likely to drop into the MVFR range, and potentially sub-1700ft but not until after the evening rush. Chances for -SN are too low for inclusion at this point but chances increase significantly after 28/06z. /OUTLOOK FOR KMSP/ Sun...MVFR/SN early, then VFR. Wind NW 10-15kts. Mon...VFR. Wind NW 5-10kts becoming SW late. Tue...VFR. Wind S 15G25kt. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...None. && $$ UPDATE...JPC SHORT TERM... LONG TERM...CTG AVIATION...JPC
Area Forecast Discussion
National Weather Service Pueblo CO
314 PM MST Fri Feb 26 2021 .SHORT TERM...(This evening through Saturday) Issued at 239 PM MST Fri Feb 26 2021 ...Increasing Fire Danger on the Plains Saturday Afternoon... Currently...windy over the higher terrain today, with occasional gusts over 40 kts through the passes of the central mountains, and 30-40 kts over the upper Arkansas Valley. Winds on the plains have gusted 20-30 kts at times this afternoon, though areas around Colorado Springs have seen some periods of light ely flow as a weak rotor circulation has apparently developed downstream of the high terrain. Winds lessen overnight at lower elevations, though higher exposed terrain will remain breezy into Sat morning. Upper wave passes quickly through the nrn Rockies into the nrn Plains tonight and Saturday, pushing a cold front south through the area Sat afternoon. Just enough moisture and forcing for some snow showers over mainly the Continental Divide from late tonight through Sat, with some light (1-3 inch) accums likely. While snow will be light, fairly strong winds accompanying the snowfall may produce some periods of low visibility and difficult travel across high mountain passes from Monarch Pass northward through the day. Over lower elevations, strong wly winds will develop quickly in the morning, then gradually turn more N-NW while remaining gusty in the afternoon. RH falls off enough over the far sern plains to produce Red Flag Conditions near the KS border for few hrs, so will hoist a highlight essentially east of a La Junta to Kim line. Winds will be strong farther west as well, though RH may stay just high enough to avoid a warning as temps cool slightly behind the front, however fire danger will still be high. Max temps tricky tomorrow with cold front and cold advection in the afternoon, though NBM looked slightly too cool given good mixing, and nudged maxes up a few degf toward warmer MOS guidance. .LONG TERM...(Saturday night through Friday) Issued at 239 PM MST Fri Feb 26 2021 Current model guidance is in decent agreement through Monday, but beyond that solutions diverge greatly, lowering forecast confidence and making ensembles much less useful. Saturday night through Monday...The upper trough over the area is expected to send a low south of the area, likely too south to really impact our area as far as precipitation goes. A brief, light dusting over the mountains cannot be ruled out entirely, but any meaningful accumulation is very unlikely at this time. High temperatures will cool down a bit from the previous few days, but should still be near seasonal norms, with high 30s-40s expected over the plains and 20s- 30s over the higher terrain. As the low continues to translate eastward, Monday is expected to remain dry, with high temperatures expected to rebound into the 40s-50s. Tuesday and beyond...The GFS and ECMWF have completely different forecasts through the rest of the extended period. The GFS does things a little more dramatically, showing a brief period of upper ridging on Tuesday and Wednesday followed by a potent upper low that impacts the area into Thursday, which would give us a healthy dose of snowfall before another dry period leading into next weekend. The low was also shown to be wrapped up, with very strong northerly winds (70 plus knots at 700mb) over the plains. The EC shows mainly calm, zonal flow over the area Wednesday before sending a closed-off low into Texas Thursday and Friday. This would bring some precipitation to the southern part of our area, but it is unclear how much. While the models have begun to agree slightly more as we have moved forward in time, the differences in the speed and structure of these potential systems still leaves too much difference to decide on one over the other. As a result, have mainly stuck with the blended forecast for that time period. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 239 PM MST Fri Feb 26 2021 VFR conditions expected the next 24 hrs at all taf sites. W-NW winds have been slow to increase this afternoon at KCOS and KALS, though latest HRRR suggests at least a couple hrs of 15g25kts possible into early evening before speeds lessen after sunset. On Sat, W-SW winds pick up quickly in the morning, with gusts 25-30 kts into the afternoon at all sites. Cold front passes through KCOS and KPUB after 21z, with flow becoming more N-NW into Sat evening. && .PUB WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from 11 AM to 5 PM MST Saturday for COZ233>237. && $$ SHORT TERM...PETERSEN LONG TERM...GARBEROGLIO AVIATION...PETERSEN
Area Forecast Discussion
National Weather Service Shreveport LA
959 PM CST Fri Feb 26 2021 .UPDATE... To add patchy fog to the overnight forecast and into mid morning. && .SHORT TERM... Cloudy and cool in the north with mostly lower 50s and a tight T/Td spread, giving way to light fog in many locales at 10pm. Half mile now in Idabel is the worse so far with quarter mile in the past. The cool air will hang in place and with temps easing down toward daybreak, thus it is a given that the fog will grow thicker. Perhaps even requiring an advisory in the predawn to daybreak hours. So expect some fog, but any rainfall which is a good chance over top of this frontal boundary, that would help mix the air a bit and could hold visibilites above criteria, so we will defer for another few hours at least if possible. The HRRR does show enhancement in the coverage of light showers during the next 6-12 hours as this boundary lifts to our N during midday on Saturday. This could push the mercury toward 65 or so for even DeQueen which will scour last in the valley. Highs near 80 in our southern tier are reasonable considering we are still near 70 down there now with the best shot at some free vitamin D via the sun. /24/ && .PREV DISCUSSION... /issued 611 PM CST Fri Feb 26 2021/ AVIATION... For the ArkLaTex terminals, a stationary front lies along I-20 from KTYR to KSHV to KELD. Current obs IFR for KTXK and all guidance indicating LIFR will dvlp on cold side soon and warm side before daybreak. L/V winds to N will keep overnight, while gusts from KLFK to KMLU are subsiding now will prevail S5-10KT overnight. This boundary will lift out to N as a warm front on Sat with some DZ and -RA 06-15Z along with fog. Gradient ahead of next impulse improves late day with ra early on Sun from NW. /24/ PREV DISCUSSION... /issued 335 PM CST Fri Feb 26 2021/ SHORT TERM.../Tonight through Saturday Night/ Across the CONUS, a shortwave trough over the Northern Rockies continues to dive ESE towards the Central Plains. Ahead of the trough, most of the country remains in southwest flow aloft, including our region. Last night`s shortwave that produced heavy rain and severe hail across the northern half of the region, continues to push eastward into the SE CONUS, with some lingering shower activity between the I-20 and I-30 corridor in wake of the system near a theta-e ridge. At the same time, the frontal boundary that moved through the region a couple days ago continues to slowly lift northward as a warm front. Its currently located along a line from near Rusk Texas to Mansfield Louisiana to near Monroe Louisiana. In wake of this boundary, clouds have thinned out and warm air advection has allowed temps to climb into the mid to upper 70s. North of the boundary, a broad stratus deck remains across the region, with some fog just north of the advancing boundary. Temps in this region have remained steady in the low to mid 50s. Not expecting much change for the remainder of the afternoon as short-term progs only advance the warm front a little to the north through the overnight period. However, showers look to continue near the theta-e boundary along with some possible isolated shower/thunderstorm development along the warm front. Expect overnight lows in the upper 50s to lower 60s south of the front, with mid 40s to low 50s across the remainder of the region. By Saturday, the shortwave in the northern Rockies will kick out into the Central Plains with another strengthening upper trough on its heels diving southward into the Great Basin Region. In response, southerly winds across the south-central CONUS will increase, and the warm front will start to advance northward during the day. Impulses will move across the region along the flow, providing enough lift for precip to develop. The best chance for convection will likely be north of the I-20 corridor near the advancing frontal boundary. Expect much warmer temperatures, as highs in wake of the front will climb into the 70s to near 80 degrees in some locations. /20/ LONG TERM.../Sunday through Friday/ Longwave troughing will dive SE through the Great Basin and into the Desert SW Sunday, before eventually closing off Sunday night over Srn NM. This troughing pattern will maintain deep SW flow over the region late this weekend through at least the first half of the new work week, and thus the elevated subtropical moisture feed will continue from Cntrl TX through the Lower/Mid MS Valley into the OH Valley. At the sfc, a shallow cold front remains progged to drift SE into the region by midday Sunday/Sunday afternoon, with PVA embedded in the dirty SW flow contributing to an increase in convection development along/ahead of the front along a SW to NE oriented theta- e axis ahead of the front. Have maintained consistency with t he previous forecast with pops increasing to categorical Sunday afternoon across much of NE TX/SW AR/NW LA, but did taper pops back a bit across the Srn zones which will be farther removed from the axis of greater large scale ascent and near and just ahead of the front. With the deep lyr flow fairly unidirectional along the frontal sfc, convergence isn`t progged to be particularly deep, even as SBCapes rise to near 1000 J/Kg across the warm sector ahead of the front. Lapse rates aloft are not impressive either, but rather am expecting convection to remain along and behind the front, with the potential for additional heavy rains to fall across the already saturated areas of NE TX/SW AR Sunday afternoon/evening, before eventually spreading SE into the Lower E TX/N LA/SCntrl AR from the late afternoon through the overnight hours. Attm, minor flooding of low lying, poor drainage areas is possible across NE TX/SW AR where widespread rainfall amounts of 1.5-3.00+ inches fell since Thursday afternoon/evening, although areas to the S should be able to take the rainfall. Very warm/humid conditions are expected Sunday afternoon ahead of the front over Lower E TX/N LA, where max temps were bumped up a couple degrees over the cooler NBM, with the front expected to shift S through the region Sunday night, exiting the area before daybreak Monday. The post-frontal rains will continue over much of the area Monday as elevated isentropic ascent in the SW flow persists. However, the aforementioned closed low over the Desert SW remains progged to slowly shift E into the Srn Plains through Monday night, although considerable timing discrepancies still exist with the slow ECMWF/Canadian slower than the more progressive GFS entering the Red River Valley Monday afternoon, with the latter two progs about 9-12 hrs slower. Prefer the slower more consistent solutions, with likely pops maintained over much of the area Monday night, before dry slotting undercutting the opening trough tapering the SHRA off from W to E Tuesday, while drier low level air advects S ahead of sfc ridging from the Ozarks into the Mid MS Valley. Temps should return back to near seasonal norms by Wednesday with increased insolation, with the outlier GFS still suggesting another developing closed low entering the TX/OK panhandles Thursday, nearly 24 hrs earlier than the ECMWF/Canadian. The NBM continues to trend closer to the GFS, with slight chance pops over much of the area Wednesday night through Friday, but did delay the reintroduction of pops a bit until Wednesday night, but confidence remains low with this solution as we round out the work week. /15/ && .PRELIMINARY POINT TEMPS/POPS... SHV 55 75 65 75 / 30 40 20 80 MLU 60 76 67 77 / 40 50 20 50 DEQ 46 65 57 68 / 20 80 70 80 TXK 51 68 62 70 / 30 60 50 80 ELD 51 70 61 74 / 50 50 40 80 TYR 54 73 64 73 / 20 60 20 80 GGG 54 73 64 75 / 30 50 20 80 LFK 62 78 65 77 / 20 30 10 50 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 24/20/15
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
844 PM MST Fri Feb 26 2021 .UPDATE... Issued at 834 PM MST Fri Feb 26 2021 00z KUNR sounding showed boundary layer mixed to 512mb with a bit of MUCAPE and thus, the isolated virga/-SHRASN early this afternoon/evening. Looking at water vapour presentation, main shortwave of interest over east central ID and it looks well- defined. 00z guidance indicates system has slowed even more and thus, onset of betters snows will likely be later in the afternoon. Compact closed 700-500mb circulation will track across central WY and then move along the SD/NE border Saturday night. Composite of forcing/QPF placement suggests best chance of moderate snow along/just south of I-90 corridor. Headlines for the Black Hills looks good with possible extension needed to west and then east/southeast into south central SD. If narrow deformation zone links up with 800-600mb frontogenesis, steep lapse rates, and upslope flow, a stripe of heavy snow could develop Saturday night. Will allow all 00z guidance, especially the probabilistic guidance, to come in before making impactful forecast changes. Stay tuned overnight. && .DISCUSSION...(This Evening Through Friday) Issued at 200 PM MST Fri Feb 26 2021 Upper level analysis shows a trough over the western/central CONUS, with ridging over the east. Weak shortwave energy crossing over the Rockies, along with some midlevel moisture, is helping to produce a few rain/snow showers across portions of the CWA. Surface map depicts a trough over the northern plains. Under partly cloudy skies, winds are westerly 10-20 kts, and temperatures are in the 30s and 40s. Today`s shortwave will exit the region tonight, and with mostly clear skies, temperatures will dip into the teens. The next, stronger, shortwave will approach the region early Saturday. Deterministic models are still not in full agreement on this system; RAP/NAM/GFS develop a closed 700 mb low that slides across the CWA (RAP farthest north), while the ECMWF/Canadian keep the wave open. Models are in agreement of a band of precipitation developing somewhere across western SD. Wet-bulb zero heights suggest mainly snow can be expected with this system, although some rain could mix in across the warmer south central SD area. Surface temperatures near to above freezing could decrease initial snow accumulation, but evaporative cooling once precip begins could negate that, along with the high snowfall rates. With deep frontogenesis, strong positive vorticity advection, prolific lift within the dendritic growth zone, steep lapse rates, and plentiful moisture associated with this low, the potential exists for a band with high snowfall rates and moderate to heavy snowfall. Most solutions, including most of the hi-res models, place the band across the southern half of our CWA. The previous runs of the RAP/EC/HRRR had a more northerly track, but the 12Z RAP/EC and 18Z HRRR runs have shifted south a bit, aligning more with the other models. Another consideration is the possibility of upslope- enhanced snow. Some upslope-enhancement will be possible over the typical northern Black Hills area, and also across the northern/eastern foothills, depending on the track of the low and the extent to which northeasterly winds develop across the western SD plains. Froude number is near to above one for the northern and eastern Black Hills Saturday afternoon during the period of peak moisture. Main changes to the forecast include delaying the onset of precipitation Saturday, according to model guidance. Also adjusted winds to have a slightly more easterly component, consistent with the upslope possibility along the eastern foothills, and increased QPF a tad there accordingly. Bumped up wind speeds Saturday evening on the backside of the low. Thinking the highest snow amounts will be over the northern Black Hills and northern/northeastern foothills, with 3-5 inches expected there. Will issue an advisory for these areas, leaving out the Rapid City zone for now. Generally 1 to 3 inches of snow is expected from southwest to south central SD, with locally higher amounts possible in banding. Models indicate a local maximum around the Pine Ridge area, but accumulation will depend on temperatures. Northeastern WY could see up to 2 inches with this system, and northwestern SD should stay mostly dry. Upper wave will shift out of the region Sunday, and strong upper ridging builds over the west coast. Dry weather and a warming trend can be expected at least through early next week, with highs reaching the 50s by Monday. A weak midweek shortwave could bring a pause in the warming trend, but warming resumes later next week as the upper ridge rebuilds. Current deterministic NBM cold bias keeps highs in the 50s through the week, but wouldn`t be surprised if temperatures warm above current forecast. && .AVIATION...(For the 00Z TAFS Through 00Z Saturday Evening) Issued At 428 PM MST Fri Feb 26 2021 Isolated -SHRASN with local MVFR conditions will end this evening. VFR conditions then expected through early Saturday. Snow chances increase across northeast WY mid-morning Saturday, spreading into southern SD Saturday afternoon with widespread IFR conditions. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...Winter Weather Advisory from 11 AM to 11 PM MST Saturday for SDZ024-025-072. WY...Winter Weather Advisory from 11 AM to 11 PM MST Saturday for WYZ057. && $$ Update...Helgeson DISCUSSION...Pojorlie AVIATION...Helgeson