Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/23/21

Area Forecast Discussion
National Weather Service Boston/Norton MA
1029 PM EDT Mon Mar 22 2021 .SYNOPSIS... High pressure remains in control. Dry weather prevails for much of the upcoming week with mild days (inland from the coast) and cool nights. The warmest day looks like Thursday. A cold front will likely bring showers Friday, along with gusty winds. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... 1020 PM Update... Nighttime Microphysics satellite imagery shows an area of low clouds pushing northwest towards the Cape and Islands as well as the RI/MA South Coast. Falmouth is reporting 3000 ft stratus but no impactful weather yet. Many locations in SE MA and RI have seen dew point depressions falling to 5 degrees or less. With a 1030 mb surface high moving offshore and light southerly winds, using pattern recognition, areas of fog that are locally dense should develop later tonight into the pre-dawn hours. The question remains timing and areal coverage. 01z HRRR has somewhat less bullish on the northward extent of the dense fog coverage, keeping it generally south of US Route 44 across Bristol and Plymouth County. In addition, it has also delayed the onset of the fog. For now, have opted to hold off on any fog headlines and will reevaluate for the next update. Otherwise, forecast remains largely on track. PREVIOUS DISCUSSION... 8 PM Update... The forecast remains largely on track this evening. The most significant change to the forecast was increasing the reach of the developing stratus layer further north to include the Boston metro and I-95 corridor. Much of the short term guidance supports the notion that the stratus layer will extend further north than it did last evening. Fog may form as far north as Providence, but will be fighting significant dewpoint depressions around ~10F, suggesting it is likely that fog will be limited to the south coast, Cape, and Islands. A dense fog advisory is not out of the question across SE MA/Cape Cod as visibilities may be reduced to 1/4 mi or less. If the stratus does in fact develop across metro west and Boston, radiational cooling may be limited, and temperatures may not reach their forecasted lows, especially across SE MA and RI. W MA and CT should remain relatively clear overnight. Previous Update... Clear skies abound this afternoon under a ridge of high pressure with light winds and temperatures well into the 60s. The only exception is along the coast where sea breezes are ongoing, holding temperatures in the 50s. Tonight surface ridging continues with winds becoming light, beginning turning E/NE. Radiational cooling should be rather efficient overnight, especially further north where skies stay clear or are slower to cloud over. We will once again be dealing with a surge of low level moisture trapped beneath a low level inversion, mainly along the south coasts and southeast MA. This will bring the return of low stratus and fog, likely more widespread than we saw this morning. Clouds advance as far north as the MA pike before retreating Tuesday morning. Low temperatures dip into the 20s for cold spots, but most will be in the 30s. Again this will be a night where the inversion means Worcester should be one of the warmest locations in the region, around 40 degrees. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Tuesday high pressure ridging continues. Main change will be boundary layer winds shifting out of the east. This will once again hold east coastal locations in check temperature-wise, in the upper 50s (low 50s on the Cape and islands). Elsewhere most locations rebound back into the mid 60s. Lingering stratus and fog south of the MA pike in the morning should dissipate by mid to late morning as the inversion is eroded. Nantucket and the outer Cape stand the best chance of holding on to clouds into the early afternoon. Tuesday night moisture advection returns to the low levels once again from the east with low/mid clouds overspreading from east to west, while in the upper levels W/SW flow brings scattered high clouds as well. Warm air advection from the south brings warmer low temps, in the upper 30s, perhaps low 40s, limited by surging dewpoints. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Highlights * East wind keeps things cooler Wednesday. Showers and spotty chance of thunder on Wednesday night. * Much warmer Thursday. * Better chance for precipitation on Friday as low pressure passes to our NW. Cold front passes through sometime Late Friday or Early Saturday. Wednesday through Thursday Night... The high pressure that was dominant Monday and Tuesday moves well northeast into the open Atlantic, but still suppresses low pressure moving off the coast of the Carolinas to our south and east. East wind off of the cold Atlantic will keep temperatures in the 50s across E. MA and Rhode Island Wednesday; areas in the CT River Valley, shadowed by the Worcester Hills, have the best shot at approaching 60. A shortwave that passes through Wednesday afternoon may bring a chance of spot showers, but a better chance of showers occurs Wednesday night as a warm front pushes in from the southeast. About 0.1" of QPF expected. K index values approaching 30, especially along the south coast and Cape Cod suggest that we can`t rule out an isolated rumble of thunder. Significant warm air advection on southwest flow in store for Thursday. Temperatures expected to reach into the upper 60s and low 70s. Some guidance suggests even warmer solutions, with the ECMWF showing highs in the mid 70s. High temperatures will hinge on how much sun breaks through the cloud deck. Southwest flow will keep areas along the south coast much cooler. Friday through Saturday... A more significant chance of precipitation arrives on Friday as a low pressure system slides to our NW across the Great Lakes and Northern New England. The chance for thunder seems more likely Friday afternoon along a cold front that moves from NW to SE across our area. The exact timing of this front differs between guidance, as the GFS favors a much faster progression compared to the ECMWF and Canadian models. With CAPE values approaching 600 in some guidance, namely the ECMWF, and the K index topping 30, isolated chances for thunder were expanded across much of Southern New England. A strong low level jet develops on Friday, as 925 mb winds gust 55- 60+ kts. Given that cold air will be ushered in behind the passing front, mixing is expected, and gusts to 30 kts cannot be ruled out sometime Friday afternoon through Saturday morning. Cooler and sunnier behind the passage of the front on Saturday, most will remain in the 50s. Sunday and Beyond... The GFS, ECMWF, and Canadian models all signal the development of a low pressure system late next weekend/early next week. The exact timing of this system, and p-type, differ significantly between the guidance. Should the storm take a more inland track, we would remain in the warm sector and should see rain. If the storm takes a more coastal track, we could see a bit of snow mix in. Given that we are heading into late March, confidence in accumulating snow is low. More attention will be paid to this system late week. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 00Z update...Moderate confidence. VFR and light winds to start the night. At the time of this writing, a stratus deck was beginning to develop southeast of Nantucket and is expected to progress to the NW overnight. Stratus and fog expected to develop along the south coast tonight and may lift north across portions of northern CT, RI and SE MA. Some guidance hints that stratus will make it`s way all the way up into Boston, which would drop ceilings into IFR/LIFR categories. Conditions will improve to VFR after about 15Z tomorrow. Easterly winds develop at this time and will extend through the end of the TAF period. Stratus/fog may develop again on Tuesday night across the south coast and SE MA, which would result in MVFR and IFR ceilings. KBOS TAF...Moderate confidence. Stratus may develop far enough north to affect KBOS, but may stay just south of the airport. Conditions will be highly influenced by the northern extend of the stratus. Fog not expected at KBOS due to forecasted >10F dewpoint depressions. KBDL TAF...High confidence. Outlook /Wednesday through Saturday/... Wednesday: Mainly VFR, with local MVFR possible. Chance SHRA. Wednesday Night: Mainly MVFR, with areas IFR possible. Chance SHRA. Thursday: VFR. Thursday Night: MVFR/IFR conditions possible. Chance SHRA. Friday: Mainly MVFR, with local IFR possible. Breezy. Chance SHRA, isolated TSRA. Friday Night: Mainly VFR, with local MVFR possible. Windy with local gusts up to 30 kt. Slight chance SHRA. Saturday: VFR. Breezy. && .MARINE... Tranquil conditions through tonight with light winds and seas. Looking at mainly light easterly flow Tuesday and Tuesday night, but increasing SE swell will result in seas building to 5-6 ft over outer southern and SE waters. Outlook /Wednesday through Saturday/... Wednesday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers. Wednesday Night: Winds less than 25 kt. Seas up to 5 ft. Rain showers likely, isolated thunderstorms. Thursday: Winds less than 25 kt. Seas up to 5 ft. Thursday Night: Winds less than 25 kt. Seas up to 5 ft. Slight chance of rain showers. Friday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Chance of rain showers, isolated thunderstorms. Friday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 9 ft. Slight chance of rain showers. Saturday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None. && $$ SYNOPSIS...BL/BW/KS NEAR TERM...BW/Chai/KS SHORT TERM...BW LONG TERM...BL/KS AVIATION...BL/BW/KS MARINE...BL/BW/KS
Area Forecast Discussion
National Weather Service Des Moines IA
645 PM CDT Mon Mar 22 2021 ...Updated 00z Aviation... .DISCUSSION.../Tonight through Monday/ Issued at 227 PM CDT Mon Mar 22 2021 Forecast Highlights: -- Light scattered showers become widespread tonight into Tuesday -- If there are breaks in the cloud cover Tuesday afternoon, there is a risk of strong to perhaps severe storms over southern Iowa -- Breezy on Wednesday as showers come to an end -- Additional precipitation chances Thursday and then again this weekend with near to slightly above normal temperatures Details: GOES-East Day Cloud Phase Distinction shows plenty of low clouds stretched from southwest to northeast over much of the state with high clouds streaming well northeast of the state as well. There are some peeks of sunshine over southeastern and far northern Iowa. The steadiest rainfall this afternoon is over western Iowa, but scattered showers also extend into parts of central Iowa. Showers will become more widespread tonight as low level thermal lift along with QG convergence increases over the state ahead of the upper low. In addition, precipitable water values around 1 inch will also be pulled into the state. The lift will remain through Tuesday and with cloud cover and periods of rain favored much of day, have trended temperatures downward from initial blend of guidance, which was at the 75th percentile. A conditional risk tomorrow is the possibility of a few strong or severe storms ahead of the upper low and the matched surface low along a wind shift if breaks in the cloud cover develop. There is an area of 0-3km MLCAPE up to around 100 J/kg that develops over southern Iowa with 15 to 20 knots of bulk shear in the same layer in the GFS. The 12z HRRR and NAM have higher amounts of 0-3km instability, though the NAM does not bring the instability as far north. Forecast soundings at LWD (12z NAM/6z GFS) show good low level turning in the first kilometer with helicity values over 100 m2/s2. The same can not be said about the 12z GFS, which does not show a favorable environment for rotation. In coordination with SPC, the midday update to the day 2 outlook has introduced a marginal risk of severe weather into southern Iowa. Many of the updraft helicity tracks from the 12z HREF are shown over northern Missouri with the 12z HRRR showing one or two tracks into our far southeast forecast area toward mid-afternoon Tuesday. Thus, a non-zero tornado risk will remain for tomorrow, but is highly contingent on some surface heating. As the upper low moves overhead and continues northeastward away from the state, the low level thermal lift will decrease Tuesday night. As QG convergence becomes subsidence on Wednesday, will see showers come to an end as winds turn breezy. Fortunately, the rain will be spread out over time with within bank rises on rivers and streams expected along with a beneficial boost to soil moisture. Winds from the northwest with gusts of 25 to 35 mph should be common over much of the forecast area as well. The next shortwave will be approaching from the Four Corners region on Wednesday and bring with it the next chance for precipitation. While the NAM, GFS, and ECMWF all show some precipitation over the state at some point Thursday -- namely the southeastern part -- there is still a good number of ensemble members that show the precipitation remaining southeast of Iowa. At this point, will keep low PoPs with the highest chances over southeast Iowa and more so points southeast of Iowa. A final shortwave rotates through the region late this week into this weekend. The GFS and ECMWF and a majority of their ensemble members have some precipitation passing over the state with the CMC and its ensembles on the drier side. At this time, a prolonged period of low PoPs is into this upcoming weekend, which will likely get parsed down to a shorter period. While much of the week will have temperatures near seasonal levels, slightly warmer temperatures are possible depending on timing of precipitation next weekend. && .AVIATION.../For the 00Z TAFS through 00Z Tuesday evening/ Issued at 641 PM CDT Mon Mar 22 2021 Widespread stratiform cloud cover blankets Iowa this evening. As of the early evening CIGs were staying at MVFR. However, rain showers will continue to spread Tuesday, and as this happens expect CIGs to drop to IFR. Depending on localized areas of heavy rainfall, visibility may drop to IFR as well. The next 24 hours will not present the most favorable aviation conditions. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Ansorge AVIATION...Krull
Area Forecast Discussion...UPDATED
National Weather Service Hanford CA
730 PM PDT Mon Mar 22 2021 .UPDATE...Have updated the Wind Advisory which had been in effect for the Central Sierra and North Kings River areas to a High Wind Warning from 100 pm PDT Tuesday until 500 am PDT Wednesday. HRRR continues to show stronger wind gusts over these areas and is now projecting gusts as high as 70 mph Tuesday evening and early Wednesday morning. && .SYNOPSIS...A trough moving through the Great Basin tonight through Tuesday will lead to a chance of light precipitation, primarily for the higher elevations of the Sierra, and higher elevations of the Tehachapi and Fort Tejon areas. Gusty winds will impact the Kern county mountains and desert into Tuesday morning. Offshore flow then develops on Tuesday into Wednesday, with strong northeasterly winds possible in the Sierra mountains and foothills. && .DISCUSSION...An upper level trough currently over central Oregon will dig southeastward through the Great Basin tonight, reaching northern Arizona by Tuesday afternoon. The current pressure gradient from SFO-LAS is 8mb, and will continue to increase through the early morning hours. This will set the stage for strong west to northwesterly winds through Tehachapi pass, and into the surrounding desert area. Wind gusts up to 50 mph are conceivable through Tuesday morning. As this system swings through the region tonight, there is a 30% chance of light precipitation, primarily for the highest elevations of the Sierra. Any amounts will be negligible. Northwest flow aloft will act to enhance upslope flow into the Tehachapi mountains and Fort Tejon area this evening through Tuesday morning. There is a 50% chance of light rain, drizzle, and snow showers generally above 5000 feet. The latest guidance shows up to 1/3 of an inch of QPF along the highest peaks, and up to 1/10 of an inch along the Grapevine and Frazier Park areas. The highest peaks may see a trace to two inches of snow, with snow levels around 5 to 6 thousand feet for most of the day. As the aforementioned trough exits into northern Arizona, northwesterly flow will turn to an offshore northeasterly flow. Although not the best setup, a weak Mono wind event is becoming more likely. The short-term ensembles are indicating wind gusts up to 60 mph starting Tuesday afternoon, continuing into Wednesday morning. Strong wind gusts up to 30 mph are also possible in the southern San Joaquin Valley Tuesday, but the current NBM probabilities of seeing winds greater than 35 mph are around 50%. Thus I will hold off on any wind products in the valley. Another trough of low pressure will swing through the Great Basin on Thursday, bringing increasing winds into Kern County, and a very slight (15%) chance of precipitation in the Yosemite area. && .AVIATION...Expect areas of MVFR with local IFR and terrain obscurations along the west and north facing slopes of the Sierra through at least 18Z Tuesday. Also, expect areas of MVFR with local IFR and terrain obscurations along the west and north facing slopes Kern County mountains from 06Z Tuesday through at least 20Z Tuesday. Strong sustained west to northwesterly winds of 25 to 35 mph with gusts up to 50 mph are likely in the Kern County mountains through at least 18Z Tuesday. Gusty northeasterly winds are then possible in the Sierra Nevada mountains and foothills after 20Z. Otherwise...VFR conditions will prevail across Central California through the next 24 hours. && .AIR QUALITY ISSUES...None. && .CERTAINTY... The level of certainty for days 1 and 2 is high. The level of certainty for days 3 through 7 is medium. Certainty levels include low...medium...and high. Please visit for additional information an/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES... High Wind Warning from 1 PM Tuesday to 5 AM PDT Wednesday for CAZ192-193. Wind Advisory until 8 AM PDT Tuesday for CAZ196>199. && $$ public...CMC/DS aviation....Molina
Area Forecast Discussion
National Weather Service Marquette MI
629 PM EDT Mon Mar 22 2021 .SHORT TERM...(This evening through Tuesday) Issued at 403 PM EDT MON MAR 22 2021 WV imagery and RAP analysis indicated a broad mid/upper level trough through the Rockies and a downstream ridge over the eastern CONUS resulting in southwest flow toward the northern Great Lakes. A shortwave trough from near James Bay to the MN arrowhead was lifting off to the northeast. At the surface, a weak front extended from eastern Upper Michigan into north central WI while high presssure building from MN into western Upper Michigan was bringing mostly clear skies. Tonight, WAA and 285k-290k isentropic ascent will increase overnight along and north of a slowly advancing 850 mb front and nearly stationary surface frontal boundary over northern WI. Light rainfall amounts of a tenth of an inch or less are expected given the modest moisture inflow and availability. With min temps in the mid to upper 30s, no freezing pcpn is expected. Tuesday, the rain band into central Upper Michigan will lift northward during the morning with a lull in the pcpn until rain increases again toward the late afternoon as isentropic lift and stronger moisture transport moves in as the mid level and sfc advance toward southwest IA. Temps will remain above average with highs in the lower 50s south and east. However, northeast winds will keep readings in the lower 40s near Lake Superior. .LONG TERM...(Tuesday night through Monday) Issued at 325 PM EDT MON MAR 22 2021 The main focus of the this long term period will be a strong surface low that will be tracking up from the central plains, across Upper Michigan Wednesday into Thursday. This low will have quite a bit of moisture associated with it, mainly in the form of rain which will be a welcome sight for Upper Michigan as we are currently in an abnormally dry time according to the latest drought monitor. Some consistency from the overnight runs and this mornings runs show the system occluding before reaching Upper Michigan with a surface low of around 995-997mb by Wednesday morning. Rain should be falling by Tuesday night and will mostly be widespread rain through Wednesday. QPF amounts will range generally from 0.25 inches to 0.75 inches of rain with possibly higher amounts near 1 inch over far western Upper Michigan. As the system begins to move away from Upper Michigan late Wednesday into Thursday, a cold front will move across Upper Michigan from west to east and will change rain showers to more of a rain/snow mix then light snow showers once the front passes, mainly over the west and possibly north central too. System will be out of the area by Thursday morning with some clearing and dry conditions for most of Thursday. Another shortwave will approach the Upper Great Lakes late Thursday into Friday and models are starting to come into a general agreement as to the track of the low. The GFS has trended further south to align more with the ECMWF and Canadian across the Lower Peninsula of Michigan which would keep the pcpn just to the southeast of Upper Michigan. With the newer guidance in, will probably go towards more of a drier solution for Thursday night and Friday. The NAM is the current outlier with the track closer to the Mackinaw Straits. We`ll see if the NAM will catch up to the others but will still lean towards a bit drier solution with some slight chc PoPs for now. That shortwave will move out late Friday before yet another shortwave will be approaching on Saturday, which will bring another chance of pcpn. This will be a mix light rain/snow showers Saturday afternoon through Sunday. This shortwave will move out by early Monday with high pressure building in for this time next week. As for temperatures, it will still be above average on Wednesday with highs in the 40s to low 50s before the cold front moves through Wednesday night into Thursday with cooler temperatures for Thursday and Friday. Friday will be the coldest day in the extended with highs mainly in the low to mid 30s. Temps will rebound a bit for the upcoming weekend with upper 30s to mid 40s. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 629 PM EDT MON MAR 22 2021 VFR conditions will prevail tonight for IWD and CMX before deteriorating to IFR on Tue morning with some pcpn moving in. Conditions will then stay IFR at IWD and CMX into Tue evening. VFR conditions at SAW will fall to IFR by late tonight as rain moves in. Conditions will fall further to LIFR on Tue with northeast upslope flow with rain and fog at SAW. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 403 PM EDT MON MAR 22 2021 Light and variable winds of 15 knots or less expected across the lake into this evening as weak high pressure builds into the area. By Tuesday, a low pressure system moving northeast from the Central Plains will result in winds veering around to NE and increasing to 20-30 kts, greatest over the western third of the lake. NE winds may even reach low-end gale force gusts over the west end late Tuesday and Tuesday night before slowing diminishing and backing northerly on Wed as the low lifts over the lake. N-NW increase again to 25-30 knots on Wed night behind the low which lifts ne of the lake. Winds become lighter and N-NE on Thu before increasing NE to 25 knots Thu night into Friday as another system tracks from the southern Plains into the Great Lakes. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...JH AVIATION...07 MARINE...JLB
Area Forecast Discussion
National Weather Service Pendleton OR
858 PM PDT Mon Mar 22 2021 .UPDATE... Latest radar and ground truth observations show that organized precipitation has either ended or moved out of the area. Short range guidance does indicate that there could be some lingering snow showers over the eastern Oregon mountains for the next few hours, little accumulation is anticipated. As a result, the winter weather advisories were allowed to expire at 800 PM/0300Z. Dry northerly flow and slight ridging will begin to build in so an lingering precipitation will come to an end by morning. For this update, made adjustments to pops...mainly to lower them. Also, updated temps where needed based on current obs and latest guidance. && .AVIATION... 06Z TAFS...VFR conditions are expected through the period under dry northerly flow and slight upper level ridging. Winds remain gusty at DLS and will likely remain elevated through the night and into Tuesday, with gusts generally 20 to 25 kts. Elsewhere, winds continue to decrease and will be 10 kts or less by morning if not sooner and remain there for the remainder of the TAF period. && .PREV DISCUSSION... /issued 426 PM PDT Mon Mar 22 2021/ AVIATION... 00Z TAFS...VFR conditions expected. Mainly isolated -SHRA around the region could pass over a TAF site through the evening, but overall impacts will be limited. Gusty winds to around 30 kts will continue through the evening hours before decreasing to around 10 kts or less overnight through Tuesday. PREV DISCUSSION... /issued 1133 AM PDT Mon Mar 22 2021/ UPDATE...A warm front that is bringing moderate to heavy snow to the Cascades and the northern Blue Mountain continues to impact these areas. Winter weather advisories are in effect for the Cascades and the Blues today. The lower elevations will receive rain, with snow levels around 2500-3000 feet MSL. This weather system will move out of the area tonight, but residual moisture and a healthy northwest flow will continue to cause upslope snow showers over the northern Blues, and may need to extend the advisory for there. However, the Cascades are expected to see snow decreasing today and will likely not need to extend the advisory for there. The atmosphere is expected to become unstable this afternoon from the John day highlands to Wallowa County. These areas have a possibility of afternoon and early evening thunderstorms. It will be windy over most of the forecast area today and tonight, with wind speeds approaching advisory speeds for the Kittitas Valley, but only for a short time. Therefore will hold off on any wind highlights at this time. A cool northerly flow will develop on Monday with still a possibility of a few snow showers over the northeast mountains as an upper ridge builds off shore. 88 AVIATION...18Z TAFs...Mountain snow continues today with rain showers at possible at PDT/ALW. Can`t rule out a shower at RDM/BDN as well. Mountain obscuration likely. Ceilings will be 4-7kft at the terminals today. Improving conditions tonight with clearing skies at the taf sites and mountain snow showers diminishing. Winds 14-24g24- 34kts today decreasing to less than 10kts tonight. PREV DISCUSSION... /issued 524 AM PDT Mon Mar 22 2021/ SHORT TERM...Today through Wednesday night...Shortwave trough will dig sewd across the region today exiting the region by Tuesday morning. This will bring rain and mountain snow to the area with rain shadowing east of the Cascades. There will be moderate to heavy snow in the Blue Mountains and near the Cascade crest today before tapering off. Latest SPC HREF is showing borderline warning amounts over the northern Blues mainly over the higher peaks. Thus places like Ski Bluewood, Tollgate, and the higher snotels could see snow totals of around 10 inches. However with the spring sun angle and borderline daytime temperatures plan on leaving the advisories that are in effect as is for now and not upgrade to warnings. Another concern for today are the winds. Current LAMP guidance is showing winds approaching advisory levels in the Kittitas Valley and the eastern Gorge but only for a short window of time this afternoon and evening so will hold off on issuing an advisory for these areas. Finally, very steep low to mid level lapse rates over the eastern portion of the forecast area may result in enough CAPE for an isolated thunderstorm or two this afternoon...mainly Grant, Union, and Wallowa Counties. Latest HRRR is showing some decent convective cells in this area from 20-23Z. All precipitation will end this evening and Tuesday looks to be a dry pleasant day with seasonable temperatures and light winds. The next storm system will drop sewd across the area late Wednesday and Wednesday night similar to the current one and produce some lower elevation rain and mountain snow. As of now QPF/snow amounts appear a bit lighter with this second storm. It will also be breezy to windy in the lower elevations Wednesday afternoon and evening. 78 LONG TERM...Thursday through Sunday. Models in good agreement with the general pattern. Upper level trough will be moving east of the region into Idaho on Thu. Lower elevation rain and mountain snow decreasing in the morning and becoming more focused over northeast Oregon mountains in the afternoon with upslope flow. Ridge building in Thu night with precipitation over the Blues ending by evening. Clearing skies overnight. The ridge will strengthen Fri into Sat with a dry northwest flow. Expect mainly clear skies and warm temperatures. Highs will be in the upper 50s and 60s. A fairly strong upper level trough and jet will be approaching the Pacific northwest on Sunday. Clouds and wind will be increasing. Slight timing differences at this point in the models. Light precipitation could overspread the Cascades during the day. This system moves through Sunday night and Mon with rain and mountain snow. Much cooler and windy Mon. 94 && .PRELIMINARY POINT TEMPS/POPS... PDT 31 52 31 54 / 10 0 0 30 ALW 33 54 34 56 / 10 0 0 40 PSC 30 59 36 58 / 0 0 0 10 YKM 28 59 32 56 / 0 0 0 30 HRI 33 58 35 57 / 0 0 0 20 ELN 31 55 33 53 / 0 0 0 30 RDM 21 50 26 52 / 0 0 0 20 LGD 29 45 24 47 / 30 0 0 40 GCD 29 48 25 51 / 20 0 0 20 DLS 36 57 36 53 / 0 0 0 50 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. && $$ SHORT TERM...77 LONG TERM....94 AVIATION...77
Area Forecast Discussion
National Weather Service Reno NV
535 PM PDT Mon Mar 22 2021 .UPDATE... No significant changes to the forecast of yet, but will be monitoring. After reviewing the data for the slider, the potential for accumulating snow on the valley floor is higher than it looked this afternoon. Thunderstorms are forming behind the front in Oregon, a signal increased instability. While snow levels are higher right now, running around 5000 feet, almost all precip with the main band will be post-frontal when snow levels and temps fall rapidly. In addition, frontogenetical forcing and modest instability will promote more intense snowfall for a 1-3 hour period. Latest HRRR runs show a fairly intense band moving through the I-80 and Highway 50 corridors around midnight. As is typical for sliders, the heaviest snow will be in western Nevada, with light if any snow in the Sierra around Tahoe, with a better chance for Mono County. At this point in time, the probability of the valley floors in western Nevada seeing an inch of snow is 40% with a 10% chance of 2 inches or more. X && .PREVIOUS DISCUSSION... /Issued 239 PM PDT Mon Mar 22 2021/ SYNOPSIS... Winds increase through Tuesday as a cold front moves through the region. Snow showers tonight will result in some slick roads into the commute time Tuesday morning, especially in elevations above 5000 feet. Another front is expected Thursday for a drop in temperatures, breezy winds, and a chance for showers. Warmer springlike conditions are likely this weekend. DISCUSSION... The first part of our slider system came in a bit wetter than expected with some light rain/snow showers moving southward across the northern Sierra and western NV this morning. This has moistened the atmosphere which should help precipitation proficiency tonight (lack of dry layer), but also raised dewpoints ("warmed" the snow level potential) which will likely limit snowfall potential on lowest valley floors below 4500-5000 feet. As a result, we increased QPF but reduced snowfall amounts on the lowest valley floors. Otherwise, timing of the front and associated forcing are still in place to bring a short-lived (1/2-1 hour) but moderate intensity band of showers tonight, starting across northeast CA and northwest NV this evening, sliding through the I-80/Hwy 50 corridors 10 pm - 2 am, and then south of Highway 50 late tonight into daybreak Tuesday. Impact- wise, expect an inch or two of wet snow in foothill areas which may result in slick roads as temperatures fall below freezing behind the band of precipitation. Warm road temperatures will limit snowfall down on the lowest valley floors with conditions remaining mostly wet. Being this is an slider type system, snowfall amounts in the Sierra will be on the light side, generally an inch or two, including the Tahoe Basin. Winds will increase behind the front with a brisk, very cool day Tuesday. Temperatures will struggle to hit 40 in the Sierra valleys and likely reach only 40s in the lower elevations. Strong northeast winds will develop across the Sierra ridges and continue into Tuesday night (gusts could approach 100 mph). We have hoisted lake wind advisories for both Lake Tahoe and Pyramid Lake for rough lake conditions. A brief break for Wednesday ahead of a second slider system to drop in from the north Thursday. This will bring another round of showers and gusty winds, although the track is slightly farther east in the latest ensemble guidance. Based on the performance of the current system against national blended guidance, we have extended some low chance POPs back to the Sierra to include most of western NV Thursday. Snow levels are a bit higher and any showers are expected to move across during daylight hours. So impacts right now are low. High pressure will finally build into the region this weekend which promises dry and warmer conditions. Temperatures will likely push to 60 in the Sierra valleys and low-mid 70s across western NV. These conditions may persist into next week although a weak trough may brush our area to the north for a slight uptick in winds Mon-Tue. Hohmann AVIATION... A fast-moving storm system moves through the Great Basin tonight with snow showers and increasing winds. There is a slight chance of blowing dust over KHTH, KNFL, KWMC this afternoon. Looks like another band of snow showers is expected overnight, mainly between 06-09z with a quick burst of IFR snow to western Nevada terminals including KRNO, KCXP, KMEV and into central Nevada near KNFL as well. Snow accumulations for the valley floors will be difficult tonight, as temperatures/snow levels will be right near valley floors and may be too warm for accumulations. Snow accumulations will be minimal, with about a 70% chance of nothing, up to a dusting of snow--but only less than 20% chance of seeing one inch of accumulations. There is a better chance of seeing snow up to an inch or two around KTRK and KTVL tonight, although with these slider-type storm systems, we tend to see better accumulations in western Nevada than Tahoe. Early Tuesday morning flights before 12z will be the most affected by this snow with potential for deicing and snow removal, but the biggest chance is that we see minimal accumulations. Snow should move out of the area by 12z Tuesday, with gusty north to east winds through the day on Tuesday. -Hoon && .REV Watches/Warnings/Advisories... NV...Lake Wind Advisory from 8 AM to 7 PM PDT Tuesday for Pyramid Lake in NVZ004. Lake Wind Advisory from 8 AM Tuesday to 5 AM PDT Wednesday for Lake Tahoe in NVZ002. CA...Lake Wind Advisory from 8 AM Tuesday to 5 AM PDT Wednesday for Lake Tahoe in CAZ072. && $$ For more information from the National Weather Service visit...
Area Forecast Discussion
National Weather Service Sacramento CA
215 PM PDT Mon Mar 22 2021 .SYNOPSIS... Mostly dry weather this week with a slight chance of mountain showers into tonight and again Thursday. Warmer temperatures expected most of this week. Breezy to locally windy Tuesday into Wednesday morning. && .DISCUSSION... A weak vort max ahead of the main short wave trough brought a few light showers to the high Sierra this morning into the early afternoon. This activity has diminished now but we will see the main short wave trough track out of OR into NV this evening. This will bring the return of light showers mainly over the mountains with the best chances at the Sierra crest. HRRR runs along with some of the other CAMs have been consistent on a few light showers pushing into some of the lower elevations mainly along the I-80/Hwy 50 corridor to the east of SAC around 11pm/6z. We do see some weak mid-level instability and that is likely why we are seeing these lower elevation showers on the CAMs. Overall should remain dry with dry low levels but maybe a few sprinkles or a light shower east of Roseville along I-80/Hwy 50 early tonight. The trough will push to the south of us by tomorrow morning and will begin to close off. This will bring breezy north and east winds to the area. MFR-SAC gradient is forecast to tighten to around 10 to 11 mb Tuesday through Tuesday evening which could result in north wind gusts in the Valley up to 25 to 35 mph, locally to 40 mph. SAC-RNO gradient forecast around 8 to 9 mb Tuesday night which could result in easterly wind gusts in the mountains up to 35 to 50 mph, locally higher in wind prone areas. Valley winds are expected to be strong enough for a Wind Advisory and went ahead and issued one with this package from Tuesday 8am/15z to 8pm/3z. Winds will begin to diminish Wednesday morning and short wave ridging will bring quiet conditions. Another short wave trough will push into the PacNW and track into NV Wednesday into Thursday. This trough looks to remain a bit further to the east than the trough today. This will bring only a slight chance for mountain showers Thursday mainly at the mountain crest south of I-80. This trough will bring some clouds to the area as well. Strong ridging will begin to build in Thursday night. Temperatures this week will climb under the high pressure. Temperatures will remain right around normal today and Tuesday before rising a few degrees for midweek. Valley temperatures are forecast right around 70 degrees on Wednesday. -CJM && .EXTENDED DISCUSSION (Friday THROUGH Monday)... EPac high pressure moves into Northern California Friday into the weekend bringing above average temperatures, lighter winds, and mostly clear skies to the area. Highs will be around 10-15 degrees above average this weekend, and the first 80 degree readings of the season will be possible across the Central Valley this weekend or Monday. A bit of spread is seen in the ensemble guidance via the cluster 500mb heights with the possibility of a trough moving across the PacNW on Monday. Main influence of the trough would be moderating temperatures back towards normals for late March. && .AVIATION... VFR cigs/visbys are expected for the next 24 hours. Light SHSN may develop across high mountain elevations over the southern Cascades and northern Sierra after 22Z with local MVFR conditions possible with this activity. Surface winds under 12 knots thru 12Z before breezy north winds in the Valley develop, becoming stronger in the afternoon. && .STO WATCHES/WARNINGS/ADVISORIES... Wind Advisory from 8 AM to 8 PM PDT Tuesday for Carquinez Strait and Delta-Central Sacramento Valley-Mountains Southwestern Shasta County to Western Colusa County-Northeast Foothills/Sacramento Valley-Northern Sacramento Valley-Northern San Joaquin Valley-Southern Sacramento Valley. && $$