Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/28/19

Area Forecast Discussion
National Weather Service Marquette MI
752 PM EDT Wed Mar 27 2019 .SHORT TERM...(This evening through Thursday) Issued at 418 PM EDT WED MAR 27 2019 WV imagery and RAP analysis indicated a trough over north central Canada and a ridge over the srn/cntrl plains resulting in zonal mid/upper level flow from the northern plains through the western Great Lakes. A shortwave trough and associated 1000 mb low was located over northwest Ontario with a cold front through the nw corner of MN and eastern North Dakota. Strong WAA 295k-300k (around 700 mb) isentropic lift supported a band of showers from eastern Lake Superior to around KERY. Some tsra lingered over eastern Lake Superior where MUCAPE values were near 500 J/Kg. Otherwise, a tight pres gradient has pushed ssw wind gusts to 35 mph as temps climbed to around 50. Tonight, radar/satellite suggests that the showers over the east will quickly exit Upper Michigan late this afternoon leaving a period of partly cloudy skies. As the cold front moves through after 03z, there may be some light pcpn. However, nothing more than sprinkles with weak to moderate 900-700 mb fgen behind the front. Southwest winds veering nw will remain strong enough to keep temps in the mid 30s. Thursday, CAA with nw winds will bring in moderately cooler air as 850 mb temps drop to around -8C. There should be enough sun to boost max readings into the mid 40s. .LONG TERM...(Thursday night through Wednesday) Issued at 351 PM EDT WED MAR 27 2019 Continued quiet with no impactful conditions expected. Starts out with partly cloudy skies Thu night and Fri with lows in the mid teens to mid 20s and highs in the mid 30s to mid 40s. An upper trough moves in Fri night into Sun night, which will only result in some light snow at times from lake effect and a shortwave. Not surprisingly, models changed significantly with the track of the surface low and now keeps any synoptic precip from that way S of the CWA. 850mb temps drop to around -15C Sat afternoon and evening, but daytime heating will limit coverage/intensity and snowfall amounts. A shortwave drops through Sun afternoon and evening according to the GFS and CMC, but the ECMWF is weaker and farther SW. Could see some light rain/snow mix with this if the better precip from the GFS and CMC verify, but nothing significantly impactful. No significant precip expected early next work week. Could see a more active period in the middle to end of next week, but there is a lot of uncertainty with details given very poor model agreement and run to run discontinuity. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 747 PM EDT WED MAR 27 2019 VFR conditions are expected at KIWD/KCMX/KSAW through this evening. Although moisture is advecting into the area under sw winds, this moisture will only lead to cloud bases in the 4000-6000 ft range this afternoon. As the cold front arrives, cigs should fall to MVFR at KIWD and KCMX overnight. A tightening sw pres gradient ahead of the front will result in LLWS this evening while west winds behind the front later tonight into Thu morning could gust up to 25 knots, mainly at KCMX. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 418 PM EDT WED MAR 27 2019 South winds of 20 to 30 knots will become west behind a cold front tonight and nw on Thursday and then diminish at or below 20 knots Thursday night. Winds increase again to 30 knots Sat from the north. These would be the strongest winds for the forecast period. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...Titus AVIATION...Voss MARINE...JLB
Area Forecast Discussion
National Weather Service Reno NV
314 PM PDT Wed Mar 27 2019 .SYNOPSIS... The ongoing storm with rain, wind, and mountain snow impacts will move east tonight. Scattered snow and pellet showers are expected Thursday afternoon with more isolated coverage Friday. Temperatures will warm to above normal this weekend with dry and pleasant weather. Additional storms are possible next week but low certainty on severity and impacts. && .DISCUSSION... Rain & Snow Through Thursday... * Slightly increased QPF for later this afternoon/evening mainly south of the Tahoe Basin and into Mono County due to position of upper level jet enhancing spillover. * Lowered snow levels for this afternoon/early evening due to the heavy precipitation band associated with the system`s cold frontal passage. Overall, not many changes were made to the short term forecast in regards to precipitation amounts and snow levels through Thursday. Taking a look at radar, a heavy and convective precipitation band is currently moving through the Sacramento Valley area and is expected to make its way into the Sierra by late this afternoon/early evening. Snow has already begun to fall in higher elevations in the Sierra, but is having a hard time sticking to the roadways. This should change as precipitation increases in intensity and snow levels drop quickly down to ~6000 ft as this band (cold front) moves through. During this time, conditions will deteriorate rapidly leading to hazardous travel, especially for areas in the Sierra. Due to the convective nature and time of year, do not be surprised to hear a rumble of thunder or see a flash of lightning due to these unstable conditions. As the core of the low pressure system shifts closer to the west coast early this evening, its associated upper level jet noses into the Tahoe Basin and Mono County region. This set up should lead to higher precipitation amounts and better spillover into the western Nevada valleys. The steadier precipitation rates should calm down and be reduced to on and off snow/pellet showers by later tonight as the bulk of the atmospheric moisture tap cuts off. These showers persist into Thursday with even the chance for afternoon thunderstorms as the unstable conditions stay in place. When it`s all said and done expect 1-2 feet of snow accumulation above 7000 ft in the Sierra, 6-12 inches between 6000-6500 ft, with minimal amounts below 6000 ft. As for the western Nevada valleys, precipitation will be mainly rain with the potential to see 0.10-0.30" of accumulation. -LaGuardia Wind Through Thursday... * Minor changes to increase wind gusts Mono/Mineral for Thursday PM. * Strong gusty S/SW winds will persist through this evening as respectable upper jet combines with low level thermal gradient. Latest HRRR has reasonable trends pushing the strongest winds east-southeastward with time as spillover works into W Nevada. Could see some pockets of high impact winds along Hwy 95/Walker Lake and Hwy 395/Washoe Valley. Sierra ridges gusting earlier over 100 MPH but those winds should start to subside some this evening as upper jet heads eastward. * Winds relax quite a bit Thursday as surface high noses in from California. Only area of some concern is S Mono and Mineral Counties where low level pressure gradient appears stronger in GFS, which could lead to some channeling of NW flow. Overall travel impacts would be on the low-end. -Chris Notes on Friday through Next Week... * Changes: Raised daytime highs for this weekend. Increased rain shower, t-storm chances and amounts for Monday. * This coming weekend looks quite pleasant with upper ridging moving overhead. Temperature guidance has trended upward and daytime humidity trends down, and have followed this. 70 at RNO and 60 at TVL/MMH is attainable Sunday if skies remain sunny enough. Would be the first 70 at RNO this year - a bit tardy since March 10 is the average first 70 (since 1990). Above normal temps will likely persist into next week which could start melting some of the lower elevation snows. This would lead to minor rises on creeks/rivers but not a flooding scenario. * Pattern next week favors weak-moderate and mild Pacific storms. Wave moving through Monday is the most obvious example with widespread rain showers even into mountain communities with high rain-snow lines. Some spots especially N Sierra, NE Cal into far NW Nev could pick up 1/4 to 1/2" rainfall. A few t-storms even possible for the 1st day of April within a weakly unstable airmass. Can`t rule out additional similar waves next week but predictability this far out is limited. * Of perhaps more interest are the increasing signs for a strong atmospheric river landfall on the west coast late next week. GEFS and EPS guidance support a feature like this, with highest probabilities for landfall in far N California up into Oregon. Our region is close enough where it wouldn`t take a radical pattern shift for us to get a dose of heavy precip in the N Sierra into NW Nevada. Not at all time to freakout, but definitely worth keeping an eye on given the ripening snowpack. We`ve had strong AR landfalls and heavy rains in early April both in 2018 and 2017. Typically the frequency of AR impacts decline rapidly during the month of April. -Chris && .AVIATION... * Passing upper level jet of 120+ kts and low level thermal gradient will lead to continued rough air across the Sierra and W Nevada through this evening. Many reports of LLWS which will persist due to substantial directional and speed changes below mountain ridgetops. Winds Thursday will be quieter with high pressure moving in. Exception would be toward MMH BIH and HTH where low level gradient will promote gusty NW winds. * Band of heavy precip working into the Sierra from Central CA this afternoon. Feature is sliding south and as it does we`ll see a period of heavy IFR/LIFR snows and even thundersnow at Sierra airfields including TVL TRK and MMH. Good chance of seeing runway accumulations even with antecedent warm pavement. 80% chance of at least an inch, with 30% chance of 4 inches or more depending on how cold temps get during heavier snow bursts. * Spillover into W Nevada will be confined into this same heavy precip band. Should see 1-3 hour period of MVFR rain showers at RNO CXP late this afternoon into early evening per latest HRRR, but probably have a hard time making it east to NFL and HTH. Wind will be the greater issue there. -Chris && .REV Watches/Warnings/Advisories... NV...Lake Wind Advisory until 11 PM PDT this evening for Lake Tahoe in NVZ002. Winter Storm Warning until 11 PM PDT this evening above 6500 feet in NVZ002. Wind Advisory until 11 PM PDT this evening NVZ001. Lake Wind Advisory until 11 PM PDT this evening for Pyramid Lake in NVZ004. CA...Winter Storm Warning until 11 PM PDT this evening above 5500 feet in CAZ071. Winter Storm Warning until 11 PM PDT this evening above 7000 feet in CAZ073. Lake Wind Advisory until 11 PM PDT this evening for Lake Tahoe in CAZ072. Winter Storm Warning until 11 PM PDT this evening above 6500 feet in CAZ072. && $$ For more information from the National Weather Service visit...
Area Forecast Discussion
National Weather Service Sacramento CA
331 PM PDT Wed Mar 27 2019 .SYNOPSIS... Pacific storm moves through today into Thursday with rain, mountain snow, and possible thunderstorms. Drier weather Friday into the weekend with unsettled weather early next week. && .DISCUSSION... The Pacific cold front attendant to the offshore upper low has just moved across the Greater Sacramento area. This has been accompanied by a broad band of slow moving southwest-northeast oriented showers. Somewhat unusual for this region, pulse-like thunderstorms are firing ahead of this line within a pool of instability. Normally this would be expected in the wake within the dome of cool, unstable air aloft. Vertical shear profiles are favorable for weak rotation so would not be surprised to see a random funnel cloud report. Otherwise, heavy downpours and the potential for gusty winds and small hail would be more likely in the stronger cells. The entire swath of locally heavy rainfall will continue advancing eastward toward the foothills/mountains this afternoon. To the north, recent HRRR model runs have shown indications of the Shasta County Convergence Zone setting up. This would support an enhanced period of rainfall generally in the vicinity of Redding. Overall, some lingering showers are possible across Valley locations into the evening with additional chances on Thursday given trailing cyclonic flow overhead. Across mountain locations, the late-season winter storm is well underway with heavy snow picking up this afternoon as the baroclinic zone shifts focus to inland locations. This could lead to a significant reduction in visibilities as well as hazardous travel. Thus, as mentioned in previous messages, mountain travel is not advised until the system clears on Thursday morning. The S-band radar is showing initial snow levels around 5,500 to 6,000 feet. Given the arrival of colder air aloft overnight, expecting the snow levels to drop to the 3,500 to 4,000 foot range early Thursday. Like the Valley, numerous showers will continue into Thursday with brief travel impacts where such precipitation falls. When it is all said and done, elevations 7,000 feet and above can expect 1 to 3 feet with locally higher amounts possible. While some showers could linger into Friday morning over northern counties (Shasta, Lassen, Tehama, and Plumas), much of the region will begin to dry out as an upstream ridge approaches. The mean ridge axis should settle over the state for the weekend ensuring a dry, mild period. High temperatures are forecast to reach the low to mid 70s over the Valley with upper 40s to lower 50s in the mountains. ~BRO && .EXTENDED DISCUSSION (Sunday THROUGH Wednesday) The extended period will start out dry with the transient ridge maintaining its presence over the southwestern U.S. There is decent agreement operational and ensemble model agreement that a shortwave will reach the northwestern California coast by Monday afternoon. An increase in cloud cover accompanied by some warm advection precipitation is expected for Monday with snow levels likely to be quite high, generally 7,500 to 8,000 feet. Once this storm clears the region, model uncertainty grows as the main operational models (GFS/ECMWF) are at odds with one another. At the very least the models show run-to-run consistency, albeit with different forecasts. The GFS favors a building of the eastern Pacific ridge while the ECMWF depicts influences from a northern stream trough. Thus, too much uncertainty exists to declare a dry forecast into the middle of next week. Looking ahead, the Atmospheric River Detection Tool and other corresponding ensemble solutions are advertising a wet, active pattern toward the end of next week and into the weekend. This has also been highlighted in the Climate Prediction Center Day 8-14 experimental Heavy Precipitation graphics. The blocking upper high over Alaska bounding an active Pacific jet are the key players in the pattern change. While there is confidence in this set up, the southward extent of its influences are a big question mark. Ensemble probabilities remain highest between 40-45 degree north latitudes. Will definitely be something to keep an eye on heading to the period of April 4-8. ~BRO && .AVIATION... Segments/lines and clusters of thunderstorms over much of interior Norcal persisting into the evening with MVFR/IFR/LIFR conditions obscuring higher terrain. Scattered showers and mainly VFR/MVFR conditions for the remainder of the night after 06z. Mainly south winds 10-20 gusts to 30 knots through 00z mainly northern Sac Vly, then lighter south winds the remainder of the night. Unstable air mass continues into Thu with scattered thunderstorms redeveloping late morning/afternoon and into early evening. && .STO WATCHES/WARNINGS/ADVISORIES... Winter Storm Warning until 5 AM PDT Thursday for West Slope Northern Sierra Nevada-Western Plumas County/Lassen Park. && $$