Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 01/30/19

Area Forecast Discussion
National Weather Service La Crosse WI
538 PM CST Tue Jan 29 2019 ...Life Threatening Cold Moving In This Evening... .UPDATE...Tonight Issued at 538 PM CST Tue Jan 29 2019 Life threatening cold is moving into the area this evening. At 5:30 PM wind chill values ranged from 30 below over far southwest Wisconsin to nearly 50 below over portions of southeast Minnesota, and these will only get worse as colder air settles in and northwest winds continue. Take this seriously! This will be the coldest conditions experienced in recent history. 1996 was last time we have felt it this cold. Check on your neighbors, especially the elderly. This will be life threatening for anyone caught outdoors for a prolonged period of time. Frostbite will start to set in, in as little as 5 minutes. If for any reason you must venture outside, cover exposed skin, wear layers of clothing. If you are traveling, bring extra clothing, let someone know of your travel plans, and be sure to bring a cell phone and a backup battery/power supply, in case you have vehicle problems or become stranded. && .SHORT TERM...(This evening through Wednesday) Issued at 320 PM CST Tue Jan 29 2019 Cold air continues to invade the U.S. with the -30F or less now into southeast MN. Currently -50 to -55F wind chills are found in the source air mass moving toward the area. Early afternoon winds were not been quite as high as forecast but lapse rates in the lowest 1 km will be highest in the next hours. The RAP guidance continues to increase winds into the 35-40kt range at 850 mb through late afternoon. 88D VWP showing generally 30kts across MN with some recent pings to 35Kts. While the mixing depth wont be to 850 mb, some increase to G35mph is suggested and 3 pm observations now are showing that verifying west of Miss River. Radar in the last hour showing the snow showers now establishing themselves in the 0-1.5km lapse rate axis from NW>SE across the forecast area. Have increased the snow shower activity in the forecast and will expand the Special Weather Statement to a broader area for: snow showers, blowing and drifting impacts. Main threat area for the evening commute is on the axis seen on radar with the snow showers will cause reduction to visibility and some accumulation will cause slick roads. After early evening, have kept the forecast pretty much the same through Wednesday, which contains life-threatening cold. Have included a section of the most likely records to be broken in the Climate section below. .LONG TERM...(Wednesday night through Tuesday) Issued at 320 PM CST Tue Jan 29 2019 An active period with disruptions in travel expected. Wednesday night looks frigid. It is amazing looking at the various model forecast lows Thursday and seeing our forecast at the median...with many solutions colder. Did some work to look back at the patterns and magnitude of the 1996 cold outbreak, specifically Feb 3 when it was the closest to the Thursday morning pattern. This suggested the lows may be a bit colder, especially the main river valleys and central WI. Thus, the forecast now contains lows into the -40s in central WI. The warm advection kicks in rapidly Thursday with a portion going into warming and another portion into lift. This lift will provide a NW-SE snow band that the models continue to agree well on with light precipitation. Have increased the snow chances above the consensus blends. With a good dendritic growth zone depth indicated, a 1-3" accumulation is becoming probable Thursday afternoon and evening. Then, as if these circus acts weren`t enough, let me introduce you to the weekend act. As large scale readjustment occurs and a trough digs into the western U.S., shortwave trough energy kicks out Saturday into the Midwest to elicit a vigorous Gulf moisture return flow surge across IA/IL/srn WI. This surge arrives Saturday south of I-90 with moisture transport convergence and even some small MUCAPE just south of the forecast area. The moisture is about 1-1.5 km deep by afternoon and deepens into the evening. Temperatures will be warming through the morning, toward above freezing highs, but with a cold start, freezing drizzle is possible, with a transition to rain/drizzle. Some light icing potential looks to exist for this weather. Final act: Sunday and Monday: the western trough energy ejects into the Upper Miss Valley to produce a heavier precipitation event. At this time, it appears to have probabilities for rain mainly, with snow on the northwest side of the forecast area. Plenty of time to let this system work itself out. Lions and tigers and bears! && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 538 PM CST Tue Jan 29 2019 Snow showers and blowing snow will produce periods of IFR conditions at the TAF sites through around 2Z. Then MVFR stratus can be expected at times through the evening then we should see a return to VFR conditions overnight as arctic air settles into the region. && .CLIMATE... Issued at 320 PM CST Tue Jan 29 2019 Record Cold Highs for Wednesday, January 30 Austin MN -7 in 2004 Charles City IA -4 in 2004 Decorah IA -8 in 1899 La Crosse WI -6 in 1899 Mauston WI 1 in 2004 Medford WI -12 in 1899 New Hampton IA -5F in 1996 Prairie du Chien WI -1 in 1996 Preston MN -2 in 2004 Rochester MN -11 in 1996 Sparta WI -4 in 1951 Record Cold Lows for Thursday, January 30 Austin MN -31 in 1994 Charles City IA -27 in 1918 Decorah IA -37 in 1996 La Crosse WI -30 in 1994 Mauston WI -29 in 1996 Medford WI -37 in 1899 New Hampton IA -27F in 1996 Prairie du Chien WI -29 in 1996 Preston MN -39 in 1996 Rochester MN -31 in 1918 Sparta WI -35 in 1996 && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Wind Chill Warning until noon CST Thursday for WIZ017-029- 032>034-041>044-053>055-061. MN...Wind Chill Warning until noon CST Thursday for MNZ079-086>088- 094>096. IA...Wind Chill Warning until noon CST Thursday for IAZ008>011-018- 019-029-030. && $$ UPDATE...Wetenkamp SHORT TERM...Baumgardt LONG TERM...Baumgardt AVIATION...Wetenkamp CLIMATE...Baumgardt
Area Forecast Discussion
National Weather Service Boston/Norton MA
959 PM EST Tue Jan 29 2019 .SYNOPSIS... Low pressure will bring a period of accumulating snow in the interior and mainly rain near the coast tonight. The heaviest snow accumulations will be across the Berkshires. An arctic front crosses the region late Wednesday into Wednesday evening, likely bringing scattered snow squalls followed by bitterly cold temperatures Wednesday night into Friday morning. Milder temperatures arrive this weekend with dry conditions as high pressure builds across the northeast. A cold front may approach early next week. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... 10 pm update ... Precipitation spread across the region out ahead of secondary low pressure development which will track along a SW-NE thermal gradient over S New England. Clearing out behind the low as it sweeps by during the early morning hours Wednesday, breezy W winds follow. Broadly speaking, isentropic lift of a decent precipitable water axis upwards of 0.50 inches aided by low-level convergent forcing and frontogenesis beneath favorable low to mid level ascent thru the dendritic growth zone region is lending to outcomes, as a light, fluffy snow over N/W MA and CT with reports already of around 1 to 3 inches given higher snow ratios, not ruling out 1" per hour snowfall rates, perhaps supported via orographic lift along the high terrain, while along a thermal gradient roughly from Hartford-Worcester-Lawrence, maintained by isallobarically driven N-wind cold air drainage, a wintry mix with reports of even sleet, this due to indeterminant outcomes given thermal layers hovering around freezing just above and at the surface, and then finally over S/E all rain given increasing onshore mild flow. Watching closely the fine-scale temperature gradient as noted, the low tracking along it overnight, whether we see any localized enhanced convergence that can alter the forecast going forward. Just a brief summary of details and threats below. Preference to latest HRRR guidance. Again, clearing out during the early morning hours, roughly around 2 to 4 am. 1.) Snowfall ... Headlines and snowfall forecasts continue. Heaviest amounts N/W within colder air / higher snow ratios. Held off on an advisory for Essex Co. MA, however the surface low tracking over the W-half of the county per RAP / HRRR, feel an E onshore flow will keep things mild, lower snow ratios, and limit accumulations. Could see spot 3" along the NH border in the W-half of the county. Highest snowfall amounts over the Berkshires. Obvious reductions in visibility. 2.) Early morning freeze contributing to icy roads ... Looking upstream W while determining the latest near-term high- res forecasts, once winds shift W, cold, dry air will drive in during the early morning hours Wednesday. Especially those areas, mainly E/SE coastal MA / CT / RI which will see mostly rain overnight and remain at or above freezing, there is the threat of any wet roadways to refreeze if left untreated. Slick conditions possible for the morning commute. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH 6 PM WEDNESDAY/... * Scattered snow squalls with brief heavy snow likely during the afternoon Polar vortex north of the Lakes with decent shortwave rotating into New England late day/evening. Sunshine to start the day, but clouds will quickly develop in the afternoon as deep moisture moves into the region ahead of the shortwave. The attending arctic front will swing through SNE mid/late afternoon into early evening. There is a strong signal for snow squalls along the front with sufficient moisture in the 0-2km layer, very steep 0-3km lapse rates 8-9 c/km and good low level convergence. The one negative factor is low dewpoints and high T/Td depression which may limit areal coverage somewhat. We will have to monitor this closely but all hi-res guidance supports snow squall potential. Brief heavy snow with whiteout conditions and wind gusts over 40 mph may accompany any squalls with a quick inch possible. Timing of squalls will be around mid afternoon in western New Eng reaching SE New Eng toward evening which may impact the evening commute. The other concern is potential for strong W/SW winds in the afternoon. Soundings show very deep mixed layer to above 700 mb. Not expecting to mix down 700 mb winds but potential for gusts over 40 mph and later shifts may need to consider a wind advisory. High wind watch continues for Cape/Islands for late afternoon and evening. Highs will range from the lower 20s to lower 30s but falling rapidly by late afternoon. && .LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/... */ Highlights ... - Mid to late week bone chilling cold, WIND CHILL headlines likely - Seasonable pattern following week with fast moving storms - Uncertain accompanying storm outcomes given thermal profiles */ Overview ... A pattern adjustment. Broadly speaking, whether equatorial Central Pacific tropical activity signaled by a phase 5/6 MJO echoing into the NE Pacific / Gulf of Alaska via higher H5 heights with SW-flow, or seemingly a less wavy global pattern coinciding per a tightening of the stratospheric polar vortex (10 mb), dangerously cold Arctic air is contained N as a more seasonable, in some cases mild, pattern emerges across the CONUS. From a N-central Pacific split-flow regime, anticipating anomalous westerly sub-tropical flow into the CONUS as W CONUS H5 troughing prevails downstream of aforementioned higher heights into the NE Pacific. Looking at a series of Pacific waves digging across the W CONUS, only to zip and deamplify SW-NE across the E CONUS under the weight of warmer S-stream southwesterlies and subsequent higher H5 heights, latent heat release contributing. But a wavering SW-NE baroclinic zone along which weak, open-wave H5 disturbances sweep, across and around New England, downstream of a split-flow regime, inherent challenges in forecasting. Deterministic models have wobbled considerably in next week forecasts. Undoubtedly varied SW surges of Pacific sub-tropical air, continued uncertainty of equatorial Central Pacific tropics per MJO forecasts. Which side of the thermal envelope will the NE CONUS reside with any sweeping storms, whether S- or N-stream dominant? It`s likely we may not see the finer details until 36-48 hours out given forecast tight NW-SE thermal gradients oriented SW-NE. Expect challenging precip-type forecasts per surface to low-level isallobaric / gradient flow. Confidence low Sunday and beyond. Break down details and forecast thinking below. */ Discussion ... Wednesday night through Saturday night ... Dangerously cold, especially Wednesday night through Thursday morn. Arctic air punch with a leading frontal boundary pushing offshore Wednesday evening with remnant snow squall activity sweeping out to sea in an environment of localized deep-layer moisture beneath steep lapse rates up around H7. Behind which, blustery W winds with gusts around 25 to 35 mph initially, gradually tapering through Thursday into Friday with increasing influence of high pressure, suppressing the depth of the boundary layer and mix-down potential. Anticipate some skin-cracking, dry dewpoints. WIND CHILL HEADLINES posted given 15 to 25 below zero values that are presently forecast, especially over the Berkshires. Beneath H85 temperatures as cold as -25C into Thursday, moderating going into Friday. Possibly record lows broken Thursday morning, but higher confidence lowest high temperature records will be broken Thursday. Also could see some record H925-7 temperatures within Chatham MA sounding climatology. A 1030+ high Saturday morn, cold exacerbated by radiational cooling, especially for areas with deeper snowpack. May come close to record lows, but a better shot of breaking record lowest high temperatures. Sunday onward ... Low confidence forecast. Certain will see SW-NE zipping lows along a NW-SE thermal gradient. Whether S- or N-stream, a wavering, wobbling gradient, additional variables of remnant snowpack, upstream N high pressure, strength of surface lows and subsequent isallobaric and gradient wind along with direction, just some of the factors that`ll influence most likely weak, open-wave disturbances / baroclinic leaf upslope events. Mixed precip-types anticipated, just depends which side of the envelope S New England will reside upon. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Wednesday/... Tonight...Moderate confidence. Widespread MVFR /I FR with areas of LIFR mostly in SN. SN mainly N/W of BDL-ORH-BED with RASN right around this line, and then RA to the S/E. Precip ending 06-08z in W New England and 08-10z in E New England followed by immediate improvement to VFR with winds shifting W. Expect stronger gusts along coastal terminals through- out. Wednesday...High confidence. Mainly VFR, but SCT SHSN / +SNSH possible 20z-0z with brief IFR- LIFR conditions. Overall, increasing W winds into afternoon with 30-40 kt gusts, strongest across S/SE coastal terminals exceeding 40 kts possible. However, with +SHSN, could see locally stronger gusts up to 50 kts possible. Watching closely for PM push impacts. KBOS Terminal...High confidence in trends. RASN presently, conditions lowering to IFR by 7z, then quick improvement during the morning push by 11z with an immediate W wind shift, accompanying blustery conditions possible. bigger concern is around 21-0z for +SHSN, brief IFR- LIFR conditions, and stronger gusts than forecast in the TAF. Quick accumulations on runways possible of around an inch if any SHSN / +SHSN. KBDL Terminal...Moderate confidence. SN moving in, expect IFR conditions 2z-9z behind which quickly improving to VFR with immediate W wind shift. Then focus is on the 18-21z period for brief IFR-LIFR with SHSN / +SHSN. Also the threat of accompanying stronger wind gusts than forecast in TAF. Quick accumulations on runways possible of around an inch if any SHSN / +SHSN. Outlook /Wednesday Night through Sunday/...Moderate Thursday Night: VFR. Windy with local gusts up to 30 kt. Friday through Sunday: VFR. Breezy. Sunday Night: Mainly VFR, with local MVFR possible. Breezy. Slight chance SN. Monday: VFR. Chance RA, slight chance SN. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Wednesday/...High confidence Tonight...Increasing SE winds with gusts 25-30 kt developing. Winds shifting W over a majority of waters by Wednesday morning. Prior to the wind shift, expect rain along with reductions in visibility at times. Wave heights 5 to 8 feet off the near-shore waters. Wednesday...W/SW wind gusts increasing to 35-45 kt by afternoon. Gale warnings issued, except storm watches for outer S waters with a low risk for 50 kt gusts. Freezing spray developing in the afternoon. Snow showers / squalls possible toward evening which could be associated with localized gusts to 50 kts as well. Outlook /Wednesday Night through Sunday/...Moderate confidence. Thursday Night: Moderate risk for Small Craft Advisory winds with areas of gusts up to 30 kt. Areas of rough seas. Freezing spray. Friday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft. Freezing spray. Friday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Saturday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas locally approaching 5 ft. Saturday Night: Winds less than 25 kt. Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft. Sunday Night: Winds less than 25 kt. Local rough seas. Slight chance of rain. Monday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain. && .CLIMATE... Record LOWEST High Temperatures for Thursday, January 31st... Boston ....... 12 (1920, 1935) Hartford ..... 15 (1951) Providence ... 15 (1935) Worcester .... 11 (1951) && .BOX WATCHES/WARNINGS/ADVISORIES... CT...Winter Weather Advisory until 5 AM EST Wednesday for CTZ002. MA...Winter Weather Advisory until 5 AM EST Wednesday for MAZ003>005-010>012-026. High Wind Watch from Wednesday afternoon through Wednesday evening for MAZ022>024. Winter Storm Warning until 5 AM EST Wednesday for MAZ002-008- 009. RI...None. MARINE...Gale Warning from 1 PM Wednesday to 1 AM EST Thursday for ANZ230>237-250-251. Storm Watch from Wednesday afternoon through Wednesday evening for ANZ254>256. && $$ SYNOPSIS...KJC/Sipprell NEAR TERM...KJC/Sipprell SHORT TERM...KJC LONG TERM...Sipprell AVIATION...KJC/Sipprell MARINE...KJC/Sipprell CLIMATE...WFO BOX Staff
should refer to earlier forecast discussions for discussion on the
setup for Wind Chils.
Snow shower potential looks qualitatively less on Wednesday given the noisier look to the lapse rates structures in the soundings. Differential AVA is expected to become quite strong by the middle of the morning as the true Absolute vorticity maximum passes the state to the south. There is a signal within the hi res guidance that shows lake effect contracting back to the Lake Michigan shoreline after 12Z Wednesday. A weak piece of energy moving through northwest flow aloft will largely pass to the south of lower Michigan Friday, with a few light snow showers possible close to the Ohio border. One more cold day will be in store Friday as high temperatures only reach into the teens, albeit a moderation nevertheless from the frigid midweek temperatures. Wind chills in the negative teens will continue into Friday morning, before increasing into the single digits by the end of the day. High pressure briefly settling over the central Great Lakes will bring dry weather for Saturday, with developing low-level southwesterly flow allowing for a noticeable uptick in temperatures as highs warm into the 30s. Unsettled weather will return for the latter half of the weekend and into early next week as a sprawling low pressure system developing over the central Plains slowly lifts northeast towards the region as a warm front lingers in the vicinity of lower Michigan. Depending on where the warm front sets up, areas to the south of the boundary will have the potential to warm into the 40s Sunday and Monday as snow, possibly with a wintry mix at the onset, transitions to rain. MARINE... A large polar low pressure system currently centered over the northern Great Lakes will produce southwest Gales over all marine waters this evening and tonight as arctic air continues to wrap in from the Ohio Valley. Gusts to gales will persist on Wednesday, as winds trend a bit more westerly Wednesday night and begin to slowly diminish. Wind gusts are expected to peak around 40 knots over southern lake Huron Wednesday afternoon. Heavy Freezing spray will be common over the open waters of Lake Huron, along with snow squalls. Wind and waves will really drop off by Friday morning as high pressure slides through the Central Great Lakes. Increasing southwest flow behind the departing high Friday night will usher in much warmer air as we head into the weekend. With the increase low level stability, winds are expected to hold in the 15 to 25 knot range ahead of a cold front which looks to quickly wash out and return north as a warm front during the second half of the weekend. CLIMATE... Temperatures next week are forecast to challenge record low high temperatures and possibly some record lows as well, especially in Detroit. RECORD LOW MAXIMUMS January 30th DTW... 7 (1951) FNT... 8 (1951) MBS... 8 (1951) January 31st DTW... 7 (1920) FNT... 6 (1971) MBS... 5 (1920) February 1st DTW... 4 (1898) FNT... 7 (1971) MBS... 5 (1918) RECORD LOWS January 30th DTW... -4 (1951) FNT... -16 (1951) MBS... -17 (1951) January 31st DTW... -7 (1920) FNT... -8 (1963) MBS... -15 (1994) February 1st DTW... -7 (1971) FNT... -18 (1959) MBS... -16 (1918) && .DTX WATCHES/WARNINGS/ADVISORIES... MI...Wind Chill Warning until 11 AM EST Thursday for MIZ047>049-053>055- 060>063-068>070-075-076-082-083. Winter Weather Advisory until 8 AM EST Wednesday for MIZ060-061-068- 069. Lake Huron...Heavy Freezing Spray Warning until 7 PM EST Thursday for LHZ361>363- 462. Gale Warning until 4 AM EST Thursday for LHZ361>363-421-422-441>443- 462>464. Lake St Clair...Gale Warning from 4 AM to 4 PM EST Wednesday for LCZ460. Michigan waters of Lake Erie...Gale Warning from 4 AM to 4 PM EST Wednesday for LEZ444. && $$ AVIATION.....AA DISCUSSION...CB/IRL MARINE.......AM CLIMATE......CB/IRL You can obtain your latest National Weather Service forecasts online at
Area Forecast Discussion
National Weather Service Hastings NE
626 PM CST Tue Jan 29 2019 ...AVIATION UPDATE... .SHORT TERM...(This evening through Wednesday) Issued at 337 PM CST Tue Jan 29 2019 Aloft: RAP dynamic tropopause analyses and WV imagery show highly-amplified cyclonic NW flow over the Cntrl Plns. A ridge was just off the W coast...and a trof was over the Cntrl/Ern USA with an anomalously deep (-3.5 SD) low over the upr Midwest. This pattern will change little thru tomorrow...but the upr Midwest low will cross the GtLks. Surface: The Arctic cold front has been sagging S thru the CWA today. Temps behind the front began slowly falling around daybreak. Arctic high pres was over MB. This high will rapidly sink SSE to the NEB/IA border by dawn Wed and then slowly drift E across IA/MO tomorrow. Now thru sunset: The Arctic air has arrived. Temps have struggled to rise in the CAA...even where sunshine has developed. Not hard to see why as temps upstream over the Sandhills are in the single digits. This air mass means business. Despite its potency it will be short-lived tho. A band of NW-SE-oriented clds conts to bisect the CWA. There have been some occasional flurries within this band...but skies are sunny on either side of it. That band will remain in place. Still can`t entirely rule out some flurries...but diminishing reflectivity suggests the threat is decreasing...espcly since low-lvl drier air is advecting in. Tonight: That cld band will remain over the CWA while thinning and breaking up a bit. Skies will be variable (m/clr) in either side of it...but after midnight it should become reinvigorated. Skies should be m/cldy over most of the CWA by dawn. Kept lows close to continuity with the 4 AM fcst. It will be coldest N and E of the Tri-Cities. No chgs were needed to the WC Advisory. Loup City-Clay Ctr- Hebron may fall a little short of -20F...but did not see any need to upset the watch/wrng/advy map. Mercifully...the coldest wind chills will occur from 12AM-4AM when everyone is in bed as that`s when winds will still be 10-20 MPH. WC`s will be -20 to -29F from ODX-GRI-JYR. Tomorrow: Similar to today. Probably m/sunny over the SW 1/3 of the CWA and m/cldy from the Tri-Cities N and E. The LFQ of at 130 kt upr-lvl jet streak will dive into NEB/KS. This bit of QG forcing superimposed over low-mid-lvl fgen should generate more clds and a narrow band of flurries/light snow...primarily N and E of the Tri-Cities. Not expecting anything more than a dusting. Am a little concerned the fcst may be a little optimistic in decreasing clouds within that band during the afternoon. Very cold! Espcly E of Hwy 281. Winds will be lightest when air temps are at their lowest. So wind chills won`t be as bad as they might have been. .LONG TERM...(Wednesday night through Tuesday) Issued at 337 PM CST Tue Jan 29 2019 Aloft: A significant adjustment will occur during this time frame. The high-amplitude pattern will be deamplifying Thu with the longwave trof settling over the Wrn USA thereafter. The flow will be from the WNW Thu with rising heights. The Wrn ridge will crest over the Plns Fri. The last 2 runs of GFS/GFS-FV3/GEM/EC/UKMET cont to fcst a weakening shortwave trof to move thru Sun or Sun night. The 00Z/12Z EC cont to be on the fast/strong side of the guidance spread while all other models are slower/weaker. With more height falls fcst over CA Sun night...believe odds favor the weaker solution. A low-amplitude shortwave ridge should move thru Mon with the flow becoming SW again Tue. Surface: Downsloping will result in development of a warm front that should lift across the CWA Thu into Thu night. Then we`re in the warm sector Fri-Sat with high pres off the Carolinas. Prefer the GFS idea that a low will head E acrs the Nrn Plns Sat with its cold front dropping thru here Sun. A lee low will still form over CO and head E acrs KS Sun night. The situation becomes more unclear after that. Does the Arctic air wrap into the KS low as it pulls away? Or does a separate Arctic front arrive Mon? Regardless of how it gets here... next wk is looking cold with the trof moving into the W. Temps: Back to normal Thu...coldest E of Hwy 281 and warmest W. Fri-Sat...way warmer than this fcstr likes to see for this time of yr. Fri looks like a slam dunk for widespread 50s. That is not fully-depicted yet. Believe our fcst is not warm enough. The same may hold true for long as low stratus doesn`t move in. Not as warm Sun...but still 10F warmer than normal. Probably near normal Mon before temps turn colder Tue. Precip: It`s looking pretty dry...which is typical. There could be a little light rain/snow Sun into Sun night. Unless you buy the aggressive EC...precip amts should be very minor. However...with the trof shifting into the Wrn USA...that does favor an increased threat of meaningful precip...probably beyond this fcst. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday) Issued at 625 PM CST Tue Jan 29 2019 General overview: Confidence is high that the majority of the period features VFR ceiling/visibility, although at least scattered low-end VFR clouds will likely hang around much of the time, and there looks to be roughly a 4-5 hour window of opportunity for at least high-end MVFR ceiling and occasional sub-VFR visibility in light snow Wed morning (especially at KGRI). Otherwise, the overall-strongest winds of the period will occur right away this evening, with northerly gusts perhaps as high as 20-25KT still possible. However, as a high pressure axis slides closer late tonight and passes off to the east, breezes will eventually become light/variable early Wednesday morning, and then mainly south- southeasterly through most of the day. Read on for more element- specific details... Ceiling/visibility/precipitation: Confidence is high in VFR and snow-free conditions through the first half of the period, although a mid-level ceiling will gradually become more predominant. The main question marks arrive during the 14-19Z time frame, which appears to be the best window of opportunity for not only at least occasional MVFR ceiling, but also a steady period of light snow, which could result in a light dusting of accumulation. Although it`s a little soon to "split hairs" for TAF sites so close in proximity, it currently appears that KGRI would be somewhat more favored than KEAR to see sub- VFR/light snow. Visibility-wise, kept KEAR VFR for now, but did nudge KGRI down to MVFR 15-19Z given the better chance of light snow. By early afternoon, better chances for sub- FR and light snow should shift east of KGRI, but did hang onto low-end VFR ceiling through the afternoon at both terminals. && .GID WATCHES/WARNINGS/ADVISORIES... NE...Wind Chill Advisory until noon CST Wednesday for NEZ039>041- 046>049-062>064-076-077-087. KS...None. && $$ SHORT TERM...Kelley LONG TERM...Kelley AVIATION...Pfannkuch
Area Forecast Discussion
National Weather Service Key West FL
1045 PM EST Tue Jan 29 2019 .SHORT TERM... A cold front is currently making its way across the southeast Gulf and will enter our northwest waters after midnight. Quite a bit of low-mid level moisture is pooling along the front, with satellite and radar indicating broken clouds and a few showers near the front. Have already updated the forecast to increase clouds and add a few showers overnight to our waters west and northwest of Key West. The 01z HRRR model even shows showers reaching Key West around 14z (9 am), and spreading across the rest of the Lower Keys during the late morning before halting its eastward spread. The halt in eastward spread will be caused by a dissipation of the front around mid-day Wed. This will occur as strong high pressure over the Ohio Valley bridges across the front and causes it to lose definition. As the Keys come under the southern periphery of strong high pressure, northeast and easterly breezes will therefore develop across all of the Keys on Wed PM. This wind direction will support a slow modification of our air mass, with this direction coming across the 78-80 degree waters of the Gulf Stream off Southeast Florida. Will still have some leftover moisture from the dissipated front in the vicinity, which will support isolated and scattered showers in easterly low-level flow. By Friday, temperatures will rise above normal, with highs flirting with 80F on Saturday. Plenty of sunshine and isolated light showers will prevail. Showers may decrease a little on Friday as the leftover moist pool from the dissipated front gets gets shoved out. .LONG TERM... Little change in sensible weather from Saturday through next Tuesday, with temperatures running a few degrees above normal for early February. Upper level heights will slowly build through the period, which will support stronger and lowering subsidence inversions. This will bring an overall decreasing trend in the already low rain chances through the weekend and early next week. && .MARINE... Light and gentle breezes will continue over most of the waters overnight. However, a cold front will slip southeast across the deep Gulf waters and the Dry Tortugas, approaching Key West on Wed morning. Behind this front, a freshening northeast breeze is expected Wed morning. The front will lose definition and dissipate around mid-day Wed, as strong high pressure centered over the Ohio Valley bridges across the front. This will cause moderate northeast to east breezes to develop over all of the waters on Wed evening. Surface high pressure will then move to and persist over the Mid-Atlantic states through Saturday, supporting mostly moderate easterly breezes. High pressure will exit into the Western Atlantic Ocean on Sunday, with decreasing easterly breezes over the Keys coastal waters. && .AVIATION... Increasing clouds late tonight in the 035-070 range as a dissipating cold front approaches. Could be a few showers near EYW from about 13z-18z before showers wither concurrent with the dissipation of the front in the afternoon. && .KEY WATCHES/WARNINGS/ADVISORIES... FL...None. GM...None. && $$ Public/Marine/Fire...Haner Aviation/Nowcasts....Haner Data Collection......DR Visit us on the web at Follow us on Facebook and Twitter at:
Area Forecast Discussion
National Weather Service Marquette MI
725 PM EST Tue Jan 29 2019 .SHORT TERM...(This evening through Wednesday) Issued at 344 PM EST TUE JAN 29 2019 ...Dangerous cold with frequent white-outs near Lake Superior over the next few days... Big concerns in near term focus on the bitter cold and winter weather headlines and the likelihood for blizzard conditions over Alger and Northern Schoolcraft counties tonight into Wednesday. WV imagery and RAP analysis indicated the center of the deep mid/upper level low (polar vortex) over northern MN resulting in cyclonic ssw flow into Upper Michigan. At the surface, a low was located near Marquette with a cold front extending south through south central Upper Mi and northeast WI. A trough extended across southern Lake Superior. The reinforcing surge of very cold Arctic air was already moving into western Upper Mi behind the front with temps dropping to around -10F at KIWD early this afternoon with winds gusting near 30 mph. The trough and its associated strong convergence over Lake Superior have contributed to a series of mesolows over eastern Lake Superior which are readily apparent on visible satellite and radar imagery. Webcams have shown whiteout conditions as these mesolow snow bands have moved onshore today. Initial mesolow snow band moving into eastern Alger County and far northern Schoolcraft County early this afternoon will be followed by an intense mesolow band in the next few hours as a secondary cold front moves through. These bands will be causing whiteout conditions and near-zero visibility along with gusty winds. Winds will pick up behind the front this evening as model soundings show deep mixing through at least 5kft. NNW winds gusts approaching 40 mph especially along the Lake Superior shore will combine with fine-flaked lake effect snow and blowing snow to cause blizzard conditions which will continue into Wednesday. Thus, have upgraded the winter storm warning to blizzard warning for Alger and northern Schoolcraft through Wed night. Winds and blizzard conditions will begin to subside late Wed evening. Tonight into Wednesday, Across the rest of the cwa northwest flow LES will continue as equilibrium heights remain in the 10k-12k ft range. However, as 850 mb temps of -30C to -33C move across the lake tonight into Wed morning and the DGZ gets squashed near the sfc of the lake this will reduce snowflake size and limit the potential for higher accumulations at most locations. However, expect focused stronger snow bands to produce at least moderate snow amounts of 3- 6"/12 hours over Porcupine Mts and also over Alger into northern Schoolcraft counties, including the Seney Stretch. The combination of gusty winds to around 35 mph and the small snowflakes will produce very low vsby in the LES areas. The winds will also be strong enough to push the bands into northern portions of Delta county and much of Schoolcraft county tonight. Even with some lake moderation in the nw flow, dangerous wind chill values into the -30 to -40 range are expected late today into Wednesday. Only other change to headlines beside the upgrade to blizzard warning for Alger-northern Schoolcraft was to extend winter weather advisory for Delta County until 18Z Wed to capture coldest wind chills into the early afternoon hours on Wed. Winter storm warnings for nw counties and Luce county til 12z Thu for extended dangerous low winds chills and lake effect snow/blsn conditions still look good. Winter wx advisories for southern Houghton thru Marquette County also look good through Wed mid-afternoon for combination of dangerous wind chills and potential for lake effect snow/blsn near the lake. Kept wind chill warnings through Wed for Iron-Dickinson- Menominee with the idea that these will likely need to get extended into Thu morning by midnight shift. Also winter storm warning for Gogebic and winter weather advisory for Delta effective until 18Z Wed will need to transition to probably a wind chill warning as some point Wed morning as winds back from nw to more westerly. .LONG TERM...(Wednesday night through Tuesday) Issued at 422 PM EST TUE JAN 29 2019 ...Dangerous cold with frequent white-outs near Lake Superior into Thursday, then rapid warming into the weekend... Highly amplified pattern featuring strong ridging/positive height anomalies over far western N America and the north Atlantic will be forcing a deep trof/bitter cold air over the Great Lakes thru Thu. Then, a big change in the pattern will occur thru the weekend. The western ridge will retrograde, forcing trof development over western N America, and in turn, building heights downstream across eastern N America. From tonight to Sat morning, 500mb heights are fcst to rise over 600m across Upper MI. Needless to say, strong warming will get underway, beginning Fri and continuing thru the weekend. Temps over the weekend will likely flip back to above normal. During next week, ensemble guidance suggests ridging building back gradually toward far western N America, which would shift troffing downstream toward central to eastern N America. Thus, while there will be some fluctuation in temps as the pattern evolves, expect a trend back toward prevailing blo normal temps with time next week. Farther down the line, high latitude positive height anomalies/blocking that have been appearing in longer range guidance generally in the Greenland or AK vcnty or in both areas suggest an increased potential of frequent or more persistent periods of blo normal temps heading thru Feb. As for pcpn, LES will wind down/end Thu/Thu night under lowering inversion and backing winds. Development of a western N America trof then suggests a potentially more active period developing for a time next week as shortwaves eject downstream across N America. May see a couple of opportunities for system snows and potentially mixed ptypes. Beginning Wed night/Thu, mid-level low centered s of James Bay Wed evening will lift ne across Quebec. As this occurs, deep moisture will depart from w to e Wed night/Thu with inversion setting in at around a low 4kft. Winds will also slowly back during this period, pushing the last of the LES to the northern Keweenaw Peninsula and from Pictured Rocks eastward, close to the shore, by late Thu aftn. 850mb temps will gradually moderate from -27 to -31C Wed evening to -20 to -24C by Thu evening. With the DGZ eliminated by the Arctic air, LES off Lake Superior will feature fine/powdery type snow that is extremely effective at reducing vis, but does not add up to significant accumulations. With the loss of deep moisture from w to e Wed night/early Thu, this will become especially true. In general, in the w to nw wind snow belts, expect Wed night snow accumulations on the order of 1 to 3 inches out w, 2-4 e. Snow accumulations will be about half that on Thu. White-outs will still be common in many of the LES bands Wed night, especially those streaming into the eastern fcst area. In addition to the vis restriction from the fine snow, blsn will be a further complication as winds remain gusty into the 20-30mph range over the Keweenaw and e of Marquette. Gusts along the lakeshore e of Marquette will likely be 35+mph. Will be dangerously cold Wed night/Thu, but especially so Wed night thru Thu morning. Although low-level winds will be gradually backing more w Wed night, winds at 850mb remain more nw, so there is some uncertainty in the lake effect cloud coverage away from the snow belts. Given the very dry, Arctic air mass, clouds will probably fade away well in the interior, setting the stage for very low temps Wed night after a bitter cold day on Wed. In the interior w half where skies become mainly clear, will likely see mins of -25 to -35F. Winds will still be stirring around 10mph in these areas to drive wind chills down to -35 to -45. If it was a clear/calm night under high pres, actual temps would be down to -40 to -50F in the traditional cold spots. Temps will range up to -5 to -15F along the Lake Superior shore. Even where it`s "warmer", wind chills will still be down to -25 to -35F. Max temps on Thu will generally be a few degrees either side of 0F with aftn wind chills generally -10 to -20. Messaging remains the same; if you have to go outside, it is crucial that you dress for the conditions wearing multiple layers and covering all exposed skin. If traveling, make sure to have a winter survival kit. Best not to take any chances with this type of cold as these conditions will be life-threatening if you are caught unprepared. Wind chill values this low will result in frostbite times of 10 minutes or less and increased risk of hypothermia. As sfc high pres ridge shifts across the area Thu night, winds will continue to back, shifting any lingering light LES offshore in the evening. With the ridge passing, the opportunity will be there for temps to tank. However, a shortwave streaking from the Northern Plains toward the Upper Ohio Valley will spread mid and high clouds into the fcst area, complicating the temp fcst. Would certainly be -30s across much of the interior and locally blo -40F if skies were clear. For now, have fcst min temps mostly around -20F in the interior and 0 to -15F along the Lakes. Winds will be calm/near calm for most of the area, so wind chills won`t be an issue Thu night. Warming trend gets underway on Fri as sw winds lock in. Highs Fri will reach 10 to 15F. Waa/isentropic regime continues Fri night with a shortwave also expected to track across northern Ontario. Best isentropic ascent and better erosion of low-level dry air will likely pass by just n and ne of the fcst area. So, expect a band of snow to streak by to the n, but a little -sn may brush the Keweenaw and ne fcst area. A northern stream shortwave is fcst to track e across northern Ontario Sat night/Sun morning. Looks like there will be disconnect btwn mid-level and low-level moisture, so if there is any pcpn, it would be light. Fcst still only has snow for ptype, but could see this end up as a -ra/-fzra event. A southern stream shortwave is fcst to eject toward the Great Lakes early next week. There has not been very good continuity with timing/track of this wave and associated sfc low pres. Recent days medium range model runs have indicated solutions ranging from all snow across the fcst area to snow, mixed ptypes, and rain across the fcst area. Timing has improved slightly with the 12z runs, basically focusing in on Mon. For now, fcst indicates just sn, but that could certainly change. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 711 PM EST TUE JAN 29 2019 KIWD and KCMX have been experiencing predominantly IFR and LIFR conditions, respectively, while KSAW is hanging out in VFR. IFR to LIFR visbys are expected to persist through much of the overnight period at KIWD and KCMX as NW winds continue to usher in snow band after snow band across western Upper Michigan. As for KSAW, MVFR may end up prevailing throughout the TAF period as the more robust snow bands look to remain to the east of the terminal area. However, brief IFR visbys can`t be entirely ruled out should these NW winds become ever so slightly more northerly, allowing for bands to directly impact KSAW. Conditions should improve at all three terminals later in the day tomorrow. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 344 PM EST TUE JAN 29 2019 North to northwest gales up to 40 knots are expected tonight into Wednesday night, especially over the central and east as a reinforcing blast of arctic air surges into the the northern Great Lakes. This will be the coldest air of the season thus far with heavy freezing spray continuing through much of rest of the week. Conditions slowly improve Thursday heading into Friday as winds gradually diminish and heavy freezing spray subsides. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Winter Storm Warning until 4 PM EST Wednesday for MIZ004-005-084. Blizzard Warning until 7 AM EST Thursday for MIZ006-085. Winter Storm Warning until 7 AM EST Thursday for MIZ001-003-007. Winter Storm Warning until noon CST Wednesday for MIZ009. Winter Storm Warning until 7 PM EST Wednesday for MIZ002. Winter Weather Advisory until 7 PM EST Wednesday for MIZ014. Wind Chill Warning until 6 PM CST Wednesday for MIZ010>012. Winter Weather Advisory until 1 PM EST Wednesday for MIZ013. Lake Superior... Heavy Freezing Spray Warning until 1 AM EST /midnight CST/ Friday for LSZ162-240>251-263>267. Gale Warning until 7 AM EST Thursday for LSZ243>251-264>267. Gale Warning until 7 PM EST /6 PM CST/ Wednesday for LSZ240>242- 263. Lake Michigan... None. && $$ SHORT TERM...Voss LONG TERM...Rolfson AVIATION...lg MARINE...Voss
Area Forecast Discussion
National Weather Service Paducah KY
948 PM CST Tue Jan 29 2019 .UPDATE... Issued at 948 PM CST Tue Jan 29 2019 Struggling to reconcile guidance with observations this evening. The majority of guidance has little or no QPF, but the HRRR does show a band of light snow translating east southeast through mainly the Pennyrile region of west Kentucky through midnight, and then another band of light snow possibly to move east southeast through southeast Missouri into the Purchase Area of Kentucky overnight. We have received 1" amounts along and north of I-64 in southwest Indiana this evening, but the accumulating snow has ended up there. Radar trends are not real coherent, but in general show a diminishing trend in space and intensity coming out of southwest Indiana. Figure that we will end up with a narrow band of snow moving relatively quickly through west Kentucky through Midnight. This will result in a dusting to a half inch, with some potential for slick spots to develop on area roadways. With the extremely dry air moving in and the strong winds, much of the moisture may sublimate by morning. All in all the forecast evolution supports the Special Weather Statement treatment already in place, and the Wind Chill Advisory still looks good by morning. We will not be issuing a Winter Weather Advisory and will continue with the Wind Chill Advisory as is. UPDATE Issued at 549 PM CST Tue Jan 29 2019 Updated aviation discussion for 00Z TAFs. UPDATE Issued at 202 PM CST Tue Jan 29 2019 The new Wind Chill Advisory and Special Weather Statement products have been issued. UPDATE Issued at 150 PM CST Tue Jan 29 2019 Updated to include the Long Term section. Also, coord with LMK, and they wish to shift the Advisory a little farther south. We will follow suit per their request. Update coming soon. && .SHORT TERM...(Tonight through Thursday) Issued at 1248 PM CST Tue Jan 29 2019 We will continue with the Wind Chill Advisory as is for late tonight through midday Wednesday. Wind chills still expected to drop to -10 to -20 in the Advisory area, and from zero to -10 over the rest of the area. Other challenge tonight is chance of light snow. Arctic front is off to our NW across mid Missouri into IL. Band of clouds with mid level energy was moving SE toward the area from the central Plains and central MO. The models continue to hint at a light snow chance tonight, likely in two time frames as a couple of waves move through accompanied by adequate frontogenetical forcing. The first wave this evening results in the best chance along and east of the MS River up into the EVV tri-state region. Anything that falls will accumulate, with 20:1 ratios established. Our confidence is lower in the spatial aspect. So we did not get too specific. A second chance is farther south after midnight across SEMO into west KY and possibly the southern tip of IL. The higher res models are much closer to the TN/AR state lines. However the GFS is farther north and suggests and additional few hundredths of QPF. We used a blend given the uncertainty aspect with where the axis with both rounds will set up. In the end, we decided to keep PoPs 50 percent or less and use scattered snow shower terminology. If things pan out, some places could see 1/2 to 1 inch of snow mainly south of Route 13. Confidence in this actually playing out is still marginal at best as overall moisture is not robust. Cold and dry Wednesday, with highs single digits north to teens south. There is a slight chance of light snow or more likely flurries Wednesday night. Temperatures will moderate through Thursday, with highs returning to the mid 20s north to mid 30s south. It will be partly to mostly cloudy as well. .LONG TERM...(Thursday night through Tuesday) Issued at 150 PM CST Tue Jan 29 2019 An abrupt pattern change will take place this weekend as a very deep upper low is replaced by a broad ridge over the eastern states. Our region will be under a deep southwest flow for most of the period. The main forecast concern centers around precipitation types and amounts Thursday night, when a warm front will displace the arctic air. The models continue to trend warmer throughout the long-term period. This is especially significant on Thursday night into early Friday, when precipitation associated with a warm front will be ongoing. The gfs/ecmwf are in good agreement that a strong southwest flow aloft (around 40 kt at 3000 feet) will produce an above-freezing layer that will minimize snow potential. However, it is not clear whether a shallow sub-freezing layer near the surface will erode. Most of the guidance takes the surface freezing line northeast across southeast Missouri before the precip even begins. On the other extreme, southwest Indiana could remain below freezing throughout the event. It is too early to get precise about the timing and location of wintry precip, but amounts will be light (under one- tenth inch). In fact, the 12z ecmwf does not produce any precip until thermal profiles are entirely above freezing, even in sw Indiana. Once the precip ends Friday, it now appears the weekend will be mainly dry. A mid-level shortwave ridge will amplify ahead of a vigorous system over the southern Rockies. A strengthening southerly wind flow will prop up temps, in some cases up to 50 degrees warmer than the mid-week Arctic air. For example, the forecast high of 60 at kevv on Monday is 51 degrees warmer than Wednesday`s forecast high. Rain chances will increase Monday into Tuesday as a storm system moves northeast into the Great Lakes region. Temps on Tuesday will cool down behind the front, though the primary surge of cold air will remain well to our north at that time. && .AVIATION... Issued at 549 PM CST Tue Jan 29 2019 Primarily VFR conditions are forecast through the period. The passage of an arctic front this evening will bring a brief period of light snow showers, which may temporarily reduce ceilings to MVFR and visibilities to MVFR or even IFR. A secondary wave later tonight may bring another round of light snow showers to mainly southern portions of the area (KCGI & KPAH). Any accumulation should be fairly light, but may add up to a half inch in some areas. Behind the front, winds will shift back around to the northwest and remain gusty through the night. A scattering of mid level clouds will be accompanied by some sunshine Wednesday. Brisk northwest winds in the morning will tend to subside by afternoon. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...Wind Chill Advisory until noon CST Wednesday for ILZ075>078- 080>094. MO...Wind Chill Advisory until noon CST Wednesday for MOZ076-086-087- 100-107-111. IN...Wind Chill Advisory until noon CST Wednesday for INZ081-082- 085>088. KY...Wind Chill Advisory until noon CST Wednesday for KYZ004-005-007- 010-013>016-018>021. && $$ UPDATE...DRS AVIATION...RJP
Area Forecast Discussion
National Weather Service Reno NV
301 PM PST Tue Jan 29 2019 .SYNOPSIS... Temperatures are expected to remain relatively mild this week before turning colder this weekend and early next week. A weak system will bring a chance for light showers late Wednesday night into Thursday, mainly in the Sierra south of Highway 50. A stronger trough develops late Friday into the weekend for increased potential for mountain snow and valley rain and snow. && .SHORT TERM... Weak low pressure has moved into the San Joaquin Valley with a weak shear axis extending into southern Nevada. We haven`t noticed any precipitation in observations around the region today with the main moisture increase remaining at the mid and upper levels of the atmosphere. One other thing of note today is in the Surprise Valley where most of the stratus has finally scoured out and temperatures have risen well into 40s after days of sub-freezing/ freezing temperatures. Unfortunately, moisture remains high and, with clearing skies, there is a moderate chance for the development of dense fog and/or low stratus tonight in the Surprise Valley. Also, the HRRR shows hints of fog in the Honey Lake Basin and in the Martis Valley although models show increasing clouds after midnight so chances are lower than in the Surprise Valley. Therefore, with much uncertainty freezing fog was not added to the Martis Valley or Honey Lake Basin. Upper ridging moves over northeast California and western Nevada tonight and Wednesday for precip-free conditions. Lows tonight and highs Wednesday will remain relatively mild with plenty of residual surface moisture and periodic high level cloudiness. Late Wednesday night and Thursday, the next upper disturbance approaches the region. That disturbance is still shown to pass over the central CA coast and down into southern CA. That position is so far removed from northeast CA and western NV that chances for showers are only low to moderate with upper forcing (modest deformation near the Mono County Sierra) barely brushing the region. We have pulled back the chance POP mainly to the Sierra south of Tahoe and trimmed out some of western NV. Moisture is expected to remain moderate so the weak forcing could bring isolated to scattered snow showers for the higher elevations of the Sierra; however, any snowfall amounts should remain very light by Sierra standards and may not even affect travel along Highway 395. All in all, a snoozer weather event! Most of Friday will bring another gap between systems before a much more substantial systems approaches for the weekend. Winds could become a bit breezy by Friday afternoon but it does not look like anything too notable with the main wind increase likely to remain in the higher elevations and along exposed ridges. -Snyder .LONG TERM...Friday night into next week... Few changes were made to the forecast in the long term. That`s not due to any real increase in confidence, but more to the fact the going forecast is in the middle of a plethora of ensemble solutions. Predictability this winter continues to be extremely low compared to normal beyond 48 hours. The main change was to focus the chance for precip spilling over into western Nevada sometime during the day Saturday. The rest of the forecast changed little. Friday night into Saturday, it still looks like there will be at least an average Sierra storm to move through. The Sierra will see precip start Friday evening with light to moderate rates into Saturday. The south flow ahead of the system isn`t very favorable for orographics or spillover, but the passes will still see decent amounts. Snow levels look to start near 7000-7500 feet falling to 5500-6000 behind it. Spillover will have to wait for the front to move through. The EC remains 6-12 hours faster with the front than the GFS and its ensemble mean is in good agreement but the ensemble spread is large. In trying to time the front with the best spillover, used a blend of the GFS/EC ideas and have it Saturday morning. Sunday, the next wave is digging off the coast, but the GFS is wetter with another wave ahead of it. At this point, kept light snow showers in the Sierra with westerly upslope flow. If the wave in the GFS occurs, it will be heavier. Cooler air continues to filter in with snow levels lowering to near or just below 5000 feet. At this point, not expecting any snow accumulation on the valley floors, but I woulnd`t rule it out either. Monday/Tuesday the GFS bleeds some cold air in with at most a few snow showers around. The EC has a potent slider like cold front and very cold air behind it as the GFS takes that portion east of the Rockies. Ensembles don`t shed any light, but the EC ensemble hints that it could come in further west like the EC as most spread is on the west side of the system. Still, I am hesitant to read too much into it as even the ensembles are seeing significant changes 6-7 days out at times. Have kept in a few showers with below average temps but nothing notable. My confidence for next week (aside from it being colder) is about 0.5 out of 5. X && .AVIATION... Lights winds and VFR conditions are expected to continue through Thursday with broken to overcast cloud decks. There could be a chance for some patchy FZFG/BR to form around KTRK and the Martis Valley during the overnight hours tonight as cloud cover slightly thins. During the day on Thursday, a cut-off low is forecast to track along the California coast creating some mountain obscuration and a slight chance of light rain and snow showers for Mono County, including KMMH. Southwest winds, along with cloud coverage, will then increase during the day on Friday as a more potent storm system is looking more likely to make moderate impacts to all area terminals starting Friday night and lasting through the weekend. Winds are forecast to be not as strong with this system, compared to recent storms, with possible ridge gusts as high as 65 kts at times. This could be due to the storm taking a more southerly trajectory. Nonetheless, mechanical turbulence is expected, especially as the front moves through on Saturday. As for the other impacts, lower CIGS/VIS, Sierra snow, and valley rain are all on the table. -LaGuardia && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$ For more information from the National Weather Service visit...