Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/15/19

Area Forecast Discussion
National Weather Service La Crosse WI
905 PM CST Thu Feb 14 2019 .UPDATE... Issued at 905 PM CST Thu Feb 14 2019 While the northwest winds are still gusting up to 30 mph, there has been enough of decrease to allow the blowing snow to pretty much end. Only a couple of sites reporting visibility reductions and those are mostly 5 miles. While the roads remain snow/ice covered and slippery, conditions do not appear to support extending the advisory and have allowed this to expire. Drifting snow will continue to be an issue into the overnight hours though. UPDATE Issued at 531 PM CST Thu Feb 14 2019 Road conditions rapidly deteriorated across southeast Minnesota and northeast Iowa with blowing and drifting snow behind the arctic front. Numerous accidents have already been reported. Visibility reductions continue to be reported upstream across the Minnesota River Valley and with no drop in the wind speeds expected until at least the middle of the evening, the blowing and drifting snow expected to remain a problem for a few more hours. Opted to go with a short fused winter weather advisory to heighten the awareness of the poor road conditions. && .SHORT TERM...(Tonight through Sunday) Issued at 250 PM CST Thu Feb 14 2019 Somewhat vigorous upper level shortwave trough dropping across the Dakotas early this afternoon, taking a bead on the local area. Good frontogenetic response on its leading edge via the RAP with favorable mid/upper level qg convergence. DGZ isn`t that deep, but good lift through it (per RAP bufkit soundings), plus a colder airmass - so resulting snow:liquid ratios favoring more in the upper teens rather than climatology. Could result in a fluffy inch for some. In addition, tightening pressure gradient for late this afternoon/evening will result in +20kts sustained and gusts upwards of 35 in the wind prone/open areas of southeast MN/northeast IA. A bit less than what is expected/occurring over southern MN/northern IA. Expect some blowing and drifting of the exiting snow pack (and whatever falls) to result - with some impacts to travel. Gave/giving some consideration to a winter weather adv for these impacts. For the moment, believe vsbys won`t be as poor as neighboring locations to the west, but still should experience some drifting and vsbys generally 1-2sm with the stronger winds. Can`t rule out some pockets where conditions worsen, and certainly not ruling out the potential for a short-lived ADV if conditions warrant. Will issue special weather statement to highlight impacts for now. Next shortwave looks to push east out of the southern Rockies, tracking across the mid mississippi river valley late Sat night through Sun night. Good qg convergence through the layers, with additional lift from the left exit region of a 130kt 300 mb jet. Inverted trough hangs well west/northwest of sfc low that holds south. Looks like a prolonged period of snow, with a few inches of accumulation - could warrant a winter weather adv. DGZ deeper than current system and upper teens seems reasonable for snow:liquid ratios. Not a ton of wind so widespread drifting/blowing doesn`t appear to be an issue - at this time. .LONG TERM...(Monday through Thursday) Issued at 250 PM CST Thu Feb 14 2019 Fairly zonal, quick moving upper level flow slated for next week. Temps mostly seasonable, but some suggestion for warm bump on Thu with some ridging/southerly fetch ahead of a shortwave trough dropping over the northern plains. For pcpn, some chances move in from the southwest in the EC and GFS, both taking shortwave energy into the Great Lakes late Tue night-Wed night. Period of light snow could/would result - a few inches of accumulation possible. Plenty of uncertainty at this time so will let blends do the heavy lifting for chances right now. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 531 PM CST Thu Feb 14 2019 The band of light snow with the arctic front has already pushed east of KRST and will be through KLSE by 01Z. After that, the issue will be the strong northwest winds and blowing/drifting snow issues for KRST. Plan to keep IFR conditions going until the middle of the evening when the winds may drop off just enough to allow most of the blowing snow and visibility reductions to end. The clouds are quickly clearing out behind the front and expecting the ceilings to break up by the middle of the evening as well. VFR conditions for the overnight into Friday as high pressure builds in over the region. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ UPDATE...04 SHORT TERM...Rieck LONG TERM...Rieck AVIATION...04
Area Forecast Discussion
National Weather Service Denver/Boulder CO
853 PM MST Thu Feb 14 2019 .UPDATE... Issued at 850 PM MST Thu Feb 14 2019 Confidence is lower in seeing freezing drizzle or rain this evening over the urban corridor and eastern plains after reviewing the newer guidance, as well as the current conditions. Lower clouds are forming near the foothills in the upslope flow, and beginning to spread east, while 0.5 degree radar echoes are increasing from the south. This would point to more possible ice crystals for a seeder-feeder process being able to form snow, rather than freezing drizzle. Viewing recent ACARS soundings from aircraft, there is a little warm layer around 700-750 mb which is above 0 degrees C, with below freezing on top and below. All of this together makes me think if precipitation does form, it should arrive at the surface as snow or sleet. I can`t totally rule out some localized spots of drizzle, but confidence is less in seeing it this evening. The better chance to see this is farther east, over the northeast plains. Another confusing point, is the 00z NAM shows precipitation around the Urban Corridor and nearby plains between 09-12Z, however the westerly downslope winds will be increasing at this point as well as QG ascent weakening and become downward motion. So confidence in this model is low. Snow continues to increase over the mountains with visibilities lowering and roads becoming more snowcovered via webcams. Winter weather advisory is now in effect until tomorrow morning. Snow should be heaviest for about the next 6 to 8 hours before trending down. && .SHORT TERM...(This evening through Friday) Issued at 242 PM MST Thu Feb 14 2019 Snow will increase again late this afternoon and early evening over the north central mountains as the next Pacific wave hits the state. Radar showing a large area of precipitation over the Four Corners area. Moisture will continue to stream east-northeast into the state through the night. Even with the unfavorable southwest upper level winds, expect enough moisture and forcing to produce 4 to 8 inches of snow across the north central mountains. Will continue the Winter Weather Advisory for this. Challenging forecast for the Front Range Urban Corridor and eastern plains for tonight. The models are doing a very poor job resolving the cold front and the amount of cold air behind it. Even the HRRR has been quite bad. The 18Z HRRR temperature 2HR forecast (for 20Z) was 16 degrees off. Feel confident temperatures will be below freezing across northeast by the time precipitation forms. This will lead to snow or freezing drizzle/freezing rain. There may be two mechanisms for precipitation. First, scattered precipitation is expected to move off the mountains and across eastern Colorado. This will fall as snow, unless there is a layer of above freezing temperatures above the cold surface. A few models show this, most don`t. A deeper layer of saturated air near the surface may form due to the cold and moist air and produce freezing drizzle. Models don`t show this happening, but with this airmass being colder and deeper than the models forecast, can`t rule out freezing drizzle. Will add this to the forecast. Precipitation amounts over eastern Colorado will be light with snowfall around an inch or lees. It will quickly dry out behind this system Friday morning with sunny skies for most of the area by late morning. Some moisture will get trapped against the mountains and produce cloud and light snow Friday. Windy conditions are expect late tonight and Friday in the foothills where gusts to 50 mph will be possible. Models indicate the cold air will scour and shift off to the east. Somewhat skeptical about the amount of warming over the plains and especially for the low lying area across the plains. Lower temperatures some, but still expect a mild day. .LONG TERM...(Friday night through Thursday) Issued at 242 PM MST Thu Feb 14 2019 For Friday night into Saturday, a low center off the Pacific NW coast will bring a 180+ kt jet around the base of the trough into the Great Basin late Friday. With the region being under the better lift of the LER of the jet, QG values are higher with good instability into Saturday morning. This will bring another decent shot of snow to the mountains early Saturday with gusty winds through the day. Over the plains, a deep lee side sfc low will keep precipitation at bay through the majority of the morning Saturday with a slight chance of snow with the help of a cold front dropping South by the afternoon. Surface winds will generally be from the NW to W that will increase downsloping effects along the front range and could keep most of the precip more over the eastern plains. Highs for Saturday will be in the 40s with lower temperatures over the eastern plains. For Saturday into Sunday, the upper disturbance will continue to push through the state with the GFS slightly slower than the EC. Snow will continue in the mountains but will come to an end gradually over the far eastern plains as the surface low slips SE across the OK panhandle. A deep low will transition across the northern portions of the CONUS pushing the jet across the South. this will keep the state under NW flow with weak moisture. This will allow for a slight chance of snow in the mountains through Sunday with highs in the lower 30s and overnight lows in the teens on the plains. For next week conditions will become colder with an arctic push from the NW. Sunday into Monday an upper level low over southern CA will begin to move eastward as a secondary system over the northern rockies moves SE. Models show the best QG ascent and lift across the southern rockies with decent moisture in the lower and mid levels from SW flow aloft. This will bring snow to the central and Southern mountains of the State starting overnight into Monday. For the plains, cold, surface high pressure will be south with winds transitioning to a NE direction and increase upslope flow along the foothills Monday morning. This will increase chances of light snow for the plains. With little jet support and the main QG south, expect light snowfall amounts on the plains. Temperatures Monday and through Thursday will start to reflect this cold push with highs in the 20s and low 30s with overnight lows in the single digits. By Monday night into Tuesday, the secondary trough will push SE from CA and move across the state Tuesday morning. Models are showing decent moisture from the SW but with surface winds from the SE, upslope flow will be limited so only expect light accumulations. By Wednesday, the trough will have pushed through drying out conditions and leaving the colder air in place. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 850 PM MST Thu Feb 14 2019 Low clouds are expected to form after 04Z, with ceilings falling below 1000 feet. There will be a chance for snow, with a tiny chance of seeing freezing drizzle as well. Precipitation is expected to be light. Low clouds and possible fog will move in as a Denver Cyclone wraps in the moisture and last through most of the night into the early morning hours. Dry air quickly moves in Friday morning helping to clear skies out. The low clouds should scatter out by 15Z. Gusty east winds will continue at the Denver airports through 04Z before winds turn northerly direction behind a Denver Cyclone that will develop somewhere around southern suburbs, then shifts east of the area. For Friday, light winds are expected during the morning with gusty west winds possible after 16Z. && .BOU WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory until 9 AM MST Friday for COZ031-033-034. && $$ UPDATE...Kriederman SHORT TERM...Meier LONG TERM...Bowen AVIATION...Meier/Kriederman
Area Forecast Discussion
National Weather Service Dodge City KS
502 PM CST Thu Feb 14 2019 ...Updated Aviation Discussion... .SHORT TERM...(This evening through Friday) Issued at 340 PM CST Thu Feb 14 2019 Objective analysis of 850 mb temperature now showing a temperature gradient of about 25 degrees C between our south central Kansas counties and the very cold boundary layer airmass over south dakota. Meanwhile a 150kt 300 mb westerly jet was moving into Colorado with all short term models indicating a vigourous shortwave to develop across western Kansas Tonight. A Winter Weather Advisory was issued for Tonight based on the idea that he mixed phase characteristics of the system was of high certainty with much less certainty on precipitation amounts. The 12Z NAM showed strong mid level warm air advection over the shallow cold air after midnight with not much precipitation QPF-wise in the southwest, however the RAP has increased QPF amounts over northern Oklahoma and southcentral Kansas especially - while thermal profiles should support a mix of freezing rain and sleet with a changeover to snow as approaching the 12z to 15 Z timeframe. Looking at the meteograms for HYS, snow amount at Hays spike around 12 Z, lasting though the morning commute time before the mid level wave exits into eastern Kansas in the afternoon, leaving the DDC area under cold easterly surface flow. .LONG TERM...(Friday night through Thursday) Issued at 340 PM CST Thu Feb 14 2019 Much colder temperatures are expected by Saturday morning across central Kansas, with high model consensus for low teen by 12Z Saturday. Highs may not exceed the 20s across central Kansas with the cold arctic airmass in place, while at the same time, the higher terrain near Liberal to Syracuse and westward should see much warmer highs in the 50s. Overall the synoptic pattern will continue to transition to a colder regime for the central High Plains though the weekend and through mid week. A series of shortwaves will impact sensible weather likely producing minor measurable snowfall in the central High Plains and possibly western Kansas as early as Saturday night and then more significant snowfall possible Monday into Tuesday. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 453 PM CST Thu Feb 14 2019 A frontal boundary has pushed through the CWA with wind gusts up to 30-35kts out of the north to northeast. Upper level ceilings currently will deteriorate after 06Z to the mid levels before going MVFR after 10Z and IFR around 12Z. The cold air will keep ceilings in through the end of the period but gradually rise to VFR by 22Z and scatter out after the end of the TAF period. Winds will subside after 06Z and stay out of the east to northeast allowing for a good upslope flow that will generate some freezing rain initially at LBL, DDC, and GCK before turning to snow for DDC and GCK prior to sunrise. HYS will see straight snow during this period being more in the cold pool of arctic air. All precipitation will come to an end by 15Z in the mid morning with visibilites improving at this point but still seeing VFR conditions down to 3sm in the precipitation. This is subject to change with the next model runs and TAF issuance, so stay tuned for the latest forecast at 06Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 23 31 17 38 / 60 30 0 10 GCK 24 34 19 42 / 40 30 0 10 EHA 32 50 25 56 / 60 10 0 0 LBL 28 40 20 51 / 70 30 0 0 HYS 19 21 13 29 / 40 90 0 10 P28 27 30 18 37 / 70 40 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 3 AM CST /2 AM MST/ to noon CST /11 AM MST/ Friday for KSZ030-031-043>046-061>066-074>081-084>090. && $$ SHORT TERM...Russell LONG TERM...Russell AVIATION...Lowe
Area Forecast Discussion
National Weather Service Goodland KS
701 PM MST Thu Feb 14 2019 .SHORT TERM...(This evening through Friday) Issued at 220 PM MST Thu Feb 14 2019 The cold front currently moving through the Tri-State area will bring in some wintry mix precipitation tonight. After latest guidance runs, decided to hold off on a Winter Weather Advisory as it appears dryer air (with 10 degree dewpoint depressions over our Colorado counties) may just hold on a little longer preventing freezing fog / freezing drizzle. So, confidence is much lower for freezing precipitation to happen. The majority of recent hi-res guidance (GFS, NAM, and HREF) are all in favor of preventing the freezing fog/ light freezing drizzle to occur, but, one outlier to mention, the high-res RAP stands out counter to them showing widespread drops in visibilities for our western CWA. So, in short, depending on how the event unfolds, there is still a slight chance for a light glaze to develop over sidewalks and roadways. We are advertise through social media the potential for freezing fog / drizzle, but at this time, felt a highlight was unnecessary. With this system, we are expecting snowfall totals to be at most up to an inch in our extreme northeastern CWA in Decatur County, Nebraska. Low`s overnight tonight will drop into the mid to upper teens. Come Friday, CAA begins to take over and prevail through the extended forecast for the Tri-State area. Depending on where the front stalls overnight, we will see a varying 30-40 degree temperature gradient across the Tri-State area tomorrow afternoon. This setup will give way from highs ranging in the mid to upper 20s for the eastern half of the CWA to mid 50s across the western half of the CWA. .LONG TERM...(Friday night through Thursday) Issued at 129 PM MST Thu Feb 14 2019 Weak ridging aloft moves over the region Friday night into Saturday, leading to dry conditions. Meanwhile, an upper trough sets up across the western CONUS. A first disturbance passes through the central and northern Plains on Saturday as a front pushes east. There seems to be enough moisture and lift to generate some chances for light rain/snow in the afternoon and evening. Little to no accumulation is anticipated at this time. Dry weather briefly returns on Sunday before additional lobes of energy pass through the longwave trough. This series of waves move from the Rockies to the Plains and produce light snow Sunday night through Monday and again Monday night through Tuesday. Uncertainty remains, but the current forecast calls for a trace to three inches of snow from Sunday night through Tuesday, with highest amounts in the south. The next opportunity for precipitation comes Thursday as a closed low drops from the Pacific Northwest to the Four Corners region. Temperatures decrease at the start of the period, reinforced with a surge of cold air late in the weekend dropping Monday`s highs into the upper teens/low 20s. Highs gradually rise thereafter, from the 20s on Tuesday to near 40 degrees on Thursday. Lows are forecast in the teens and low 20s Friday and Saturday nights before single digits/teens through midweek. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 651 PM MST Thu Feb 14 2019 MVFR ceilings and light snow will be possible at both terminals late tonight and Friday morning, primarily between 09-18Z. Otherwise, expect VFR conditions to prevail. NE-ENE winds at 10-15 knots this evening will veer to the ESE-SE overnight and S-SSE during the day on Friday. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...EV LONG TERM...JBH AVIATION...VINCENT
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
601 PM CST Thu Feb 14 2019 .SHORT TERM... (Through Late Tonight) Issued at 225 PM CST Thu Feb 14 2019 A strong cold front is moving through northeast and central Missouri at this time, and it will continue to move southeast through the forecast area tonight. Afternoon temperatures warmed up into the mid 50s and low 60s which are more normal for late March and early April than mid February. The taste of Spring will be brief, as temperatures will turn sharply colder behind the cold front tonight. It`s already down to the mid 20s in far northwest Missouri on the cold side of the front. MOS guidance shows a fairly large temperature gradient between low teens and single digits in northern Missouri and mid and upper 20s in southeast Missouri for lows on Friday morning. This actually looks reasonable given the upstream temperatures from northwest Missouri into southeast South Dakota at this time. The shortwave that`s driving this cold front southeastward becomes negatively tilted tonight and lifts northeast into the Great Lakes. This causes the front to stall over Arkansas by early Friday morning and keeps the center of the Arctic high bottled up over the northern Plains, so the temperature gradient we`re seeing in guidance looks reasonable. Little if any precipitation is expected as this cold front passes due to lack of moisture, but there will be a band of cold advection strato-cu that follow the wind shift by a couple of hours. Carney .LONG TERM... (Friday through Next Thursday) Issued at 225 PM CST Thu Feb 14 2019 Two low pressure systems will bring widespread precipitation to the region, first on Friday/Friday night and then again on Saturday night into Sunday. Additional low pressure systems may affect the area during the early to middle part of next week. A Winter Weather Advisory has been issued for the Friday/Friday night system. Broadly speaking, a swath of 2-3" of snow (perhaps closer to 4" in some spots) is expected in central and eastern MO into southwestern IL. A wintry mix of snow and sleet is expected across the southern CWA, and a light glaze is also possible in this area. Based on the current timing, wintry precipitation would affect the Friday afternoon/evening rush hour. The PV anomaly associated with Friday`s system was visible along the CA coast early this afternoon on water vapor imagery and via RAP analysis of the 1.5 PVU field. The observed position of the PV anomaly at 18z agreed well with model forecasts. This system will finally be fully sampled by the upper air network at 00z Fri as it progresses inland. By 12z Fri, the PV anomaly is forecast to be located over the Rockies, and isentropic ascent ahead of this feature over KS/MO will yield increasing clouds as well as precipitation development. Widespread precipitation due to isentropic ascent will continue progressing from west to east through the day. Models also show favorable jet coupling at H5 and H3 which will provide another source of large-scale lift across the region to support precipitation development and maintenance. Some model solutions also depict the LSX CWA being located within the favorable left exit region of an H85 low-level jet on Friday afternoon, which would provide yet another source of ascent. Bands of frontogenesis were also noted. BUFKIT soundings suggest that the atmosphere will be cold enough for snow across nearly all of the LSX CWA except for the southern tier or two of counties. After evaluating time-height cross sections in BUFKIT from multiple models at multiple locations, the lift appears to be centered within the top half of the DGZ (and in some cases it is centered slightly above the DGZ). In a classic cross-hair signature, the greatest lift would be centered within or just below the DGZ such that hydrometeors would be readily lofted into the favorable dendritic growth zone; rapid crystal growth ensues. Although these are not classic cross-hair signatures, they`re close enough that one might reasonably expect to see periods of efficient snowfall production across parts of the area, especially because the column is supersaturated with respect to ice at the levels at and above where the forecasted ascent overlaps with the DGZ. The cold air mass which will be in place behind today`s cold front also supports higher snow-to- liquid ratios than were previously forecast. Farther south, a warm layer aloft will introduce a mix of precipitation types. The dominant types should be snow and sleet, but a light glaze of ice cannot be ruled out. There is some question about the strength and depth of the warm nose, and for this reason there is still some uncertainty regarding exact precipitation types and amounts across the southern part of the CWA. Given that this system will not be fully sampled until the 00z Fri RAOBs, the next scheduled forecast package may include a significant adjustment to these precipitation types and/or amounts. Attention then turns to the next low pressure system which should bring widespread precipitation to the region on Saturday night into Sunday. The dominant precipitation type should be snow across most of the area for most of the event, but models are still showing a sufficiently strong warm nose to raise a threat of freezing rain. Similar to 24hrs ago, models are showing an elongated vorticity zone across the region, and this feature justifies retaining low PoPs across the northern CWA through late Sunday afternoon. Snowfall amounts should range from up to an inch in NE MO and west central IL to a dusting along the I-70 corridor. Models continue to show low run-to-run continuity regarding the upper air pattern for next week. At least one low pressure system should affect the region when a deep trough lifts through the region, but there is low certainty at this time regarding the details. Temperatures will be similar from day to day from Friday through next Tuesday with highs in the 30s to lower 40s and lows in the teens and 20s. Temperatures may be slightly warmer during the middle and late part of next week, but there is low certainty regarding those temperature trends due to the aforementioned model disagreements regarding both the upper air pattern and important surface features. Kanofsky && .AVIATION... (For the 00z TAFs through 00z Friday Evening) Issued at 540 PM CST Thu Feb 14 2019 A cold front will move southeastward through the St. Louis metro area early this evening. The surface wind will become northwesterly after fropa as well as strong and gusty as the surface pressure gradient tightens. A band of post frontal MVFR clouds around 1500 feet will advect southeastward through the taf sites this evening. Should see a return to VFR conditions late tonight, and the surface wind will gradually decrease in strength. An upper level disturbance will bring snow to the taf sites Friday afternoon and evening, particularly in COU and the St Louis metro area. The cloud ceiling and visibilities will drop Friday afternoon as the surface/boundary layer saturates with conditions deteriorating to IFR conditions in COU and the St Louis metro area. SPECIFICS FOR KSTL: A cold front will move southeastward through STL early this evening. The surface wind will become northwesterly after fropa as well as strong and gusty as the surface pressure gradient tightens. A band of post frontal MVFR clouds around 1500 feet will advect southeastward into STL later this evening. Should see a return to VFR conditions by early Friday morning, and the surface wind will gradually decrease in strength. An upper level disturbance will bring snow to STL Friday afternoon and evening. The cloud ceiling and visibilities will drop Friday afternoon as the surface/boundary layer saturates with conditions deteriorating to IFR conditions. GKS && .LSX WATCHES/WARNINGS/ADVISORIES... MO...Winter Weather Advisory from 9 AM Friday to midnight CST Friday night for Audrain MO-Boone MO-Callaway MO-Cole MO-Crawford MO-Franklin MO-Gasconade MO-Iron MO-Jefferson MO-Lincoln MO- Madison MO-Moniteau MO-Monroe MO-Montgomery MO-Osage MO- Reynolds MO-Saint Charles MO-Saint Francois MO-Saint Louis City MO-Saint Louis MO-Sainte Genevieve MO-Warren MO- Washington MO. IL...Winter Weather Advisory from 9 AM Friday to midnight CST Friday night for Clinton IL-Madison IL-Monroe IL-Randolph IL-Saint Clair IL-Washington IL. && $$ WFO LSX
Area Forecast Discussion
National Weather Service Marquette MI
850 PM EST Thu Feb 14 2019 .SHORT TERM...(This evening through Friday) Issued at 415 PM EST THU FEB 14 2019 WV imagery and RAP analysis indicated a prominent shortwave trough through MN that supported an area of light snow from ne MN through ern MN and nw WI. At the surface, a trough extended from wrn Upper Michigan into nw IL with gusty nw winds and strong CAA in its wake. A narrower band of snow had developed into far s to se Upper Michigan in line with a band of 800-600 mb fgen. Patchy fzdz was also reported in higher terrain portions of north central Upper Michigan where upslope low level se flow prevailed along with a lack of ice nuclei. Tonight, expect the fgen band to strengthen through the southeast into this evening with a narrow band of moderate to heavy snow. However, there is still some uncertainty with where the axis of heaviest snow will develop. As the MN shrtwv approaches, light snow will also spread across Upper Michigan with an inch or two of accumulation and intensify as it moves to the est where 3 to 5 inch amounts are expected. Gusty northwest winds will develop from west to east from late evening overnight. Northwest flow LES will increase as 850 mb temps drop to around -13C with favorable 850-700 mb moisture lingering near the mid level trough axis. Friday, nw flow LES will continue with 850 mb temps remaining around -14 and equilibrium levels around 6k ft. Although additional amounts will be more limited, especially over the west where upstream ice cover is most extensive, but additional amounts of 1 to 4 inches are expected. In addition, considerable blowing snow will continue over the northeast, where the winter storm warning will continue. Conditions should improve during the afternoon as inversion heights drop with the exiting mid level trough and winds diminish. So, winter headlines remain unchanged with advisories for the se near Lake Michigan tonight and the northwest through Friday morning. The winter storm warning for Alger, nrn Schoolcraft and Luce will also continue through Friday. .LONG TERM...(Friday night through Thursday) Issued at 409 PM EST THU FEB 14 2019 Generally a quiet stretch of weather with slightly below normal temps is in store into early next week. Shortwave and sfc low that brings the system snow this aftn and evening slides off to southern Quebec by Fri evening while ridge builds upstream northern Plains to scntrl Canada. NW low-level winds persisting btwn the sfc ridge and exiting low along with H85 temps -14c to -16c will be sufficient enough to continue light lake effect for nw flow snow belts east of Marquette to Whitefish Point. Soundings indicate inversions 3-4kft and DGZ within the entire lake effect convective layer. Even so, the lower inversions and increasing anticyclonic flow will keep snow amounts in check. Winds will also be settling down on Fri evening, so blsn will become less of an issue as night goes on. Partial clearing could occur over western/southern Upper Michigan, so kept idea of blo zero temps there. Light lake effect will continue into Sat for north wind flow areas of Alger and northern Schoolcraft counties. Not expecting much more than light snow and flurries though with anticyclonic flow and inversions 2-3kft. Elsewhere will see some partial sunshine. Temps on Sat will top out in the upper teens to near 20F, which remains a bit blo normal. As high pressure ridge builds across Ontario to Quebec sfc-H9 winds will turn to the east, so may see some light snow or flurries over northern Marquette county into the Keweenaw. Next system heads out over the cntrl Plains on Sun but shears out as it heads across the Ohio Valley and lower Great Lakes Sun night into Mon. Net result is little if any snow making it as far north as Upper Michigan. Looks more like a MN/IA/WI/IL moderate snow event. As the wave of low pressure with that system slides by to the south of the Upper Great Lakes Sun night, may see some light northerly flow lake effect snow showers and flurries into north central Upper Michigan. Some light lake effect could continue on the Keweenaw on Tue. Next chance of system snow lifts across the Upper Great Lakes Wed, though right now the main focus with the main sfc low looks to stay more over the lower Great Lakes. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 643 PM EST THU FEB 14 2019 Snow will be overtaking all three terminals within the next few hours, already ongoing at KIWD. Generally speaking, visbys should remain IFR through much of the overnight hours with some brief drops to LIFR with any heavier localized band that marches through. The precip will taper off later in the day on Friday with some light lake-effect snow showers remaining possible through the end of the TAF period as NW winds take over at the surface. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 415 PM EST THU FEB 14 2019 NW gales to 45 knots will return to the e half of Lake Superior late tonight into late Friday in the wake of a low pres system. Heavy freezing spray will return as well and continue into Sat morning. Quiet conditions are expected through much of the weekend into early next week. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Winter Storm Warning until 7 PM EST Friday for MIZ006-007-085. Winter Weather Advisory until 1 PM EST Friday for MIZ001>003. Winter Weather Advisory until 7 AM EST Friday for MIZ013-014. Lake Superior... Heavy Freezing Spray Warning from 1 AM Friday to 1 PM EST Saturday for LSZ248>251-265>267. Gale Warning from 10 PM this evening to 1 AM EST Saturday for LSZ248>251-265>267. Lake Michigan... None. && $$ SHORT TERM...JLB LONG TERM...JLA AVIATION...lg MARINE...JLB
Area Forecast Discussion
National Weather Service Pendleton OR
208 PM PST Thu Feb 14 2019 .SHORT TERM... Latest radar imagery showed the bulk of precipitation in Washington with more showery and less coverage over portions over western and central Oregon with another area over far eastern Oregon. The NAM and RAP have had a better handle on precip coverage all day, while the GFS has been too overdone. Overnight, the cold air will deepen in the mid levels and any freezing rain threat should become more of a snow threat. Low pressure off the coast will drag a warm front through on Friday before the low comes onshore and weakens. Temperatures will increase on Friday, and expect more showery precipitation either in the form of rain at the lower elevations and snow at the higher elevation and a decrease in precip chances overall. Guidance differs a bit on where the best chances are, but there seems to be agreement that there will be a decent gap over a good chuck of Oregon for at least a portion of Friday, outside of eastern areas, except for a few passing rain or snow showers. Friday night through Sunday...A large and cold upper level trough will be over the region. There are no clear organized shortwaves expected to impact the forecast area during this time but there will be periods of rain or snow showers especially Saturday afternoon and into the evening. Showers will begin to taper off Saturday night and into Sunday as a cold northerly flow begins advecting drier air into the region. Temperatures are expected to remain colder than normal. .LONG TERM... Sunday night through next Thursday...The active pattern continues into next week as general long-wave troughing continues as multiple upper-level lows and shortwave troughs drop south along the east side of blocking high and down into the PacNW. Back door cold front Sunday night into Monday will slide south across eastern WA/OR and bring mountain snow showers, especially across the Blues/Wallowas. In its wake, transient ridging will likely bring a dry day on Monday, but the dry weather will be short-lived. Next Tuesday into Wednesday, as the blocking ridge amplifies north into Alaska, the polar jet will dive south and allow for more disturbances to work into the PacNW bringing more snow and a reinforcing shot of cold air. For Thursday, models begin to diverge with the EC diving an upper-level low south into northern CA/NV with transient ridging and drier conditions across the PacNW, while the GFS and GEFS mean are more progressive with the flow and work the low/trough into the intermountain west and bring continued northwest flow into the PacNW with snow showers, especially over the mountains, ahead of another approaching system. With the persistent troughing through the long term and north to northwest flow aloft, temps will remain quite cold for this time of year, running 5-15 degrees below normal, with highs generally in the mid 20s to 30s and lows in the teens to lower 20s. Breezy winds possible at times with each trough/frontal passage, but should remain below advisory criteria. && .AVIATION... 00Z TAFS...Multiple bands of mix precip (snow/freezing rain/rain) will lift north tonight across all terminals. Best potential for moderate to heavier precip will be through the evening. More scattered, lighter precip possible then afterwards. Expect IFR to LIFR categories through most the period. Areas of mist/fog possible in between precip bands. Icing and mountain obscuration expected. Winds generally 5-15kts with some gusts up to 20kts. && .PRELIMINARY POINT TEMPS/POPS... PDT 27 40 24 33 / 60 20 10 20 ALW 30 41 26 35 / 60 40 10 20 PSC 25 38 26 33 / 50 20 10 10 YKM 23 37 21 33 / 60 30 10 10 HRI 26 39 26 35 / 50 20 10 10 ELN 21 36 20 34 / 70 30 10 10 RDM 27 41 24 37 / 20 20 30 40 LGD 31 39 23 35 / 60 50 20 30 GCD 29 39 25 36 / 40 30 20 40 DLS 28 40 28 37 / 50 30 20 20 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...Winter Storm Warning until 10 PM PST this evening for ORZ041-510. Winter Weather Advisory until 10 PM PST this evening for ORZ044- 507-508. Winter Weather Advisory until 4 PM PST this afternoon for ORZ511. WA...Winter Storm Warning until 10 PM PST this evening for WAZ024-026- 027-521. Winter Weather Advisory until 10 PM PST this evening for WAZ028- 029-520. && $$ 77/84/84
Area Forecast Discussion
National Weather Service Pocatello ID
619 PM MST Thu Feb 14 2019 .SHORT TERM...Today and Friday. A quick update this evening as moderate snow was falling from Craters of the Moon to Mud Lake and within the Big and Little Lost River Valleys. Radar was showing abroad area of ongoing snowfall in that region with another fairly enhanced line of showers making its way through Mountain Home yet to come. As a result, have added the aforementioned region to the highlights with a Winter Weather Advisory through 6 AM MST Friday morning. See the previous discussion below. Huston An upper level low on the Pacific coast is starting to fill and move inland. This system continues to bring moisture into our area. Expect another wave of moisture this afternoon into the evening in Southwest flow. This Southwest flow has risen snow levels to around 5500 to 6000 feet. Expect heavy snow for the Central Mountains and Eastern Highlands this afternoon and evening. Below 5500 feet expect significant rain on snow, 0.25 to 0.75 across the Eastern Highlands, Snake River plain and the Southern Highlands where a flood watch remains in effect. Ponding of water as well as elevated small streams is likely. Please see hydro section and flood watch for more information. A cold front moves through this evening into Friday morning bringing snow levels down to the valley floor. The GFS model brings another wave of moisture through Friday afternoon into the evening. The NAM12 model doesn`t start this wave until Friday evening. Expect 1 to 4 inches of snow for valleys along the Eastern Magic Valley, Southern Highlands, Snake River plain, and Eastern Highlands. Expect 4 to 6 inches of snow, with locally higher amounts, for mountains including the Central Mountains, Carbiou Range,Marsh and Albion Highlands as well as the Eastern Highlands along the Wyoming border. Wyatt .LONG TERM...Saturday through next Thursday. Drier conditions are expected this weekend, but still might see some chances of snow. An upper trough remains over the western US through much of the long- term period, though the upper flow will be weak. Snow bands, should they develop, should be weak and disorganized Saturday and Sunday. Accumulations will be rather light as well. As we head into Monday, an upper trough will drop in from the north. This will bring some better snow chances, mainly to the Central Mountains. Accumulations Monday and Monday night again will be on the light side...about 1 to 3 inches. That upper trough will pass through on Tuesday while we get a brief period of drier weather Tuesday afternoon, but we will see another trough move in from the northwest as early as Tuesday night. GFS and ECMWF keep a broad upper trough over the West through Thursday, but the GFS is a bit more progressive while the ECMWF cuts off an upper low over California. Hinsberger && .AVIATION...A couple more waves of precip will move through this afternoon and tonight. Temperatures are warmer today and tonight, so precip should fall as rain across the Snake Plain. Snow is expected at KSUN and KDIJ, though some rain may mix in with it. Flight categories will fluctuate as precipitation falls this afternoon and evening. The stronger wave of precip will be tonight along a cold front, and will generally lead to IFR or LIFR conditions. HRRR and other high-res models suggest a brief heavy band of precip moving through with tonight`s wave, so conditions could drop to airfield minimums temporarily. Winds are expected to increase along the front, but will taper off by sunrise. Hinsberger && .HYDROLOGY...Warm temperatures along with rain on snow continues to melt away the snow over the Eastern Magic Valley through the Snake River Plain up to around Blackfoot. This extends to the adjacent valleys into the South Central and Southeast Highlands. This will cause ponding of water in low-lying areas below 5500 ft as well elevate flow in small streams. A flood watch remains in effect through late tonight for those areas. Keeping drains open well help minimize ponding of water. Hinsberger && .PIH WATCHES/WARNINGS/ADVISORIES... Flood Watch through late tonight for IDZ051-054>059-062. Winter Storm Warning until 6 AM MST Friday for IDZ071>075. Winter Storm Warning until 5 PM MST Friday for IDZ060-062>067. Winter Weather Advisory until 6 AM MST Friday for IDZ052-068-069. && $$
Area Forecast Discussion
National Weather Service Phoenix AZ
845 PM MST Thu Feb 14 2019 .SYNOPSIS... Unseasonably high atmospheric moisture levels will accompany an upper level disturbance moving through the region through Friday morning. This will result in widespread moderate rainfall amounts falling today and tonight across the lower deserts and locally heavy amounts over high terrain areas north and east of Phoenix. Rain chances will decrease during the day Friday, but second drier weather system will bring more chances to mainly central and northern Arizona Sunday and Monday. A significant cool down will occur this weekend through early next week with temperatures falling well below normals. && .DISCUSSION... At 8 pm this evening, a strong short wave continued to push east and into Arizona, ahead of a large upper closed low situated off the Pacific northwest coast. Associated surface cold front was pushing into the western Arizona desert and will be racing east across the area tonight. It should pass through the Phoenix area around 11 pm to midnight; a strong 180kt upper jet moving into southern CA and far southern Nevada is helping to quickly advect the wave to the east. With the jet axis moving through far northern Arizona tonight and putting southern Arizona on the anticyclonic shear side of the jet, it may be helping to limit rain accumulations over the southern deserts. Additionally, the low/mid level flow has become more westerly, reducing the potential for strong orographics and also limiting rain accumulation over higher terrain areas east of Phoenix. Although this event brought extreme amounts of rain to favored areas west of our CWA today, we have not really seen significant accumulations - even across Joshua Tree NP and other portions of Riverside County. Park and Riverside County officials reported no significant flood impacts earlier in the day and as such we allowed the Flood Watch to be cancelled early for our California zones. A Flood Watch does remain in effect for the northern portion of our CWA in Arizona although at this time it is likely overdone. Current radar showed showers rapidly dissipating over much of the desert to the west of Phoenix and the latest 1 hour rain totals across the Maricopa County Flood Control gage network were meager - mostly below 0.10 inches Latest mesoscale models such as HRRR suggest that most of the showers will be over for the greater Phoenix area shortly after midnight as the wave races quickly to the east and drier more subsident air spreads into the western/central portions of the Arizona deserts. Latest model cross sections of RH and UVV also shows the deep moisture rapidly thinning by 06z from Phoenix west, with near saturation only found near or below 850mb. Overall it appears that we may not get nearly as much rain as we had previously expected across south-central Arizona. Latest guidance and observations suggest that we will not see a large upswing in precip over the next several hours, rather everything will keep shifting east and decreasing from the west. Possibly too much of the deep moisture associated with the massive atmospheric river was wrung out by the high terrain west of our CWA (coastal mountains). Forecasts have been tweaked to lower our POPs for tonight into Friday morning and they may still be too high. Otherwise everything is in decent shape for the moment. && .PREVIOUS DISCUSSION... The wet and dreary Valentine`s Day forecast has arrived as advertised with a large and impressive atmospheric river transporting a dense amount of tropical moisture into the Southwest. So far, nearly 1.50 inches of rain has fallen in Joshua Tree National Park while the North Shore Salton Sea area has also seen nearly an inch. Nevertheless, most of forecast area has seen at least some rain at some point since last night. Current radar shows the deepest showers focused from Mountain Springs in Imperial County northward towards Desert Center, which is where the mesoanalysis shows the deepest moisture plume. In addition, 17z upper air sounding from Yuma indicated 1.35 inches of precipitable water which is at the extreme high end for this time of year for the area. The moisture will continue to push through into Arizona today with showers continuing across southeast California and south-central Arizona. While some isentropic and jet dynamics will aid in shower development, the primary forcing for heavier showers will be topography, so higher rainfall totals will occur over the mountainous terrain where the rain process will be most efficient. The rain should subside in southeast California between 0-2z (4-6 pm PST) and dissipate later over the Phoenix area around midnight (MST). Rainfall totals upwards of 2-4 inches are likely across the mountains north and east of Phoenix, with lower desert locations more likely to see 0.25-0.75 inches. The concern, however, is the runoff that will flow out of the mountains and into normally dry washes and river creating potentially dangerous flooding conditions at any low water crossings. As of now, the thinking identifies Tonto Creek, Cave Creek and New River areas as the most susceptible, but problems elsewhere may easily come to fruition. As such, a flood watch remains in effect. Beyond today, we may see light lingering showers Friday and Saturday with cooling temperatures. Significant drying will occur on Friday with PWATs lowering to a half an inch or below, but more active weather is on the horizon for later in the weekend. Another large Pacific trough will develop off the Pacific Northwest coast tonight, diving southeastward into the Great Basin Friday into Saturday. This trough will eventually bring several shortwaves quickly through the Desert Southwest this weekend through Monday. Moisture will be limited during this period, but significantly colder air working its way south into our region and strong upper level dynamics will aid in the potential for scattered showers beginning Saturday. The best potential for more widespread light precipitation looks to be Sunday and Monday, mainly focusing from Phoenix north and east. QPF amounts are fairly light (less than 0.10") over the south- central Arizona deserts with upwards of 0.33" over higher terrain areas. Snow levels will drop through the weekend, bottoming out on Monday between 3000-4000 ft. The colder air with the system will keep temperatures well below normal with highs mostly in the 50s for Sunday through Tuesday. Overnight lows will likely dip into the 30s beginning Sunday night with Monday and Tuesday night possibly being the coldest nights. The coldest prone desert areas may again see lows near freezing. Model spread greatly increases for the middle of next week, but there is general consensus on another deep trough forming across the Western U.S. next Wednesday and Thursday. The GFS/GEFS is on the drier side whereas the European leans more toward a wet system. Either way it seems rain chances will again be in the picture during the latter half of next week. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL: Very wet Pacific weather system continues to move into the central deserts late this afternoon; CIGs have fallen into the 3-5k ballpark for the most part and light rain was occurring at the TAF sites. So far, visibility is generally above 5sm. Best window for heavier rain, and really low CIGS, is in the 02z-07z time frame. We could see CIGS down in 1-2k foot range at the TAF sites, at least briefly during moderate showers, and visibility could fall below 3sm in heavier rain or mist. After 07z we expect showers to quickly taper off from the west, but some lower CIGS - 5k or lower - could persist into the middle of the morning on Friday. Winds should not be a major issue; initially looking at east/southeast winds up to 10kt, turning to the west by around 03z. Do not expect west winds much over 10-12kt but we have seen sufficient signals that LLWS will become an issue for several hours or so as west winds strengthen to near 35kt at the 2-3k foot level while surface winds remain somewhat light. Of course, thick clouds and stable conditions will prevent mixing those winds to the surface leading to the LLWS conditions. Southeast California/Southwest Arizona including KIPL and KBLH: As of 6 pm, showers have pretty much ended from the lower Colorado river valley westward; we may see VCSH in the lower deserts for a few more hours but overall the rains look to be over for the next 24 hours at least. There may be a few CIGs in the 4-6k foot range through mid evening, otherwise low cloud decks should mostly scatter out with some continued high cloud spreading overhead. One possible issue for later tonight and into Friday morning is fog. We have mentioned visibility 3-5sm after 10z at the TAF sites, supported by guidance suggesting temp-dewpoint spread down to zero. With all the rain that occurred boundary layer will be very humid. Some flys in the ointment - so to speak - are continued high clouds limiting radiational cooling, and possibly west breezes greater than 6kt. So, confidence in some patchy fog remains high but getting visibility below 3SM is rather low. Otherwise, winds should favor the west at KIPL next 24 hours with speeds mostly 12kt or lower. Winds tend to favor southwest at KBLH but there will be variability at times. Aviation Discussion not updated for amended TAFs. && .FIRE WEATHER... Saturday through Wednesday: The active weather pattern will continue into next week with temperatures well below normal through the period. Precipitation chances will favor high terrain areas in Arizona Saturday through Monday with good chances of wetting rains for most areas over the three day period. A brief break in the activity is likely for Tuesday before another weather system moves in later on Wednesday. RH values will remain elevated for much of the period finally lowering into the twenties for Tuesday and Wednesday. Periods of breezy west winds can be expected Saturday through Monday. && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...Flood Watch through Friday morning for AZZ530-533-534-537-541- 542-545-547-549-552-555>558-560>563. CA...None. && $$ DISCUSSION...CB PREVIOUS DISCUSSION...Deems/CK AVIATION...CB FIRE WEATHER...Kuhlman