Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/13/19

Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
826 PM MDT Tue Mar 12 2019 .UPDATE... As the line of storms continue to shift eastward into Texas, the tornado threat has diminished. Therefore, the Tornado Watch has been cancelled for Lincoln, Quay, Chaves, Curry, De Baca and Roosevelt counties. ZFP out shortly. 34 && .PREV DISCUSSION...523 PM MDT Tue Mar 12 2019... .AVIATION... 00Z TAF CYCLE Upper low circulation over central and srn AZ at 23Z to swing across nrn and central NM and over sern CO by 13/15Z as it intensifies. Mts obscured in sct to nmrs MVFR to IFR cigs/vsbys in rain and snow showers and fog as well as thunderstorms but the precipitation is expected to begin to decrease in areal coverage aft 06Z becoming more focused over the higher terrain of the west and north. A line of thunderstorms moving from west to east over the ern plains at 23Z may contain isold strong to severe storms with large hail and wind gusts to 50kt mainly south of Interstate 40 until around 03Z when the southern portion of the line should exit NM into TX. Very strong sw- wly winds to develop between 09Z-15Z over ern and srn NM sustained to 35-45kt with gusts to 60kt. && .PREV DISCUSSION...349 PM MDT Tue Mar 12 2019... .SYNOPSIS... Weather conditions will be fickle and unsettled over the next few days. A potent Pacific low pressure system continues to approach New Mexico, drawing in copious amounts of moisture ahead of it. This will continue to lead to scattered to numerous showers and thunderstorms across northern and central New Mexico through the evening with strong to severe thunderstorms expected, primarily in the eastern half of the state. As the Pacific cold front sweeps eastward across the Land of Enchantment overnight, look for snow levels to lower while the threat of severe thunderstorms diminishes toward midnight. Snowfall accumulations will be most significant in the higher elevations above 8,500 feet, but some light snow could be observed as low as 6,000 feet through Wednesday morning. A dangerous high wind scenario will then unfold on Wednesday as the Pacific low rapidly strengthens as it exits northeastern New Mexico. Strong to severe wind gusts will inundate much of the state throughout the day Wednesday with areas along and east of the central mountain chain observing the highest wind speeds of 60 to 75 mph. Winds will drop significantly on Thursday, but lingering precipitation could continue over the northern mountains and surrounding highlands of northeastern and central New Mexico. && .DISCUSSION... Overall, most of the qualitative and general sensible weather elements seem to have been well forecasted by preceding shifts, but this forecast package has plenty of challenges regarding quantitative precipitation amounts, timing of the lowering of snow, and of course the finer details of the severe threat in the east this evening. Pacific low has moved inland over southwestern AZ with mid- tropospheric pressure heights of about 548 decameters with a healthy plume of moisture visibly evident on water vapor and other satellite channels. The strongly diffluent flow ahead of the low is providing widespread and strong upward forcing amid the juicier and high PWAT airmass, and low level moisture and instability fields are catering to scattered to numerous showers and thunderstorms. Cells should continue turn more numerous and intense through the evening, with the strongest axis of lift likely preceding the main north-south baroclinic zone as it overtakes the central mountain chain and progresses toward the eastern plains. HRRR follows this thinking, and peering through some of the other noise, the local WRF and other short term, higher resolution guidance does too. Will keep the Winter Storm Warnings intact, however have high concerns that not much impact from snow accumulation will really hit parts of the northwest highlands (Cuba) and the far upper Rio Grande (Taos). Much of the eastern plains should be void of precipitation by Wednesday after daybreak with the focus remaining over the higher terrain of western and central NM, and more specifically the northern mountains. Snow levels will begin raising through the late morning and into the afternoon, creeping up from roughly 6,000 feet up to 7,000 to 8,000 feet. This could allow opportunity for early cancellations of some of the lower terrain zones in the Winter Storm Warning. Meanwhile the higher elevations above 8,000 will continue racking up the snow and blowing snow with the northern high peaks observing impressive totals over one to two feet. The bigger story for many zones will be the horrendous winds. Forecast models continue to show dramatic cyclogenesis (bombogenesis) as the upper low crosses the northeast corner of NM and enters western KS (about a 21 decameter drop at 500 mb over a span of 12 to 15 hours!). The surface low is also advertised to be record-breaking as it deepens to 969 mb per the GFS model for Wednesday afternoon. The flow at 700 mb is still advertised to be beyond stout with widespread 60 to 80 kt speeds across NM. Needless to say, many of the High Wind Watch zones will be upgraded to a warning, and will be doing that with this package. Blowing dust could be limited by recent precipitation, but blowing snow will cause further impacts in high terrain areas. Winds will gradually abate Wednesday night, but will be slower to do so northeastern NM where the back door cold front will have entered with a stiff surface pressure gradient due to the proximity of the KS surface low. Precipitation will also dwindle more Wednesday night into Thursday, except in the northern mountains and adjacent highlands. In the wake of the low exiting to the central plains, a subsequent short wav will keep perturbed flow over northern NM with orographics staying sufficiently strong to keep northern mountain snow persistent, occasionally seeping into adjacent highland areas. Otherwise winds will be notably less through the day on Thursday, but still windy in far northeastern plains. In the extended forecast, Friday still appears to be a relatively down day with just light flurries possible in the northern mountains while below normal temperatures continue area wide. The next Pacific low that is set to cross NM on Saturday still appears fairly anemic with regards to forcing and moisture, but the GFS does introduce isolated to scattered light precipitation over the state. Another ill-formed wave could move over the state by Monday of next week. 52 && .FIRE WEATHER... A broad upper level low pressure system centered south of Phoenix this afternoon will migrate northeastward across NM for the remainder of this afternoon and tonight with widespread wetting precipitation in the form of rain showers, thunderstorms and mountain snow. Some storms will be capable of producing strong wind gusts over 60 mph and large hail, especially east of the continental divide. A Pacific cold front will cross with a wind shift out of the west and southwest this afternoon and evening. The front will drop the snow level down to around 6500 feet, but accumulations will generally remain above 7000 feet with several inches above 8000 feet. Wednesday, winds will become very strong as a surface low bombs out in eastern CO with record breaking low pressure for that area. Meanwhile, the jet stream will cross southern NM as a secondary shortwave trough crosses the state from the northwest. West wind gusts from 50 to 60 mph will be common, with a broad area of damaging wind gusts around 75 mph expected across much of the east central and southeast plains. Winds will weaken gradually with sunset, while remaining hazardous through the evening, and even into Thursday behind a back door cold front across the northeast corner of NM. Accumulating snow is forecast to linger through Wednesday evening in the northern and western mountains, where the 24 hour snow accumulations (tonight through Wednesday night) should reach several inches to near 1 foot, except over 18 inches in the northern mountains above 8500 feet. The chance of precipitation will linger over parts of the state Thursday through the end of the week as three additional shortwave troughs cross in succession. None of them look very strong, but portions of the mountains could receive wetting accumulations. Areas of poor ventilation will also be expected. 44 && .ABQ WATCHES/WARNINGS/ADVISORIES... High Wind Warning from 3 AM Wednesday to midnight MDT Wednesday night for the following zones... NMZ521>524-526-539. High Wind Warning from 6 AM to 9 PM MDT Wednesday for the following zones... NMZ506-507-518>520-525-528-529-531>538-540. High Wind Warning from 9 AM Wednesday to 6 AM MDT Thursday for the following zones... NMZ527-530. Winter Storm Warning until midnight MDT Wednesday night for the following zones... NMZ502>504-508-511. Wind Advisory from noon to 6 PM MDT Wednesday for the following zones... NMZ501-505-517. Winter Storm Warning until midnight MDT Wednesday night for the following zones... NMZ510-513-514. Winter Storm Warning from midnight tonight to midnight MDT Wednesday night for the following zones... NMZ512-515-516. && $$ 34
Area Forecast Discussion
National Weather Service Denver/Boulder CO
930 PM MDT Tue Mar 12 2019 .UPDATE... Issued at 930 PM MDT Tue Mar 12 2019 A little more detail regarding precipitation rates, there are very large hourly rates expected, and this is back up in the latest HRRR runs. These are not typically seen here with hourly rates of 0.20 to 0.25 inch per hour liquid equivalent (while snowing). That may lead to a very quick degradation of travel conditions from wet roads to slush and snow, and whiteout conditions! UPDATE Issued at 911 PM MDT Tue Mar 12 2019 ...POWERFUL WINTER STORM WINDING UP THIS EVENING... ...BLIZZARD STILL ON TRACK FOR MUCH OF NORTHEAST COLORADO WEDNESDAY INTO WEDNESDAY NIGHT... The latest satellite imagery shows the powerful winter storm moving northeast across Arizona. Transverse banding on the IR imagery is showing just how strong this system is, and is a good indicator of strength and heavy precipitation. Latest RAP QG analysis shows deep pressure falls and 40 decameter/12 hour falls, and surface pressure drops of 7-8 mb/3 hours. Very strong cyclogenesis is underway and will continue through Wednesday. It is being fueled by very strong thermal advection, a coupled jet basically creating a vacuum, and the strong vorticity advection with the approaching upper level low. Scattered showers and even a couple thunderstorms were already developing well ahead of the best lift. These will become more numerous overnight. With regard to the forecast details, if anything there has been a slight westward trend to the heaviest precipitation over the last 12 to 18 hours. This puts the I-25 Corridor under greater risk of heavier snowfall. However, there is still the downslope component to offset some of this threat, so we`ll keep all the highlights the same for now, with Blizzard Warnings anywhere east of I-25. That could change with an ever slight westward/upslope shift yet. Just a matter of miles could make all the difference. The current Blizzard Warning includes the eastern half of metro Denver and DIA, and the Palmer Divide/Douglas County, and all points to the east. The slight westward shift could lead to a little less snow total over the far northeastern corner of the state. Whatever the snow amounts will be, the big concern is the amount of wind in combination with the snow. 24 hour pressure falls reach bomb status by 21Z tomorrow, just an indicator of the intensity of this surface low pressure system. Checking the NAEFS 30 year return intervals on 700 mb wind speeds (70-75knots) we are near 30 year return intervals (something that occurs once every 30 years). Thus, we`re looking at an extreme event, with gusts to 60-75 mph expected. Forecast soundings would also back those gusts up, with any mixing from snowfall bringing that momentum transfer to the ground. ALL IN ALL, A VERY DANGEROUS BLIZZARD is shaping up for areas just east of I-25 Wednesday afternoon into Wednesday evening. We`ll continue to closely monitor the potential west of I-25. Don`t travel if you don`t have to! Travel conditions may change very rapidly Wednesday morning into Wednesday afternoon, with road closures, power outages, and zero visibility in these powerful winds. Finally, we are still a little concerned with temperatures and local downslope effects, but those details are extremely hard to work out at this point given the heavy precipitation rates and significant cooling of the column through melting. Some models like the NAM would argue for a 6-7 AM changeover along the I-25 Corridor, but most would suggest closer to 9-11 AM which agrees with the present forecast. This changeover will need to be watched carefully as just an hour or two difference in the heavy rates could bring 3-4 inches more, or 3-4 inches less snow to the going forecast. && .SHORT TERM...(This evening through Wednesday) Issued at 339 PM MDT Tue Mar 12 2019 For tonight, airmass will be unstable ahead of the approaching storm system. Lapse rates from 300-600mb will be 7-9 C/km. This combined with the lift from the approaching storm is expected to produce scattered showers and isolated thunderstorms from late this afternoon through this evening. Precipitation turns into a more widespread rain/mountain snow event late tonight as synoptic lift takes hold. It will remain warm through the night with snowfall limited to the higher foothills and mountains. Rain will continue into Wednesday morning. As the surface low deepens over southeast Colorado, cold air gets pulled into northern Colorado. This cold air rapidly spreads south and east changing the rain to snow. By noon, precipitation should be all snow expect for far eastern Colorado. The blizzard is still on track for northeast Colorado on Wednesday. Latest trends with the models have been slightly stronger with the surface low, slightly slower, and a little west. This will be a very strong and quick hitting storm with blizzard conditions lasting 4-8 hours from late Wednesday morning into Wednesday evening. For the Denver area, conditions quickly deteriorate late morning, around 10am when rain changes to snow. Most of the models have been showing lower snowfall amounts west of I-25 due to north-northwest downslope winds. Kept snowfall amounts a little higher than these models because not all the models show this. Latest 12Z ECMWF shows higher amounts against the foothills and north of I-70, if this pans out, will likely need to upgrade to a Blizzard Warning due to the longer period of near zero visibilities. Lowest surface pressure from the RAP and ECMWF models show the low bottoming out at 973mb over northwest Kansas. This low of surface pressure is in the range of category two hurricanes. Strong winds are nearly certain given how strong the low will be. Wind gusts of 60 to 75 mph are expected over eastern Colorado. Localized higher gusts will be possible. Strong winds will also be possible west of I- 25, which it is usually sheltered from the strong north winds. Here gusts of 40 to 60 mph will be possible. Given these strong winds and expected snowfall, widespread near zero visibilities are expected over northeast Colorado late Wednesday morning through Wednesday evening. Snowfall amounts are expected to greatly vary due to upslope/downslope effects. For areas east of I-25 where the best lift from the low will be, expect 5 to 10 inches of snow with locally higher amounts east of the Denver area. West of I-25, snowfall amounts are forecasted to be 3-7 inches. Lower amounts are due to the downslope north-northwest winds. Many of the mountains will do well with this storm with 8 to 16 inches expected. Airmass will be unstable over northeast Colorado Wednesday morning and early afternoon with surface based CAPE from the RAP model up to 500 J/kg, so thunder snow will be possible across the area. This will help with higher snowfall amounts as well. Travel will become very difficult to impossible along and east of Interstate 25 late Wednesday morning and Wednesday afternoon. This will be due to near zero visibility and snow accumulating on the roadways. When rain changes to snow, the snow will be wet and likely stick to power lines and tree branches. Broken branches and power lines will be possible because of the strong winds and weighted down branches and power lines. .LONG TERM...(Wednesday night through Tuesday) Issued at 339 PM MDT Tue Mar 12 2019 After all of the action during the day tomorrow, Wednesday evening will begin the process of winding down. Gusty winds should still be in force early in the evening along with some lingering snow. Snow intensities will be decreasing through the evening, and only the eastern plains should be seeing any snowfall after midnight. As the surface low moves off and pressure gradients relax after midnight, winds will begin to taper off. The rest of the week will see northwesterly flow aloft continue over the state with scattered snow showers in the mountains through Thursday night. Upper level ridging will dominate the weather over the weekend with dry weather across the forecast area. Temperatures will be gradually moderating through the beginning of next week, but will be remaining cooler than normal. Next Tuesday may see an upper trough rotate over the state from the northwest. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 911 PM MDT Tue Mar 12 2019 ...SIGNIFICANT AVIATION IMPACTS FROM WEDNESDAY`S BLIZZARD... Scattered showers developing as expected, and they will become more numerous through the overnight hours. Rain will become widespread and change to a heavy, wet, wind driven snow most likely in the 15Z-17Z time frame Wednesday. Heavy snow, strong winds, and blowing snow will continue at KDEN and the Denver area 17Z-22Z Wednesday with extended period of visibilities less than a quarter mile are expected, and this may last through about 02Z depending on how much snow falls. Extremely strong winds expected to develop with the onset of snow, with 30-35 knots sustained winds with gusts to 50-60 knots expected during the heavy snow. Considerable blowing snow. conditions slowly improve with less snow and a slow decrease in winds 02Z-06Z Thursday. && .BOU WATCHES/WARNINGS/ADVISORIES... Blizzard Warning from noon Wednesday to noon MDT Thursday for COZ042-044>046-048>051. Winter Storm Warning until 6 AM MDT Thursday for COZ035. Winter Storm Warning until noon MDT Thursday for COZ033-034. Winter Storm Warning from 10 AM Wednesday to midnight MDT Wednesday night for COZ036-038-039. Blizzard Warning from 10 AM Wednesday to midnight MDT Wednesday night for COZ040-041-043. High Wind Warning from noon Wednesday to 6 AM MDT Thursday for COZ047. && $$ UPDATE...Barjenbruch SHORT TERM...Meier LONG TERM...Dankers AVIATION...Barjenbruch
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1157 PM EDT Tue Mar 12 2019 .AVIATION... High pressure ridge will maintain VFR conditions throughout the overnight. Ascent ahead of vorticity max tracking through the northern Great Lakes tonight and very strong warm advection along return flow surge will support rapid expansion of low cloud and precipitation into Southeast Michigan after 10Z this morning. Greatest synoptic scale forcing will pass to the north of the area. With a veered wind profile over Southeast Michigan, expecting the area to remain in a anticyclonic flow trajectories. This will cause more of a glancing shot from the precipitation. Maintained the inherited VFR category of light rain during the late morning/early afternoon. Shortwave ridge amplification during the late afternoon will support a loss of cloud deck ahead of the approaching storm system. For DTW...High pressure and antecedent low level dry air will inhibit rain showers until 16Z. Model data trends have been moderate in the delay of precipitation onset. A later timing of the precipitation further limits any potential for freezing rain Wednesday morning. .DTW THRESHOLD PROBABILITIES... * High in precipitation fall as all rain Wed morning. * Moderate in ceilings below 5000 ft Wednesday morning and afternoon. && .PREV DISCUSSION... Issued at 326 PM EDT Tue Mar 12 2019 DISCUSSION... Area of surface high pressure centered over Ohio today has lead to a sunny day with dry air extending from the surface to 550mb. PWAT on the morning KDTX sounding was only 0.16 inches and dewpoints at the surface are around 20F this afternoon. Southwesterly winds around the high with full mid March sun has allowed temps to rise into the low 40s. Conditions begin to change this evening with mid/high clouds streaming into the area down stream of the storm system that will affect the region through the mid week period. A strong northern stream jet diving down the west coast will phase with a cutoff low over southern California tonight into Wednesday causing rapid cyclogenesis in the lee of the Rockies over the Central Plains. This surface low will quickly deepen to 980mb or more by late Wednesday before then weakening and occluding as it lifts northeastward through the Midwest late Thursday and Thursday night. This system will present a few opportunities for showers and thunderstorms between tonight and Friday morning as waves of deeper moisture and forcing are released out of the trough. First chance of precipitation will come late tonight as a lead shortwave rounds the top of the ridge through the northern Great Lakes. Aided by strengthening low level jet and broad isentropic ascent showers will spread across the northern part of the state tonight. Question is how far south into lower MI do the showers expand? Dry low levels and lack of jet support should keep most of the area dry tonight, an outcome now supported by the NAM, NAM3KM, ARW, NMM, GFS, and EURO. RAP and HRRR still holding onto a lead batch of showers with the leading edge of the theta e advection tonight. Lowered pops across the south but held onto pops across Mid MI prior to 12Z Thursday. The ridge amplifies early Wednesday as the system draws nearer so a good portion of the east and south could remain dry into the afternoon. The ridge axis then folds through lower MI later in the day allowing deeper moisture to spread over the area for the overnight. A band of showers will likely lift through ahead of the occluded front with most of the activity still elevated with the surface fronts still lagging to the southwest. Strong low level jet exceeding 50 knots will lift into southern MI during this time with diffluence aloft and upper level jet pushing 100 knots. Elevated showers with embedded thunderstorms will be possible through the Thursday morning hours. Could see a lull for a few hours in the wake of the morning activity as the low level warm sector slides through SE MI. With strong low level jet in place (50 knots down to around 4kft possibly) and warm mixed layer lifting through the area, could see some strong southwesterly winds in the afternoon Thursday. Though models have been supporting higher gusts Thursday it should be noted that local probability graphics show a decreasing trend in likelihood of seeing wind gusts in excess of 40 mph. A several hour period with gusts of 30-40 mph seems reasonable at this point. Caveat to that will be if any showers can persist or afternoon redevelopment of showers mixes down the stronger winds. Strong southwesterly warm air advection will help temperatures climb into the 60s for most locations Thursday steepening low level lapse rates. CAPE values of a few hundred j/kg may aide in the development a broken line of storms moving across lower MI. Strong winds will be the primary threat with any storms or stronger showers as the low level jet will still be strong. Dry slot surging into the area overnight will help shut off the showers for most of the area overnight. The low pressure system will continue departing to the northeast Friday with lingering breezy conditions through much of the day. Trailing northern stream shortwave energy will dive southeast behind the departing surface low from the upper Midwest and promote at least widely scattered shower activity during peak daytime heating. Temperatures warming into the 40s will result in any precipitation falling as rain. Cool and relatively dry northwest flow will then setup across the Great Lakes for the weekend as temperatures settle back below average into the 30s. Weakening shortwave energy diving southeast through the northwest flow will attempt to squeeze out widely scattered rain/snow showers late Sunday before broad and dry high pressure sets up across the region to start next week. As weak return flow sets up around the high early next week, temperatures will begin to slowly moderate back towards normal for mid-March (low/mid 40s). MARINE... The departure of high pressure to the east tonight and the slow approach of a low pressure system will establish a prolonged period of south-southeast winds across the lakes Wednesday into Thursday night. Strong low level warm air transport across the icy lakes will support strong stability and will thus keep wind speeds largely in check. The strength of the gradient alone may however support a few gusts up to 25 knots on Lake Huron Thursday. The passage of the sfc low to the northeast of the region will drive a cold front across the lakes on Friday and will result in a veering of the winds to the west-northwest. Post frontal cold air advection may support a few gusts up toward 30 knots Friday. HYDROLOGY... The approach of a slow moving low pressure system on Thursday will provide a good chance for at least a couple intervals of showers with a few thunderstorms late Wednesday night into Thursday night. Total forecast rainfall amounts are expected to range from a quarter inch to three quarters of an inch. Mild air will be driven into the area Wed into Thursday with this system. This will result in a melting of the snowpack across Central Lower Mi, impacting the Tittabawassee River basin. So despite relatively low rainfall totals, the Tittabawassee (and in thurn Saginaw) Rivers are forecast to approach flood stage this weekend. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. Lake Huron...NONE. Lake St Clair...NONE. Michigan waters of Lake Erie...NONE. && $$ AVIATION.....CB DISCUSSION...DRK/IRL MARINE.......SC HYDROLOGY....SC You can obtain your latest National Weather Service forecasts online at
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1042 PM CDT Tue Mar 12 2019 .UPDATE... Scattered showers have recently developed along and east of Interstate 35. These should remain just showers as there is a strong cap beginning at around 800 mb which should suppress any further vertical development into thunderstorms. Scattered showers should continue through the overnight period for the I-35 corridor region. Southeasterly winds continue to ramp up out ahead of this strong system, with sustained winds as high as 20 to 25 mph and gusts up to 30 to 35 mph. This should also continue through the overnight period out ahead of the eventual line of storms. Speaking of which, the line of thunderstorms currently reside (as of 10:40 pm Tuesday) from near Lubbock south into the Big Bend. A few discrete cells are tying to form out ahead of this line, but for now remain north of Val Verde County. This line will continue to move east overnight and into the morning hours of Wednesday. The best chance for severe weather will be across the southern Edwards Plateau (Val Verde and Edwards Counties) in which all severe weather hazards will be in play. Accordingly, a Tornado Watch has recently been issued for Val Verde County until 5 AM Wednesday morning. Subsequent convective watches (most likely of the Severe Thunderstorm variety) may be issued further east later tonight as the storms progress eastward, in which strong winds will become the primary hazard. The line of storms should weaken as they progress east due to decreasing instability and a more stable boundary layer. There is still some disagreement on the timing of the line. The HRRR and Texas Tech WRF bring the line through slower, reaching the I-35 corridor in the 7 to 9 am time frame. The NAM Nest is quicker, bringing it through in the 5 to 7 am time frame. More than likely, the line of storms will be sub severe by the time it reaches Austin and San Antonio. However, there will be plenty of low level and deep layer wind shear, so if the line of storms can generate a solid cold pool and can manage to sustain itself well enough as it reaches the I-35 corridor, severe weather will be in play, primarily in the form of some isolated strong wind gusts up to 60 mph. The line of storms will continue to weaken as they track east of I-35. They should be completely out of the region by late morning/early afternoon, in which skies will clear and gusty west/southwesterly winds will take hold. && .PREV DISCUSSION... /ISSUED 630 PM CDT Tue Mar 12 2019/ AVIATION... All sites VFR with gusty southeast winds. Gusts as high 34kts has been observed at KAUS, though will maintain 22-25kts in the TAF. A line of strong storms are expected to move through the area overnight and into the morning along a Pacific front. Timing for storms to reach KDRT around 08Z and for terminals along I-35, 11Z. PREV DISCUSSION... /ISSUED 359 PM CDT Tue Mar 12 2019/ SHORT TERM (Tonight through Wednesday Night)... Upper low over Baja region will be moving east and then northeast across the southern plains over the next 24 hours. Water vapor imagery shows strong diffluence ahead of the system and associated lift is already occurring over northern Mexico. As this system approaches, our cwa has transitioned to a warm sector, bringing the needed instability to support convection later tonight. A foggy start of the day has improved drastically as the warm front pushed north through all the cwa and this unstable and breezy atmosphere will remain in place overnight. Will continue small pop for the late afternoon and evening for showers, and maybe isolated TS out west. A few of the HRRR runs are starting to show some pre- squall line sh/ts come across the Rio Grande near DRT in the late evening hours. Will have to watch for severe threat with this activity before the forecast squall line associated with the pacific front/dry line pushes into the CWA after midnight. Looks like the far western Edwards Plateau will be under the threat of strong/severe storms between midnight to 3AM...Hill Country 3-6 AM...pushing into the I-35 corridor around morning rush hour...6-10 AM, and 8 AM-noon east of I-35, and along I-10. Once the line passes AUS/SAT...mid the late morning clearing with the POP ending quickly west to east as large dry slot moves in from the SW and wraps into a surface low over the TX/OK panhandles. Severe parameters are best out west, and with the storms coming into AUS/SAT region around dawn which is historically the most stable time of the day, widespread severe weather is not expected over our eastern areas. Lower humidities behind this system and some gusty west winds will bring some near critical fire conditions to the far west and Rio Grande Plains both Wed and Thu. With the downsloping west winds on Wednesday, temps will still warn into the mid 70s to lower 80s. Mainly 50s Wed night. LONG TERM (Thursday through Tuesday)... As we get into Thursday, the upper low and surface low will be moving east into the upper MS valley with cool air filtering down into Texas on the back side. Will see an associated cool down with respect to day and night temps...highs mainly in the 60s and lows in the 40s. A upper zonal flow will keep pop out of the extended forecast. Long range models do show an upper low coming into the southern Rockies but with surface ridging still in place, dont expect enough moisture return to lead to any significant pop...just an increase in clouds. A slow warmup may be in store early next week but the models are keeping a stubborn surface ridge axis over the state not allowing for deeper southerly flow until beyond the 7 day forecast period. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 61 78 51 71 43 / 80 70 10 0 0 Austin Bergstrom Intl Airport 62 78 51 71 43 / 70 70 10 0 0 New Braunfels Muni Airport 62 79 52 72 43 / 70 60 10 0 0 Burnet Muni Airport 55 75 47 65 40 / 90 50 0 0 0 Del Rio Intl Airport 57 80 51 73 46 / 70 - 0 0 0 Georgetown Muni Airport 59 77 49 67 41 / 80 80 10 0 0 Hondo Muni Airport 61 80 51 75 45 / 80 10 10 0 0 San Marcos Muni Airport 62 79 51 72 43 / 70 70 10 0 0 La Grange - Fayette Regional 66 77 55 72 44 / 50 70 20 10 0 San Antonio Intl Airport 61 79 53 73 44 / 80 50 10 0 0 Stinson Muni Airport 63 81 54 75 46 / 70 40 10 0 0 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Aviation...YB Short-Term/Long-Term...BMW
Area Forecast Discussion
National Weather Service Grand Junction CO
549 PM MDT Tue Mar 12 2019 .SHORT TERM...(Tonight through Wednesday night) Issued at 100 PM MDT Tue Mar 12 2019 A major early spring storm continues to affect the Four Corners region this Tuesday afternoon. Over the next several hours, the primary focus will continue to be on southwest Colorado and far southeast Utah with regard to the thunderstorm and convective threats. The past several runs of the HRRR continue to show remarkable consistency in the development of strong to possibly severe convection over far northeast New Mexico, which eventually moves north into southern Colorado. SPC mesoanalysis as of 18z this afternoon indicates over 500 j/kg of SBCAPE, around 45 knots of bulk shear, and SRH values in the 50-100 range. While not particularly notable in the eastern two thirds of the nation, these values are cause for alarm west of the Continental divide above 5000 feet elevation....with small hail, gusty winds, and heavy rain all realistic threats. Short term CAM guidance indicates any thunderstorms that do develop will move rapidly northeast into the Cortez-Durango-Pagosa Springs corridor between 21z and 0z this afternoon. Of particular note will be the heavy rain threat - much of this region currently has a deep snowpack and decaying convective downpours could easily result in localized flooding. This will be especially true in the foothills of the San Juan mountains, where large rockfalls and debris slides have already occurred overnight into this morning. After 0z tonight, the convective threat diminishes rapidly. Focus will then turn to the potent shortwave trough diving in through the Great Basin, behind the main area of low pressure moving east across New Mexico. 500mb vorticity progs from 0z tonight through tomorrow afternoon depict a spectacular phasing of these two systems, resulting in explosive cyclogenesis over the eastern high plains. Closer to home, impactful weather will include moderate to heavy snow above 9000 feet in all mountain ranges, with around 0.5 inches of rain falling in the valleys. Cold air will eventually filter south and eastward behind this system in the form of a 700mb thermal boundary, which is expected to lower snow levels to the valley floors along the US 40 corridor by early- morning on Wednesday. In this forecast package, the main changes have been to expand the winter weather headlines across all of the northwestern Colorado valley zones, as well as the introduction of an advisory for the US 50 corridor near Cerro Summit. While surface temperatures will remain relatively mild (low 30s) in the lowest elevations, moderate snow rates and plenty of cold air aloft will result in accumulations of over 3 inches in these locations. Elsewhere, much of the previous forecast package was retained: snow totals in the higher terrain have remained consistent in today`s model runs and no changes were needed. By Wednesday night, the powerful area of low pressure over the central high plains will head eastward. Northerly flow on the back side of this system will keep snow going on all favored northern facing slopes throughout the central and northern mountain ranges. 700mb temperatures by this time will run in the -12 to -14 range, resulting in a much lower density snowfall than at the onset of this storm. .LONG TERM...(Wednesday night through Monday) Issued at 329 AM MDT Tue Mar 12 2019 Classic mid level cyclone will be pounding the Plains with a fully stacked system and surface low moving toward the occluded stage by Wednesday evening. This system is so tightly wound by this time that it appears the trowal will be East of the divide and really feeding a good frontal band across the High Plains to the Dakotas where blizzard conditions are looking nasty. What we will have on our side of the hills is strong cold advection in the lower and mid levels with PV advection aloft. The deep northerly flow will be favorable for orographics on north facing slopes and initially when residual moisture is present...a potential Uncompahgre Gorge event late Wednesday into early Thursday. Showers are likely to continue through the day Thursday as instability will be easily released. Both the GFS and NAM hint at weak mid level low also developing over the SE San Juan Range as the last part of the jet moves through Thursday evening. This last push leads to upslope once again into this region and could easily keep snow going over CPW through sunrise on Friday. We look to finally get a more prolonged break in the precipitation so folks can dig out...literally. Below normal temperatures will hang around in the wake of this system through Saturday. We then get ridging followed by WAA and this should bring us back up to near normal for mid March. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 544 PM MDT Tue Mar 12 2019 Limited vsby and low cigs across the southern TAF airports will become widespread through the evening hours. Most TAF sites will see some level of impact by 13/06Z as rain and snow spread across the region. These impacts will persist through at least Wednesday evening as this storm wraps up on the East side of the divide. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...Winter Weather Advisory until 6 AM MDT Thursday for COZ004-012. Winter Storm Warning until 6 AM MDT Thursday for COZ003-009-010- 013-017. Winter Storm Warning until 6 AM MDT Thursday for COZ018. Winter Weather Advisory from midnight tonight to midnight MDT Wednesday night for COZ001-002-005-014. Winter Storm Warning until midnight MDT Wednesday night for COZ019. UT...Winter Weather Advisory until 6 AM MDT Thursday for UTZ023-025. Winter Storm Warning until 6 AM MDT Thursday for UTZ028. && $$ SHORT TERM...MAC LONG TERM...15 AVIATION...TGJT
Area Forecast Discussion
National Weather Service Lincoln IL
850 PM CDT Tue Mar 12 2019 .UPDATE... Issued at 850 PM CDT Tue Mar 12 2019 Despite increasing southeasterly flow on the back side of departing high pressure, the atmosphere has been slow to moisten this evening. The 00z KILX upper air sounding showed ample dry air below 700mb, which has thus far prevented much in the way of measurable precip across central Illinois. Have seen a few reports of sprinkles reaching the ground along/west of I-55, but the most widespread precip remains well to the SW across Missouri. HRRR quickly caught on to this trend and has been consistently showing a delayed onset to the rain over the past several runs. As a result, updated the forecast earlier this evening to carry just chance PoPs across the west until around midnight when the Missouri precip spreads into the area from the southwest. && .SHORT TERM...(This evening through Wednesday) ISSUED AT 312 PM CDT Tue Mar 12 2019 Showers will be possible overnight as warm air advection continues ahead of a strong low pressure system deepening into the central Plains. With cloudy conditions and steady south to southeast winds 10 to 15 mph temperatures will only fall to the mid 40s. Warm advection and disturbances embedded in strong southwesterly flow aloft will continue into Wednesday bringing periods of precipitation possible, as well as a few thunderstorms by Wednesday afternoon, followed by the main frontal system late afternoon Wednesday into Wednesday evening. Highs should reach the 60s, especially south of I-72 as the warm sector reaches this area. Quite breezy south to southeast winds will develop, over 20 mph with gusts over 30 mph. Showers and thunderstorms should become most plentiful Wednesday evening. .LONG TERM...(Wednesday night through Tuesday) ISSUED AT 312 PM CDT Tue Mar 12 2019 Several hundred J/kg of CAPE look to develop early in the day Thursday in a narrow warm sector, which will produce a threat for severe thunderstorms when combined with strong shear. SPC has a marginal risk of severe thunderstorms, mainly for high wind threat, Decatur to Bloomington eastward. Combined with south to southwest winds 30 mph and gust potential 50-60 mph southeast of the Illinois River, any storms that form should have little trouble producing severe wind gusts. Temperatures will be quite mild Thursday, with highs reaching 60 in Galesburg to 71 in Lawrenceville, before cold advection arrives late in the day Thursday. Temperatures will drop back below normal Friday through the weekend. Mainly dry conditions can be expected this period. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 641 PM CDT Tue Mar 12 2019 Showers are trying to spread into central Illinois from the west early this evening: however, a dry boundary layer is slowing the onset of the rain. HRRR continues to delay the rain, with widespread showers likely holding of until after midnight. In the meantime, will feature VCSH at all terminals except KDEC/KCMI through the evening. Have lowered ceilings to MVFR and introduced predominant showers at KPIA by 05z...then further east at KCMI by around 11z. Once the overnight/early morning showers come to an end, the main aviation forecast concern will then shift to the increasing southerly winds. Forecast soundings and numeric guidance both suggest gusts reaching 25-30kt from around midday through the afternoon. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Barnes SHORT TERM...37 LONG TERM...37 AVIATION...Barnes
Area Forecast Discussion
National Weather Service Blacksburg VA
856 PM EDT Tue Mar 12 2019 .SYNOPSIS... High pressure will remain overhead through Wednesday. After this high heads offshore during Wednesday night into Thursday, a cold front should bring the next chance of rain for Thursday night and Friday. High pressure will return later this weekend. && .NEAR TERM /THROUGH WEDNESDAY/... As of 856 PM EDT Tuesday... Little changes were made the forecast tonight, with the biggest forecast challenges cloud cover and temps. The 00Z RNK sounding shows the upper levels of the atmosphere, around and above 300 mb, have moistened since 12Z. Also, as an upper level trof lifts and the mid to upper flow becomes more westerly, an increase in cirrus clouds should enter the forecast area, primarily across the mountains, as the 23Z HRRR depicts. However, the a bigger influence on low temperatures tonight may be the winds, which will increase across the higher elevations in the west as the axis of sfc high pressure shifts east of our forecast area. As a result, bumped up low temps at BLF and other higher mountain elevation sites. At 00Z (8 PM EDT), Roanoke is running a few degrees warmer than forecast, but once valley winds diminish here, temps should fall to near previously forecast values. Look for more clouds to emerge from the west before sunrise and persist into Wednesday as depicted in the MET MOS guidance. Light south winds should offer some warm air advection during the day. As a result, highs for Wednesday were nudged slightly upward but kept well below MAV MOS guidance due to it not accounting for the cloud cover and consequently being considerably warmer. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... As of 200 PM EDT Tuesday... The most active weather through the next seven days will occuring during this portion of the forecast. Temperatures will continue to trend higher through Thursday in advance of the approach of a strong cold front. Moisture levels will be ramping up during the day in advance of this feature on increasing, deep southwest flow. While the entire area will be mostly cloudy to cloudy because of this feature, those locations along and near the crest of the Blue Ridge will experience isolated to scattered showers thanks to upslope conditions maximizing in this area. This is expected to start Thursday morning, and potentially as early as late Wednesday night across the Northern Mountains of North Carolina. Parts of southeast West Virginia and neighboring counties of southwest Virginia may see isolated to scattered showers Thursday afternoon as the cold front at its associated dynamics draw closer to the forecast area. Low temperatures Wednesday night will range from the low 40s to the mid 40s for most of the region. Far southwest Virginia and parts of the North Carolina Piedmont will be closer to the upper 40s. Highs on Thursday will reach the mid to upper 60s for most of the area. The higher elevations will be closer to the upper 50s to around 60 degrees. Thursday night the cold front is expected move even closer to the area, being on our western doorstep by daybreak Friday. Expect rain showers to progressive increase through the night with very good coverage for most locations by daybreak Friday. The one exception may be the far southeastern parts of the region. Here coverage may still only be scattered early Friday morning. Thursday night, lows will range from the the lower 50s to the mid 50s across the mountains with mid to upper 60s over the Piedmont. Friday, highs will range from the upper 50s to lower 60s over the mountains to the upper 60s to around 70 over the Piedmont. On Friday morning, the cold front and its associated showers are expected to progress across the region from west to east. The associated 850mb front is expected to lag about six hours behind the surface front. It will be this elevated feature that we will want to see clear the region before the associated precipitation ends, and a turn towards a colder northwest flow begins to invade our region. Timing of this feature will coincide best with the peak heating of the day across the eastern half of the region. We will still be offering a forecast with a slight chance of thunderstorms until the 850mb front is east of the area. Friday, highs will range from the upper 50s to lower 60s over the mountains to the upper 60s to around 70 over the Piedmont. By Friday evening, precipitation immediately associated with the cold frontal passage will be east of the region. However, as northwest winds increase, look for temperatures to fall quickly. Upslope flow will switch to western parts of the area where isolated to scattered rain/snow showers are expected across parts of southeast West Virginia and neighboring counties of southwest Virginia. As the night progresses, these will decrease in number. Low temperatures Friday night will range from the low to mid 30s across the mountains to around 40 to the lower 40s across the Piedmont. Confidence in the above portion of the forecast is high. && .LONG TERM /SATURDAY THROUGH TUESDAY/... As of 230 PM EDT Tuesday... Some lingering rain/snow showers will be possible across western Greenbrier County, WV Saturday morning, but these aren`t expected to last much into Saturday afternoon as drier air progresses into the region. Dry conditions will continue into Sunday as surface high pressure moves overhead. A reinforcing shot of colder air is expected on Monday with the passage of a shortwave trough moving through the mid-Atlantic and New England regions. This feature may bring a few more isolated rain/snow showers into southeast West Virginia and neighboring southwest Virginia. Low temperatures during this portion of the forecast will range from the upper 20s to lower 30s across the mountains most night with low to mid 30s most nights across the Piedmont. High temperatures will generally range from the upper 40s to lower 50s across the mountains with low to mid 50s across the Piedmont. Confidence in the above portion of the forecast is moderate. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... As of 120 PM EDT Tuesday... VFR conditions will prevail over our forecast area through Wednesday as high pressure dominates our weather. Winds will continue to diminish tonight, then become southeast during the day Wednesday with most locations at or below 10 knots. High cirrus clouds will increase on Wednesday, but confidence remains high that VFR conditions will remain in place at all TAF sites through at least Wednesday. EXTENDED AVIATION DISCUSSION... High pressure should drift offshore during Wednesday night into Thursday, but VFR conditions should remain throughout that time. By Thursday night, confidence is increasing that a cold front will bring the next chance of rain along with MVFR ceilings and visibilities into Friday. After the frontal passage, scattered rain and snow showers could be possible in the western mountains during Friday night into Saturday. VFR conditions should resume late Saturday into Sunday as high pressure returns. && .EQUIPMENT... As of 130 AM EDT Monday... KFCX Doppler radar in Floyd county will be down for maintenance March 11-15, 2019. The WSR-88D Radar operated by NOAA National weather Service in Blacksburg Virginia will be out of service through approximately March 15 for the refurbishment of the transmitter. Although the form, fit and function of the transmitter will remain the same, old breakers and cables original to the radar will be replaced with modern fuses and new cables. This will keep the 20- year- old radar operating smoothly for another 20 years. This transmitter update is the second major project of the NEXRAD Service Life Extension Program, a series of upgrades and replacements that will keep our nation`s radars viable into the 2030s. NOAA National Weather Service, the United States Air Force, and the Federal Aviation Administration are investing $150 million in the seven year program. The first project was the installation of the new signal processor. The two remaining projects are the refurbishing of the pedestal and equipment shelters. The Service Life Extension Program will be completed in 2022. During the downtime, adjacent radars include KRLX, KLWX, KGSP, KMRX, KRAX and KAKQ. For direct access to any of these surrounding radar sites, go to the following web page: https:/ && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...PW NEAR TERM...PH/PW SHORT TERM...DS LONG TERM...DS AVIATION...PH/PW EQUIPMENT...KK
Area Forecast Discussion
National Weather Service San Diego CA
159 PM PDT Tue Mar 12 2019 .SYNOPSIS... An upper level trough will move southeast across Nevada tonight, increasing west winds along the desert slopes and the high desert. A few showers will develop tonight, favoring the coastal mountain slopes of Riverside and San Diego County. Dry and warmer conditions will prevail Wednesday through the weekend with periodic gusty northeast winds along the coastal mountain slopes and below canyons and passes. Dry and warm conditions will continue into at least early next week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... The storm system that brought rain and significant mountain snow to Southern California has departed the area into Arizona this afternoon. This system will continue to move away from the region while another trough races southeast across Nevada overnight. West winds will increase ahead of this feature with strong wind gusts to 55 mph, isolated to 65 mph, along the desert mountain slopes overnight. Gusts of 30-40 mph are expected over the high desert, possibly to 50 mph east of Apple Valley. A few light showers look to re-develop tonight and favoring San Diego County, but not so much near the coast, more so well inland towards the coastal mountain slopes and extending to the Riverside County mountain west facing slopes. WRF and HRRR both show all the rainfall occurring there. Still, can`t rule out isolated showers along the coast. No rain is expected across our northwestern areas, from Orange County through the NW Inland Empire through the San Gabriels as well as across the deserts. The most rain will fall along the coastal mountain slopes of the San Diego County mountains extending north to the Riverside County coastal slopes. Amounts there will average near 0.25 inches, but some locales could receive near a half an inch. The snow level will be at around 6000 feet with max amounts to 1 inch at Mt. San Jacinto. West winds will crank up along the desert slopes and across the high desert this evening through early Wednesday morning with gusts to 55 mph, isolated to 65 mph, forecast at rural desert slope locales. A Wind Advisory is in effect for these areas this evening through early Wednesday morning. Wednesday through Friday will see a moderation in temps under a mostly clear sky. However, warming will be tempered on Friday due to a dry shortwave diving southeast and across the area. This basically acts to keep temps between Thu-Fri status quo. Temperatures over the inland valleys will be quite cold Thursday and Friday morning. A clear sky, light winds and dry air should provide for good radiational cooling (away from the northeast wind corridors where the atmosphere will stay mixed). This will bring temps into the 30s with frost potential in and around areas extending from Corona to Lake Elsinore to Valley Center to Ramona. Lowered temps across these areas using a GFS- NAM-EC MOS blend. Global models show heights rising substantially this weekend. This will lead to further warming Sat-Sun and warmth will continue through Tuesday under abundant sunshine. The next chance of precipitation could arrive during the middle part of next week. && .AVIATION... 122000Z...Coast/Valleys...SCT-BKN clouds with bases 2500-5000 ft MSL, layered to 12000 ft MSL, through 03Z. Higher terrain will be obscured with local vis 1 mile or less. Low clouds and -SHRA could impact TAF locations west of the mtns between 03Z and 12Z Wed with cigs 1500-2500 ft MSL and local vis 1-3 miles at times. Expect SCT clouds after 15Z Wed. Elsewhere, SCT clouds with bases at or abv 10000 ft MSL and unrestricted vis through tonight. && .MARINE... Increasing winds and building seas, generating hazardous conditions this afternoon through early Wednesday. A Small Craft Advisory remains in effect. No additional hazardous marine weather is expected Wednesday afternoon through Saturday. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Wind Advisory from 6 PM this evening to 8 AM PDT Wednesday for Apple and Lucerne Valleys-Riverside County Mountains-San Bernardino County Mountains-San Diego County Deserts-San Diego County Mountains-San Gorgonio Pass Near Banning. PZ...Small Craft Advisory until noon PDT Wednesday for Coastal Waters from San Mateo Point to the Mexican Border and out to 30 nm- Waters from San Mateo point to the Mexican Border Extending 30 to 60 nm out including San Clemente Island. && $$ PUBLIC...Gregoria AVIATION/MARINE...PG
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