Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/29/22

Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
609 PM CDT Thu Apr 28 2022 .AVIATION... South to southwest winds are expected to be in the 10 to 15 knot range overnight. Southwest to west winds are then expected to pick up to around 25 knots with higher gusts by mid to late morning on Friday. Skies are expected to remain VFR. However, some blowing dust may reduce the visibility to less than 6 miles at times. Confidence in dust is not high enough to insert at a certain time in the TAFS at this moment. && .PREV DISCUSSION... /Issued 248 PM CDT Thu Apr 28 2022/ SHORT TERM...Today through Friday Night A storm or two today if the cap breaks in the east. Fire weather in the west today with fire weather conditions across the southern Plains tomorrow. Models are still in great disagreement about storms today. The NAMNest wants to fire up 1 storm in the eastern Panhandles later this afternoon. The GFS wants to fire up one in the southeast. Others like the HRRR don`t start storms at all and hold the cap. What will be the truth will depend on the dryline position and the timing of the shortwave later today. Models disagree on how far east the dryline will push. So far, the dryline has pushed just east of Amarillo, but wavers back towards Dalhart and the into the far northeast corner of NM. With the dryline being fairly slow to shift eastward, not going to discount the NAMNest solution as a possibility. Forecast soundings show plenty of CAPE and DCAPE for a storm to become severe if it does form. Wind could get up to 70 mph and hail could be anywhere from an inch to 2 inches depending on how much CAPE it can tap into. The most likely outcome is for no storms to form, because the cap is fairly strong and it will have to hit the dryline just right as it comes across. Meanwhile the west is sitting with critical fire weather conditions today. More is expected tomorrow across the area, but it could be somewhat conditional or spotty in nature based on the rains we received yesterday and possibly later today. The mid level trough axis will pass through the area tomorrow and bring mid and low level jets through the area. The lee side low will shift into central KS through the afternoon. This will set the LLTR up over our eastern Panhandles. Forecast soundings show we can mix to 600mb. The 700mb jet should have 40 to 50 mph winds that can mix down to the surface. As the surface low moves, the cold front will push quickly into the Panhandles. This will turn winds to the north behind the front. Temps behind the front will cool overnight lows into the low 40s to low 50s. Beat FIRE WEATHER...Today and Friday... Today we are seeing RH drop into single digits to low teens in the west where we expected critical fire weather conditions as the dry line shifts eastward into the Panhandles. Winds are still expected to be breezy this afternoon with southwest winds of 15 to 25 mph gusting to 30 mph. RFTI values are between 0 and 6 across the critical area so far. We are continuing to monitor how the rainfall from yesterday is affecting the fuels. Friday is looking for critical fire weather across the Panhandles. However, this will be conditional. The recent rain may affect pockets of fuels, so anywhere that didn`t receive rain, or has immense fuel loading would be far more likely to burn than some of the spots that received a couple inches of rain and has far less fuel loading. There will still be plenty of drying from today and tomorrow with all the sunshine and breezy conditions. Winds will be southwesterly at 25-35 mph with gusts upwards of 50 mph. There is a LLTR in place and jets will be somewhat overhead, but kind of weak. Hence the winds not being stronger. RH will be in single digits, so between this and the winds, we can see RFTI values of 7 to 8 across the area. Most activity should be IA but significant fires will be possible, 40 percent. The bigger concern may be the frontal timing. If there are fires ongoing by the late afternoon, the front looks to come into the OK Panhandle around 5 or 6 PM and cruise through the Panhandles quickly. It should be out of the southern TX Panhandle by around 10 PM or so. Winds will turn sharply to the north behind the front, but shouldn`t be more than breezy at 15 to 25 mph. Beat LONG TERM...Saturday through Wednesday... While there is some hope for at least some semblance of a pattern change that might favor better precipitation chances in the extended, there are still enough differences in the models and ensembles to not be overly confident. The first decent chance for some May thunderstorms will occur late Sunday into Sunday night when a trough moves across the southern Rocky Mountains. This evolution will take place after a mild and dry day on Saturday within a post frontal environment. As the trough approaches, return flow will increase and the dryline setup possibly as far west as the eastern NM plains. The big questions that remain are 1) how substantial will the low level moisture return be and 2) will a subtle lead wave be enough to break any cap that might be present. The GFS remains the most aggressive with QPF and overall convective coverage, but there has been a drier trend for western zones. The EC has been coming more in line with GFS and is now producing convection across the southern zones Sunday afternoon. The CMC keeps most of the convection south of the Panhandles with a slower return of low level moisture. There has been an uptick in overall ensemble members producing QPF at AMA in the CMC and EC, while the GEFS has remained fairly consistent with the overall mean QPF. With the overall parent system not being in the most optimal position and some differences with the strength of the system, was pleased with keeping PoPs mostly below likely across the area (with exception of far southeast Texas Panhandle Sunday evening). Any storms that do form along/behind the dryline within the 50s to low 60s dew points will have potential to become severe, especially if GFS forecast soundings verify with large directional shear and ample CAPE. Monday and Tuesday should be dry, but another system might bring storms on Wednesday. Models are not in good agreement beyond Tuesday, so there are many possible scenarios possible ranging from dry to very wet. The good news is that there are no big signals for fire weather, yet each afternoon may be breezy enough for some elevated concerns until our fuels green up. Ward && .AMA Watches/Warnings/Advisories... TX...Red Flag Warning from 10 AM to 10 PM CDT Friday for the following zones: Armstrong...Carson...Collingsworth... Dallam...Deaf Smith...Donley...Gray...Hansford...Hartley... Hemphill...Hutchinson...Lipscomb...Moore...Ochiltree... Oldham...Palo Duro Canyon...Potter...Randall...Roberts... Sherman...Wheeler. Red Flag Warning until 8 PM CDT this evening for the following zones: Armstrong...Carson...Dallam...Deaf Smith... Hansford...Hartley...Hutchinson...Moore...Oldham...Palo Duro Canyon...Potter...Randall...Sherman. OK...Red Flag Warning from 10 AM to 10 PM CDT Friday for the following zones: Beaver...Cimarron...Texas. Red Flag Warning until 8 PM CDT this evening for the following zones: Cimarron. && $$ 15/5
National Weather Service Sioux Falls SD
1033 PM CDT Thu Apr 28 2022 .SHORT TERM...(This Evening through Friday Night) Issued at 421 PM CDT Thu Apr 28 2022 Early afternoon satellite imagery shows low/mid level stratus moving from southeast to northwest, with upper level cirrus streaming overhead from west to east. Radar is showing scattered showers and thunderstorms, with most activity occurring north of the I-90 corridor. Have gotten a report of half-dollar sized hail near Windom, likely due to the low freezing levels, which has now prompted a severe thunderstorm warning for Jackson County, MN. Models only show a couple hundred Joules of CAPE available, though lapse are fairly decent, with the effective shear layer roughly 35 to 40 knots giving the storm enough shear to keep itself organized. Though this is occurring well north of the warm front, this activity could remain on going or even back-build a touch given the weak flow at the mid-levels, but will eventually peel off to our northeast. Very subtle shortwave under southwesterly flow in the mid-level could potentially lead to more showers and thunderstorms later this afternoon into the evening hours, though due to the weak forcing confidence is not high in this occurring. As a digging trough moves over the Rockies from the west coast, more favorable conditions begin to set up across the region. By Friday morning, lee cyclogenesis will spawn a Colorado low on the eastern slopes, which will be moving across the central plains throughout the day. Aloft, frontogenesis ahead of the mid-level low will likely lead to one or two round or showers and thunderstorms for areas west of I-29 throughout the morning hours. With roughly 500 J/KG of CAPE and deep layer shear values around 25 knots available, these morning storms are not expected to be severe, but will instead be the first round of much-needed rainfall across central South Dakota. By the afternoon hours, will likely see a lull across eastern portions of the region (east of I-29) before another round of non- severe showers and thunderstorms will be likely moving from southwest to northeast. The thunderstorms to watch for will be the ones forming across central Nebraska during the late afternoon hours near the deepening surface low or along the occluded front, as 1000- 2000 J/KG of CAPE will be available along with steep mid-level lapse rates around 7-8 deg C/km. Though not great, deep layer shear of 30 knots should be enough to allow the storms to remain at least somewhat organized before growing upscale into bowing line segments as they move towards the area. Large hail and strong winds remain the main threats, with the threat trending towards hail as the boundary layer stabilizes and the storms become elevated. Due to the close proximity to the surface low, stronger winds return to the region throughout the afternoon hours, with gusts likely up to 35 mph. As for temperatures, despite the cloud coverage, surface warm air advection will keep our afternoon highs in the upper 50s to lower 60s. Expect scattered showers and thunderstorms to continue into the overnight hours as the main upper level wave starts to traverse the region and the surface low lifts up towards the region. .LONG TERM...(Saturday through Thursday) Issued at 421 PM CDT Thu Apr 28 2022 After sunrise on Saturday, majority of the ensemble consensus keeps the center of the low pressure in the near vicinity of the SD/NE/IA border. As has been the trend, the EC and NAM continue to favor the slightly further north trend with the center of the low, while the GFS and RAP keep it slightly further south. Given the model consensus of climatologically high PWAT`s across the region, moderate to periods of heavier rainfall remain expected. While all the solutions point towards the periods of showers and thunderstorms continuing throughout the day as the surface low tracks eastwards, the location of the deformation band(s) on the backside of the low will determine where the heaviest rainfall will fall across the region. The north to south oriented band will be occurring across central South Dakota, looking most likely along our western fringes from Winner to east of Pierre. However, a westwards shift, or even a second deformation band west of the initial one towards I-29, is not out of the question. Throughout the afternoon hours, the initial deformation band in the TROWAL region should decrease, with a newer deformation band forming along the mid-level frontogenesis continuing to focus the moderate/heavier rainfall towards the I-29 corridor and into SW MN. All of this to say, rainfall amounts over an inch are likely across the region, possibly in excess of 2 inches for areas west of the James, with potential for these higher amounts spreading eastwards towards the I-29 corridor. Also of note, strong winds are expected to develop on the western fringes of the surface low as it strengthens throughout the day on Saturday. Strongest winds are anticipated for areas west of I-29, where sustained winds over 30 mph are likely and gusts up to 55 mph will be possible. There is potential for areas in/near Gregory county to see wind gusts in excess of 60 mph given strong mid level flow, which has prompted high wind watches to our south and west, but with Gregory county on the eastern fringes of where this looks possible have forgone the high wind watch at this time. The upper level trough begins to lift by Saturday evening, causing the surface low to weaken as it moves east-northeastwards into MN and WI. Cooler air isn`t brought into the region until late Sunday, so afternoon highs will still likely be in the upper 40s and lower 50s. The coldest air arrives Sunday evening, and will lead to overnight lows into the lower to mid 30s. Upper level flow remains active into next week, with another weak trough moving towards the region spawning another Colorado low on Monday morning. Rain chances look to reach the SD/NE/IA border by Monday afternoon/evening, though the best instability will likely remain well off to our south, keeping severe weather at bay. Model consensus begins to drift after that, though the upper level flow looks to remain active. && .AVIATION...(For the 06Z TAFS through 06Z Friday night) Issued at 1030 PM CDT Thu Apr 28 2022 Scattered convection driven by an increasing low level jet continues to develop across portions of the forecast area. Meanwhile, low MVFR to IFR stratus is beginning to advect westward. Convection will likely continue for the next 1-2 hours before lifting to the north, this should leave most of the area void of any convection through daybreak. Meanwhile stratus will spread westward, falling into IFR levels in some areas. After daybreak, some drizzle or reduced visibility by fog may be possible. Otherwise, next line of convection will move east off the High Plains by mid-morning Friday. Anticipating impacts to HON by midday with FSD/SUX seeing impacts towards the late afternoon/evening hours. Brief reductions in visibility can be expected in moderate showers. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ SHORT TERM...APT LONG TERM...APT AVIATION...Dux
National Weather Service Hastings NE
1012 PM CDT Thu Apr 28 2022 .UPDATE... Issued at 1007 PM CDT Thu Apr 28 2022 Main focus of this forecast update was to try to capture the current extent of rainfall and thunderstorms in the PoPs and updated the overnight hours, mainly by blending with the HRRR for the next few hours. Also updated the temperatures where cooling has occurred due to the rainfall. A few thunderstorms are still possible across the area into the early morning hours Friday morning. && .DISCUSSION...(This evening through Thursday) Issued at 253 PM CDT Thu Apr 28 2022 A near-stationary boundary might be the focus of some late afternoon and evening convection. With little in the way of a cap, we will have a scenario where deep layer shear will be marginal, near 30 KTS or so, but MLCAPE 2000-2500 J/kg this afternoon/evening will be enough for some pulse-like marginal severe storms at least. We might even get a brief spin-up along the stationary boundary, especially with the low-shear environment. Strong signal for low stratus this morning, and perhaps some reduced visibility. We could also stand a chance at some short-term near-critical fire weather issues in at least our Kansas counties as the dry air surges north ahead of the cold front. Strong negatively tiled shortwave trough heads into the northern/central Plains tomorrow. Hi- res CAMS indicate that as the surface low tracks northeast across the CWA tomorrow, the triple point may wind up being near the tri- cities, putting tornado threat as far north as the tri- city area for Friday afternoon/early evening time frame. Plenty of moisture wraps around into the triple point region and could be a sneaky busy day for severe weather. Even storms farther west look like potentially producers of large hail and quite strong severe gusts. The window for severe activity will be relatively short-lived from mid afternoon to mid evening time frame before heading east of the area by late evening. Cold front surges through and still a strong signal for near-high wind criteria wind gusts near 60 mph from the northwest, especially near and west of tri-cities. Saturday looks like a quite windy and potentially damp day with wrap around moisture on the backside of the low. Signals from models still point toward at least marginally high wind with gusts near 60 mph for Saturday. Next week looks rather cool with potentially several periods of meaningful rain chances, with increasing consistency with this trend. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Saturday) Issued at 642 PM CDT Thu Apr 28 2022 VCTS could be in the area for much of the night as storm fire near a boundary this evening. Some storms contain strong to severe wind and large hail. The severe threat should decrease with time by overnight, but could become more widespread severe by afternoon Friday. One caveat for this forecast is a low-level stratus layer consistently forecast to develop overnight tonight and persist into Friday morning, with the possibility of elevated thunderstorms nearby overnight and in the early morning. More surface based convection is possible by Friday afternoon at both terminals, especially toward KGRI. Some MVFR visibility is also possible along with the stratus developing, and LIFR stratus is possible for a short time, especially between 09Z and 14Z Friday. && .GID WATCHES/WARNINGS/ADVISORIES... NE...High Wind Watch from Saturday morning through late Saturday night for NEZ039-040-046-047-060>062-072>075-082>085. KS...High Wind Watch from Saturday morning through late Saturday night for KSZ005-006-017-018. && $$ UPDATE...Hickford DISCUSSION...Heinlein AVIATION...Heinlein
Area Forecast Discussion
National Weather Service Goodland KS
929 PM MDT Thu Apr 28 2022 .UPDATE... Issued at 926 PM MDT Thu Apr 28 2022 Updated the forecast over the next 24-36 hours. Bought wind and RH values stated in the Red Flag Warning and High Wind Watch that are still in effect across the area into agreement with the current forecast values. && .SHORT TERM...(This evening through Saturday Evening) Issued at 211 PM MDT Thu Apr 28 2022 An active short term period is in store for the Tri-State area. This afternoon and through the evening isolated to widely scattered thunderstorms are possible as a shortwave moves through the area. A conditional threat for a severe storm or two does exist, as a cap is currently present on RAP forecast soundings a dry mid level. The highest potential for storms lies along and east of a Goodland to McCook line, where destabilization in the form of a CU field is developing. The main hazards appear to be large hail up to ping pong ball size as RAP forecast soundings in near Hoxie, KS showed MUCAPE up to 2000 j/kg, and an effective bulk wind difference greater than 39 knots which is supportive for larger hail stones to occur. Tonight overnight lows will be mild with temperatures in the upper 40s to upper 50s across the area. Friday morning, a low pressure system begins to develop over the CWA. As this occurs winds will become northeasterly and will advect in moisture return from the east resulting in patchy fog mainly along and north of Highway 36; if driving be prepared for sudden drops in visibility around sunset. As the low pressure system matures the risk for severe thunderstorms and critical fire weather increases. For information regarding the Red Flag Warning for Friday please see the "Fire Weather" section below. A risk does exists for scattered severe thunderstorms starting as early as 12pm MT Friday and persisting through the afternoon. The most likely area to see showers and storms looks to remain along and north of Interstate 70. Large hail and damaging winds are the primary severe threat, although a brief weak tornado can`t be ruled out especially east of a McCook to Grainfield line. The potential does exists for a significant hail (2+ inches) threat to develop across the eastern portions of the CWA, but will be highly dependent on how long an updraft can sustain itself as a multicell cluster storm mode looks most likely with 0-6 shear of 30-40 knots. The cold front as mentioned earlier will be fully through the area by Friday evening. Behind the front strong pressure rises of 8-12 mb over 6 hours will support the potential for strong to potentially damaging winds to occur through Saturday afternoon. Forecast soundings indicate strong low level wind field to develop overnight Friday and into Saturday morning with up to 60 knot winds at times within the mixing level. Typically overnight winds have a hard time mixing to the surface, but with the pressure rises this may be able to occur. Due to the lack of confidence in this occurring and the best time for the strongest winds to occur opted to leave the High Wind Watch in place for now. Localized areas of blowing dust are possible with how dry the past few months have been, overall the dust parameters from in office research aren`t favorable for a more widespread blowing dust event at this time. Showers will linger through the early morning hours on Saturday before moving out by mid morning. High temperatures Friday will vary widely based on the position of the cold front as mid 60s are currently expected for Yuma County to the mid 80s across Graham county. Overall cooler temperatures will be widespread Saturday with high temperatures in the 60s. .LONG TERM...(Saturday night through Thursday) Issued at 115 PM MDT Thu Apr 28 2022 Shortwave ridge will move across the area Saturday night and Sunday with a lull in the precipitation chances. Lows will be in the 30s and highs on Sunday around 70. Next shortwave trough will approach Sunday night with increasing rain chances. GEFS currently shows around a quarter of an inch possible by 12z Monday morning. Rain continues into Monday as an upper low cuts off near or over the forecast area. Temperatures may struggle to reach the 50s for highs. Rain gradually pulls away to the northeast Monday night. GEFS shows additional rainfall amounts between 12z Monday and 12z Tuesday of a quarter to a half inch, highest amounts toward McCook and northeast forecast area. Given the cool temperatures, instability will be lacking for severe storms, though an isolated rumble of thunder will be possible at any time Sunday night through Monday night. However, overall appears to be a very beneficial rain event for the area. Shortwave ridge briefly follows that system on Tuesday with temperatures recovering to the 60s/lower 70s. Models differ on timing, track and strength of the next upper low. GFS is faster and further north with be rain and thunderstorm chances occurring Tuesday night through Wednesday morning. ECMWF is slower and further south, with best rain and thunderstorm chances occurring Wednesday and even into Thursday with a deep closed low directly over the forecast area. Given the discrepancy in the models, confidence is low on the details, including any risk of severe storms which will be highly dependent on storm track. However, does appear that there will be another chance of rain and thunderstorms towards the end of the long term period. Given the expected clouds and precipitation, temperatures will be near to slightly below normal Wednesday and Thursday. As for fire weather, chances appear to be low for critical conditions with the expected precipitation and cooler temperatures through the long term period. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 540 PM MDT Thu Apr 28 2022 VFR conditions are expected at GLD with a potential for MVFR to IFR conditions due to lower ceilings and fog between 09-15Z. Low clouds and patchy fog are expected, but confidence in lower flight conditions is lower than needed to make it a prevailing condition. Any low clouds and fog that forms will dissipate after 15Z with afternoon CU with scattered thunderstorms forming after 20Z. Have left thunderstorms out of the prevailing conditions as coverage will be low. MCK will start out VFR with a transition to IFR due to low ceilings and fog between 09-17Z with easterly flow transporting low level moisture into the area. MVFR conditions are expected between 17-20Z as winds turn to the north northwest, fog dissipates, and low ceilings begin to lift. After 20Z, expect scattered thunderstorms across the area. && .FIRE WEATHER... Issued at 211 PM MDT Thu Apr 28 2022 A Red Flag Warning was issued for Cheyenne County Colorado along with Greeley and Wichita counties. These counties will be within the warmer/drier sector of the system. A cold front will be moving through the area where wind gusts of up to 45 mph from the NW will be likely. The counties surrounding the Red Flag Warning(Kit Carson, Wallace, Logan) will also be susceptible to an hour or two of critical fire weather conditions; opted to hold off on a highlight for them as the final overall positioning of the low will be highly dependent on if they are in the warm/dry sector or the showers/storms portion of the system. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...High Wind Watch from Friday evening through Saturday afternoon for KSZ001>004-013>016-027>029-041-042. Red Flag Warning from noon MDT /1 PM CDT/ to 7 PM MDT /8 PM CDT/ Friday for KSZ041-042. CO...High Wind Watch from Friday evening through Saturday afternoon for COZ090>092. Red Flag Warning from noon to 7 PM MDT Friday for COZ254. NE...High Wind Watch from Friday evening through Saturday afternoon for NEZ079>081. && $$ UPDATE...LOCKHART SHORT TERM...TT LONG TERM...024 AVIATION...LOCKHART FIRE WEATHER...TT
Area Forecast Discussion
National Weather Service Lubbock TX
638 PM CDT Thu Apr 28 2022 .AVIATION... VFR expected to prevail through the next 24 hours. LLWS expected at all terminals beginning late this evening through Friday morning with SSW winds remaining breezy overnight. West winds will increase notably Friday afternoon with gusts in excess of 30 kt possible at all sites. && .PREV DISCUSSION... /issued 233 PM CDT Thu Apr 28 2022/ SHORT TERM... Upper air analysis this afternoon depicts a subtle impulse rotating northeastward over the CWA ahead of an amplifying shortwave trough digging into the Cascade Mountains towards the northern Great Basin. This has resulted in an eastward progression of the low-amplitude ridging, with high-level flow becoming slightly difluent over New Mexico and the southwestern High Plains as per recent 250 mb streamline analysis and earlier 12Z upper air map data. At the surface, a 1008 mb cyclone was centered across southeastern Colorado with a sharpening dryline extending southward across the TX PH and is currently nearing the I-27 corridor as per regional METAR and West Texas Mesonet data, respectively. A gradually strengthening warm front orthogonally oriented to the dryline continues to move northeastward into southern Kansas and northern Oklahoma, with a broad moist sector across the Rolling Plains characterized by surface dewpoints in the lower 60s along a line from Childress southward to Aspermont amidst temperatures in the lower-middle 80s, yielding mean mixing ratios between 12-14 g/kg as surface winds remain slightly backed near and east of the 100th meridian. An undular bore, previously propagating into the eastern periphery of the CWA this morning, has become increasingly ill-defined owing to intense, diabatic heating but has also enhanced differential vertical mixing among several locales based off of mesonet data. As the dryline continues to mix eastward this afternoon while also sharpening due to the combination of increasing low-level confluence, intense dry-bulbing in the dry sector, and a slight uptick in large-scale geostrophic deformation aloft, it is expected to stall across the east-central Rolling Plains, along a line roughly from CDS south-southwestward towards SNK in the northern Permian Basin as surface winds in the moist sector continue to back from the gradually deepening cyclone in southeastern Colorado. The boundary-layer across the moist sector strongly capped owing to veered flow within the 850-700 mb layer near 20 kt per recent LIDAR data out of LBB. Convective temperatures are expected to be reached late this afternoon, and with the diffuse undulations intersecting the sharpened dryline (i.e. ~30 deg F dewpoint gradient over 30 miles) combined with increasing low-level confluence, the initiation of an isolated thunderstorm or two will be possible as these mesoscale processes may be able to overcome the strong CINH (at or around -50 to -100 J/kg per RAP analysis). Thinking from the previous forecast assessments from this morning and yesterday remains the same, with a multi-cellular storm characteristic initially before the potential for splitting storms given small, but straight, hodographs above the PBL. Effective bulk wind differences near 30 kt to locally 35 kt will support a weakly supercellular storm mode during the early evening hours with left- and right-moving propagation possible. The primary hazards associated with storms that become supercellular will be large hail events up to two inches in diameter as MLCAPE increases to near 2,500-3,000 J/kg due to the contribution of steepening 700-500 mb lapse rates from gradual geopotential height falls and the PBL characteristics mentioned in the previous paragraph, in addition to damaging downdrafts up to 70 mph as the sub-cloud layer remains well-mixed with LCLs near 800 mb. The potential for thunderstorms is low and remains conditional, and most convection-allowing model (CAM) guidance has struggled due to the lack of stronger large-scale forcing for ascent with the HRW-NSSL, HRW-ARW, and the HRW-FV3 among the few that indicate >40 dBz composite reflectivities. The above meteorological thinking aligns with what has been inspected with the trends in CAM guidance. Any chances for thunderstorms (even if it occurs) will wane after 29/03Z as the PBL stabilizes and the dryline translates westward, veering surface flow and undercutting surface-based inflow parcels. Overnight, the westward translation of the dryline will be impeded as an amplifying shortwave trough pivots over the Four Corners region, with the surface cyclone progressing into western Kansas while also deepening to <=998 mb. The central and eastern two-thirds of the CWA will moisten once again with relative humidity recovering to near 80-90 percent as breezy, southwesterly winds offset the potential for near-surface and low-level saturation. The low-level jet (LLJ) will also intensify, especially across the Rolling Plains to near 50 kt, in response to the ejecting shortwave trough over the west-central Great Plains. Low clouds are therefore not expected through the morning hours prior to sunrise Friday across the Rolling Plains. The dryline will rapidly mix eastward late tomorrow morning as the base of the shortwave trough rotates overhead over the OK/TX PH region, with intense dry-bulbing expected as vertical mixing heights ascend into the mid-levels. Hot surface temperatures are expected with westerly winds increasing to near 20 mph with locally higher gusts. Patchy blowing dust will be possible, particularly across the extreme southwestern TX PH and northwestern South Plains where the gradient winds are strongest. Sincavage LONG TERM... The main concern in the long term will be convective and severe potential on Sunday afternoon/evening. Models are in fair agreement in dropping an upper low from the Pacific Northwest into the Great Basin from Saturday evening through Sunday evening. Stronger upper level winds will begin to move overhead on Saturday with short wave ridging. A weak jet max of 80kt or so will be oriented from southern Arizona up through the Texas Panhandle by Sunday afternoon. The approach of the larger short wave and stronger upper tropospheric winds will lead to large scale ascent spreading over the region. Any minor short waves that will emerge on Sunday are too difficult to discern at this time range. With the main short wave trough well to the west of the region, low level moisture will be able to hold in the area through the afternoon. The previous day on Saturday, a cold front will move through shoving moisture to the south but will still be located in central Texas. With moisture not so far away, it will be able to make a quick return beginning early Sunday. The dryline will likely sharpen up near the Texas/New Mexico state line or even back a little farther into eastern New Mexico. This should allow for healthy low level theta-e air leading to strong uncapped instability values by late in the afternoon. With surface dew points progged to be around the upper 40s to lower 50s, cloud bases will be relatively high based. A brief return to fire weather conditions may occur on Monday as the short wave moves east leaving the area in dry westerly flow followed by another cold front late Monday. There is considerable uncertainty in the forecast beyond Monday but a semi-active pattern could encompass the area for the second half of the week with increased convective chances. FIRE WEATHER... Critical fire weather conditions are expected on Friday across the Caprock and Rolling Plains due to the combination of hot surface temperatures, westerly winds near 20 mph with locally higher gusts, and relative humidity values as low as 5 percent. A Red Flag Warning is in effect between 10 AM and 9 PM CDT across the entire forecast area as conditions will be favorable for the growth and spread of fires, with winds diminishing to near 10 mph after dark. No wind shifts expected with a prevailing direction out of the west. && .LUB WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from 10 AM to 9 PM CDT Friday for TXZ021>044. Red Flag Warning until 9 PM CDT this evening for TXZ021>024- 027>030-033>036-039>041. && $$ 30/09/01
...Updated Aviation Forecast Discussion...

.DISCUSSION... Issued at 415 PM CDT Thu Apr 28 2022 At 415 PM, the most notable features were the ongoing thunderstorms in northeast Nebraska, a marketable increase in the cumulus field over the last 3 hours and a stationary frontal boundary just northwest of Norfolk. Surface observations suggest good convergence along the boundary and this was seconded by the strong 925 mb frontogenesis indicated by the SPC Mesoanalysis. Otherwise winds were out of the southeast, surface dewpoints had inched back into the mid 50s and temperatures were in the upper 70s and lower 80s. Thunderstorm Potential this Evening and Tonight: The main challenge with the forecast tonight is the timing and location of thunderstorm activity. Given the current location of front across northeast Nebraska, the ongoing convection, and strong 925 mb frontogenesis, the most likely scenarios is that thunderstorms will increase in coverage along a line from Grand Island to Norfolk between now and 6 PM. Storms should then gradually drift southeast and could affect the Omaha or Lincoln Metros between 11 PM this evening and 6 AM Friday. Given the scatter shot nature of the CAM output today, this scenario relies on the more frequent HRRR updates and current observational trends. Sounding profiles suggest a multicellular storm mode, with a few embedded supercells possible. The primary threats should be hail to size of quarters and/or locally heavy rainfall. Though with Flash Flood Guidance values of 2 inches or more, it will take a solid training event to generate and flooding concerns. A More Significant Severe Thunderstorm Risk Friday Evening: The severe weather threat will increase through the day on Friday as a strong storm system moves into the Plains. Strong southerly WAA and moisture advection during the day on Friday should increase instability from eastern Texas to eastern Nebraska. Meanwhile it looks like low level cloud cover should keep our region largely capped through the day, limiting our shower and thunderstorm chances to whatever is left from tonight. The same probably won`t be true in western Nebraska where storms should be ongoing Friday morning near a surface trough. As we advance towards the evening, the risk for severe weather will increase significantly as as surface low and front/dryline advance through central and eastern Nebraska. Forecast soundings, hodographs and shear profiles, and the CAMS generally favor a line of storms. Within any line there could be embedded supercells. The primary hazards are expected to be hail of golf ball size or larger, damaging winds in excess of 65 mph and possibly a couple tornadoes. The peak period for severe weather is expected to be between 7 PM and 11 PM. The Weekend and Early Next Week: The surface low will move through Iowa and Wisconsin very slowly over the weekend. As this occurs it will open the door for another round of strong northwest winds on the backside of the low Saturday. The NBM 4.1 peak wind gust probabilities would suggest peak wind gusts in the 40 to 60 mph range (10th to 90th percentile). This looks to be supported by the deterministic guidance which suggest 850 mb winds of 45 to 60 kts. Winds toward the higher end of this range are most likely in northeast Nebraska. Wrap around rain shower activity should accompany the winds on Saturday and storm total rain amounts (Friday & Saturday) of 0.50 to 1.50 inches are possible. A Wind Advisory is likely Saturday (>90% chance) and a High Wind Warning could be needed (~40% chance). It won`t be quite as windy on Sunday (sustained 10 to 20 mph with gusts up to 35 mph), and any lingering rainfall should end in the morning as the surface low drifts east. Another storm system could bring more rainfall to the region by Monday. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 629 PM CDT Thu Apr 28 2022 Scattered showers and thunderstorms are the primary concern through tonight with lowering ceilings and potential for drizzle through much of Friday. Any storms tonight may produce hail up to the size of quarters with pockets of very heavy rainfall. IFR to LIFR conditions are expected at all sites through much of Friday through the end of the TAF period. Just beyond this TAF period, strong to severe thunderstorms are possible Friday night but more on that in later issuances. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Albright AVIATION...Kern
Area Forecast Discussion
National Weather Service San Diego CA
900 PM PDT Thu Apr 28 2022 .SYNOPSIS... Breezy onshore winds will continue overnight. The stronger winds over the mountains and deserts will gradually diminish after midnight. Warming will occur Friday and Saturday as a weak ridge builds into the region. Several weak shortwaves will follow for the second half of the weekend into early next week, with cooling and breezy onshore winds expected to make a return. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Update: It was a cooler day area wide today thanks to increasing onshore wind flow. High temps at most locales this afternoon were in the 60s to lower 70s. Mountain locations were mostly in the 50s while the lower deserts were in the mid-upper 80s, some 5-10 degrees cooler than yesterday. West winds have increased this evening over the mountains, especially along the desert slopes, through and below the passes and across the deserts. Peak gusts have been in the 30-40 mph range with localized gusts higher in wind-favored areas such as Whitewater registering a peak gust of 63 mph so far. Winds will continue strong through midnight with a gradual weakening expected overnight as a shortwave moves east of the area. Marine layer cloudiness will continue west of the mountains with some breaks though. HRRR and WRF are not indicating any precip overnight, so decided to keep patchy drizzle out of the forecast overnight. Subsidence behind the shortwave should limit the drizzle potential, so thinking it stays dry overnight. No changes were needed to the forecast this evening. Previous Discussion (Issued at 153 PM PDT Thu Apr 28 2022): Longwave troughing is dominating the West Coast today. A weak, embedded shortwave will move through Southern California today, allowing for persistent clouds and gusty onshore winds. Surface pressure gradients are trending more strongly onshore this afternoon, with 11.6 from SAN-TPH. Winds will strengthen further today, peaking late this afternoon into the mid-evening hours, with peak gusts of 45 to 55 mph. The highest winds will occur across the desert slopes and wind-prone passes and canyons. Blowing dust may lead to locally reduced visibility. At 2 PM, mid-level clouds covered areas west of the mountains away from the immediate coastline. Temperatures are running 5 to 10 degrees cooler than at this time yesterday. Today will be the coolest day of the week, with highs reaching the 60s for the coast and western valleys, the 70s for the Inland Empire, the 50s in the mountains, and the upper-80s for the deserts. A weak, short-lived ridge will build on Friday with the axis off the coast of Southern California, briefly allowing for winds to turn offshore. Temperatures will be noticeably warmer to close out the work week, with highs near seasonal averages. Further warming is expected on Saturday before a strong upper-low moves into the Pacific Northwest late Saturday into Sunday. Flow will turn back onshore that afternoon as an upper-low moves through the Great Basin, with a second low moving through the Pacific Northwest and Northern Rockies Monday and Tuesday. With this pattern, cooling is expected to spread farther inland each day. The degree of cooling remains in question, especially for Sunday; wide spread exists amongst the ECMWF ensemble members high temperature values, especially across coastal areas and the western valleys. At this time, it looks like highs will fall a few degrees each day into Tuesday. The 12z ECMWF Ens and the GEFS begin to diverge more noticeably by Tuesday as the upper low moves into the Central Rockies. The ECMWF Ens shows a slower solution and onshore flow remaining across the region into Wednesday with a ridge building behind it into Thursday. The GEFS is more progressive, with the system moving eastward on Tuesday, with ridging building by Wednesday. The timing of this system will impact daily temperatures, but continuous onshore flow with shortwaves moving through will support several periods of breezy winds across the mountains and desert slopes. && .AVIATION... 290400Z...Coast/Valleys...Mostly BKN clouds will prevail overnight with bases mostly 2000-2500 ft MSL with tops 3500-5000 ft MSL with higher terrain locally obscured. Most vis will remain above 5 miles below the clouds overnight. Clouds will clear earlier Fri, mostly 15Z-17Z, with unrestricted vis Fri. Patchy stratus could develop again mainly near the coast after 03Z Sat, with cloud bases likely below 1500 ft MSL. Mountains/Deserts...Mostly clear skies with mostly unrestricted vis will continue through Friday evening, except for areas of coastal terrain obscurations below 5000 ft MSL in clouds. Areas of west surface winds will continue through 09Z Fri from the mountain crests east through the desert slopes and into the deserts with gusts 30-40 (locally 50) knots, along with areas of strong up/downdrafts and LLWS, with local vis below 3 miles in blowing dust/sand in the deserts. && .MARINE... Winds will locally gust over 20 knots across the outer waters this evening with local seas to 8 feet/8 seconds. Similar conditions are possible again Saturday night and Sunday. Otherwise, no hazardous marine conditions are expected through Tuesday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Wind Advisory until midnight PDT tonight for Apple and Lucerne Valleys-Riverside County Mountains-San Diego County Deserts- San Diego County Mountains-San Gorgonio Pass Near Banning. PZ...NONE. && $$ PUBLIC...Gregoria (Update)/Schenk (Previous Discussion) AVIATION/MARINE...Maxwell