Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/18/24


Area Forecast Discussion
National Weather Service La Crosse WI
1041 PM CDT Wed Jul 17 2024 .KEY MESSAGES... - Quiet and comfortable weather for the next week with slowly rising temperatures to near normal /80-85F/ by the weekend into next week. - Rivers will get some much needed time to fall areawide with little rainfall runoff expected through the middle of next week. && .DISCUSSION... Issued at 118 PM CDT Wed Jul 17 2024 The large scale pattern over North America will stay nearly steady over the next week under an Omega block over the eastern Pacific and North America per Grand Ensemble forecasts. The area will remain under north-northwest flow which will keep temperatures below or near normal. With some cool air aloft and mild instability, chances of afternoon showers or a storm begin Saturday. GOES water vapor imagery is showing shortwave trough energy rotating through the U.P. of Michigan and northern WI as of 18Z, bringing broken skies and cooler than forecast temperatures in north central WI. Ridging will build in overnight and dominate Thursday and Friday. Some fog is possible tonight along the WI river and possibly into northcentral WI with cooler highs observed today and clearing expected. Another weak weather impulse in the northwest flow "generally" phases with the remnants of the low currently over the Pacific NW for late week. GOES water vapor has an impressive low lifting north through OR/WA at this time...which has a well-agreed on guidance track over the ridge position and into the northcentral U.S. This carves out a weak, broad trough position over WI into the deeper low center over western IA/swrn MN. This will promote afternoon showers centered on that trough axis beginning Saturday as the surface ridge weakens and shifts east, lasting through Wednesday. Instability is modest with MLCAPE of 300-750 J/Kg. Would expect much of the area to remain dry in the afternoons with clouds increasing with heating. Precipitable water values are about normal for mid-July at 1.25" suggesting normal rainfall intensity. Runoff should be minimal over the week allowing rivers to fall. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1041 PM CDT Wed Jul 17 2024 VFR conditions are generally expected through the TAF period with surface high pressure in place resulting in calm winds and some scattered VFR cumulus during the afternoon. Valley fog remains possible early this morning however, current dewpoint depression trends and afternoon mixing would suggest a less favorable environment for fog at KLSE. That being said, with the 18.02z RAP increasing the depth of light winds to around 6kft and the aforementioned surface high in place, would say there is still a low probability (20% chance) for valley fog at KLSE that would introduce category reductions. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ DISCUSSION...Baumgardt AVIATION...Naylor
Area Forecast Discussion
National Weather Service Denver/Boulder CO
904 PM MDT Wed Jul 17 2024 .KEY MESSAGES... - Thursday will be warm with scattered gusty afternoon storms. - A cool and wet pattern will exist from Friday through Monday. There will be a threat of flash flooding in the burn areas on Friday and Sunday. && .UPDATE... Issued at 905 PM MDT Wed Jul 17 2024 There are a few showers lingering this evening across the forecast area. The high resolution models have the convection over across the CWA by 06Z for the most part. Will adjust the pops accordingly. Will make some minor wind adjustments to the grids as well getting drainage patterns in place by 06Z. Will also adjust sky grids based on current reality and trends. Temperatures grids are in pretty good shape. && .SHORT TERM /Through Thursday evening/... Issued at 319 PM MDT Wed Jul 17 2024 Current radar shows scattered showers and thunderstorms this afternoon over the mountains, foothills, Palmer Divide, and northern Weld County. MLCAPE values range in the 500-1500 j/kg range from west to east. Across the I-25 corridor, shear is on the weaker side keeping storms weaker and capable of brief gusty winds, small hail, and locally heavy rain. Over the eastern plains, shear is more sufficient combined with higher instability (MLCAPE > 1000j/kg) to support a few strong to severe storms. Into early evening, high resolution CAMs show scattered showers and storms pushing east across the plains. A few solutions show a transition into a more linear mode over the far east plains. Given the more favorable severe environment is there, we`ll have to watch for a severe wind,hail threat and if storms slow more, perhaps potential for minor local flood impacts in those areas. RAP mesoanalysis shows DCAPE values >1000j/kg over the east plains support the gusty wind threat. Most activity will have exited to the east by mid-evening. For Thursday, the 500mb ridge centers to the west of Colorado, around the Four Corners region with N/NNW flow aloft over Colorado. Model cross sections/soundings show subtle drying in the low levels and some in the mid-levels from Wednesday. There will be marginal instability around with ample daytime heating; however, limited upper level support for ascent. This will support scattered afternoon showers and thunderstorms lesser in coverage compared to Wednesday with the higher chances over the higher terrain. MLCAPE values 800-1500 j/kg and DCAPE 900-1500 j/kg will support a few stronger storms, capable of strong gusty outflow winds and small hail on the plains. Temperatures trend slightly warmer with less cloud cover and building of the ridge to the west. Highs range in the upper 80s to low 90s across the plains. && .LONG TERM /After midnight Thursday night through Wednesday/... Issued at 319 PM MDT Wed Jul 17 2024 The upper level pattern will be stagnant and quite unusual for July or much of the long term period. A broad upper level trough will move south out of Canada and park itself over the Midwest. 500 mb flow may be northerly for a few days over our forecast area. This will lead to wet and cool weather for the long term period. Getting into specifics, there will be a small shortwave trough that will move across northeast Wyoming through northeast Colorado Friday afternoon. At the surface, there will be a weak cold front that will move trough northeast Colorado along with lowering pressure. The forcing from the trough and cold front will combine to create scattered showers and storms across the area. There will be a concern for flash flooding over the burn areas since there will be upslope flow and good moisture in the area. Across the northeast plains, there will be enough instability for storms to become strong to severe. Since there is organized forcing with the shortwave, these storms may quickly congeal into a line and produce wind gusts up to 60 mph. The primary threat will be east of a line from Fort Morgan to Deer Trail. On Saturday, our forecast area will be under slight subsident flow behind the shortwave that will have moved through the area. The post- cold frontal airmass will have a bit less moisture and will be more capped than Friday. Despite the low level upslope northeasterly flow, the coverage of showers and storms will be limited. Storms will form primarily over the southern foothills as that area is favored with low level northeast winds. On Sunday, there will be another small shortwave trough that will move towards northeast Colorado. At the surface, low level northeasterly flow will increase and moisture will increase as well. There will be widespread showers and thunderstorms over the higher terrain. Some of these storms may train over the same area and there will be a flash flood threat as a result. Storms may also form over the plains but coverage will be lower. By next work week, temperatures aloft will increase and moisture will decrease in the low levels. There will be more stable conditions which will limit coverage of storms. Storms will mostly stay over the higher terrain. By the end of the week, temperatures will rise and there will be less of a threat of storms as a ridge aloft moves overhead. && .AVIATION /00Z TAFS through 00Z Friday/... Issued at 851 PM MDT Wed Jul 17 2024 A strong outflow boundary moved across DIA between 00Z to 01Z earlier this evening, Winds still have an easterly direction which should gradually become more southwesterly then southerly around 06Z this evening. The normal drainage patterns should persist overnight. There will be no ceiling issues. && .HYDROLOGY... Issued at 319 PM MDT Wed Jul 17 2024 Low level moisture trends downward for Thursday, resulting in lower coverage of showers and thunderstorms. There is little to no threat for flash flooding over the burn areas Thursday. Friday and Sunday will have the best coverage of storms. Some of these storms will produce heavy rainfall and there is potential for training storms. The Cameron Peak will have an elevated threat of flash flooding each day while the other recent burn areas will have a limited threat. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE.......RJK SHORT TERM...Mensch LONG TERM....Danielson AVIATION.....RJK HYDROLOGY....Mensch/Danielson
Area Forecast Discussion
National Weather Service Cheyenne WY
1001 PM MDT Wed Jul 17 2024 .KEY MESSAGES... - Increasing moisture today will support strong to briefly severe thunderstorms through this evening. Additionally, heavy rainfall could lead to localized flash flooding. - Severe potential late in the week followed by cooler weather for the weekend. Warm-up begins to start the week. && .SHORT TERM /THROUGH FRIDAY NIGHT/... Issued at 240 PM MDT Wed Jul 17 2024 Stationary front lays along the east slopes of the Laramie Range from Cheyenne to Douglas to Sheridan...then northwest into western Montana this afternoon. Still seeing 60 Tds in the Panhandle and 50 Tds on the southeast Wyoming plains. Radar showing a good coverage of convection in this moist air to the east of the front. Have a few reports of large hail with the strongest storms. Looks like HRRR simulated radar is doing a pretty good job on the development and track of storms this afternoon. RAP mesoanalysis showing SBCAPE still pretty high around 2500 J/KG in the central Panhandle with 2000 J/KG extending just west of the Wyoming Nebraska state line currently. As the storms move into the Panhandle...they tap into this instability and go severe for a time before weakening. The central Panhandle still has been untapped...so would expect this is where the strongest storms are going to occur. Looks like storms continue through 02Z before beginning to dissipate. This lines up with the mesoanalysis forecast CAPE and what the HRRR simulated radar is showing as well. Evening shift will need to keep a close eye on TAFS overnight as GFS continues to show 850mb humidity increasing across the southern Panhandle in southerly low level flow. GFS showing 80-90 percent 850mb humidity from Sidney to Alliance and west to Cheyenne at 12Z Thursday. May be dealing with low stratus and fog around that time. Diurnal showers and storms expected once again Thursday afternoon/evening. Greatest concentration of storms looks to be along the I-80 corridor from Sidney to Laramie Thursday. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Issued at 345 AM MDT Wed Jul 17 2024 Northwesterly flow will continue across the region for much of the weekend into early next week. With a stout, 500mb high over the Four Corners region, monsoonal moisture will continue to advect into the region, increasing precipitation chances. Friday will have the best chance for precipitation as an upper-level shortwave traverses through the ridge and 500mb cyclonic vorticity advection increases. A 700mb low attempts to develop with this upper-level shortwave with a surface low trying to organize. The surface low will bring with it a cold front and strengthened winds at the surface. The approaching cold front will support lift across the region, leading to the development of showers and thunderstorms. The NAM currently shows around 1000-1100 J/kg of MLCAPE across the Panhandle for Friday afternoon. Forecast soundings suggest an inverted-V profile with strong mid-level lapse rates around 9 C/km. Relatively weak steering flow supports slower moving storms and 1.0in PWAT values indicate the potential for slow moving, heavy rain producing showers. However, the dry low-levels will likely lessen some of the heavy rain as a good portion will evaporate before hitting the surface. Nonetheless, strong to severe thunderstorms cannot be ruled out and the Storm Prediction Center currently highlights the Panhandle in a Marginal Risk for Friday. The active pattern will continue for the weekend as northwesterly, upper-level flow remains over the region. The 500mb high begins to retrograde to the west, which will decrease the monsoonal moisture across the region, evident by PWATs decreasing towards the 0.5-0.8in mark on Saturday. Northwesterly flow is favorable for precipitation across the region, as several vorticity maxima will traverse through the ridge and initiate afternoon showers and thunderstorms both days this weekend. With lower moisture in the area, these showers are expected to be more isolated in nature and likely not overly heavy rain producers. Temperatures will be pleasant this weekend in the mid-70s to mid-80s area-wide. Predominantly northerly upper-level flow will develop by Monday as the upper-level ridge amplifies to the west and a large fetch of northerly flow develops across the region. With this fetch of Canadian air, temperatures will be quite nice on Monday, with highs in the mid-70s to mid-80s area-wide once again. Afternoon showers and thunderstorm remain possible throughout the early portions of the week, typical for this time of year. Long range models are in agreement on increasing temperatures by mid-week, with highs returning to the mid-80s and mid-90s area-wide by Wednesday. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 957 PM MDT Wed Jul 17 2024 Northwest flow aloft will continue. Scattered to broken clouds from 8000 to 12000 feet will prevail. Areas of fog, with visibilities from 2 to 4 miles, and ceilings near 1500 feet, will occur at Cheyenne and the Nebraska terminals from 09Z to 14Z. Winds will remain at or under 12 knots. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...GCC LONG TERM...AM AVIATION...RUBIN
Area Forecast Discussion
National Weather Service Quad Cities IA IL
622 PM CDT Wed Jul 17 2024 ...Updated for 00z Aviation... .KEY MESSAGES... - Pleasant and dry conditions tonight, with well below normal temperatures. - Much welcomed dry weather through the rest of the work week and into the weekend. - Moderate to major river flooding continues on the Mississippi River. The Rock River is now expected to see moderate flooding by the end of the week. && .SHORT TERM /THROUGH TONIGHT/... Issued at 205 PM CDT Wed Jul 17 2024 A large 1023mb surface high to move over the Midwest overnight tonight bringing a rather dry and cool airmass to the region. Taking a look at 12z upper air data, the 850mb temp at INL was 6C or near its 10th percentile per SPC sounding climatology. This air will advect into WI overnight tonight, with RAP 850mb temps dropping into 7-9C range locally. This also will be near the 10th percentile of our soundings here at DVN. So long story short, it will be a very nice and cool night for July standards. In fact, with clearing skies and light winds, temperatures and dewpoints will drop into the low to mid 50s. This will be within shouting distance to record lows for the 18th. See climate section below for details. Thursday...surface high to be centered over the region, with some more fair wx Cu developing in the afternoon. Highs will top out in the upper 70s. && .LONG TERM /THURSDAY THROUGH WEDNESDAY/... Issued at 205 PM CDT Wed Jul 17 2024 Comfortable and dry conditions are expected Friday and Saturday, as surface high pressure drifts east into IN/OH/MI. An upper level wave will drop southeast into the Great Plains Saturday afternoon and evening, bringing an increase in clouds. Better moisture and lift will be just to our west and have kept PoPs below mention through Saturday. The NBM and the LREF 100 member ensemble probabilities of measurable QPF also support this. Small slight chance PoPs in our far western counties are seen Sunday and Monday, as the open upper wave rotates just to our west. Moisture will be the limiting factor. Most of the area should remain dry through the weekend and into next week. Looking ahead, the upper air pattern remains unfavorable for any widespread rainfall. A few weak waves early in the week may bring some chances for rain, but the threat for any strong storms remains low. Temperatures will be near seasonable, with highs in the 80s and lows in the 60s. && .AVIATION /00Z TAFS THROUGH 00Z THURSDAY/... Issued at 619 PM CDT Wed Jul 17 2024 VFR conditions will persist through the period. Occasional gusty NNW winds 10-20 kt and FEW-SCT cumulus 5-7kft agl will diminish with sunset. && .HYDROLOGY... Issued at 1125 AM CDT Wed Jul 17 2024 The Mississippi River has crested at all sites, with some reaches continuing to experience somewhat stalled falls or steady trends over the next few days due to recent bouts of heavy rain, local run- off, and tributary input. L&D 19 at Keokuk and Gregory Landing will even experience secondary rises into the weekend. Tributary Rivers: The recent rounds of heavy rain on the Rock River basin will continue to produce significant rises on the Rock, but after assessing the extent of run-off and upstream flow trends, Joslin and Moline are now projected to remain below the Major flood stage. The Rock at Como will be in Minor flood through Friday evening. The Pecatonica River is projected to rise into Minor flood at Freeport IL Friday night. The lower Wapsipinicon River near Dewitt, IA performed a secondary crest around 11.2 feet yesterday/Tuesday evening, but is now dropping below flood stage. With the dry weather into the weekend, the Wapsi is now expected to remain in the decline mode and remain below the flood stage. Backwater effects from the Mississippi River will keep the lower Iowa River just below flood stage through early next week. Further south, torrential rainfall and run-off from Monday night may produce a large rise to action stage on the La Moine River near Colmar in west central IL by Thursday. But the extent and speed is still somewhat uncertain and will have to watch river rise trends over the next 24 hours. && .CLIMATE... Issued at 205 PM CDT Wed Jul 17 2024 Record Low Temperatures: July 18: KBRL: 53 in 1924 KCID: 49 in 2009 KDBQ: 51 in 1979 KMLI: 54 in 2014 && .DVN WATCHES/WARNINGS/ADVISORIES... IA...None. IL...None. MO...None. && $$ SHORT TERM...Gross LONG TERM...Gross AVIATION...McClure HYDROLOGY...12 CLIMATE...Gross
Area Forecast Discussion
National Weather Service Sioux Falls SD
1042 PM CDT Wed Jul 17 2024 .KEY MESSAGES... - Patchy fog may develop in river valleys and other low lying areas early Thursday morning. - Below normal temperatures will continue through the weekend as northerly flow filters cooler air into the region. - Low to moderate rain chances (30%-70%) will return this weekend, highest Friday night into Saturday. While exact location and timing remain uncertain, an isolated severe storm risk and pockets of heavy rain are possible during this period. && .DISCUSSION... Issued at 156 PM CDT Wed Jul 17 2024 TONIGHT AND THURSDAY: Satellite images for early this afternoon show a broad diurnal cumulus field. A shallow, weakly unstable layer could bring occasional sprinkles or brief light showers through early this evening. Otherwise cooler than normal temperatures, low humidity, and a light northeast wind make for excellent conditions for outdoor activities tonight and Thursday. The atmospheric pattern over the Northern and Central Plains remains largely stagnant in dry northern flow aloft with strong 1022mb sfc high pressure centered over MN. This pattern favors at least patchy fog development early Thursday morning with 12z HRRR guidance suggesting areas of fog at least in river valleys and/or low lying areas around dawn. On Thursday morning, a weak ridge riding shortwave slides through western SD/central NE. This may bring a few light showers into south central SD, but the main impact is much more likely to be slightly increased cloudiness. Otherwise expect another pleasant day with a light south wind gusting into the teens west of I-29 and highs in the mid 70s to mid 80s. THURSDAY NIGHT AND FRIDAY: Low (<30%) chance for isolated showers and storms develops with warm air advection and another weak ridge riding shortwave late Thursday night into early Friday west of I-29. Aside from this, should still see largely drier conditions than wet through at least the first half of Friday. Warm air advection brings subtly warmer and more humid conditions as well, with highs again in the mid 708s to mid 80s. Chances for scattered showers and storms increase heading into Friday afternoon and night, triggered by a strengthening northern stream shortwave gliding south into the region. Moderate instability and 20-30 kts 0-6km deep layer shear would suggest potential for isolated/marginal strong to severe multicell storms. With a messy wind profile and fairly weak winds aloft, large hail, damaging wind gusts, and locally heavy downpours remain the main threats with the strongest storms Friday afternoon and night. SATURDAY AND BEYOND: Though there will be breaks/dry periods, isolated to scattered showers and storms are expected to linger through Monday with good model agreement in the maturing upper low stalling over IA/NE. This brings fairly humid, though mild (highs in the 70s and 80s) weather for mid-late July. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1042 PM CDT Wed Jul 17 2024 VFR conditions are expected to prevail this TAF cycle. Should see light and variable winds continue for much of the overnight period, with direction turning more southerly by mid-morning. Otherwise, expect chances for scattered showers and storms return by the end of the period, mainly along and west of the James River Valley. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. IA...None. NE...None. && $$ DISCUSSION...BP AVIATION...SST
Area Forecast Discussion
National Weather Service Grand Junction CO
503 PM MDT Wed Jul 17 2024 .KEY MESSAGES... - Temperatures are expected to remain a few degrees above normal with daily thunderstorm chances through the remainder of the week with a slight drying trend possible over the weekend. - Threats from thunderstorms will mainly be from gusty outflow winds though a few storms will be capable of producing smaller hail and moderate to heavy rainfall rates. Overall flooding threats remain low. - The combination of high based storms, gusty outflow winds and lightning will keep also keep a threat of new wildfire starts in the picture. && .SHORT TERM /THROUGH THURSDAY NIGHT/... Issued at 248 PM MDT Wed Jul 17 2024 The storm mode has changed this afternoon with less shear and slightly drier conditions in place. The best coverage remains over the San Juans where slow moving storm or training storms could lead to excess runoff through sunset but the probability of this is low. Similar conditions are expected Thursday though slightly higher PWAT will begin to creep into the 4 Corners region...westward moving Gulf of Mexico moisture in the wake of the lee side frontal passage and deep upslope flow. Storms should initialize on the higher terrain by mid-day as usual and migrate southeastward to adjacent valleys...with the southern valleys favored thanks to the better moisture profile. The HRRR attm is more bullish in keeping nocturnal convection into Thursday night which makes sense as we advect in additional moisture trapped under the main circulation aloft. This is an outlier solution attm so pops remain fairly light and will keep an eye on this trend. Temperatures will be fairly static with highs continuing to run several degrees above normal. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Issued at 248 PM MDT Wed Jul 17 2024 Mostly a rinse and repeat forecast through the long term period as we just keep watching the area of high pressure waver back and forth across the Great Basin. On Friday the ridge will be centered over southern Arizona as an embedded shortwave associated with the parent trough dominating Hudson Bay brushes the Continental Divide. This will result in an uptick in shower and thunderstorm activity as PWATs continue to trend 110 to 140 percent of normal. Saturday will be more of the same, although storm coverage will gradually taper off across eastern Utah and more-so focus along the Divide into the evening hours. As we head into the weekend odds begin to favor a trend towards drier weather as the ridge of high pressure amplifies farther north into the Intermountain West. Certainly won`t lock in a dry and benign forecast by any means as unsettled weather continues just to our east as the trough stays trapped over the eastern CONUS. As this regime continues PWATs will gradually begin to trend down but aren`t anticipated to drop below normal until early next week. Regardless, pesky low level moisture paired with daytime heating and orographics will be sufficient to fuel at least scattered convection each afternoon into the new work week. But, as we transition a bit each day, the potential for heavy rain will become less likely as we shift more towards the threat of gusty outflow winds. As we head into Tuesday the ridge looks to slowly de-amplify as a trough of low pressure dives south from the Gulf of Alaska. Temperatures will remain largely stagnant through the period as we don`t see any notable shift in the synoptic pattern. This translates to continued hot temperatures with highs trending near to slightly above normal. Overnight lows each night will generally be mild for mid July. && .AVIATION /00Z TAFS THROUGH 00Z THURSDAY/... Issued at 501 PM MDT Wed Jul 17 2024 Most of the showers and storms have dissipated, but an isolated cell or outflow is possible this evening. Another round of showers is expected tomorrow afternoon very similar to today. Gusty winds are possible with these showers. Otherwise expect VFR conditions through the period. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...15 LONG TERM...MMS AVIATION...TGJT
Area Forecast Discussion
National Weather Service Goodland KS
945 PM MDT Wed Jul 17 2024 .KEY MESSAGES... - Thunderstorm chances continue through the end of the week with a risk for severe storms each day through Friday. - Temperatures remaining near normal through next week. - Locally heavy rainfall possible through Friday night. && .UPDATE... Issued at 750 PM MDT Wed Jul 17 2024 A large area of showers and thunderstorms over the northwest 1/3 of the area where precipitable water values run from 1.2-1.4 inches is forecast by the latest RAP/HRRR models to move to the east and southeast very slowly (0-6km wind speeds within the greatest confidence for rainfall under 10 mph) through perhaps 12 AM MDT (1 AM CDT). RAP model shows PWAT values increasing perhaps up to 1.7 inches generally north of Interstate 70. After midnight, some dissipation is forecast and could be a bit sooner. Increased and capped pops at 70% for now where confidence was highest in shower/thunderstorm activity to continue over the next several hours. Radar mosaic showing a slow decrease in storm intensity and despite the high precipitable water values and slow storm motions the overall threat for flash flooding looks to remain low and somewhat isolated. Severe threat looks to have diminished as well with some gusty winds and small hail the primary hazards with the locally excessive rainfall. && .SHORT TERM /THROUGH FRIDAY NIGHT/... Issued at 1205 PM MDT Wed Jul 17 2024 17Z Water vapor imagery and RAP analysis indicated CWA under broad northwest flow with H5 ridge centered near the four corners region with trough centered over the northeast CONUS. PV analysis suggests at least 2 smaller disturbances moving over top of ridge to the west. At the surface broad and light easterly flow observed across area as surface ridge settles over the area. With dewpoints in the low 60s, already seeing CU fields develop, with storm initiation already occurring along weak convergence zone near KLIC. Primary short term concerns will focus on thunderstorm potential each afternoon and evening through Friday. As mentioned earlier, already seeing thunderstorm initiation on subtle convergent zone along Palmer Divide and expect this to continue on through the afternoon. While no major short wave trough is apparent upstream, inhibition looks rather weak allowing for several areas of thunderstorms to develop. The first will likely be along convergent zone/south of Interstate 70 in eastern Colorado, with storms moving east southeast through the afternoon hours. A second round of storms will likely initiate over the higher terrain and merge into more of an MCS in the evening hours. This will likely bring more widespread storms as it moves east into Kansas. Have doubts about how far east storms will make it as there is a rather sharp gradient in available instability and have opted to be a bit conservative on eastward progression. With instability around 1000 J/KG and fairly straight hodographs expect a few stronger storms early on, but think biggest threat will be organized cold pools/ damaging wind gusts. High precipitable water values, slow storm movement and high freezing levels support a heavy rain threat as well, but best potential does not seem to line up with where heavy rain has fallen recently. On Thursday, sfc ridge retreats to the east as trough strengthens over eastern Colorado. This will result in increasing southerly winds as well as increasing temperatures. While a similar upper level pattern will be in place during the afternoon, H7 temperatures will be several degrees C warmer than today resulting in stronger capping. Given the weak overall forcing, confidence in thunderstorm development not as high as today although threats will be similar to the last several days. Pattern continues on Friday although afternoon forcing looks to be stronger as weak cold front sweeps across the area. With more focused forcing along front, looks like Friday evening may be the best chance for rain across a large part of the area. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Issued at 1233 PM MDT Wed Jul 17 2024 Medium range models in general agreement with the overall large scale pattern through the middle of next week as flow aloft becomes more northerly and rather weak as H5 ridge remains firmly in place across southwest CONUS and weak cut of low develops over the Central Plains. While there is a bit of uncertainty with exact track of this low, somewhat surprised that it is pretty well accounted for in the GEFS mean showing at least broad consensus between ensemble members. Net result will be a cooler and cloudy weekend with showers possible through Monday. With current data, does not appear to be a great severe weather threat with weak shear and limited available instability. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 945 PM MDT Wed Jul 17 2024 KGLD...VFR conditions are expected through the period. A light and variable wind at taf issuance is forecast to continue through 12z. From 13z through the rest of the taf period, a southeast wind around 11kts is forecast, except in the 17z-02z timeframe where sustained speeds of 12-15kts with gusts up to 25kts are likely. Similar to the past several days, weather systems move through the area from the northwest. Given timing and coverage of storm issues, confidence is too low that the terminal would be impacted so no precipitation mention in this forecast. KMCK...VFR conditions are expected through the period. A light and variable wind at taf issuance is forecast to continue through 13z. From 14z through the rest of the taf period, southeast winds up to 11kts are expected except in the 22z-24z timeframe where speeds pick up into the 12-15kt range with gusts up to 25kts. Given timing and coverage of storm issues, confidence is too low that the terminal would be impacted so no precipitation mention in this forecast. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...None. CO...None. NE...None. && $$ UPDATE...99 SHORT TERM...JRM LONG TERM...JRM AVIATION...99
Area Forecast Discussion
National Weather Service Louisville KY
948 PM EDT Wed Jul 17 2024 .KEY MESSAGES... * Scattered showers and storms continue through this evening, with a northwest to southeast drying trend expected tonight behind a cold front. * Cooler temps and lower dewpoints expected Thursday and Friday. * Gradual warm up this weekend with increasing mugginess by early next week. Shower and storm chances also return in that time frame. && .UPDATE... Issued at 947 PM EDT Wed Jul 17 2024 At this hour, scattered showers and thunderstorms continue to push from north to south across central Kentucky and southern Indiana along and ahead of a cold front which is dropping through the region. There is still 1000-1500 J/kg of mixed-layer CAPE available at this hour, and though low- and mid-level lapse rates remain quite poor, limiting overall development, the mid-level trough axis sliding through the region has supported an increase in shower/storm coverage over the past hour or so. Recent HRRR solutions support this increasing coverage of showers/storms mainly along and south of I-64 over the next few hours, with cells becoming more numerous as they approach south central KY. Brief heavy downpours and gusty winds would be the main hazards associated with showers, in addition to lightning with any thunderstorms. As we head through the night, a drier and more stable air mass will continue to filter into the region from the north, bringing an end to precipitation chances from north to south. With the front not expected to clear southern KY until tomorrow morning, lingering precipitation chances are expected through most of the overnight hours. Areas of fog continue to look like a good bet tomorrow morning across the Lake Cumberland region, as low-level moisture will be slow to scour out. Localized patchy fog will be possible elsewhere in locations which received substantial amounts of rainfall today/tonight, though light northerly winds should help to limit fog extent once the cold front passes through. Only minor tweaks to the forecast were made, mainly to handle near- term precipitation trends. Otherwise, the forecast remains on track. && .SHORT TERM /THROUGH THURSDAY/... Issued at 314 PM EDT Wed Jul 17 2024 Scattered showers and storms are developing across the region as expected this afternoon. Despite the cloud cover earlier, we have been able to warm into the low 80s, but being in a pre-frontal airmass, we still have dewpoints in the low to mid-70s. We`ve been able to realize instability ranging from 1500-3000 J/kg, with the greatest thermodynamics across our south. Storms having been firing across south-central KY this early afternoon, which is where the higher CAPE values are located along with steeper low level lapse rates. Shear remains rather weak due to the upper level jet streaks well to our north, so still expect most storms to be unorganized. DCAPE is highest to our south, but any stronger cell could lay down some gusty winds. High PWATs will remain across the region until the front brings in drier air, so until the front passes through, any shower or storm will also be capable of torrential rain rates. Luckily, the current storms this afternoon appear to be progressive enough to minimize flooding concerns. However, any additional rounds of heavy showers or storms over the same areas this evening could result in a localized flood issue. For tonight, any leftover precip along the front will be getting push to the southeast as the front slowly passes through. Could still see some heavy rainers even after sunset with CAPE lingering, but again the shear will be fairly meager. Drier conditions will be settling in from northwest to southeast this evening and tonight. The cold front should be through just about all of our area by 06z, and entirely post-frontal by daybreak tomorrow. Tomorrow`s forecast is a great one to see: drier weather, much less humidity, and cooler temperatures will be in store for us. Northerly flow behind the front will push out the humid airmass we`ve been stuck with the last several days, and temperatures will reach the low 80s, several degrees below normal for mid-July. After having dewpoints in the 70s, tomorrow`s dewpoints will be in the upper 50s and low 60s. Clouds will be departing with the cold front, so we should have more sunshine by the late morning or early afternoon. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... Issued at 314 PM EDT Wed Jul 17 2024 The cooler/drier post-frontal airmass will continue into Friday with highs in the lower 80s and lower humidity expected. By the weekend, the upper level pattern will shift to a baggy trough over the Plains which will remain in that area through mid week next week. This will leave southern IN and KY under an active southwesterly flow. A sfc boundary from the Gulf state will gradually lift north toward the lower Ohio Valley this weekend bringing showers/storms to southern/eastern portions of KY. By Mon/Tue time frame the sfc front will lift north through our region bringing better chances for showers/storms over all of southern IN/central KY each day especially afternoon/evening hrs. Temperatures will warm back into the mid to upper 80s for highs Sat/Sun when there`s less convection around. Then temps drop back slightly into the middle 80s for highs during the first half of the work week. Low temperatures will remain in the 60s for the weekend and through mid next week. && .AVIATION /00Z TAFS THROUGH 06Z FRIDAY/... Issued at 737 PM EDT Wed Jul 17 2024 This evening, scattered showers and a few embedded thunderstorms are located along and south of a cold front which is currently dropping from NW to SE across the region. Since the showers are fairly isolated in coverage and disorganized, it is difficult to have enough confidence to carry prevailing SHRA or TSRA, except at RGA, where there is a slightly stronger signal. As a result, the forecast is fairly low confidence over the next 3-6 hours, and short-fuse amendments to the forecast may be needed to handle reduced VIS/CIGs from heavier showers. Additionally, as the front sinks south tonight, lowering ceilings are expected along and south of the front. Expect the front to clear SDF and HNB quick enough for continued VFR conditions, but LEX/BWG and especially RGA have a chance to see brief MVFR CIGs/VIS before drier air rushes in behind the front. Winds will become northerly behind the front later tonight, continuing through the day tomorrow with speeds generally between 8-12 kt. As dry air continues to work farther to the south, VFR conditions are expected at all sites from mid-morning tomorrow through the end of the current forecast period. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ UPDATE...CSG SHORT TERM...CJP LONG TERM...AMS AVIATION...CSG
Area Forecast Discussion
National Weather Service Raleigh NC
810 PM EDT Wed Jul 17 2024 .SYNOPSIS... A cold front will approach the region on Thursday, bringing showers and storms to the area. The front will remain stationary through the end of the week resulting in unsettled weather and cooler temperatures. && .NEAR TERM /THROUGH TONIGHT/... As of 810 PM Wednesday... Expired the Heat Advisory for the day... As the lee trough moves across the region early this evening showers and storms are possible over the next few hours. The stronger storms along the VA/NC border are expected to continue east along the border, with heavy rain and gusty winds being the main threat. Storms in SC moving into NC is expected to bring another round of isolated showers and storms to the Sandhills and southern Coastal Plain region in the next few hours. The entire area is anticipated to be clear of all precipitation shortly after midnight. Lows in across the area will be in the the mid 70s. As of 242 PM Wednesday...Early afternoon satellite imagery and surface obs depict a weak NE/SW oriented boundary across central NC, located roughly along US-1 as of 18Z. Dewpoints east of the boundary remain in the low to mid 70s whereas they have mixed out into the upper 60s to the west. Along this interface, quite a bit of cu have developed and the first returns of the day are showing up on radar. SPC mesoanalysis suggests nearly 3000 J/KG of MLCAPE on offer eastward into the Coastal Plain and I would expect these storms to continue to develop and expand through mid afternoon. There isn`t much in the way of upper level forcing driving this convection and deep shear remains relatively weak around 20kts, so I wouldn`t expect much in the way of severe weather with this line as it moves east but brief periods of heavy rain and gusty winds are a safe bet with the strongest storms. Meanwhile to the west, longwave troughing across the OH valley and upper level jet dynamics associated with the 120kt 250mb jet over northern Ohio will help support additional showers and storms across the western Piedmont later this afternoon into the evening hours. A few storms have already developed on the mountains and these should expand/move eastward into the CWA by mid/late afternoon. 12Z HREF and several HRRR runs maintain convection along and north of I-85 into the evening hours and I will maintain 40-60 PoPs in those areas through late evening. Meanwhile to the east I`ll keep a few hours of 20-40 PoPs to cover the ongoing convection along the central NC boundary. With storms already starting to develop and an increasing veil of cirrus moving northward, we`re likely at or very close to our maximum heat index for the day which ranges from around 100 upwards of 107-108 depending on location (upper 90s in the western Piedmont). The ongoing Heat Advisory covers things well and may ultimately be able to be cancelled a few hours early but with numerous readings still in the triple digits, we`ll leave it as is for now. It`ll be another mild night tonight with temps falling into the mid 70s. && .SHORT TERM /THURSDAY AND THURSDAY NIGHT/... As of 242 PM Wednesday... Longwave troughing and the attendant surface cold front will move eastward during the day Thursday, eventually making its way across the mountains and into NC during the afternoon hours. With southwesterly flow aloft, the front will make slow eastward progress as it traverses the state. While the day may start off mostly dry, showers and storms should quickly develop along the front by early afternoon. Exactly where storms initiate tomorrow is still TBD but HREF would suggest somewhere around or just east of the Triad would be the most favored area. From there, anywhere from 1000-1500 J/KG will be on offer but once again deep shear remains meager. By this time upper level support should be displaced well north into New England although we may still feel the effects of the nearby right entrance quadrant of the upper level jet. SPC has placed much of NC within a MRGL risk for severe weather tomorrow, and some of the stronger storms may be capable of producing gusty winds bordering on severe thresholds. PoPs will remain generally less than 20 percent in the morning hours, quickly ramping up to 80-90 percent during the afternoon. Given the slow progression of the surface front through the area, training cells could be a concern. However nearly a week removed from our last heavy rain event, soils should be able to accept at least some rainfall before saturating. Isolated flooding of low lying areas and normally flood-prone locations is a possibility but we aren`t expecting widespread flooding as this line of convection moves through the area. HREF PMM QPF indicates 1-2 inches of rain with the front as it moves through central NC (lesser amounts around 0.50 - 0.75 inches around the Triad, highest amounts across the Coastal Plain). This fits in with NBM QPF and aligns with the WPC ERO SLGT risk for Thursday. As for temperatures, expect highs to range from the upper 80s in the west to the low/mid 90s in the east. For portions of the southern Coastal Plain that will reside in the warm sector for most of the day, heat indices may hit triple digits for a brief time. Elsewhere the arrival of storms and/or debris clouds should keep heat index values below Heat Advisory thresholds. Lows tomorrow bottoming out in the lower 70s. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... As of 142 PM Wednesday... The extended will continue to feature high rain chances, particularly in the beginning part of the period into the weekend. Somewhat lower chances, but still above climo, will exist for the early to middle part of next week. On Friday, the cold front approaching from Thu is forecast in most of the guidance to settle along the NC/SC border, then slowly lift back north as a warm front Fri night to Saturday evening. During this time, a trough/shortwave will be present over the TN valley, fueling energy streaming in from the SSW and PWAT values roughly 120- percent of normal. Storm chances will remain elevated at this time with the boundary in place. WPC has retained a slight risk of excessive rainfall across our SE zones Fri along the stalled front. A marginal risk remains in place Sat as the front lifts back northward in the moist southerly flow. Temperatures Fri/Sat look to top out in the mid to upper 80s, warmest in the south to near 90. This will be lower than the past several days with added rain chances and cloud cover. As we head from Sunday into the middle of next week, the front looks to become more diffuse and washed out. A Bermuda high will exert more influence, with continued warm and humid flow persisting. Aloft, the trough over the TN valleys weakens and a ridge over the western Atlantic will gradually shift west, resulting in a slight rise in heights. This should favor a trend toward less rain chances each day. However, PoPs will remain above climatological normals as we remain in that moist and unstable environment, as well as with slight troughing to our west over the Mid-Mississippi Valley advecting in energy from mid-levels. WPC has another marginal risk of excessive rainfall over the entire area Sunday. While there may not be any main surface features, a Piedmont trough and sea-breeze may enhance storm chances, focused mainly in the afternoon and evening hours. Highs will largely hover in the mid/upper 80s to lower 90s, trending warmer by midweek. Heat indices currently look to stay below advisory criteria given the daily rain chances above seasonal normals. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... As of 750 PM Wednesday... Generally VFR conditions are expected through 15z Thursday. The exception is for scattered storms north and east of RDU to RWI through 04z. Storms on Thursday are likely to hold off until after 18Z. Outlook: A cold front will sag into and stall across the region Thursday through Saturday which will increase the chances for sub-VFR conditions in showers/storms through this weekend. && .CLIMATE... Record High Temperatures: July 17: KRDU: 100/1887 KFAY: 102/1932 Record High Minimum Temperatures: July 17: KGSO: 75/2013 KRDU: 80/1887 KFAY: 77/2019 July 18: KGSO: 76/1986 KRDU: 79/1887 KFAY: 77/2019 July 19: KGSO: 75/2016 KFAY: 77/2023 July 20: KGSO: 75/2019 KRDU: 76/2020 && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Leins NEAR TERM...CA/Leins SHORT TERM...Leins LONG TERM...Kren AVIATION...PWB/Leins CLIMATE...RAH
Area Forecast Discussion
National Weather Service Riverton WY
350 PM MDT Wed Jul 17 2024 .KEY MESSAGES... - Stationary ridging keeps seasonally hot temperatures and light winds across the region for the next week or so. - Showers and thunderstorms will be possible each afternoon through the end of the week. Most widespread showers/thunderstorms look to be Thursday afternoon. - Low confidence in any notable pattern change for the next 7 to 10 days. && .DISCUSSION... Issued at 252 PM MDT Wed Jul 17 2024 Have you been enjoying the weather for the past several days? Well, whether you have or not, it will be much of the same for the foreseeable future. A longwave ridge will remain nearly stationary through the rest of the week and likely through much of next week as well. A weak monsoonal push will strengthen over the next few days resulting in diurnal showers and thunderstorms across the region. Thursday looks to be the day with the most prolific widespread moisture and associated shower activity as PWATs increase to 1" +/- 0.2" across much of the region, especially across central portions of the region. A similar push of moisture looks likely for Friday as well, though PWATs do not appear to be quite as high. Most convection will be terrain enhanced, with showers developing along the east slopes of most of our terrain features. Today, focus has been primarily along the Bighorns and across the northwest portion of our CWA so far, but as of 230 PM, convection is also firing up along the Salts and Winds. Again, expect convection to be much more widespread tomorrow given a weak wave that will push northeastward out of Utah, and lead to further enhancement. One other note with convection over the next few days is that these are fairly slow moving storms, and with PWATs near to above normal, localized flash flooding is an increasing concern. With the ridging, steering flow is weak, and convection develops along the same terrain features, leading to slow-moving and training cells. This will be a continued threat through the end of the week. The ridge does look to oscillate and shift slightly through the weekend, but not appreciably. Hot, mostly dry weather continues to be favored through much of next week, with continued afternoon shower and thunderstorm chances. PWATs remain seasonal, so dry thunderstorms are not a concern, and with generally light winds and the shower activity, fire weather concerns remain limited. GFS and ECMWF solutions do start to hint at a closed low pushing southeastward into the PACNW late next week. This could help to precipitate a pattern change, but confidence is low at this time. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 349 PM MDT Wed Jul 17 2024 Any remaining showers and thunderstorms come to an end the first few hours of the TAF period. All convection is done by 05Z, if not sooner. Winds are light overnight, with a mostly clear sky. Shower and thunderstorms are once again possible Thursday afternoon and evening. Have PROB30 groups at most sites to cover this risk. As is normal with diurnal convection, there is low confidence in exact timing and location of showers/storms, so the PROB30 groups cover the convective chances. Main threat with these showers will be gusty outflow winds, generally up to around 30 knots being possible. Smoke spreads from the northwest towards KCPR through Thursday morning. The latest HRRR smoke shows the most dense smoke occurring along and northeast a KCOD to KCPR line. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on smoke, icing, and turbulence forecasts. && .RIW WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Hensley AVIATION...Wittmann
Area Forecast Discussion
National Weather Service Shreveport LA
1009 PM CDT Wed Jul 17 2024 ...New UPDATE... .UPDATE... Issued at 938 PM CDT Wed Jul 17 2024 Radar has been active this evening across the Four State Region as a line of thunderstorms, with a robust outflow boundary, worked from west to east. This outflow boundary not only supported pulsing convection, but also averaged wind gusts between 30-50 mph during its trek across the FA. While a few thunderstorms remain present on radar, questions surround the overnight forecast as there is uncertainty given the performance of the afternoon hi-res solutions, and the early arrival of the afternoon convection. Upper troughing will continue to dig into the ArkLaTex overnight, with upper level vorticity spinning across East Texas through daybreak as seen on RAP analysis and HREF hi-res. This has the potential to support an uptick in convection overnight and through sunrise. As a result, elected to not stray far from the afternoon package given rain chances prevailing overnight. Only adjustment made in this update was to adjust hourlies to reflect the passing convection. RK && .SHORT TERM... (This evening through Thursday Night) Issued at 122 PM CDT Wed Jul 17 2024 Current visible satellite imagery shows a surface low spinning across portions of Oklahoma. This low will be the catalyst for our first round of thunderstorms through the evening hours, and into tomorrow morning. This remnant MCS will first move east into C. Arkansas, where some heavy rainfall may be possible overnight in our far northern zones. Additionally, a few of these storms may be strong to severe, with damaging winds being the primary threat with any storm that does become severe. Thankfully, this threat is relatively marginal, with only a marginal risk from the SPC in place for locations north of I-20. This MCS will begin to drop south overnight, as the cold front begins to force its hand. Here, additional showers and thunderstorms will be possible through the day tomorrow, with heavy rainfall being possible with these as well. With their mid- day update, the WPC has introduced a slight risk for excessive rainfall for our portions of E. Texas and NW. Louisiana. Isolated flash flooding could be possible during this timeframe, but most guidance has this MCS progressing through the region at a rather reasonable rate. In turn, widespread flash flooding is not anticipated, with most locations seeing between 2-4 inches of rainfall into Friday. /44/ && .LONG TERM... (Friday through next Tuesday) Issued at 122 PM CDT Wed Jul 17 2024 Longwave troughing will continue to work into the region through the weekend, reinforcing itself into Monday. This will allow for cooler air to remain filtering into the region, with afternoon highs running around five degrees below normal. As better rain chances return to the region by Monday, some locations could run 10 degrees below normal, with afternoon highs hovering in the mid to upper-80s. Given the location of this troughing, and a few disturbances riding the upper-level flow, rain chances will linger for most of the long-term. /44/ && .AVIATION... (00Z TAFS) Issued at 815 PM CDT Wed Jul 17 2024 Difficult 00z TAF package given the TSTM changes over the next 24 hours across our area terminals. Prevailed VCTS with TEMPO groups through most terminals through around the 06z timeframe with a break in convective trends until closer to 12z. A majority of High Res progs are hinting at pre-sunrise convection developing near or around the I-20 Corridor in NE TX and NW LA with this convection advancing south and east post sunrise. Handled this with additional VCTS FM groups through the morning hours with a break in convective coverage expected from west to east late in the TAF period on Thu. Cannot rule out the likelihood of at least MVFR ceilings accompanying convection after midnight and through the morning hours on Thu as well. Winds will be mostly variable overnight, becoming northeast on the back side of the convection with the arrival of a cold front. 13 && .PRELIMINARY POINT TEMPS/POPS... SHV 75 87 73 87 / 70 70 50 40 MLU 73 89 71 85 / 60 80 60 60 DEQ 70 83 67 86 / 70 60 10 10 TXK 73 85 70 86 / 70 70 20 20 ELD 70 83 68 83 / 70 80 30 30 TYR 74 86 71 87 / 50 60 30 30 GGG 73 85 71 86 / 60 70 40 30 LFK 73 88 71 86 / 50 70 50 60 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ SHORT TERM...44 LONG TERM....44 AVIATION...13
Area Forecast Discussion
National Weather Service San Angelo TX
627 PM CDT Wed Jul 17 2024 ...New AVIATION... .SHORT TERM... (This evening through Thursday) Issued at 209 PM CDT Wed Jul 17 2024 Convection continues to develop along the outflow boundary draped across northeast and north central Texas this afternoon. Satellite and radar images indicate some showers starting to develop along the outflow boundary draped across the southern portions of the Big Country and northern portions of the Concho Valley and Heartland. NBM POPs for tonight and Thursday appear to be a little low so have adjusted them slightly higher based on the latest HRRR progging convection developing along the outflow boundary this afternoon and the latest NAM and GFS models progging convection developing overnight into Thurs morning as the outflow boundary moves further south. Rain chances will shift southward Thursday with convection likely across portions of the northern Edwards Plateau and the northwest Hill Country. SPC does have a marginal risk of severe weather across portions of the CWA today and tonight...mainly where the outflow boundary is currently at but the main threat is for damaging winds (likely microbursts) due to the hot temperatures across the CWA this afternoon. Temperatures will be near normal across most of west central Texas Thurs afternoon. && .LONG TERM... (Thursday night through next Wednesday) Issued at 155 PM CDT Wed Jul 17 2024 The upper level ridge currently over the Four Corners region will continue to expand across the Western CONUS during the day on Friday. This will create a weak upper level troughing regime over the Midwest/Central Plains. With the frontal boundary south of our area on Friday (meaning little to no low level convergence), conditions should remain mostly dry. Temperatures will still be able to climb into low to mid 90s (upper 90s possible in the Concho Valley) which may erode any capping and allow for some diurnal activity during the afternoon and early evening hours. These storms would be weak overall as instability will be very limited across the area due to the relatively dry low/mid-levels. By Saturday, the aforementioned upper level troughing will begin to expand south/southwestward into the Southern Plains. A frontal boundary to our north is expected to provide a focus for convection as it continues to move south towards our area Saturday evening into early Sunday. Rain chances increase significantly by Sunday as we see the return of more deep level moisture with model soundings showing PWat values climbing over 1.5 inches across the area. With the weak upper trough holding across in the area and the front expected to stall out in our general vicinity, chances for showers and storms remain decently high through Wednesday (peaking around 50- 70% areawide). Due to the nebulous forcing across the area, how widespread all of this activity remains difficult to say. The moisture will certainly be available but changes in the troughing pattern and/or placement in the frontal/outflow boundary may create significant differences in who sees high totals and who "misses out". Have had to broadbrush QPF amounts but confidence is low that all areas will see totals that high (generally 1-2 inches) with the higher totals expected across our southern/southeastern counties. At the very least, cooler temperatures will prevail with highs during this timeframe below average in the mid 80s to lower 90s. This wetter and cooler pattern looks to hold through the end of the work week with our more typical summer pattern potentially making its comeback by next weekend. && .AVIATION... (00Z TAFS) Issued at 627 PM CDT Wed Jul 17 2024 Scattered thunderstorms should dissipate after sunset this evening. Several outflow boundaries exist which could make the winds erratic at times. Otherwise, light and variable winds are expected through the night. Another round of thunderstorms is possible, mainly from San Angelo southward, in the morning. && .PRELIMINARY POINT TEMPS/POPS... Abilene 72 93 68 94 / 30 20 10 10 San Angelo 73 96 70 98 / 30 40 10 20 Junction 73 94 71 96 / 30 40 10 30 Brownwood 72 93 68 93 / 30 30 10 10 Sweetwater 73 94 69 96 / 30 30 10 10 Ozona 72 93 70 96 / 20 40 10 20 Brady 73 93 69 93 / 30 40 10 20 && .SJT WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...61 LONG TERM....50 AVIATION...SK
Area Forecast Discussion
National Weather Service Salt Lake City UT
259 PM MDT Wed Jul 17 2024 .SYNOPSIS...High pressure will persist across the region for the next week. Very hot temperatures are expected to increase the risk of heat-related illness across lower Washington County and Zion National Park this weekend. && .SHORT TERM (Through 12Z Friday)...A broad area of high pressure aloft continues to sit over the Four Corners region this afternoon, as evidenced by anticyclonic flow on satellite image. With the center near the Four Corners, flow aloft over our area is generally southwest to northeast. The latest SPC mesoanalysis shows a few hundred J/Kg CAPE over northern Utah to 500-1000 over the southern end of the state with PWATs of 0.6"-0.9" over the same extent. Convection has been scattered over southern Utah mountains, along the UT/NV border, and in the Uintas, and isolated elsewhere. With increased lower-level moisture vs several days ago, convection is not creating much in the way of wind gusts. Thus, the main hazards are lightning and brief heavy rain. There is some low-end flash flood potential for any areas favored in west-to- east flow such as Capitol Reef. Also, there are hints of colliding outflow boundaries in Washington County this evening which bears monitoring for heavy rain potential. The aforementioned high pressure will continue to retrograde through tomorrow, setting up a more ideal southerly advection regime to pull in deeper monsoonal moisture tomorrow. EC ensemble mean PWATs look to approach 150% of normal for the majority of the forecast area. Meanwhile, high-res models are clearing out most convective activity overnight, allowing for a generally clear start to the day which could help maximize instability (currently averaging around 500 J/Kg for the area in the 12Z HREF mean). The HRRR model in particular has been excited with the 12Z and 18Z cycles showing scattered to widespread convection across the entire area including several convective lines and colliding boundaries in the Wasatch Front. The normal flash flood prone areas (e.g. slot canyons, slick rock, burn scars) will all see increased flash flood potential. .LONG TERM (After 12Z Friday), Issued 308 AM MDT... High pressure will persist through the long-term, with a ridge centered overhead to start on Friday. With mid-level moisture in place from the previous day, showers and thunderstorms are once again expected across much of the forecast area, with the highest chances across southern UT. Flash flooding will again be a threat across the south given PW nearing 1 inch, though we`ll have to keep an eye on burn scars across the entire area. The upper-level ridge will then gradually nudge westward over the weekend, allowing drier air to filter into the area from the north. This will greatly limit precipitation chances across northern areas, though southern areas will still see chances for daily showers and thunderstorms through Day 7. Heat will also likely become a threat across far southwestern UT this weekend, given persistent days of above-normal high temperatures and limited overnight relief with lows in the low 80s. A Major HeatRisk (Red) is noted across Lower Washington County and parts of Zion National Park specifically for Saturday and Sunday. An Excessive Heat Watch remains in effect, with slight variations in ensembles regarding the strength of the event leading to ongoing uncertainty as to just how hot it will get and which areas will see the most unusual heat. Currently, for the St George metro there is a 50-70% chances of highs exceeding 110 and an 80-90% chance of "lows" remaining above 80. Model guidance points toward moisture making a return mid-week, though there is still plenty of uncertainty with if/when a PacNW trough pushes far enough south to flatten the persistent ridge. Either way, temperatures and precipitation chances will remain largely unchanged through the end of the long-term period. && .AVIATION...KSLC...Generally light northwest winds will prevail this afternoon before shifting southeast around 05z this evening and remaining light. Tomorrow evening, southerly winds are looking to increase before a potential shift to the northwest into the overnight hours. Wind gusts have an approx 50% chance of exceeding 30 mph after 00z. The northwest shift looks to be convectively driven and therefore uncertain at the moment. VFR conditions are expected throughout the forecast period with a slight chance for a thunderstorm building nearby, potentially bringing briefly gusty outflow winds today and again tomorrow. .REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions are expected throughout the forecast period across the region with mostly high based clouds or clear skies. There will be scattered thunderstorms across the region through early this evening, bringing risk for briefly gusty outflow winds. Additionally, heavy rain and lightning may result if a storm moves over the terminal. && .FIRE WEATHER...A dome of high pressure will continue to stubbornly sit over the state for the next week. A slight shift in the position of this high Thursday will allow deeper monsoonal moisture to move into the area. This will bring a net increase in humidities for the higher terrain of around 3-5%. While the valleys will dry slightly this weekend, with ongoing thunderstorms/showers, elevated humidity should persist over the higher terrain with minimum humidities near 25-35%. This pattern lingers through the weekend and into next week over southern Utah in particular, along with hot temperatures in the lower valleys. Northern Utah and parts of central Utah will partially dry out by early in the week as flow aloft turns northwesterly, though with most areas still seeing appreciable overnight RH recoveries as overall moisture remains somewhat elevated. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...Excessive Heat Watch from Saturday morning through Sunday evening for UTZ123-124. WY...None. && $$ Van Cleave/NDeSmet/Cunningham For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity