Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/05/22

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
759 PM PDT Thu Aug 4 2022 .SYNOPSIS...04/732 PM. Monsoon showers and thunderstorms will be possible over parts of northern Ventura and Los Angeles Counties mainly Friday afternoon, then again next week. A warming trend is expected across southwest California over the weekend with highs near to slightly above normal in most areas. && .SHORT TERM (THU-SUN)...04/757 PM. ***UPDATE*** Better coverage of monsoon showers and thunderstorms this afternoon with the heaviest activity north of Lockwood Valley Road in northern Ventura County, and east of Lancaster in the Antelope Valley. Radar-based rainfall estimates were over 1 inch for both areas and possibly up to 2 inches near Pine Mountain Club. Sparse rain gauges in these areas did not capture nearly this amount and there were no significant flood reports. There was also a few pictures of a landspout when cells developed near Littlerock this afternoon. Instability remains along the Kern County line this evening and moderate showers were about 30 miles north of the county-line rotating over that area from the east. Will continue a convective threat for that extreme northern border area until 06Z, however, the air mass continues to stabilize and expect an end to any thunderstorm potential for the remainder of the night. There are plenty of mid to high level clouds over the region and this has also hampered instability this evening along with playing havoc with the stratus along the coast south of Pt Conception. Still expect plenty of low clouds on the Central Coast through Friday morning and a chance of clouds or fog redeveloping in other places of the Ventura and south Santa Barbara County coasts before sunrise. HREF data and HRRR indicate just an isolated cell developing Friday afternoon over the northeast corner of the Antelope Valley around 1-2pm that quickly exits northward. There remains plenty of higher PWATs and some resemblance of a weak vorticity off the coast that could still bring a quick shower or thunderstorm to the northern mountains tomorrow, so will leave that in the forecast. Southwest flow quickly returns behind this feature late Friday with PWATs and monsoon moisture decreasing through the weekend. ***From Previous Discussion*** A little more active today with a thunderstorm along the Kern/Ventura County border and plenty of storms well to the south and east, including a huge area over the northern Baja mountains that is sending a giant high cloud shield towards LA County. We should continue to see storms developing over the mountains with the afternoon heating providing additional lift. And increasing high clouds from the southeast as that cirrus shield moves over the area. A weakening easterly wave moving into California from AZ may provide enough energy to maintain showers and possible storms across LA County overnight, though models have backed off that idea somewhat in recent runs. Not as sold on it now but wouldn`t be surprised to see a few showers and possibly even a thunderstorm over the LA County coast/valleys this evening into the overnight hours. Somewhat better chances though over the eastern mountains and Antelope Valley. Friday still has the potential for being an active thunderstorm day despite rapidly decreasing PW`s and a shift of the upper level flow from southeast to southwest. Forecast soundings over the LA/Ventura mountains had considerably higher CAPE values than today and 850 dewpoints from 10-14c which is about the same as today. Most of the hi res models and ensembles show less activity than today, but there is the potential for some strong cells and periods of heavy rain. Not much chance of storms south of the mountains with the steering flow from the southwest. After Friday PW`s drop off quickly and air mass stabilizes so the weekend forecast remains thunderstorm free. With less moisture in the air, fewer clouds, strong high pressure aloft, and weakening onshore flow, most areas should see a warming trend Sat/Sun with highs in the lower 100s in the warmer coastal valleys and mid to high 80s across the inland coastal plain. Marine layer will be less disrupted with no debris clouds drifting through so likely a more solid stratus coverage with areas of dense fog near the coast. .LONG TERM (MON-THU)...04/207 PM. Monsoon moisture returns next week with showers and thunderstorms possible over the eastern mountains most days. Models do show signs of a couple easterly waves moving through, mainly Monday and again Thursday so can`t rule out overnight convection or showers/storms over the coast/valleys at times, mainly LA County. Onshore flow remains pretty light most of next week but temperatures may fall slightly with increased clouds and moisture aloft. Overall, pretty typical August conditions across southwest California. && .AVIATION...05/0005Z. At 2344Z at KLAX, the marine layer was 800 ft deep. The top of the inversion was at 2500 ft at a temperature of 25 C. High confidence in KPRB, KBUR, and KVNY. Moderate confidence in KWJF and KPMD. There is a 20% chance of brief thunderstorms through 12Z. Any thunderstorm that develops is capable of producing brief heavy rain and reduced visibility, gusty and erratic winds, and dangerous lightning. Low confidence in coastal TAFs, especially for LA and Ventura County sites. High clouds will disrupt the marine layer, so there is a 40% chance of IFR cigs developing any time after 03Z for sites without cigs forecast. There is a 40% chance of no low clouds for KSBA. Arrival of low clouds at KSBP and KSMX may be off by an hour. KLAX...Low confidence in TAF. There is a 40% chance of IFR cigs anytime after 03Z. Any east wind component will be under 5 kt. KBUR...High confidence in TAF. There is a 10% chance of a brief isolated shower or thunderstorm through 06Z. && .MARINE...04/652 PM. High confidence in winds and seas remaining below Small Craft Advisory (SCA) level through Friday morning. There is a 50-60% chance of SCA level winds from Point Conception to San Nicolas Island late Friday afternoon through evening. If SCA level winds do develop, there is a chance they may spread into the southern and western half of the Santa Barbara Channel. SCA level winds are also possible across the waters between Anacapa and Catalina Islands. On Saturday, gusty NW winds become more widespread to the north across the outer waters along the Central Coast. The best chance for SCA level winds will be from Point Conception to San Nicolas Island (including the southern/western half of the Santa Barbara Channel) once again and will likely be stronger than Friday. SCA level winds will likely continue across all the waters from the Central Coast to San Nicolas on Sunday and potentially into the early part of the next work week. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Small Craft Advisory in effect from 4 PM Friday to 3 AM PDT Saturday for zones 673-676. (See LAXMWWLOX). && $$ PUBLIC...EB/MW AVIATION...Stewart MARINE...Stewart SYNOPSIS...EB Experimental Graphical Hazardous Weather Outlook at:
Area Forecast Discussion...UPDATED
National Weather Service Portland OR
857 PM PDT Thu Aug 4 2022 Updated Short Term and Aviation sections .SYNOPSIS...Upper level trough will push east Friday allowing temperatures to climb back into seasonable norms. Ridging will build north across the Pacific NW and temperatures will climb over the weekend. Temperatures are expected to cool Tuesday. && .DISCUSSION...EVENING UPDATE: At 0330Z water vapor imagery revealed an upper level trough situated over British Columbia and Alberta extending south through much of the Pacific Northwest. A dry slot/jet streak could be seen over Washington and far northwest Oregon. The monsoonal moisture continues to be shunted over the Great Basin with some thunderstorm activity slipping into far southeast Oregon. Primary tweaks to the forecast include a little less sky cover tonight, even for the coast. Also, with dew points generally in the mid 40s to lower 50s, have lowered min temps in many areas. Some of the normally cooler interior valleys will likely see mid to upper 40s. Elevated valley bottoms in the Lane County Cascades may drop into the lower 40s. The remainder of the forecast looks to be in good shape. Weishaar REMAINDER OF DISCUSSION FOLLOWS: Tonight through Wednesday...Models show a shortwave spinning off the parent low over British Columbia and dropping back towards the Pacific NW Friday morning. This will keep a slight onshore component along the coast and will help to moderate temperatures slightly on Friday. Nonetheless, with mostly clear skies Friday morning and boundary layer winds shifting northerly by the afternoon, high temperatures will trend back into seasonable norms. The 12Z model guidance shows the trough departing the region sometime on Saturday allowing the upper level ridge over the Desert Southwest to build north. Weak offshore flow will bring drier, warmer air west and with 850mb temps climbing into the mid teens daytime highs will build into the low 90s across the Willamette Valley. Medium range guidance continues to point to Sunday as the warmest day in this upcoming stretch as the ridge axis builds directly overhead and pushes 500 mb heights to around 588 dam while temps climb back to around 19-22C. This should correspond to afternoon highs at least in the mid 90s, with NBM probs for reaching 100 degrees continuing to trend upward to around 50 percent in most valley locations. The forecast remains more uncertain beyond Sunday as the persistent cutoff low begins to approach the coast again early next week. Something that may disrupt the temperature forecast is the transport of smoke aloft over the weekend. N-NE winds as depicted by the HRRR smoke model shows the potential for haze across the area Saturday morning from wildfires across Washington. If there are enough aerosols then temperatures may be cooler than expected. Temperatures are likely to settle back into the 80s by Tuesday as most guidance depicts the low starting to move inland, but confidence remains low given the models` struggles to handle this feature dating back to last week. Lastly, the conceptual model of increasing southerly flow and mid level moisture ahead of the approaching trough would seemingly favor at least some thunderstorm potential in the central OR Cascades by Monday and Tuesday, but ensemble solutions have notably been been lacking in depicting any thunderstorm potential to this point. That will be one more thing to monitor in the coming days as the evolution of the pattern comes into clearer focus. -BMuhlestein/CB && .AVIATION...06Z TAFs: Low level northerly flow continues Thursday night, with VFR flight conditions continuing everywhere as of 04z Friday. Such will be the case inland throughout the TAF period, while there is a bit more uncertainty in what will occur along the coast. There, guidance is giving around a 25-40% chance for low stratus to result in MVFR or lower flight conditions during the 11-17z time period. By midday, northerly winds will pick back up and may gust over 20 kts at times along the coast. For detailed Pac NW aviation weather information, go online to: KPDX AND APPROACHES...VFR conditions are expected through the end of the TAF period. Northwest winds may gust to 15 kts or higher in the mid afternoon through late evening Friday. Bumgardner && .MARINE...High surface pressure offshore and thermally induced low pressure inland will continue the northerly winds through the weekend. This set up will bring a period of northerly Small Craft Advisory winds for all zones. Small Craft winds will start for zones PZZ270 and PZZ255 tonight, followed by zone PZZ270 Friday morning with PZZ250 coming online Friday afternoon. These Small Craft winds are expected to continue through late Friday night/early Saturday morning. Seas will remain around 5 to 8 ft at 9 to 11 seconds with a dominant northwesterly swell with the highest seas expected in PZZ275. There is also a small, 1 to 2 ft, southerly swell around 14 seconds. /42 For information about upcoming marine zone changes, go online to: && .PQR WATCHES/WARNINGS/ADVISORIES... OR...Heat Advisory from noon Sunday to 8 PM PDT Monday for Central Columbia River Gorge-Greater Portland Metro Area-Upper Hood River Valley-Western Columbia River Gorge. WA...Heat Advisory from noon Sunday to 8 PM PDT Monday for Central Columbia River Gorge-Greater Vancouver Area-Western Columbia River Gorge. PZ...Small Craft Advisory from 2 PM to 11 PM PDT Friday for Coastal waters from Cape Shoalwater WA to Cascade Head OR out 10 nm. Small Craft Advisory until 3 AM PDT Saturday for coastal waters from Cascade Head OR to Florence OR out 60 nm. Small Craft Advisory from 2 AM Friday to 3 AM PDT Saturday for Waters from Cape Shoalwater WA to Cascade Head OR from 10 to 60 nm. && $$ Interact with us via social media:
Area Forecast Discussion
National Weather Service Springfield MO
631 PM CDT Thu Aug 4 2022 Key Messages: 1. Isolated showers/storms possible later this afternoon into evening. 2. Isolated showers and storms possible again Friday afternoon into early Friday evening over the eastern Ozarks. 3. Heat Advisory issued for Friday afternoon into early evening. Excessive heat continues into this weekend. .SHORT TERM...(This evening through Friday) Issued at 250 PM CDT Thu Aug 4 2022 Latest satellite imagery shows cloud cover from the overnight/morning convection having pushed south of the CWA, with an area of cumulus/stratocumulus having developed across central Missouri. Some of this cumulus is beginning to look a bit more agitated in the vicinity of Pulaski/Phelps/northern Texas counties. A stationary front was also observed across central Missouri. Temperatures have rebounded nicely into the 80s across most of the area, with Joplin having reached 90 degrees as of 2 PM. Expect afternoon high temperatures to top out in the mid 80s to low 90s, with the hottest temperatures across far SE Kansas and western Missouri. These temperatures were dropped a couple degrees from earlier forecasts due to the lingering cloud cover this morning. Nonetheless, heat index values in the low 100s will occur in the aforementioned hottest areas, with the remainder of the area generally seeing heat index values top out in the mid to upper 90s today. For late this afternoon and evening, the humid airmass will continue to linger over the area with progged PWATs of 1.4-1.8 inches. RAP and model thermal profiles suggest 1800-2500 J/kg of uncapped surface-based CAPE will be available during this timeframe with weak mid-level troughing over the eastern Ozarks/Mississippi River Valley acting as a catalyst for isolated, sub-severe pulse showers and thunderstorms. Coverage and intensity should be overall limited given substantial dry air above 800 mb and poor lapse rates aloft in a 20-25 knot effective bulk shear regime. HREF/Hi-res guidance further support this limited coverage and relegate the best chances for convective development to east of Highway 65, particularly over the eastern Ozarks. Warm temperatures continue into tonight, with lows around 70-74 degrees. Several models are indicating the potential for some low stratus or shallow fog over the eastern Ozarks tonight given the lingering humidity and moisture in this area that saw several inches of rain earlier today. The signal for dense fog is not present at the moment, but will need to monitor forecast trends closely for any changes. Heat begins to ramp up on Friday as the upper-level ridge builds into the Central Plains. Progged 850 mb temperatures of 22-24 degrees C support high temperatures in the mid to upper 90s over much of the area, though some scattered cloud cover and additional isolated afternoon/early evening showers and storms could form over the eastern Ozarks and lead temperatures to be a few degrees cooler in our east if this scenario comes to fruition. As a result, have issued a Heat Advisory for our SE Kansas and western Missouri Counties where confidence is highest that high humidities and hot temperatures will combine to produce heat index values in the 103-107 degree range. This Heat Advisory is in effect from 1 PM - 8 PM. .LONG TERM...(Saturday through Thursday) Issued at 250 PM CDT Thu Aug 4 2022 This Weekend: Excessive heat will continue into Saturday and Sunday as the upper-level ridge slides over the central Plains and central CONUS. 850 mb temperatures of 22-24 degrees C will persist over the area, with heat index values of 100-107 in the forecast due to high temperatures likely in the mid to upper 90s extending from southeast Kansas into the Rolla area. Temperatures in the low to mid 90s are more likely for the eastern Ozarks and south- central Missouri through the weekend. We did introduce some very low PoPs (around 20%) over far south-central Missouri for Saturday afternoon due to the influence of a weak upper-low over Kentucky nudging underneath the ridge. Forcing looks weak and possibly too far east with this feature, so chances for any diurnal convection look unlikely at the moment. Late Sunday - Tuesday night: Fairly good agreement in an upper-level trough traversing the northern periphery of the ridge and pushing east across the upper Midwest and Great Lakes from late Sunday into Tuesday. This feature would bring an associated surface cold front into and through the Missouri Ozarks region, which could lead to additional chances (currently 30-50%) during this timeframe. The WPC Cluster Analysis Tool has a ECMWF-heavy cluster that has less rain chances for Sunday, mainly due to later arrival of the cold front. However, all 4 clusters have at least some precipitation across the area for Monday and Tuesday, with a mixed signal for Tuesday night/Wednesday morning depending on how quickly the front moves south of the area. Still several days out, but GEFS precipitation probabilities do not point to a washout at the moment. Probabilities for greater than 0.25" of rain are 30-50% over south-central Missouri and less elsewhere. Greater than 0.5" is less than 30% for the same area, and 1.0" or greater probabilities are almost non-existent. Mid-Late next week: The NBM temperature forecast indicates a slight "cooldown" into mid to late next week behind the cold front with slightly drier dewpoints, as well. Therefore, current forecast highs are for the mid 80s to isolated mid 90s during this timeframe, though some differences in the upper-level pattern/ridge are creating a bit of uncertainty in these temperatures as reflected in wider NBM temperature spreads. Looking ahead to mid-August: CIPS Extended Analog guidance continues to point to a general above average trend in temperatures as we approach mid-August with also generally drier than normal precipitation. This is further supported by the CPC 8-14 outlook. While recent rainfall may reduce the severity of drought conditions for portions of the area, a return of this trend of warmer and drier conditions is expected to keep drought conditions going through August. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Pilots flying in and out of the southwest Missouri airports can expect fair weather VFR conditions over the next 24 hours. Residual cumulus clouds will eventually clear out of the region this evening as light and variable winds at the surface evolve. A summertime high pressure system will move closer to the Ozarks tomorrow while very dry mid level air spreads in. This will limit the amount of thunderstorm activity that develops tomorrow afternoon. However, it`s possible that a couple of thunderstorms develop near the Branson airport, but not likely. Safe Travels. && .SGF WATCHES/WARNINGS/ADVISORIES... MO...Heat Advisory from 1 PM to 8 PM CDT Friday for MOZ066-067-077- 078-088-089-093-101. KS...Heat Advisory from 1 PM to 8 PM CDT Friday for KSZ073-097-101. && $$ SHORT TERM...Rothstein LONG TERM...Rothstein AVIATION...Cramer