Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/09/23

National Weather Service Bismarck ND
947 PM CDT Sat Apr 8 2023 .UPDATE... Issued at 944 PM CDT Sat Apr 8 2023 Satellite picture this evening features streams of mid-level clouds and stratus through the Turtle Mountains. Some fog still looks possible tonight, with high-res models showing just patchy to areas of fog in coverage after 05Z. No changes needed with this update. UPDATE Issued at 623 PM CDT Sat Apr 8 2023 Forecast issue tonight continues to be stratus and fog. Modestly high dew points this evening should allow for some fog to develop as winds become light overnight, especially to the central and east ahead of the pressure trough. Can`t rule out stratus returning as well, though confidence hasn`t really increased from the previous shift. With this update the sky forecast was bumped up a bit as mesoscale models do continue to hint at fog or cloud cover expansion, but further details will need to wait until observational trends develop. && .SHORT TERM...(This Evening through Sunday) Issued at 150 PM CDT Sat Apr 8 2023 The main forecast issue in the short term period will be fog/stratus and temperatures. Latest surface analysis shows a warm front from northeast Montana into northwest Montana. Surface high pressure was over the Great Lakes with low pressure in the lee of the Northern and Canadian Rockies. Latest satellite imagery showed high clouds propagating from central into eastern North Dakota, with thinner cirrus/ more sunshine across the west. A pesky area of stratus over the southwest looks to be diminishing as it lifts northeast. For late this afternoon through tonight. The far southwest should warm into the lower 60s this afternoon, but most of the area, especially north and east of the Missouri River will remain in the 30s. Tonight, uncertainty remains in the potential for low stratus/fog. Mesoscale models show the stratus over the southwest lifting north northeast and RAP shows possible stratus/fog moving into Minot this evening, with more widespread stratus/fog over eastern ND. Not certain at all with this and have leaned more towards a partly cloudy sky. With that said, the pressure gradient does relax tonight and with mainly thin high clouds this evening, can not rule out some patchy fog. Previous shift had added some patchy fog and see no reason to pull it at this time. Sunday looks like another warm day in the far southwest and westtratuscentral, with cooler temperatures as you go north and east (but warmer than today). Like today, expect that there will be a sharp transition zone between the warmer temperatures with bare ground and colder temperatures under the deep snowpack. As we go forward into the extended period think this sharp gradient in the transition zone will slowly weaken as we lose our snowpack. But with the melting snowpack comes the threat of flooding of low- lying areas. See the current Hydrologic Outlook (ESF) for further details. This transition zone could also be a focus for fog stratus issues as well. .LONG TERM...(Sunday Night through Saturday) Issued at 150 PM CDT Sat Apr 8 2023 The main forecast issue in the long term period will be temperatures through mid week, then precipitation chances later in the week. For what seems to be ages, we have a spell of unseasonably warm temperatures to deal with early next week. Except for portions of the far west central and southwest, snowpack remains substantial. Looking at the trend of the NBM 4.1 ensemble temperatures Sunday through Tuesday, the ensemble spread has increased the last couple of days, especially over central ND, including Bismarck and Minot, while spreads in the west are much more reasonable, even a bit too tight. For instance on Monday and Tuesday the ensemble spread at Dickinson is 6 and 5 degrees, respectively. At Bismarck the spread is 23 and 29 degrees, for the same days. As you go east, the spread is also high, but is delayed a day or so. Perhaps there may be a target of opportunity in the west, or spreading into the central later in the period, but as long as the snowpack remains and ensemble spreads are wide, will stick with our given guidance. In addition to the temperatures, we see building upper level ridging through mid week. At the surface, the pressure gradient does not seem overly tight throughout the period. There are periods when it tightens a bit but also periods when you see it relax. Therefore, we would not be surprised to see occasions with stratus/fog issues, especially near the boundary between bare soils and the snowpack. Beyond Wednesday, we transition to more of a southwest upper flow and will see periodic chances of rain/snow as we head through the latter portions of the work week. && .AVIATION...(For the 00Z TAFS through 00Z Sunday Evening) Issued at 623 PM CDT Sat Apr 8 2023 Return of IFR stratus or some fog is possible tonight, but certainty is low for any one location. It does seem the south central to southeast, KBIS-KJMS, looks to have a bit of a higher potential for some sort of impact. So the TAFs were kept VFR with this forecast due to uncertainty, but included SCT IFR cigs at both sites with VCFG. Winds generally become westerly during the day Sunday after becoming light tonight. && .BIS WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...AE SHORT TERM...TWH LONG TERM...TWH AVIATION...AE
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
604 PM CDT Sat Apr 8 2023 ...New AVIATION... .SHORT TERM... (Tonight through Sunday night) Issued at 249 PM CDT Sat Apr 8 2023 Plenty of clouds remain intact across most of south central Texas early this afternoon. We are seeing some breaks in the clouds across portions of the Hill Country and I-35 corridor near San Antonio. These areas will see a little extra heating and some re-development of low clouds as the afternoon progresses. For tonight, cool and moist air in the boundary layer will persist, allowing for widespread low cloudiness, patchy fog and overnight lows in the lower 50s to near 60. Some of the hi-res models show some weak shower activity is possible out west across the Rio Grande plains as southeasterly flow in the low-levels begins to strengthen. Confidence in this is low, so we will not mention in the forecast at this time. Mostly cloudy skies along with afternoon highs in the upper 60s to upper 70s are expected on Sunday. We will see some weak disturbances embedded in the west-northwest flow aloft move into the region beginning late Sunday afternoon and continuing through Sunday night. We will keep a low chance for showers and thunderstorms limited to northwestern Val Verde county during the mid to late afternoon hours, then slowly spread rain chances farther east into the Rio Grande plains during the evening Hill Country, with the Hill Country seeing some activity during the overnight hours. Coverage will likely not be much more than isolated to widely scattered, so we will keep rain chances limited to 20% for now. && .LONG TERM... (Monday through Saturday) Issued at 249 PM CDT Sat Apr 8 2023 A shortwave trough advances across the state on Monday before evolving into a cutoff upper level low near the northwestern to northern Gulf Coast into midweek. The shortwave will help to initiate a region of convection across the Texas panhandle late Sunday. The north-northwesterly flow behind this shortwave should help to propel the convection southward toward our region into Monday. The main question that remains, however, is if this convection is able to hold together during the overnight on that journey? The global models, especially the GFS, are optimistic whereas the hi-res guidance coming into range (NAM12, the HRRR through 12Z Monday) are less optimistic on the activity holding together and approaching from the north. Will keep the chance of rain/storms in the forecast but will lower PoPs from the NBM guidance. Tuesday may also potentially offer a slight chance for rain across our eastern zones but this will all depend on the proximity of where the low pressure system wraps up. The farther east it wraps up, the drier the forecast would be. Expect for afternoon highs in the 70s and overnight lows in the 50s through midweek with the northerly flow on the western side of the low. Afternoon temperatures return to the 80s and dew points will be climbing back into the 60s by late this week as the winds become southeasterly with the gulf system moving away to the east- northeast. In addition, a shortwave ridge builds over the state during Thursday into Friday ahead of a trough moving through the Desert Southwest. The approaching trough may be a catalyst for returning rain/storm chances from Friday night through Saturday, including perhaps the chance for some organized convection as instability builds and shear increases with a stronger southwest flow aloft. && .AVIATION... (00Z TAFS) Issued at 546 PM CDT Sat Apr 8 2023 The San Antonio airports are enjoying VFR conditions as clouds spread and continue to lift late this afternoon. However, for KAUS, overcast skies around 1 to 2 Kft are expected to remain through the overnight hours. For KDRT, mostly sunny skies are in place and expected to stay for the next few hours with partly cloudy skies this evening. Increased moisture arrives this evening for the San Antonio terminals with MVFR cigs forecast for the tonight into Sunday morning period. There is a chance for IFR cigs to affect the San Antonio and KDRT airports around 10 to 12z and last for several hours. VFR conditions are forecast to show around 20z. Light northeast winds are forecast for area airports for most of the forecast period with a moderate southeast wind flow for KDRT. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 57 75 58 74 / 0 0 10 30 Austin Bergstrom Intl Airport 55 73 57 73 / 0 0 10 30 New Braunfels Muni Airport 55 75 58 74 / 0 0 10 30 Burnet Muni Airport 54 73 55 72 / 0 0 10 30 Del Rio Intl Airport 61 79 63 80 / 0 10 20 40 Georgetown Muni Airport 55 72 55 72 / 0 0 10 30 Hondo Muni Airport 55 75 58 76 / 0 10 10 40 San Marcos Muni Airport 55 74 57 74 / 0 0 10 30 La Grange - Fayette Regional 57 73 58 72 / 0 0 10 30 San Antonio Intl Airport 56 74 59 74 / 0 10 10 40 Stinson Muni Airport 57 75 60 75 / 0 10 10 30 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Short-Term...17 Long-Term...27 Aviation...17
Area Forecast Discussion
National Weather Service San Diego CA
1241 PM PDT Sat Apr 8 2023 .SYNOPSIS... Fair and mild weather today will turn even warmer tomorrow and Monday as a ridge builds over the Southwest. Weak onshore flow and a shallow marine layer could lead to areas of dense fog along the higher coastal terrain, and even along the coast for the next few nights. Cooling begins on Tuesday as the ridge drifts to the east, and is replaced by a trough. This sets up much cooler weather for the latter half of next week, along with a limited shower threat Thursday or Friday. The weather looks dry and a bit warmer again by next weekend. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Satellite imagery at midday showed patchy high clouds drifting SE, and a large area of low, marine clouds just offshore. Weak onshore sfc pressure gradients were holding and supporting some westerly wind gusts over 30 MPH near the passes. Surface dewpoints were in the 50s F along the coast and over the near-shore islands. As these are maintained by sea breezes this afternoon, there should be sufficient moisture for fog development overnight, provided the skies remain mostly clear. In the meantime, skies will be fair as temperatures approach the 70 degree mark this afternoon. A weak trough along the West Coast has kept the weather over SoCal on the cool side for the past few days, but that is about to change as a ridge begins to build tonight. By tomorrow, the warming will be noticeable, especially inland, peaking on Monday under sunny skies. Weak sea breezes will temper the warming along the coastal strip, to just a few degrees Fahrenheit in the afternoons, but inland, highs will be 6-10F above average. A shallow marine layer is likely to persist as well, raising the prospects of fog. Based on the latest HREF and HRRR model runs, the best chance for dense fog (60-70%) will be along the higher coastal terrain tonight, and then closer to sea-level Sun night/Mon morning. The greatest potential for widespread, dense fog, appears to be Sunday night/Mon morning, but some fog is likely each night through Monday night. The ridge aloft peaks over AZ on Monday, but continues to be the main feature controlling the weather over SoCal through Tuesday. The onshore sfc pressure gradient will begin to accelerate then, but this will mainly be felt west of the mountains in the afternoon. The lower deserts will remain quite warm. By Wednesday, our weather pattern flips completely as a trough digs down the West Coast and the ridge fizzles. This will result in noticeably windy and colder conditions over over SoCal, that will continue through Thursday. Track, intensity, and outcome of the energy moving through our next digging West Coast trough remains elusive, as evidenced by the spread in outcomes on the last few control runs of the global models. The problem centers around the energy cutting off a low pressure center somewhere near SoCal....Tis the season. Therefore, confidence in our weather for the middle of next week is quite low, especially for precipitation. For now, we can be quantify it with the trend in the ensemble output. At this point it still suggests some light precipitation is likely around the Thursday timeframe, but exact timing is difficult to gauge. Strong and gusty westerly winds, and cooling look more certain, peaking on Thursday. Count on some warming as the system exits to the east next weekend, but even that looks somewhat muted as the global models try to adjust to the potential development of a blocking pattern over the West. Blocks are difficult, especially around the edges where cut-off lows frequent. && .AVIATION... 081930Z...SCT conditions expected for much of the afternoon, with BKN-OVC low clouds redeveloping after 00Z Sun. Bases are expected to start at 1000-1500 ft MSL, with the potential to lower to 600-800 ft MSL. 12Z ensemble guidance has 70-80% of cigs under 1000 ft after 10Z Sun at coastal TAF sites. Vis reductions of 1-3SM expected near areas of higher coastal terrain. Cigs and vis restrictions should clear by 17Z Sun. && .MARINE... West-northwest wind gusts could briefly reach 20 kt in the outer coastal waters through early this evening. Areas of fog and reduced visibility possible over the waters tonight. Low confidence in widespread dense fog. Better chances of more widespread, potentially dense fog Sunday night into Monday. For the middle to end of next week, gusty northwest winds near 25-30 kt expected along with seas of 9-11 feet. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ PUBLIC...10 AVIATION/MARINE...CO