Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/08/21

Area Forecast Discussion
National Weather Service La Crosse WI
1000 PM CDT Sat Aug 7 2021 .UPDATE... Issued at 949 PM CDT Sat Aug 7 2021 At 9pm...the surface front was located near Rochester toward Preston to near Boscobel and Lone Rock. South of this front, SBCAPE was around 4000 J/kg. Deep layer shear was noted 35 to 45kts over parts of central MN and also eastern Neb. The low level jet is forecast to increase overnight and this combined with the favorable moisture and instability environment should result in additional thunderstorm re-development. The 88-D mosaic is already showing an uptick across Clark Co and we have been seeing convection across Adams and Juneau Co. Look for westward development along and north of the front with efficient storm producers of 1 to 2 inch rainfall rates. Due to the heavy rainfall from Saturday - widespread 1 to 3 inch amounts and several counties with 3 to 5+ inch amounts. A flash flood watch is in effect for areas most prone to flash flooding. We will continue to have a severe weather risk as well with the moderate instability overnight and 0-3km shear vectors from IA into SE MN and Wrn WI of 35 to 45kts Sunday morning. && .SHORT TERM...(This evening through Sunday) Issued at 236 PM CDT Sat Aug 7 2021 TODAY...Current satellite imagery places the meridionally elongated positively tilter upper-level trough over eastern WY into western NE. Primary convection has been focused downstream of the trough axis from eastern NE into northern IA and southeastern MN/western WI. This morning`s lingering precipitation has appeared to temporarily halt northerly progression of the surface frontal boundary based on repeated post frontal convection firing in northeast IA. If/when the warm front progresses, low-level moisture transport concentrates into central MN and western WI. Similarly, the NAM & RAP take higher CAPE values further north than the GFS/ECMWF based on the warm sector inclusion. The concavity of the hodographs within the warm sector increase into the afternoon favoring right moving supercells containing max helicity values ~375 m2/s2. RAP 0-3km shear has increased for this afternoon to >40 kts with 0-6km shear remaining at 40-50kts. A few storms could produce large hail and localized flooding with precipitable water values nearing 2.00 inches. Isolated tornadic activity also remains possible, dependent on frontal set up and the ability of elevated convection to become surface-based. TONIGHT...The upper level trough continues it`s eastward progression overnight, bringing our forecast area into a primary area for synoptic ascent. Surface boundaries are forecasted to continue their north and eastward progression associated with the upper & mid-level forcing. Moisture transport increases across central IA into SE MN near midnight local time tonight. Precipitable water values increase to >2 inches along this moisture transport axis, progressing eastward in the early morning hours directed towards central WI. Convective allowing models continue evening convection through the overnight hours, with the HRRR and NAM4km including a training area of higher reflectivity in our forecast area. While the exact location of localized heavy rainfall remains more variable, the synoptic-level variables such as absolute vorticity advection remain favorable for increased convective activity in the early morning tomorrow. The combination of synoptic-level forcing with such high precipitable water values can result in anomalous precipitation in the early morning hours. Currently, RAP shear remains 20-30kt at 0-3kt and minimal 0-6km shear indicating smalled likelihood for organized convection at this time. Will still be important to keep an eye on set up overnight for the possibility of storms repeating over the same areas. .LONG TERM...(Sunday night through Saturday) Issued at 236 PM CDT Sat Aug 7 2021 Water vapor satellite today indicates the approaching long wave trough extended from the wester Dakotas into northern Colorado and was working east toward the region. The pattern ahead of this trough continues to look to be very messy with numerous short wave troughs out ahead of and embedded in the long wave trough. Depending on how tonight`s convection evolves, will have an impact on where the boundaries will set up for Sunday. At this time, there is good agreement from the hi-res meso-scale models that the convection that develops tonight should exit/end early Sunday morning. The attention then looks to be focused on a stronger short wave trough embedded in the equatorial end of the long wave trough that should be swinging across far southern Iowa and Missouri in the late afternoon and evening and translating into Illinois overnight. The low level moisture transport axis will gradually shift east ahead of the short wave trough and looks to briefly be focused into southwest Wisconsin in the late afternoon before shifting farther south closer to the main short wave trough. With only around 25 knots of shear in the 0- 3 km layer, would not expect much potential for hail or winds with the activity that develops in the moisture transport axis across the eastern parts of the area. The bigger threat will be for heavy rains with warm cloud depths in the 3.5 to 4 km range and precipitable water amounts approaching 2 inches. This activity should primarily be southeast of where most of the convection/heavy rains are expected to occur tonight. Thus not anticipating the need for a flash flood watch at this time, but of course, that can change based on what happens during the overnight. Attention will then quickly turn to Tuesday with the next system coming in and the potential for severe weather. The system currently just off the western British Columbia coast will quickly rotate across the northern Rockies and should be entering the Upper Midwest Tuesday afternoon. This system looks to have a rather potent short wave trough embedded in the equatorial end of the long wave trough that will be entering western Minnesota by late in the day. In the low levels, the surface boundary looks to possibly be a bit out ahead of the upper level support but an area of low pressure could be moving along the front and be over or near the local area. This type of set up looks to put the best deep layer shear behind the front but there could still be around 30 knots in the 0-3 km layer over the boundary. Ample CAPE looks to be in place ahead of the front with the possibility of 3000+ J/kg MLCAPE. Some signals of enhanced 0-1km shear along a warm front extending from western Wisconsin into the southeastern part of the state. These signals would suggest that all severe threats could be in play Tuesday afternoon along with the potential for another heavy rain episode. The low level moisture transport looks to be focused into the warm front with warm cloud depths of 3.5 to 4 km and precipitable water amounts again around 2 inches. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 629 PM CDT Sat Aug 7 2021 As of now, all the convection has moved off to the east of both airports. More convection is expected to develop later this evening into the overnight. The front has remained nearly stationary and will not move much overnight. As the low level jet ramps up overnight and intersects the front, a east/west line of convection is expected to form in the Interstate 90 corridor. This will likely impact both airports with MVFR/IFR conditions. This should hopefully end around sunrise with VFR conditions developing by mid to late morning. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...Flash Flood Watch through Sunday morning for WIZ029-032>034- 041>044-053>055. MN...Flash Flood Watch through Sunday morning for MNZ079-087-088-095- 096. IA...Flash Flood Watch through Sunday morning for IAZ010-011. && $$ UPDATE...Zapotocny SHORT TERM...JAR LONG TERM...04 AVIATION...04
Area Forecast Discussion
National Weather Service Bismarck ND
937 PM CDT Sat Aug 7 2021 .UPDATE... Issued at 937 PM CDT Sat Aug 7 2021 We added areas of fog to the forecast from 09-15 UTC roughly along and east of a Harvey-Steele-Ashley line with this update based on a residual moist boundary layer with dewpoints in the 60s F, light winds, and evening precipitation. Recent HRRR and GLAMP cycles all support that. Otherwise, the convection associated with the MCV in the James River valley as of 0230 UTC has gradually been weakening and that trend is expected to continue given its upscale growth, decreasing bouyancy with the onset of nocturnal cooling, and the absence of a notable low-level jet. Moreover, the MCV is steadily shifting eastward and extrapolation suggests precipitation chances in our forecast area should end by about 06 UTC, if not earlier. UPDATE Issued at 623 PM CDT Sat Aug 7 2021 New convection has initiated on the eastern and northern arcs of ascent downstream of the long-lived, slow-moving MCV centered in far south central ND as of 2315 UTC. The convective environment is characterized by moderate instability with MLCAPE of 1500-2500 J/kg, but poor midlevel lapse rates around 6 C/km and effective- layer shear on the order of 20 kt per recent VWP hodographs and RAP-based objective analyses suggests the severe-storm risk will continue to be minimized. This scenario was already well-handled in the current forecast, with precipitation chances highlighted along and east of the MCV through the evening, mainly along and south of I-94 and along and east of ND Highway 6. Thus, while we did refresh forecast fields through Sunday using the most recent NBM cycles, little overall change was needed with this update. && .SHORT TERM...(This evening through Sunday) Issued at 202 PM CDT Sat Aug 7 2021 An MCV continues churning very slowly along the ND/SD border near the Missouri River. Not a lot of thunder remains with the system as of now, although CAMs are fairly consistent in the idea that it will redevelop as it moves further east this afternoon and the environment becomes more unstable. Even with a bit more unstable environment, more favorable wind shear is progged to remain further south and east of this system. Thus, while strong thunderstorms are possible and a storm or two could pulse to severe levels near or over the James River Valley, severe weather is generally not expected this afternoon. Cloud cover continues to clear out behind this system with smoke still blocking out the blue of the sky over most of the area. Conditions dry out for the day Sunday with hot temperatures returning and highs reaching the low to mid 90s for most of the forecast area. .LONG TERM...(Sunday night through Saturday) Issued at 202 PM CDT Sat Aug 7 2021 Another trough begins to enter the area Sunday night with the best precipitation chances during the day Monday, especially for the northern third of North Dakota. By Tuesday afternoon, any remaining remnants of the system will likely have moved out of the area and the remainder of the extended period looks dry. High temperatures on Monday range from the mid 70s in the northwest to the low 90s in the southeast. Otherwise, high temperatures look seasonable for this time of the year as northwest flow persists over the region Tuesday through the remainder of the workweek. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 937 PM CDT Sat Aug 7 2021 Showers and thunderstorms with local MVFR to IFR conditions in the James River valley should end and/or move out of the area before 06 UTC. However, confidence continues to increase in development of fog and stratus with potential MVFR to IFR conditions in parts of south central ND into the James River valley between 09 and 15 UTC, likely impacting KJMS. Elsewhere, VFR conditions in the west and north will continue through the 00 UTC TAF cycle. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...CJS SHORT TERM...Telken LONG TERM...Telken AVIATION...CJS
Area Forecast Discussion
National Weather Service Denver/Boulder CO
655 PM MDT Sat Aug 7 2021 .UPDATE... Issued at 650 PM MDT Sat Aug 7 2021 Thunderstorms have cleared out of the forecast area completely so have updated to drop them from the grids the rest of evening. Smoke will be the prevalent issue overnight and into Sunday. No other changes needed at this time. && .SHORT TERM...(This evening through Sunday) Issued at 247 PM MDT Sat Aug 7 2021 The passage of the upper level trough can be seen on water vapor progressing across the northern boundary and into the northeastern plains counties. This progression and the associated vort max are helping to drive some convection across Morgan and northeast into Logan, Phillips, and Sedgwick counties over the next few hours. Pressure rises across the northern mountains and into Weld will continue to progress through the forecast area increasing subsidence behind the upper trough. A boundary across Elbert and into northern Lincoln counties helped to fire off some convection that will bring hail, wind and lightning over the next few hours. CAMs have struggled with the convection today as instability has been hampered by smoke impacts with most areas struggling to reach convective temperatures. The added lift provided by the trough and boundary have helped in this department but maintain it will not be widespread and continue to impact areas mainly east of I-25. Dropped temperatures a few more degrees given that solar insolation is nearly at its max and we are still sitting in the upper 70s to lower 80s in most areas. Will maintain lows overnight in the lower 60s with smoke impacts continuing. For Sunday, the upper ridge increases and elongates across the southwest bringing zonal flow over the region. There will be a slight reprieve from smoke during the morning hours before it increases again during the late afternoon to evening per latest HRRR smoke guidance. Post-trough subsidence will help to bring more stable conditions and keep areas dry. High temperatures will be slightly warmer than today but still muted slightly by smoke so reduced a few degrees into the lower to mid-90s for the plains and mostly 70s for the high country. .LONG TERM...(Sunday night through Saturday) Issued at 247 PM MDT Sat Aug 7 2021 Westerly flow aloft will continue through Monday as an upper trough moves across the northern Rockies. This will push a cold front through sometime Monday. Temperatures Monday will depend on the timing of the front and how thick the smoke is. There will likely be another batch of smoke concentrated along the front/trough, though there could be cleaner low level air behind the surface front since that air will likely be coming from less smoky areas of the northern Rockies. The current forecast of mid 90s looks alright for now, but it might not get that warm. For the middle and later parts of the week, we`ll have decreasing northwest flow aloft. It will be quite dry for a couple of days, and highs will likely still be in the 90s. Our air will be coming more from the northwest border areas, so the smoke will depend on fire activity in that region. There will be some, it`s just a matter of how much. By the end of the week, there should be gradual moistening after another weak surface front about Thursday combined with mid level moisture creeping up into the ridge from the southwest. At this point it still looks like limited moisture and still warm aloft, so a gradual increase in convection is in order. Since we`ll be sitting under the ridge axis, we could start to see a burn area flood threat again by Friday or Saturday. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) Issued at 650 PM MDT Sat Aug 7 2021 Smoke will result in ILS approaches and reduced visibility through midday Sunday. Visibility anywhere from 4 to 7 SM expected. North/northeast winds early this evening will return to normal drainage winds 03Z-06Z. && .FIRE WEATHER... Issued at 247 PM MDT Sat Aug 7 2021 Fire danger will be elevated in most areas through Sunday with humidity levels dropping into the 10-18% range in lower elevations, with 20-30% above 8000 feet. Currently however winds are expected to remain below criteria with some increased gusting up to 25 mph across the northern mountains and high mountain valleys. There will be some enhancement of fire danger on Monday afternoon with stronger winds over the mountains and low humidities. Fuels are pretty green for this time of year in the windier areas though. Tuesday will likely see a bit less wind but quite low humidities over the northern mountains. && .HYDROLOGY... Issued at 247 PM MDT Sat Aug 7 2021 No hydro concerns for the burn areas through Sunday with no significant rainfall expected. A small flood threat for the burn areas may return by Friday or Saturday as moisture increases with slow storm motions likely. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Cooper SHORT TERM...Bowen LONG TERM...Gimmestad AVIATION...Cooper FIRE WEATHER...Bowen HYDROLOGY...Bowen/Gimmestad
Area Forecast Discussion
National Weather Service Des Moines IA
640 PM CDT Sat Aug 7 2021 ...Updated Aviation Discussion... .DISCUSSION.../Tonight through Saturday/ Issued at 326 PM CDT Sat Aug 7 2021 The primary messaging highlights through the period include... * Convective trends and severe weather potential into tonight, and again Tuesday * Heat and humidity Monday * Convective trends and severe weather potential Tuesday * Cooler, drier, pleasant weather to end the week The immediate concern will be convective trends into the night, and is a waiting game for the moment. The current situation has three areas of concern west to east: a surface cold front across central NE, weaker elevated convection approaching the MO River across NE, and a warm front across southern MN into northeast IA. The weak upstream elevated convection across NE certainly has inhibition limits keeping that essentially steady-state as it moves into western IA early this evening and is not a severe weather concern. Similar inhibition concerns exist farther upstream along the cold front, but the convection allowing hi-res models (CAMs) continue to suggest this will be our primary event with the combination of synoptic forcing, low level convergence, and a maturing low level jet blossoming an MCS across NE this evening, and reaching western IA just after midnight. The latest RAP suggests plenty of available instability into the evening, maintaining 2500-3500+ j/kg MLCAPEs. Deep shear will be the limiting factor, but most CAMs suggest an eventual QLCS mode leaving strong winds and possibly a transient tornado or two as 0-1km shear and SRH increase with the low level let. As mentioned above, 3-6km winds are less favorable however, limiting sufficient 3km shear to maintain healthy QLCS tor conditions for long, if at all. Farther north along the warm front right now, the tornado parameter space is much more favorable with elevated effective shear, ESRH, 0-3km CAPE and reduced LCLs. Moisture convergence has been steadily increasing near the front all afternoon, with objective RAP analysis indicating CINH has all but eroded. However examination of several GOES-16 images and RGB composites has shown little cloud top cooling or phases changes yet suggesting convective initiation isn`t eminent. If anything happens to form it would likely just brush our northern/northeast counties based on WSW Bunkers supercell projections. Much like the aforementioned upstream convection, this may also wait to activate until larger scale and low level jet influences with similar pluses and minus as noted with the evolution of the NE MCS. By tomorrow morning, upper air and surface features will become further disconnected. Mid level forcing will be crossing the MS River with lower based 850/700 QG forcing still lingering south and east by afternoon. There will be little surface reflection however with a southerly wind component to some degree anticipated, outside of lingering convective boundaries. MLCAPEs are again expected to surge into the 2500-3500 j/kg range, but with low level focus and deep shear lacking, the severe weather potential should be reduced. The low level jet and associated moisture convergence should be south and east of the area by Sunday Night, but lingering support along and ahead of the 1-3km trough may keep spotty weaker convection going into the night as well, especially east. For Monday, the primary theme will be heat and humidity as the the upper trough now approaching BC/WA reaches the northern Rockies and begins to be our primary influencer. A developing warm front across northern IA associated with the aforementioned low may limit the northward extent of the warm conditions, but highs are still expected to reach the lower 90s area wide. However with oppressive dewpoints well through the 70s, peak heat indices should still reach 100-105 central and south even with temps not being extreme. The northern Rockies trough should be into the Dakotas by midday Tuesday with the associated surface trough/weak front and synoptic scale lift into central and southeast Iowa during the afternoon. Low level convergence and large scale support should develop at least scattered convection into the evening, but there is some inhibition concern due to warm 1.5km temps. If anything develops there will certainly be adequate instability available with 2500-3000 j/kg MLCAPEs and steep lapse rates aloft leading to some hail and wind potential, but the wind profile is unimpressive with weaker low and mid level flow resulting in corresponding lower shear values. Thus any severe threat seems brief seems somewhat limited to a degree. A pattern change will be the main weather story for the end of the period as a Canadian mean trough matures and pushes a cold front through late Thursday. This environment will again include moderate to high instability, but the severe potential offset by inhibition and continued lack of deep shear. Subsidence and cooler, drier northerly flow should finally usher in pleasant weather and a refreshing airmass change for the weekend. && .AVIATION.../For the 00Z TAFS through 00Z Sunday evening/ Issued at 627 PM CDT Sat Aug 7 2021 Still anticipating convection overnight into Sunday morning, but the latest hires models suggest less coverage and duration across central Iowa. Thus shrunk the window for convection to mainly from 06-10z and then another chance b/t 13-17z Sunday. Low confidence with any MVFR visibility or ceilings and left out mention attm. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...Small AVIATION...Podrazik
Area Forecast Discussion
National Weather Service Grand Junction CO
538 PM MDT Sat Aug 7 2021 .SHORT TERM...(Tonight through Sunday night) Issued at 202 PM MDT Sat Aug 7 2021 Hot topic of the day continues to be the dense smoke that has engulfed our forecast area from wildfires burning across California, Oregon, Washington, Idaho and Montana. What should have been a bluebird day has deteriorated into the grey abyss. No real good news at this point with poor air quality likely to persist as high pressure over the Great Basin continues to guide the dense smoke across the Great Basin and then driving it southeast across Eastern Utah and Colorado. Latest HRRR smoke runs indicate some subtle improvement late tonight and Sunday, so backed off definite smoke wording into more of the "areas of" wording. The good news about the smoke is that it`s helped to knock temps down a few more degrees off the already cooler forecast temps for today. Expect mild conditions tonight and for max temps on Sunday to nudge up a few degrees with a bit more sun expected and significant warming at the h7 level. Otherwise, this is a dry forecast for the next 36 hours with locally gusty winds during the late afternoon/early evening hours, especially in areas of clearing or thinning smoke. .LONG TERM...(Monday through Saturday) Issued at 202 PM MDT Sat Aug 7 2021 A closed low will move east across the Northern Rockies Monday, increasing the pressure gradient over much of the Intermountain West. This will lead to breezy conditions across northeastern Utah and northwest Colorado, and potential critical fire weather conditions. High pressure will build into the Great Basin following the passage of the closed low, keeping the region under clear skies and generally dry conditions. Temperatures will run 5-10 degrees above average through this period. The bulk of the moisture looks to remain to the south, although enough may sneak north into the Four Corners region that a slight chance of late-day showers or thunderstorms will be possible from mid-week onward, mainly along the Continental Divide. By late week, models are hinting at a return of monsoonal moisture to western Colorado and eastern Utah. Confidence is still very low, as there is quite a lot of model disagreement. Stay tuned. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 536 PM MDT Sat Aug 7 2021 Obviously, the big story is the smoke and restrictions to visibility it`s bringing. Currently, vis has dropped to between 3 to 5SM across the area. These MVFR conditions will continue through 03Z and should then lift to 6SM but the smoke does look to linger. Similar conditions tomorrow with a few gusty afternoon winds mixed in as well. && .FIRE WEATHER... Issued at 202 PM MDT Sat Aug 7 2021 High pressure centered over the Great Basin will continue to sweep widespread smoke from Western Wildfires across the region with significantly reduced visibility at times. These conditions are expected to persist through at least midweek. There will be a few weak disturbances passing to the north, increasing winds a bit and resulting in heightened fire weather concerns Monday. Next chance for more moisture and showers moving back in looks to hold off until late in the week when another push of monsoonal moisture will attempt to lift northward across Arizona. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...JDC LONG TERM...BGB AVIATION...TGJT FIRE WEATHER...JDC
Area Forecast Discussion
National Weather Service Goodland KS
945 PM MDT Sat Aug 7 2021 .UPDATE... Issued at 703 PM MDT Sat Aug 7 2021 Conditions have improved in Gove, Greeley, Logan, and Wichita counties allowing the Severe Thunderstorm watch to be cancelled. && .SHORT TERM...(This evening through Tuesday) Issued at 200 PM MDT Sat Aug 7 2021 Tonight...strong to severe thunderstorms are expected generally east of the Colorado Kansas border this evening as a weather disturbance moves off of the Palmer Divide and into the area this evening, exiting the area before midnight. It appears that a line of storms will develop along and south of the interstate with an east then northeast movement. DCAPE values early this afternoon are in the 1500-1700 range and support the last few runs of the HRRR wind gust forecast in excess of 75 mph. Hail up to the size of golf balls and locally heavy rainfall will also be possible. Smoke will also be possible for much of the night producing some reduced visibilities and unhealthy air quality. Sunday-Sunday night...a sunny sky is expected during the day with a clear sky overnight. High temperatures are expected to be in the low to upper 90s with low temperatures in the low to upper 60s. Monday-Monday night...some mid and high level clouds move in during the afternoon, moving east and out of the area during the night. There is a slight chance for showers and thunderstorms near the KS/NE border. High temperatures rise back into the mid 90s to around 102 degrees with low temperatures in the upper 50s to around 70. upper level trough moves across the northern plains with its cold front moving through during the day. High temperatures arent quite as hot as Monday with readings in the low to mid 90s. No precipitation is currently expected. .LONG TERM...(Tuesday night through Saturday) Issued at 131 PM MDT Sat Aug 7 2021 The extended period continues to trend hot and dry for majority of the period thanks to the ridge over much of the western CONUS. There is concern for elevated to near-critical fire weather conditions Wednesday and Thursday in the northwest corner of the area due to low relative humidity values. The current forecast keeps the winds peaking around 20 mph during the afternoon hours. Overnight lows on Tuesday are expected to be in the upper 50s to mid 60s. Temperatures appear to briefly increase in the middle of the week with values in the 90s across much of the area and a few locales along and west of US 83 approaching 100 degrees Wednesday. Thursday is currently expected to be slightly warmer, ranging from the mid 90s to 100 degrees. Overnight lows are forecast to remain in the upper 50s to upper 60s both nights. A cold front is expected to move south across the area Friday morning. With the front, temperatures are expected to cool into the upper 80s to lower 90s for afternoon highs. Behind the front, guidance suggests a few weak disturbances will move across the High Plains providing an opportunity for showers and storms to develop Friday afternoon and continue through Saturday morning. This far out confidence is not very high, so PoPs are less than 20%. Overnight lows are expected to be in the upper 50s to mid 60s. Saturday, both the GFS and ECMWF have a shortwave trough traveling along the edge of the ridge, which will help strengthen a lee trough along the Front Range. This could provide yet another opportunity for showers/storms to develop off the Front Range and move across the Tri-State area during the afternoon and evening hours. Temperatures are currently forecast to be close to normal in the mid 80s to lower 90s for afternoon highs and the upper 50s to lower 60s overnight. && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 935 PM MDT Sat Aug 7 2021 KGLD begins the 06Z TAF period with MVFR conditions with visibility at 5SM due to smoke from the western wildfires residing over the terminal along with westerly winds at 6 kts. By 10Z, VFR conditions come to KGLD as the smoke clears and visibility improves with winds increasing to 9 kts before turning northwesterly at 14Z. At 18Z, KGLD winds slow to around 4 kts then become southerly around 6 kts by 00Z. KMCK expects to see VFR conditions throughout the 06Z TAF period starting with westerly winds around 5kts. At 14Z, KMCK sees winds turning northwesterly before turning southerly at 23Z and then becoming southeasterly around 7 kts at 03Z. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...MRC SHORT TERM...99 LONG TERM...KMK AVIATION...076
Area Forecast Discussion
National Weather Service Gray ME
1037 PM EDT Sat Aug 7 2021 .SYNOPSIS... A weak cold front will settle into the region tonight with a few showers and thunderstorms. This front will stall over the region tonight and serve as a focus for additional shower and thunderstorm activity on Sunday with locally heavy downpours possible. After temperatures cool somewhat for Sunday and Monday...the remainder of the coming week is looking increasingly warm and humid with shower and thunderstorm chances gradually increasing. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... High Impact Weather Potential: *Patchy dense fog possible tonight. 1035 PM...Convection associated with the weakening and slowing sfc front is winding down to a few showers late this evening and should be done by midnight. Expecting fog to develop in the valleys, and in places across nrn NH where it rained this evening. Temps in the S a touch warmer than forecast, but overall mins will come pretty close to prev forecast, generally 65-70 outside the mountains, and in the low 60s in the mtns, and some spots on the mid-coast. 7 PM...Previous forecast working out fairly well as to coverage and location of SH?RA, with a few TSRA as well. The mid-lvl cap /weak lapse rates/ has held fairly well with cells of only moderate vertical extent at best, so mainly just a few heavy downpours and some isolated lightning expected through about 00-01Z in the N zones. To the S, increasing cirrus and mid level clouds expected later tonight, and Tds will only drop off a bit, so lows range from the low 60s in the mtns to the mid- upper 60s in the south. Pattern: Water vapor imagery shows a shortwave trough extending from the Great Lakes region south into the Ohio Valley. East of this trough...we see confluent mid level flow between larger scale troughing east of Hudson Bay and ridging off the Atlantic coast. Through the near term...the larger scale trough to our north will push east while the shortwave to our west cuts off from the stronger westerlies to its north. A cold front associated with the northern trough has moved towards our northern zones with shower/embedded thunderstorm activity. The progression of this feature as it slowly drops south /becoming increasingly parallel to the mid level flow/ will be our focus for the overnight forecast. Through this evening: Showers have very slowly increased in coverage over the past two hours and expect this to continue into the evening with a couple of thunderstorms possible. Some gusty winds remain possible given modest DCAPE values especially over interior western ME...but feel the severe threat is rather low. By 8pm...expect temperatures to fall back into the 70s for most spots...with MHT-ASH- PSM likely remaining at or above 80. Tonight: Waning instability should allow shower/storm activity along the front to weaken with the front slowly moving towards southern NH by daybreak Sunday. Interestingly...recent runs of the HRRR and the 07.12Z NAM are more robust with wave of low pressure forming off the Delmarva overnight. While this feature will remain well south of our forecast may help to back the llevel flow to more southerly across southern New England towards daybreak Sunday...potentially providing for lift over the stalled frontal boundary. Thus...will carry a small chance for a shower towards daybreak in this area. The other potential sensible weather impact will be fog....which is likely across the northern valleys where there will be some partial clearing north of the front. Depending on frontal timing...some fog is possible along the coast of ME before the flow turns northerly...but the window for this is pretty short. Cloud cover and the stalled front over southern areas will lead to a warm and muggy night with a few spots potentially not falling below 70...with 60s expected elsewhere. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... High Impact Weather Potential: * Localized flood potential Sunday due to slow moving storms. * Dense fog possible Sunday Night. Sunday: Stalled frontal boundary remains over southern zones with the llevel boundary layer flow turning more southerly over New York and western New England. At the same time...weak area of surface low pressure south of New England will sit and spin as it/s parent wave remains cut off from the stronger mid level flow to the north. The focus of our attention will be along the boundary and some implied lift over it in the midst of very weak mid/upper level flow given the cutoff to our south. Temperatures aloft will be just a bit lower than on Saturday with mid level lapse rates improving /H7- 5 lapse rates nearing 6C/km / Thus...expect a decent amount of instability /500-1000 J/kg MLCAPE/...but in the presence of less than 10kts of deep layer shear. Triggering mechanism will likely be the residual frontal boundary likely draped somewhere across the southern half of NH with the CAMs pinpointing this area as well as the mountains as locations for convective initiation. Slow moving- pulse storms would be the favored mode which naturally suggests flooding as the greatest concern. CAPE profiles look skinny with PWATs at or a bit above 1.5" with wet bulb zero heights over 11kft. Thus...completely agree with WPC`s day 2 marginal risk of excessive rainfall given what looks to be the potential for isolated areas where flash flooding is possible. As for temperatures...T8s will drop just a bit from today with upper 70s north to lower/middle 80s south. Despite the somewhat cooler air aloft...llevel dewpoints look to pool some along the stalled frontal boundary and therefore push over the 70F mark over southern areas which may allow heat indices to again reach the 90F mark in parts of southern NH. Sunday Night: As mid level cutoff moves east over southern New England...heights will actually rise over the Gulf of Maine. This will bring a building influence of high pressure over the Canadian maritimes with marine air making a decided push west. See little in the way of forcing through the overnight for shower/storm activity and thus...outside of dwindling PoPs in the evening given the loss of instability will keep the night mostly dry. What the marine influence will likely encourage is fog development and will include mention throughout the forecast area. The setup favors the potential for dense fog again in the northern valleys...but also along the ME coast from PWM north to RKD and up to AUG. Another relatively mild night will be in store...but a good bit cooler than on Saturday night over the southern part of the forecast area given the marine push. Expect lows generally in the lower 60s. && .LONG TERM /MONDAY THROUGH SATURDAY/... The main story next week will be increasing heat and humidity over the region with bouts of showers and storms. We can thank the synoptic/hemispheric pattern for this trend, with the Bermuda high in place expanding west into the southeast CONUS... which in turn sets up deep southwest flow into the Northeast. Looking at ensemble anomalies and extremes, warm and humid conditions peak late in the week... around Thursday into Friday. This is well supported by CPC outlooks calling for a 60+ percent chance of above normal temperatures in the 6-10 day period, indicative of the grander scale trend. The coolest day next week will be the first one... on Monday, a steady onshore flow will continue as cut off low pressure crosses south of New England. As mentioned in the short term discussion... the marine layer will be actively pushing into the area with morning fog and possibly a stratus deck... in addition to the higher clouds present from the upper level low. Thus am expecting temperatures to be limited to the 70s over Maine, warming to the low-80s by the time you get to the Merrimack and Connecticut River Valleys. Coolest conditions will be felt along the coast, particularly the Midcoast where temperatures may struggle to hit 70. Cloud cover will have major bearing on temperatures, so those trends are what we`ll look to for the temperature forecast. A few showers are possible as the cut- off low makes its closest approach later in the day. Ridging behind the eastward- drifting cut off low will suppress showers and storms through Tuesday, except for possibly over the mountains and Connecticut River Valley with continued S/SErly flow transporting a humid airmass upslope to where better heating and instability can be realized. Still only have just a slight chance of a shower or storm there however. The remainder of the work week comes down to timing out subtle waves generating showers and storms in westerly to southwesterly upper level flow. Little confidence is offered in terms of timing these waves, however the ever warming and moistening atmosphere will almost certainly offer the instability to produce diurnally driven shower and storm activity, enhanced and prolonged into the overnight hours when forcing is nearby. As mentioned previously the main story will be temperatures... h850 temperatures are progged to trend steadily warmer Wednesday through Friday with readings of +20C possible by early Friday (and an ensemble mean a little closer to +18C). This may be somewhat moderated by clouds from increasing convective activity however. High temperatures thus increase to the 80s to near 90 Wednesday to Friday, although it could go as warm as the mid-90s where better mixing occurs (southern interior) by Friday. When combined with dew points around 70 degrees, give or take, conditions may warrant heat advisories across the southern interior. On the flip side onshore flow will keep conditions a little more hospitable along the Midcoast of Maine with highs in the 70s to low-80s. Warm overnights may be the more impactful, only cooling into the mid/upper-60s... closer to 70 for our population centers, indicative of the humid air mass. Toward the end of the week, there is deterministic model consensus signaling a late-week cold front that will deliver relief from the heat along with more showers and storms. Will curb my enthusiasm for now since cold fronts that far out in model guidance tend to slow and weaken as initialization nears the event... but the upper level wave is there regardless. Just a matter of surface front progression, which will be tricky since the front will be near the international border for much of the latter half of the week, waffling north and south as weaker waves pass aloft. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... Short Term... Summary: A cold front will settle into the region tonight with a few showers and thunderstorms and some patchy overnight fog developing. Another round of isolated afternoon showers and thunderstorms is expected on Sunday before more widespread stratus and fog develop Sunday night. Restrictions: VFR attm all sites and this will generally continue through this evening outside of a few showers and embedded thunderstorms which may impact LEB-HIE late this afternoon and early evening. Tonight...LIFR/IFR fog is likely at these terminals with some fog possible at RKD/AUG as well. On Sunday...isolated restrictions in SHRA/TSRA possible away from the coast...with more widespread IFR fog/low stratus for HIE/LEB and our ME terminals Sunday night. Winds: South and southwesterly winds around 10kts will diminish to light and variable overnight and remain less than 10kts from the south on Sunday before going calm/light-variable Sunday night. Lightning: Isolated TSRA possible LEB-HIE through this evening and again Sunday afternoon in all areas away from the coast on Sunday. LLWS: No LLWS is expected through Sunday night. Long Term...While VFR is expected to prevail for most of next week, periodic restrictions are likely for all terminals with little confidence in timing. MVFR/local IFR is possible in FG/BR and low ceilings over the coastal plain early Monday. Tuesday looks to be VFR except for perhaps some patchy fog early in the morning. Wednesday through the end of the week features more unsettled weather with daily restrictions chances in -SHRA/TSRA and overnight BR/FG. && .MARINE... Short Term...Winds and waves are expected to remain below small craft levels through Sunday night as a weak cold front settles into the region and dissipates over the waters. Marine stratus and fog is likely Sunday night as easterly flow begins to develop. Long Term...Next week starts with high pressure firmly in place over the waters. While there will be steady pressure falls through the week, culminating in what may be a late-week cold frontal passage, conditions should remain fairly quiescent in terms of winds and waves. Rain showers and a few storms will be possible at times, but am not expecting a ton of activity over the waters... with the most consequential weather conditions likely being periods of fog. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ SYNOPSIS...Arnott NEAR TERM...Arnott/Cempa SHORT TERM...Arnott LONG TERM...Casey AVIATION...Arnott/Casey MARINE...Arnott/Casey
Area Forecast Discussion...UPDATED
National Weather Service Twin Cities/Chanhassen MN
1058 PM CDT Sat Aug 7 2021 .UPDATE... Issued at 724 PM CDT Sat Aug 7 2021 A Flash Flood Watch has been issued for parts of west central WI due to the likelihood of training thunderstorms tonight into early Sunday. A line that has since diminished had produced 2 to 4 inches in the vicinity of Eau Claire earlier this evening. Similar occurrences could unfold later this evening as another batch of thunderstorms develops late. Otherwise, PoPs were reduced substantially elsewhere this evening. Little forcing has prevented development so far and it may wait until the compact, potent wave over north central SD begins to approach. && .SHORT TERM...(This evening through Sunday night) Issued at 230 PM CDT Sat Aug 7 2021 Short term concerns haven`t changed much, and continue to focus on potential for convection (possibly severe) this afternoon into tonight. Latest mesoanalysis and satellite imagery show the surface warm front near the Minnesota Valley at the current time. It continues to make some progress northward, and should get near the south metro by later this afternoon. MLCAPE south of the boundary is in excess of 3000 J/Kg, but decent values exist on the "cool side" of the boundary as well given the high dewpoints north of the front. The best deep layer shear (per effective bulk shear) is mainly north/east of the surface boundary, but there is some overlap where greater than 35 kt is available to storms. The best low level shear (per 0-1 km bulk shear) is to the south in western Iowa and to the southeast of the area. However, there is a ribbon along the frontal boundary where winds are backed and values near 20 kt are indicated. So, there is certainly sufficient instability for some severe storms capable of large hail and downburst winds, and there is also at least a portion of the area where supercells could produce isolated tornadoes late this afternoon into this evening. The CAMs have struggled, as usual, with much of the elevated convection we`ve seen, which makes it tough to rely on their handling of redevelopment of boundary layer-rooted convection this afternoon/evening. The HRRR has been reasonably consistent in its runs today, and does manage to generate isolated storms near the warm frontal boundary around/after 22Z, with more widespread activity near and after sunset as the low-level jet increases with the upper trough to the west getting closer. Given that heights are currently rising a bit in southwest Minnesota ahead of that trough (and the cap is strengthening per model soundings in that area), it seems later timing make sense (other than perhaps some isolated earlier storms forced along the boundary. All of the CAMs increase the coverage of activity later this evening into the overnight, so everything could certainly evolve more toward a heavy rain scenario as the night progresses. The best chance for storms on Sunday will be over the eastern portion of the area, but some low PoPs seem warranted across most of the area given lingering instability. .LONG TERM...(Monday through Saturday) Issued at 230 PM CDT Sat Aug 7 2021 Although we currently have an upper trough moving through it, the large scale flow across the CONUS is predominantly zonal and looks to remain that way through Tuesday. At that point, the upper low along the British Columbia coast will be making its way into our region, and looks to push through late Tuesday into early Wednesday, bringing a renewed chance for precipitation as it drags a cold front through the area. Ridging builds in the western CONUS and Canada in the wake of that system, setting up northwest flow our area, which looks to linger into next weekend. This should bring warm and dry weather for the second half of the week in to next weekend with any precip chances looking too low to mention at this point (tied to weak shortwave troughs dropping southeast with the upper flow). && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1058 PM CDT Sat Aug 7 2021 IFR cigs overnight across central and western Minnesota overnight. Continued to leave -TSRA out of most TAF sites through the period due to such low confidence in occurrence, however did add a tempo in for MKT and EAU. Cigs will improve Sunday morning. KMSP...IFR likely into early Sunday. Thunderstorms are still possible toward sunrise, but confidence is low enough to keep mention from this TAF issuance. /OUTLOOK FOR KMSP/ Mon...VFR. Wind SE 5 kts. Tue...VFR. Chc -TSRA. Wind S 5-10 kts becoming W. Wed...VFR. Wind W 5-10 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...None. WI...Flash Flood Watch until 10 AM CDT Sunday for Chippewa-Dunn-Eau Claire-Pepin. && $$ UPDATE...Borghoff SHORT TERM... LONG TERM... AVIATION...Borghoff
Area Forecast Discussion
National Weather Service San Francisco Bay Area
841 PM PDT Sat Aug 7 2021 .SYNOPSIS...Onshore flow during the afternoon and evenings this weekend should help improve air quality from yesterday`s smoke. Gradually cooler and wetter conditions over the coming days and into early next week, then, warmer and drier late next week. && of 08:41 PM PDT Saturday...Much of the state remains blanketed in smoke from various wildfires while satellite imagery shows low clouds along much of the coastline. Expect low clouds to move inland to the valleys overnight and persist through mid to late tomorrow morning before dissipating. The marine layer is still sitting at about 1,500 ft AGL per the Fort Ord Profiler. Humidity values along the coast are quite high between about 70 and 90 percent where inland locations and areas above the marine layer are still fairly dry in the 20s and 30s. Temperatures this evening are about 5 or so degrees cooler than yesterday as an upper trough sits off the coast of the Pacific Northwest. The forecast remains on track with continued cooling tomorrow by about 5 or so degrees. Expect afternoon highs in the 60s to low 70s along the coast, 70s to low 80s around the Bay Shoreline, and mid 80s to mid 90s inland. Gradual warming is then in store for next week as high pressure builds over the eastern Pacific and over the Great Basin simultaneously. Triple digit heat may be headed our way late next week and into the weekend across the interior. Will have more details over the coming days. The latest HRRR smoke model forecast shows gradually improving total and near surface smoke tomorrow afternoon and evening as we get another good push of onshore winds. Smoky conditions look to linger a bit longer at the far eastern boundaries of the forecast area into tomorrow night, but should still be an overall improvement compared to the past couple of days. For additional details please see the previous discussion. && .PREV of 01:45 PM PDT Saturday...Early afternoon satellite imagery definitely does not show clear skies across the state for us today. Instead, a vast swath of wildfire smoke exists throughout most of non-coastal Northern and Central California and remnant marine stratus and stratus eddy circulations but less smoke populate the coastal areas. This smoke is sourced from a number of wildfires, including the Dixie, River Complex, Monument, and McFarland, but it is primarily the smoke that was transported southward on the lee of Thursday night`s trough from the Siskiyou and Trinity county fires that have resulted in our local hazy to smoky conditions yesterday and again today. While we are not directly receiving smoke from the Dixie fire as it is transporting S-SE, it is worth noting at the state level that this fire has become historic in size/impacts and has prompted to closure of Lassen National Park and damaged or destroyed communities near Lake Almanor. Thus far, the wildfire smoke has been modeled fairly well by the HRRR, both at the near-surface and total column data levels. The HRRR may not have completely nailed the timing or coverage, but the main message was spot on. This message indicated that most smoke would remain suspended aloft above the marine layer, some would filter down midday prior to the arrival of the sea breeze, and then the afternoon/evening seabreeze would push the smoke deeper inland without completely clearing it out. This scenario played out yesterday and is expected to play out again today, and once more tomorrow. Each smoke day has/will see successively more onshore flow and lower smoke concentrations between yesterday and tomorrow. Latest HRRR near surface/vertically integrated datasets indicate that tomorrow`s onshore seabreeze should be sufficient in evacuating most of the smoke out of the coastal and bayshore areas, while some may continue to linger in the deeper reaches of the interior valleys. Additional pulses of more smoke from the north is possible over the coming days, but given a tendency towards weaker fire growth in the fires to the north, and more of easterly component to the the transport winds, the worst looks behind least for this event, by tomorrow evening. Please use this event as a reminder that the state is in a significant drought and more wildfires are likely. This is the perfect opportunity to consider your plans to mitigate the impacts of worse smoke events or potential wildfires in your area. Smoke aside, today is running 3 to 10 degrees cooler than the same time yesterday as a cooler, moister air mass settles in to place behind the retreating high pressure influence to the south. This trend will continue into Sunday with further cooling and deepening of the marine layer expected for tonight into tomorrow as low pressure troughing nudges nearer from the northwest. Looking ahead to the coming week, seasonable conditions will become gradually warmer and drier as ensemble cluster analysis are all in good agreement that strengthening high pressure along our periphery is in our future. Both an eastern Pacific/Gulf of Alaska high and Great Basin high are looking increasingly likely to build to our north and east and could both eventually strengthen and merge into a more robust high pressure system along our borders by mid to late next week. Surprisingly, not seeing a lot of higher temperatures associated with this potential scenario in the ensembles members just yet, but given that NBM percentiles show possibilities of record temperatures just along and offshore of the Central Coast... have decided to nudge days 5-7 closer to the hottest 90th percentile of members in order to at least account for the possibility of warmer conditions. That said, could see triple digit air temperatures throughout the interior by late next week. It remains to be seen what these potential warmer (and drier) conditions could do to fire behavior... and production of smoke. Smoke trapped under any possible heat ridge would be tougher to scour out than it would be under neutral flow or troughing. && of 05:05 PM PDT Saturday...For the 00z TAFs. Satellite imagery shows stratus has cleared back to the coast, though wildfire smoke is pervasive. This will reduce slant range vis through the period. As onshore breezes pick up this afternoon, smoke may collect downwind in interior valley locations, potentially reducing surface vis at terminals such as KLVK. HZ should also be pervasive, at least until onshore winds help clear out suspended particulates closer to the coast. Stratus will return tonight as the marine layer should rise to around 1500-2000ft. Potential for MVFR/IFR/local LIFR CIGs and reduced vis from HZ/BR. Cigs will lift with lingering HZ as smoke exits the region. Vicinity of KSFO...VFR. Stratus remains offshore, with a few remnant low clouds around the terminal. Hazy skies are observed on area webcams, which will likely impact slant-range vis throughout the day. Typical onshore winds build this afternoon. Medium chance for CIGs returning overnight into Sunday morning around the terminal, with potential MVFR/IFR conditions. HZ will begin to mix out by the end of the TAF period as smoke exits. KSFO Bridge Approach...Similar to KSFO. Monterey Bay...IFR/VFR. Satellite imagery shows stratus over the Bay, Monterey Peninsula and coastal areas. KMRY/KSNS currently VFR but IFR at KOAR/KWVI. These terminals may see CIGs through early afternoon with lingering FEW/SCT through the day. Slant-range vis impacts possible through the day due to FU/HZ. Early return of low CIGs this evening, reducing to IFR/LIFR conditions under stratus and BR/HZ. Cigs will then lift by 16-18Z with lingering HZ through the early afternoon. && of 08:35 PM PDT Saturday...Gusty northwest winds will continue over the northern outer waters through the rest of the weekend with light to moderate breezes across the rest of the waters. Additionally, gusty westerly winds are expected in the afternoons and evenings through the Golden Gate gap and into the Delta. These winds will generate steep waves which may be hazardous for smaller vessels. The sea state remains dominated by steep short period northwest waves at 7 to 9 seconds along with a moderate period southerly swell. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...SCA...Pt Arena to Pigeon Pt 10-60 nm SCA...SF Bay until 9 PM && $$ PUBLIC FORECAST: AS/DRP AVIATION: Diaz MARINE: Diaz Visit us at Follow us on Facebook, Twitter, and YouTube at:
Area Forecast Discussion
National Weather Service New York NY
942 PM EDT Sat Aug 7 2021 .SYNOPSIS... A weak low slowly tracks towards Long Island tonight and then offshore on Sunday. The low then drifts away from the region and dissipates later Monday and Monday night. High pressure remains over the western Atlantic for much of the week. A cold front approaches very late in the week. && .NEAR TERM /THROUGH SUNDAY NIGHT/... A weak low pressure was located near Wallops Island as of 9 pm. Showers are located on the northern quadrant of the low, moving along the Delaware and southern New Jersey coastline. Regional radar mosaic shows some of this activity approaching the Long Island coastline and the NYC metro. However, rain has only been reported as far north as Atlantic City so far. The 00z OKX RAOB shows a significant amount of dry air between 500 and 625 mb with RH below 5%. There is also dry air below 625 mb down to the surface. This dry air is going to make it difficult initially for anything more than a few sprinkles to make it down to the surface. Some the returns out there may also diminish as well until the low pressure and stronger lift are able to saturate the column. Subsidence to the north of the low will also aid in making it difficult for rain to spread northward tonight. Have adjusted PoPs to account for the latest trends. There remains a fair amount of spread in the model guidance, but the latest 00z HRRR seems to be initializing fairy well to the current environment. The latest thinking is that the Lower Hudson Valley and southern Connecticut should largely be dry tonight with just mostly cloudy to overcast conditions. A few sprinkles are possible near the NYC metro and Long Island coast around or just after midnight with some showers possible towards day break. Do not anticipate any of this activity to be on the heavy side as the lingering dry air and subsidence north of the low is going to be make it difficult, especially given the compact nature of the low. There could be a few moderate showers that make it across Long Island in the morning, but largely the bulk of the substantial showers should stay just south of the coast. Otherwise, for Sunday a light onshore flow for the most part, along with a good deal of cloud cover will keep temperatures at bay. Expect temperatures overall to average touch below normal with middle and upper 70s across southeastern most coastal sections, to the lower 80s further inland. Clouds will be locked in once again, and the synoptic set up will favor more stable conditions in the lower part of the column. Thus have gone with mainly showers as wx, and have kept out mention of thunder for the most part for now. The exception cloud be for northern parts of the Hudson Valley where an isolated t- storm is possible with more breaks of sunshine, but the overall chances are low for Sunday afternoon and evening. QPF amounts for the low pressure system nudging up from the south should be on the order of a half inch or so across extreme southeastern sections, otherwise look for a few hundredths of an inch elsewhere. For Sunday night look for decreasing clouds very gradually from west to east across the area. Dew point readings overall should remain well into the 60s, thus it will remain humid with night time temperatures continuing to run near normal. As the low slowly pushes northeast look for the ongoing chance of showers across eastern most sections, with mainly dry conditions elsewhere. && .SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... On Monday with little in the way of a pressure gradient look for light winds mainly onshore to begin the day, but then veering to the southeast, then south into Monday night. With more sunshine on average across the area, especially west on Monday look for temperatures to be a few degrees warmer with mainly 80s, with a few upper 70s across eastern coastal sections. More instability is expected by later Monday afternoon, especially further inland so a slight chance of a thunderstorm was included for Monday afternoon and the early evening across the northwestern interior. Any activity should be weak. As far as temps and humidity levels, forecast highs for now have been kept the same with mainly middle and upper 80s for today with a few metro spots hitting 90 across NE NJ. Dewpoint readings indicate moderate humidity with mainly lower and middle 60s through the day.speed shear. The moderately humid conditions will continue into Monday night with dew points remaining mostly well into the 60s, and night time minimum temperatures in the middle 60s to the lower 70s. && .LONG TERM /TUESDAY THROUGH SATURDAY/... High pressure over the western Atlantic will result in a typical summertime airmass with increasingly hot and humid conditions. This comes from a continuous south to southwest flow that will be in place as a result of the region being on the western periphery of surface high pressure that will be anchored out in the Western Atlantic. With respect to temperatures, which will be the main highlight for the week, continued to run with the, NBM 50th percentile which continued to be slightly warmer than other guidance sources. Models are showing a consensus of warming 850mb temperatures to 16 to 18 degrees C Tuesday through Thursday. With temperatures rising well into the 80s and low to mid 90s, coupled with dew points in the upper 60s and lower 70s, heat indices should warm into the mid 90s to lower 100s, with the warmest day on Thursday. For now, Friday should be slightly cooler, but still warm with heat index values in the 90s. As we typically see here in our area, the highest temperatures and heat indices will occur in the NYC Metro, urban Northeast NJ corridor extending into Nassau and southern parts of Lower Hudson Valley into SW CT. For now, it appears the best days for any potential heat advisory criteria to be met would be Tuesday through Thursday, and potentially Friday. There will be a chance each afternoon for showers and thunderstorms each afternoon as daytime surface troughs development. Chances each afternoon will gradually increase through the week. A cold front approaches late in the work week into the first half of the weekend. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... High pressure slowly weakens tonight as weak low pressure approaches from the Middle Atlantic coast late tonight into Sunday. The low should remain just south of Long Island Sunday. VFR tonight. MVFR may develop early Sunday morning as some mainly light showers occur near the coast. Showers are possible near NYC and coastal terminals the rest of the morning, then possibly continuing over Long Island terminals in the afternoon. MVFR ceilings are most likely to occur in the morning, with some improvement to VFR in the afternoon. KISP should see MVFR conditions last the longest into Sunday evening. S-SW winds around 10 kt or less this evening will diminish overnight. Winds will be light and/or variable overnight. The wind direction should become NE- ENE late tonight and continue into Sunday, 5-10 kt. NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Amendments likely for showers and flight categories tonight into Sunday morning. .OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY... .Sunday night...VFR, MVFR is possible early. A chance of showers in the evening. .Monday...VFR. An isolated shower possible with local MVFR. .Tuesday...VFR. A slight chance of thunderstorms in the afternoon and early evening north and west of the NYC terminals. .Wednesday...VFR. Chance of showers and thunderstorms in the afternoon and evening with MVFR possible. .Thursday...VFR. A chance of showers and thunderstorms, likely across the lower Hudson Valley, in the afternoon with MVFR possible. Detailed information, including hourly TAF wind component forecasts, can be found at: https:/ && .MARINE... Wind gusts at times tonight will approach 20 kt across some of the southern most near shore waters and the ocean, but sub-SCA conditions should still prevail. Ocean seas may approach 4 ft at times through Monday, otherwise sub-SCA conditions are expected through the remainder of the forecast period Tuesday through Thursday. && .HYDROLOGY... No hydrologic impacts are expected through the forecast period. && .TIDES/COASTAL FLOODING... There is a moderate rip current risk thru Monday. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...None. && $$ SYNOPSIS...BC/JE NEAR TERM...JE/DS SHORT TERM...JE LONG TERM...BC/JE AVIATION...DS MARINE...BC/JE HYDROLOGY...BC/JE TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Phoenix AZ
407 PM MST Sat Aug 7 2021 .UPDATE...Updated Aviation Discussion. && .SYNOPSIS... Temperatures will remain near normal this weekend with little chance of rain. High pressure lifting north of the region early next week will allow deeper moisture to return to the Desert Southwest. Conditions will become more favorable for showers and storms along with higher chances of below normal temperatures. && .DISCUSSION... Latest RAP streamline analysis depicts a well-defined mid- latitude trough moving steadily eastward into the northern Plains. This has suppressed the Monsoon High into southern Arizona, generally resulting in a westerly flow across the Desert Southwest. While conditions remain moist at the surface with dewpoints in the lower 60s, water vapor imagery reveals dry air aloft overspreading much of the region. Latest mesoanalysis indicates PWATs of only 1.3 inches across central Arizona. This mornings 12z PSR sounding also showed a mid-level subsidence inversion, which is hindering convection this afternoon. The only exception has been across far eastern Gila County, where isolated storms have developed along the tail end of the aforementioned trough. Latest CAM ensemble indicates little potential for activity late this afternoon and this evening and PoPs generally remain below 5 percent. Time-lagged HRRR also suggests very low probabilities for outflow winds above 35 mph. The anticyclone will weaken somewhat Sunday, however dry westerly flow will persist and conditions will generally remain unfavorable for showers and storms. Latest HREF indicates perhaps an isolated cell across Pinal County, though maximum winds will likely remain below 40 mph. Thereafter, models continue to suggest an increased chance of convection Monday, owing to an increase in moisture associated with an approaching inverted trough. An increase in clouds will also temper the heat with forecast high temperatures likely dropping into the lower 100s, which is a few degrees below normal for this time of year. && .PREVIOUS DISCUSSION... Beginning Tuesday a balanced mix of the Cluster family start to show some signals of increasing QPF and storm chances. This is the result of Clusters favoring anomalous high pressure repositioning further to the N and NW of the region which should give easterly waves and inverted troughs in N MX better access to S-Cent AZ. However there is still plenty of uncertainty on the timing and position of any storm intrusions into the region. For now NBM POPS favor 20-40% by Tue-Wed while WPC QPF remains mainly on the modest side. GEFS plumes mean QPF favors fairly diurnal rainfall amounts around Phoenix of approx 0.05-0.07"/day beginning Tue through late in the week. NBM POPs have also nudged up into the low double digits (10-20%) for SW AZ and SE CA by the middle of the week. What is more certain is the moderating effect that the increase in moisture will have on temperatures next week. Highs are favored to fall to below normal by Monday. After that below normal high temperatures remain favored through late next week with highs mostly in the low 100s around Phoenix and 105-110 degrees out west. && .AVIATION...Updated at 2310z. South-Central Arizona including KPHX, KIWA, KSDL, and KDVT: Current stronger than typical westerly winds will continue into the evening, with gusts of 18-22 kt likely. West winds are likely to persist overnight at weaker speeds, with low confidence in any easterly shift occurring at KPHX, while outlying terminals are more likely to see a shift to easterly closer to sunrise. Chances for thunderstorms in the terminal area are low, below 10%, but a few storms could develop close enough to the terminal area giving a 10-20% chance for outflow winds from the south or east. Chances for blowing dust capable of reducing visibility cannot be ruled out, with chances around 10%. On Sunday, westerly winds will increase during the daytime hours, similar to what was seen today. Thunderstorms are not expected. Southeast California/Southwest Arizona including KIPL and KBLH: There are no major aviation weather concerns. At KIPL, light southerly winds will shift back to southeasterly winds overnight and continue into Sunday. At KBLH, winds will favor the south to southwest at speeds of 9-14 kts and early evening gusts nearing 25 kts. && .FIRE WEATHER... Monday through Friday: Highs over S-cent AZ will settle a few degrees below normal and near to slightly above normal in western areas. Storm chances increase Monday and especially Tuesday and Wednesday, with an increasing signal for possibly locally heavier rainfall over south-central Arizona by the middle of next week. Humidity values also improve Tuesday and beyond with the increasing moisture and slightly cooler temperatures. Min RH will remain above 20% in all areas except for the drier parts of SE CA where they will occasionally fall into the upper teens. Apart from thunderstorms, anticipate diurnal southerly breeziness over southeast CA and southwest AZ during the afternoon and evenings (lighter overnight/morning hours). Lighter diurnal winds are favored elsewhere including westerly directions in the afternoon and evening (modest breeziness at times), then favoring downvalley patterns in the overnight and morning hours. && .SPOTTER INFORMATION STATEMENT... Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...Hirsch PREVIOUS DISCUSSION...Sawtelle AVIATION...Hodges/Rogers FIRE WEATHER...Sawtelle
For frequently asked questions about the Area Forecast Discussion
Area Forecast Discussion
National Weather Service Las Vegas NV
840 PM PDT Sat Aug 7 2021 Updated Aviation Section .SYNOPSIS...Smoky skies will persist in areas along and northwest of Interstate 15 through the weekend, and perhaps beyond. Dry weather and minor breezes are expected this weekend with near to slightly above average temperatures. Looking ahead to next week, a return of monsoonal moisture looks likely, especially for northwest Arizona. Chances for showers and thunderstorms return to the forecast for the middle of next week and possibly into the weekend. && .UPDATE...Smoke continued to plague much of southern Nevada, northern Inyo County, and far northern Mohave County this afternoon. Area webcams and surface observations have shown some improvement in the smoke this evening, with visibility slowly increasing as the smoke plume retreats to the north. Think this trend will continue through early tonight as northerly flow diminishes slightly. This also matches up with HRRRSmoke trends through tonight, which shows near surface smokes lifting out of Clark, Nye, and Esmeralda counties. However, as the flow turns more west, additional smoke from central California will likely spread over the region from west to east. So it is likely that, while there may be improvement in conditions tonight, smoke will move back in by Sunday morning to many of the same areas that dealt with smoke and haze today. Other than the smoke issues, quiet weather is expected tonight. Light winds, clear skies (where not obscured by smoke), and dry conditions are expected. Overnight lows should be comparable to last night. && .PREVIOUS DISCUSSION...145 PM PDT Sat Aug 7 2021 .SHORT TERM...through Sunday night. Visible satellite loop showed very few clouds areawide, with thick smoke blanketing the southern Great Basin and northern Mojave Desert, roughly along and north of a line from Olancha to Las Vegas to Mount Trumbull. Most of the smoke originated from the wildfires in northern California, most notably the Dixie Fire. The 18Z run of the HRRR Smoke model shows very slight erosion from the south through the early evening, but then another slug of smoke west of the Sierra makes it to the Tehachapi Gap, catches the typical evening westerly wind push in that area, and makes it all the way to Las Vegas and the Colorado River by early Sunday morning. The smoke has held temperatures down below forecast highs today, and with another murky day in store for all but the southeast third of our area tomorrow, manually adjusted forecast highs down for Sunday as well. .LONG TERM...Monday through Saturday. Models continue to show a more active weather pattern developing across the region next week. Both the EC and GEFS show a broad high developing over the four corners region early in the week. This high will then gradually shift westward and elongate during the second half of the week. Both models are also hinting at a series of inverted troughs passing south off the area across the Sonoran Desert on Tuesday and again on Saturday. The combination of these features should result in increasing southeasterly flow aloft that will bring higher moisture levels from northern Mexico. The chance of thunderstorms should return to Mohave county as early as Monday, with daily chances likely continuing into next weekend. Storm chances should also return to higher elevations of southern Nevada and the Mojave Preserve by Tuesday and the Sierra on Wednesday. Initially the activity in these areas will be more isolated, but coverage should increase as the week progresses. With the increase in moisture and cloud cover next week, temperatures are expected to stay within a few degrees of normal. && .AVIATION...For McCarran...Smoke clearing to the north overnight will be replaced by additional smoke coming in from around Bakersfield early Sunday morning about 12Z. The latest indications are that the smoke will not be as dense as Saturday morning and visibility will most likely drop no lower than around 4SM between 14Z and 19Z. However, there is a slight chance it could drop to near 2SM. Partial clearing in the afternoon should improve visibility to around 6SM or higher followed by further clearing Sunday evening. For the rest of southern Nevada, northwest Arizona and southeast California...Smoke and haze due to wildfires will be the primary concern through Sunday evening. Brief clearing at KBIH this evening and overnight will give way to another smoke influx around 14Z Sunday with VSBY values likely around 2SM Sunday morning then improving to 4SM Sunday afternoon. Southern NV will see clearing overnight before smoke returns early Sunday from the west with VSBY generally 4-6SM. Fairly dense smoke should remain near and north I- 15 which may limited VSBY at DAG to around 6SM at time, but should stay north of IFP and EED. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ UPDATE...Nickerson SHORT TERM...Morgan LONG TERM...TB3 AVIATION...Adair For more forecast information...see us on our webpage: or follow us on Facebook and Twitter