Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/14/21


AREA FORECAST DISCUSSION
National Weather Service Albany NY
1039 PM EDT Fri Aug 13 2021 .SYNOPSIS... A cold front will bring some scattered showers and thunderstorms to the region overnight. The front will move south of the region tomorrow with isolated to scattered showers and thunderstorms ending as cooler and drier air moves in. Less humid conditions and pleasant weather are expected Saturday night through Sunday as high pressure builds in. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... UPDATE...As of 1030 PM EDT, remaining portions of severe thunderstorm watch 437 has been cancelled. Still some isolated showers/thunderstorms across portions of the western Mohawk Valley/SW Adirondacks, with dissipating showers across western New England. For the overnight hours, expect a relative lull in shower/thunderstorm coverage through around 3 AM, with best chances for isolated coverage across the southern Adirondacks and western Mohawk Valley. After 3 AM, showers/thunderstorms across NW PA may expand northeast into central NYS and the SW Adirondacks/Mohawk Valley region, with increased forcing ahead of the approaching cold front and also mid level height falls. Locally heavy rainfall could occur. Showers/thunderstorms may eventually increase in coverage into northern/western portions of the Capital Region and Schoharie Valley by sunrise. Otherwise, remaining warm and humid overnight, with lows mainly in the mid 60s to lower 70s. Some patchy fog may form, especially in areas which received heavy rainfall earlier this evening. Previous discussion follows... The Heat Advisory has expired and the Severe Thunderstorm Watch was canceled north and west of Albany in eastern NY. A severe thunderstorm produced the gambit of severe weather for portions of Albany and the Capital Region. WFO ALY office was also rocked by numerous close CG strikes, heavy rainfall, wind gusts estimated to 45-50 mph, and M & M size hail. Voorheesville reported 1" hail, and several wind damage reports have come in with some flash flooding near Route 20 in Albany. Please see our LSR for all the reports. A few strong to potentially severe thunderstorms are moving across the mid Hudson Valley. Moderate amounts of instability remain southeast of the Capital Region with dewpts in the lower 70s. The instability will continue to wane as the prefrontal trough moves through. The cold front is getting close to western NY and the St Lawrence River Valley. Some isolated to scattered showers and a few thunderstorms are possible overnight but they are not expected to be severe after midnight. The latest 3-km HRRR continues to show limited and isolated activity overnight with the most coverage west of the majority of the forecast area. We continued slight and low chance PoPs after 06Z. Low temps will be in the 60s to around 70 though a few upper 50s are possible in the southern Dacks. The cold front should be moving across the western Adirondacks, northern NY and the Mohawk Valley in the morning. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... Tomorrow...The cold front makes steady progress across the region from northwest to southeast. A chance of showers or isolated to scattered thunderstorms is possible from southern VT, the Capital Region and northern Catskills. The limited heating should preclude a severe threat but some stronger thunderstorms with gusty winds may be possible close to I-84 in the afternoon. Stronger cold advection should kick in during the early afternoon from the Capital Region north and west and then southeast. A distinct change in the air mass should be felt with dewpoints falling into the 50s or lower north and west to northwest winds. Again, this dewpoint boundary may not move through the southern most zones until the late pm and early evening. Highs will be in the upper 70s to lower 80s in the valleys with a few mid 80s near KPOU. Expect upper 60s to mid/upper 70s over the higher terrain. Saturday night...Relief from the heat will be felt across the entire area. Dewpoints will fall into the mid 40s to mid 50s with northwest to north winds with high pressure building in from the Great Lakes Region and southeast Canada. Lows will be in the 50s with some 40s over the southern Greens, southern Dacks, and eastern Catskills. Sunday...A beautiful close to the weekend with the 1025 hPa or so anticyclone building in over NY and New England with lots of sunshine and fair weather. The strong subsidence from the sfc high will yield mostly sunny or sunny skies with light winds. Max temps will be near or slightly below normal for mid-August. Highs will be in the 75-80F range in the valleys, and mid 60s to mid 70s over the higher terrain. Sunday night into Monday...The fair and pleasant weather continues into early next week with a cool night with lows in the mid 40s to mid 50s with perhaps some shallow radiational mist over the river valleys with clear skies and light to calm winds. High pressure remains over New England with mid and upper level heights increasing along the East Coast. Temps increase to seasonal levels with a slight increase in humidity levels but still fairly comfortable for August with dewpoints in the 50s to lower 60s. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... After a brief respite from very humid conditions, it looks like humidity levels will climb through the middle/end of next week, along with increasing chances for showers and thunderstorms, as ridging rebuilds off the eastern seaboard. Shower/thunderstorm coverage looks to be modulated mainly by diurnal heating, however additional forcing from any remnant tropical entity from the southeast states could enhance coverage of showers/thunderstorms, with best chances looking to be sometime next Wed-Thu. Otherwise, Tuesday looks to be the transition day in terms of increasing humidity levels, with dewpoints climbing into the lower/mid 60s by afternoon. Dewpoints will likely rise into the mid/upper 60s by Wednesday afternoon, with perhaps some upper 60s to lower 70s in valley areas late Wednesday into Friday. Highs will mainly be in the lower/mid 80s in valleys, and 75-80 across higher terrain, with min temps generally in the lower/mid 60s, except 55-60 across higher elevations. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... A prefrontal trough will focus some showers and thunderstorms tonight. The cold front will move across the region late tomorrow morning into the afternoon. High pressure will build in for Saturday night. VFR conditions are expected ahead of showers and thunderstorms with a pre frontal disturbance. The showers and thunderstorms will impact KALB prior to 02Z/SAT, and potentially KPOU/KGFL/KPSF between 02-06Z/SAT. Conditions will briefly lower to MVFR/IFR levels with some gusty winds. Expect some partial clearing and some stratus or patchy MVFR/IFR mist or fog may form, especially at KGFL/KPSF. KALB may also have some form due to the recent wet ground. Some showers associated with the front may arrive shortly before or after 12Z/SAT. We tried to address these showers with VCSH or TEMPO groups with reductions to the MVFR levels. The cigs and vsbys may briefly increase to VFR levels at KGFL/KPSF before the showers arrive. The threat showers decreases after 17Z/SAT for KALB/KGFL, but may continue for KPSF and KPOU depending on the placement of the boundary.There is a small chance for thunderstorms and later TAF issuances can address it. Any storms this evening could result in briefly strong wind gusts and a sharp wind shift to the west. Winds then become light and variable overnight before turning west to northwest tomorrow morning into the afternoon increasing to 8 to 12 kts with some gusts to around 20 kts at KALB/KPSF. Outlook... Saturday Night to Monday Night: No Operational Impact. NO SIG WX. Tuesday: Low Operational Impact. Isolated SHRA...TSRA. Tuesday Night: Low Operational Impact. Isolated SHRA. Wednesday: Moderate Operational Impact. Scattered SHRA...TSRA. && .FIRE WEATHER... A cold front and an upper level disturbance will bring some strong to severe thunderstorms into tonight. The front will move south of the region tomorrow with isolated to scattered showers and thunderstorms ending as cooler and drier air moves in. Less humid conditions and pleasant weather are expected Saturday night through Sunday as high pressure builds in. The RH values will increase to 90 to 100 percent in the morning, and lower only to 40 to 60 percent Saturday afternoon. The max RH values will be in the 80 to 100 percent range Sunday morning. The winds will be southwest to west at 5 to 15 mph tonight. Expect the winds to shift toward the west and northwest at 5 to 15 mph on Saturday. Northwest winds of 5 to 10 mph will persist Saturday night. Winds gusts in excess of 30 mph will be possible with any thunderstorms. && .HYDROLOGY... Some heavy downpours and localized hydro issues are possible late this afternoon into Saturday morning with any thunderstorms. Dry weather returns late Saturday into early next week. Any storms with high precipitable water values could bring some minor flooding of urban, poor drainage and low lying areas and isolated flash flooding. Some notable rises may occur on the main stem rivers with heavy rainfall over them. However, widespread main stem river flooding is not expected at this time. Flows should lower over the weekend into early next week, as high pressure ridges in. The next chance of widespread rainfall will be on Wednesday. For details on specific area rivers and lakes, including observed and forecast river stages and lake elevations, please visit the Advanced Hydrologic Prediction Service /AHPS/ graphs on our website. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. MA...None. VT...None. && $$ SYNOPSIS...Wasula NEAR TERM...KL/Wasula SHORT TERM...Wasula LONG TERM...KL AVIATION...Speciale/Wasula FIRE WEATHER...Wasula HYDROLOGY...BGM/Wasula
Area Forecast Discussion
National Weather Service Charleston SC
952 PM EDT Fri Aug 13 2021 .SYNOPSIS... High pressure will prevail across the area into the upcoming weekend. A front will then stall northwest of the area late this weekend and early next week while Tropical Cyclone Fred moves onshore along the northeastern Gulf Coast. Fred will then weaken as it moves north into the southern Appalachians into mid week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... As of 950 PM: Latest IR satellite detected several patches of mid and high clouds across the forecast area, steadily expanding across coastal GA. Based on the satellite trends, the forecast update will feature greater sky cover through the rest of the night. The increase sky cover should limit the fog potential during the pre-dawn hours, we will keep a mention of patchy fog across the region. Temperatures are on track to reach the low to mid 70s inland and the upper 70s along the coast. As of 720 PM: KCLX detected the sea breeze across Allendale south to Candler County, pushing inland. Previous shower and thunderstorm activity along the sea breeze has dissipated over the past hour. Latest HRRR indicates that the rest of the evening and overnight will remain dry. However, based on guidance and the passage of the sea breeze, I will add a mention of patchy fog during the pre-dawn hours. Previous Discussion: High pressure and subsidence have kept most of the area rainfree with the exception of a few short-lived showers just along the sea breeze. From the 18Z RAOB sounding, PWATs at KCHS are around 1.70" with decent instability in place. Although, the sounding also shows quite a bit of dry air aloft. Therefore, for the rest of the afternoon, only isolated showers/thunderstorms are expected, with most convection (if any) forming along the seabreeze. A stray shower cannot be ruled out elsewhere though. By this evening, any lingering showers should diminish quickly with the loss of daytime heating. Thereafter, a mostly quiet night is expected. By late tonight, a few showers move into the coastal waters. Low temperatures will be in the 70s. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... High pressure at the surface and aloft will remain in place across the SE coast into the Atlantic to start the weekend, along with an ill-defined sfc boundary/trough along the Appalachians down into the Lower Mississippi River Valley. A little stronger SE flow and moisture push off the Atlantic into the South Carolina and Georgia coasts may bring slightly better shower/thunderstorm chances to the forecast area Saturday afternoon...as compared to what we`ve seen the last few days...particularly across SE Georgia where higher dewpoints/better instability will reside. Severe weather potential remains low. But any showers/storms could produce localized heavy rainfall. Sunday into Monday: Still anticipating Tropical Cyclone Fred to slide up through the northeast Gulf into the Florida Panhandle by early Monday morning, although forecast track and heavier QPF forecasts have been trending westward. But with further increasing moisture transport into the SE states and larger scale forcing, most active weather period is anticipated through this time. As mentioned, higher QPF forecasts have shifted slightly westward. But the area remains within the WPC Day 3 marginal risk for excessive rainfall through early Monday...and likely beyond. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... Larger scale upper level ridging will remain the dominant pattern from the SE states into the Atlantic through next week, keeping the door open for a more active tropical weather. Region will likely still be feeling the impacts from Fred during the early part of next week, primarily in the form of decent moisture flow off the Atlantic, resulting increased instability and shower/thunderstorm chances that will largely follow the diurnal heating cycle. Inherited forecast features some fairly high pops through Wednesday before trending downward through the latter half of the week as what remains of Fred dissipates over the SE. But main forecast challenge and impacts will continue to revolve around localized heavy rainfall possibilities. For the later half of the week and eventually into next weekend, will have to see what happens with potential tropical cyclone seven. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... The terminals are forecast to remain dry with VFR conditions through late tonight. Patchy fog may develop inland of the terminals during the pre-dawn hours. However, KSAV could see a period of light fog between 9-12Z. A band of showers are forecast to approach the coast during the mid-morning, pushing onshore during the mid-day into the afternoon. 0Z TAFs will feature VCSH at KSAV and KJZI on Saturday. Extended Aviation Outlook: Forecast continues to hinge on Tropical Cyclone Fred. But overall risk for flight restrictions/impacts increases late this weekend through the early part of next week, as Fred works into the SE part of the CONUS and brings increased shower/thunderstorm possibilities to the region. && .MARINE... Rest of today and tonight: High pressure and a southerly flow will prevail. Winds less than 15 knots and seas 2-3 feet are expected. Saturday through Wednesday: Atlantic high pressure persists through the period. Tropical cyclone Fred is expected to work into the eastern/northeastward Gulf bringing minimal impacts to the coastal waters. No marine headlines anticipated at this time. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...NED SHORT TERM...TBA LONG TERM...TBA AVIATION...NED MARINE...RAD/TBA
Area Forecast Discussion
National Weather Service Cheyenne WY
514 PM MDT Fri Aug 13 2021 .SHORT TERM...(This evening through Saturday) Issued at 136 PM MDT Fri Aug 13 2021 Latest satellite picking up on a growing cumulus field mainly over the higher terrain across the Snowy and Sierra Madre Ranges in addition to portions of the Rocky Mountains in CO as a few have begun to be tall enough to return echoes on the KCYS radar. Lingering broken cloud deck across the high plains have limited early diurnal heating with KIBM, KCYS, and KSNY reaching only in the middle 70s as of latest obs. High res CAMs are not all favorable for widespread convection especially east of the Laramie Range with the 17z HRRR run showing some additional convective development across portions of the Laramie Range and then again across portions of the North Platte River Valley in NE late tonight as a LLJ begins to impact the region. Time frame for KLAR this afternoon that is of concern for any potential for strong to severe storms between 5 and 10 PM MDT. Latest sounding from CSU PRECIP study shows a well capped environment hence the lackluster thinking for severe convection early on today as well as a fairly dry mid to upper level as lapse rates remain less than ideal. Some decent inverted V on soundings across the region to keep a wind threat alive even under 20 dBZ echoes. SPC with latest update has removed the slight risk as marginal risk of strong to severe thunderstorms remain as stationary front continues its influence over us. Expect highs today to be on a touch cooler with upper 80s near Chadron but low to middle 80s across the rest of the high plains in WY and NE as well as west of the Laramie Range. Lows tonight from the low 50s into the upper 50s for most. .LONG TERM...(Saturday through Thursday) Issued at 420 AM MDT Fri Aug 13 2021 Afternoon showers and possibly a few thunderstorms will again be possible on Saturday, mainly focused over western Nebraska as easterly upslope flow remains in place. On Sunday, a weak ripple trough will pivot around the top of the broad ridge in place over the southwestern CONUS. This feature will help increase convective coverage on Sunday afternoon over both southeast Wyoming and western Nebraska. Temperatures will run a bit warmer on both Saturday and Sunday with afternoon highs around 5 to 8 degrees above average. Weak ridging will return to the high plains on Monday and Tuesday with dry weather likely. By the middle of next week however, differences between the ECMWF and GFS emerge with regard to our next weather event. A broad trough is expected to move ashore over the Pacific Northwest. The GEFS favors a deeper trough and higher precipitation chances over the high plains by Wednesday and Thursday. The ECMWF and its recent ensemble runs favor a slightly weaker system and a better chance of rain by Thursday. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 507 PM MDT Fri Aug 13 2021 MVFR to VFR conditions across southeast Wyoming and the Nebraska panhandle with some lower cigs and gusty winds to 35 knots. Timing to showers and thunderstorms this afternoon for southeast Wyoming is between 23Z and 5Z, then for the southern Nebraska panhandle it is between 3Z and 10Z, and for the central Nebraska panhandle between 6Z and 12Z. Gusty and erratic winds are likely around these showers and thunderstorms, as well as frequent lightning, hail, and briefly limited visibilities during heavy rainfall. Skies should clear by tomorrow morning. Confidence is fairly low at this time with any convection developing east of the Laramie range, with the atmospheric dynamics being much less impressive than earlier model runs. Nevertheless, there is some convective development around Laramie with upwards to 35 knots and some hail signatures. As a result, went ahead and left VCTS in the TAFs. && .FIRE WEATHER... Issued at 140 PM MDT Fri Aug 13 2021 Afternoon shower and thunderstorm chances today have minimized overall fire weather concerns for today outside of the exception of lightning starts. Some low precipitation chances into the weekend and early work week before dry conditions set in once more under high pressure. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...WM LONG TERM...MAC AVIATION...LK/MD FIRE WEATHER...WM
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
243 PM PDT Fri Aug 13 2021 .SYNOPSIS...Areas of smoke and haze along with hot interior temperatures will continue into the weekend, with high pressure aloft persisting. There will be a slight chance of thunderstorms around portions of Trinity County this afternoon and evening, otherwise expect dry weather is forecast to prevail. && .DISCUSSION...We had one cloud-to-surface strike over the coastal waters this morning with a brief 40dBz cell. Composite radar imagery show another area of elevated returns offshore Central California this afternoon. Convective allowing models brings this area of returns aloft into NW California waters tonight. It appears to be very high based and completely disconnected from the surface. Based on current trends and recent observations, we added a slight chance of thunderstorms over the coastal waters for late tonight into early Saturday morning. Convective allowing models keep the returns mostly offshore tonight, though a distant rumble of thunder near the coast is certainly not out of the realm of possibilities. The heat risk will increase this weekend, however thick smoke in Trinity and NE Humboldt Counties will likely reduce that threat. The smoke aloft and hazy conditions in Mendocino and Lake Counties has been less of a factor in blocking out solar insolation. With heat risk forecast to reach high to very high levels in portions of Lake and Mendocino Counties this weekend, we hoisted a heat advisory. Highs may peak near 110F in Lake and southern Mendocino Counties, though NBM indicates only a 50% chance for 105F or more at Ukiah both days. Otherwise layers of smoke from various wildfires across the region will continue across regions of northwest California today and tonight, however the most intense surface and low-level smoke continues to be mostly restricted to Trinity County and some adjacent portions of interior Humboldt. Air quality along most of the the coast remains very good this morning, while some limited smoke has brought some moderate air quality levels to interior Mendocino. HRRR and Blue Sky smoke modeling along with larger scale model wind fields continue to suggest that the coast will remain mostly protected from any surface smoke, and if anything areas of interior Humboldt to the west of the fires should see some improvement due to some increase in westerly flow. That may even help some areas near the fires with dispersion, but otherwise expect areas to the east including Trinity County to stay pretty socked in with smoke through the weekend. Later in the weekend and especially early next week, increasing southwest to westerly flow aloft should help make for more blue skies. That said, we will probably tend to see a bit more marine layer cloudiness by then along the coast as well, at least during the nights and mornings. All the smoke around will likely continue to limit daytime heating, as many interior valley temperatures have been running 5 to 10 degrees cooler than most guidance for the last couple days, on average. We should expect this trend to continue into the weekend, though if the smoke aloft thins out anywhere, heat risk may be locally elevated enough to threaten advisory levels, particularly around Lake County. Although the diminished daytime heating will likely minimize instability, have decided to leave a slight chance of thunderstorms along the eastern border of Del Norte, northern Humboldt and eastern/northern Trinity this afternoon. SREF/HREF probabilities and CAMs suggest the best shot in northeast Trinity County for isolated thunderstorms, but with the smoke probably limiting things once again, currently not expecting more than a stray storm, and if any form they will likely track northeast toward either Siskiyou or Shasta counties. Extended forecast...850MB temperatures begins to wane early to mid next week as a weak upper trough moves across the Pacific NW and marine air pushes deeper into the coastal river valleys. The heat risk will likely diminish early next week, however daytime highs are still forecast to be above normal across portions of interior Mendocino and Lake Counties. In Trinity County, the smoke from the forest fires will continue to impact high temperatures each day. Also, ensemble and deterministic guidance indicates offshore flow developing next week, with potentially gusty northerly and northeasterly winds over the ridges and warmer coastal temperatures. That remains to be seen as 925mb and 850mb winds from the deterministic and ensemble guidance are not looking too strong at this point except over the King Range where northerlies will howl. The potential for another round of heat will increase into the latter portion of the week as an upper ridge re-builds toward the West Coast and the trough departs. && .AVIATION...The marine layer is ragged and shallow along the coast today. It has mostly scattered out this afternoon to VFR with some brief pulses of IFR conditions. As the clouds scatter, they have given way to overcast smoke aloft from interior fires. The marine layer should bring IFR conditions back late this evening. Gradually warming interior temperatures will help keep the marine layer shallow, but may also strengthen the inversion a tad over the weekend. This may keep IFR conditions around a bit more consistently into the morning tomorrow. In the interior, smoke continues to blanket the area through tomorrow, though VFR conditions should remain for all areas except those closest to and downwind of active fires. && .MARINE...Light to gentle breezes are expected to prevail over the coastal waters through this evening. Winds will slowly increase in a fan south of Cape Mendocino this weekend and reach over 20 knots by early Sunday in the southern outer waters. A small crafts advisory has been issued starting tomorrow evening to reflect this. Winds are forecast to quickly increase further to fresh to strong breezes on Monday over the outer waters with gale force gusts. These conditions will slowly weaken from south to north on Wednesday. After Wednesday, northerlies will remain elevated over portions of the northern outer waters through the rest of the work week. Otherwise, a mid-period northwest swell will wane through Wednesday and a south-southwest swell will linger throughout portions of the waters during the next several days. && .FIRE WEATHER...Areas of thick smoke will continue to limit daytime heating today, keeping the atmosphere more stable and weakening the thunderstorm threat for this afternoon. Best chances for storm development remain in northeastern Trinity this afternoon. Will continue to headline zone 283 for isolated thunderstorms, with the caveat that if anything goes it will likely be restricted to eastern or northeastern portions. Otherwise, RH recoveries will remain rather poor through the weekend into early next week outside of valleys and lower slopes. Smoke will continue to limit daytime heating, particularly around Trinity County, but some gradual uptick in westerly flow later in the weekend may help with smoke dispersion, especially west of the fires. Winds will remain fairly light outside of local terrain-driven up-valley and west to northwest gap winds late each afternoon and early evening into the weekend. Stronger diurnal westerlies in the wind channeled gaps and valleys in the interior will be possible late Sunday into Monday as an upper trough moves toward and eventually across the area. Possible stronger E-NE ridge level winds and poor overnight RH recoveries will be possible as we head into mid next week. Yhere is considerable uncertainty regarding the magnitude and duration of the offshore wind flow, however. && .EKA WATCHES/WARNINGS/ADVISORIES... CA...Heat Advisory from 1 PM Saturday to 8 PM PDT Sunday for CAZ110- 111-113>115. NORTHWEST CALIFORNIA COASTAL WATERS... SMALL CRAFT ADVISORY IN EFFECT FROM SATURDAY EVENING THROUGH SUNDAY EVENING FOR PZZ475. && $$ Visit us at https://www.weather.gov/eureka Follow us on Facebook and Twitter at: https://www.facebook.com/NWSEureka https://www.twitter.com/NWSEureka For forecast zone information see the forecast zone map online: https://www.weather.gov/images/eka/zonemap.png
Area Forecast Discussion
National Weather Service Grand Junction CO
544 PM MDT Fri Aug 13 2021 .SHORT TERM...(Tonight through Saturday night) Issued at 223 PM MDT Fri Aug 13 2021 Radar and satellite tell the story as increased moisture and daytime heating has allowed another round of convection to fire this afternoon. As anticipated, this convection has spread further northward with only showers noted north of I-70. The San Juans look to be the big winners as a few thunderstorms move from northeast to southwest, quite slowly. Skew-Ts do show moisture increasing down south with V-profiles becoming less so, indicating less of a wind threat and more rain possible. Even so, any convection can produce some gusty outflow winds so that will remain a concern with some of the storms bringing brief, heavy rain. Most of this activity will end near and after sunset though the HRRR does want to keep a few showers going over the San Juans and southern foothills through midnight. Tomorrow, more of the same though moisture will continue to slowly increase. This is borne out as dewpoints will increase anywhere from about 5F to nearly 10F for central portions of the CWA. Like today, daytime heating and moisture will lend themselves to convection firing in the afternoon with favored areas remaining the same though the eastern Uintas may also see a bit more activity. Smoke has decreased noticeably across the region. This will allow more shortwave radiation to reach the surface and thus, the hotter temperatures we`re expecting over the next few days. Fingers crossed it stays that way as guidance shows plenty of smoke over the PacNW. .LONG TERM...(Sunday through Friday) Issued at 223 PM MDT Fri Aug 13 2021 An upper level trough is still projected to push inland across the Pacific Northwest Sunday night, leading to a flattening of the high over the Great Basin. However, the flow over western Colorado and eastern Utah is not expected to shift much in response to this, so moisture will continue to push into the area. Monday, flow becomes more southerly to southwesterly due to the approaching trough, allowing deep monsoonal moisture to begin pushing northward in earnest, with PWATs expected to increase to at or slightly above average for this time of year. An increase in coverage of showers and storms is also expected, but without upper level support, these storms are expected to be weak and tied to the higher terrain of the San Juans and along the divide. As with afternoon convection in previous days, a few heavy rainers will be possible, especially in the San Juans. PWATs are expected to increase to near an inch for much of the area from Tuesday onward, which is 150% of the average PWAT for this time of year. Wednesday is looking to be the wettest day, as the trough finally approaches eastern Utah and western Colorado. From this point onward, though, forecast confidence decreases rapidly. The EC continues to present a drier solution, with the trough moved out of the area Thursday and northwesterly flow on the back side shutting off the moisture. The GFS continues to be wetter, although it has come a bit more into line with the EC. Instead of the brief shift to northwesterly flow and then return to southerly flow within 12 hours that previous runs had, the GFS now indicates that the main trough will linger for an extra day, keeping moisture and precipitation chances in the forecast for Thursday before shifting to northwesterly flow Friday. Ensembles are evenly split between these two solutions at this point as well. Either way, cooler and unsettled conditions will be the story through at least mid-week. If travelling next week, pay special attention to the I-70 corridor for any closures if/when heavy rains move back in. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 538 PM MDT Fri Aug 13 2021 VFR conditions will persist for the next 24 hours. Showers and thunderstorms across the San Juans and along the Continental Divide will dissipate after 03Z with the loss of daytime heating. Until then, gusty outflow winds and perhaps brief downpours are possible, mainly at KASE and KTEX, if anywhere. Otherwise, quiet weather expected overnight with winds becoming light and terrain driven. Similar weather expected on Saturday with another round of showers and storms possible over the higher terrain and adjacent valleys of southwest Colorado after 18Z. Gusty winds and downpours are the primary threats once again. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...TGR LONG TERM...BGB AVIATION...MDM
Area Forecast Discussion
National Weather Service Goodland KS
831 PM MDT Fri Aug 13 2021 .UPDATE... Issued at 831 PM MDT Fri Aug 13 2021 Based on the current radar coverage over Colorado/Wyoming, have opted to remove mention of precipitation across the CWA thru 06z Saturday. Any activity currently is very weak...slow moving and not even close to affecting the forecast area over the next 3-4 hours. Will re-assess in a few hours for the 06z-12z timeframe. Low chance of some development along the warm front draped over the CWA, but can`t rule out entirely. && .SHORT TERM...(This evening through Saturday night) Issued at 205 PM MDT Fri Aug 13 2021 Satellite imagery and 500 mb RAP analysis showed high pressure centered over Utah this afternoon, with a trough over the Great Lakes region. This pattern placed the High Plains under northwest flow. Meanwhile at the surface, the leftovers of a frontal boundary were draped across the region. Cloud cover prevailed across much of the area through the morning hours and has begun clearing early this afternoon as east/southeast winds increase to 10 to 15 mph. At 2 PM MT, skies were mostly to partly sunny, with temperatures mainly in the upper 70s and low 80s. Due to lingering cloud cover, instability appears much lower than originally expected for today. Have lowered storm chances to 20 percent this afternoon and evening as a result, and even that may be too optimistic. Additionally, severe thunderstorms are no longer anticipated. That being said, a few storms could develop off of the higher terrain in Colorado/Wyoming and travel towards the area. Confidence in these storms making it into the CWA is low. Temperatures fall into the mid 50s to low 60s tonight. Guidance does suggest the potential for another shot at some showers/storms early Saturday, mainly east of Highway 25. If precipitation does develop, it will likely move out of the eastern portion of the region by midday as temperatures climb into the upper 80s to low 90s. While the overall pattern remains largely the same, a weak shortwave looks to pass through the northwest flow over the High Plains during the afternoon and evening hours on Saturday. As temperatures warm and instability increases, thunderstorms should develop over western Nebraska and track southeast into the region. Moderate shear and instability could result in a few strong to severe storms along and north of the Nebraska border during the late afternoon and evening. The main threats will be large hail and damaging winds. Otherwise, precipitation chances shift south and east overnight (exiting by morning) as temperatures fall into the upper 50s to low 60s once again. .LONG TERM...(Sunday through Friday) Issued at 143 PM MDT Fri Aug 13 2021 H5 Ridge will give way to a series of short wave troughs as ridge center retreats to the west. Medium range models in reasonable agreement through the first half of the period, although significant differences appear towards the start of next weekend with the development of closed low. While Canadian,ECMWF and GFS all agree this system develops, the Canadian is much more aggressive at moving system into the plains while the GFS/ECMWF offer a slower solution. GEFS mean seems to support the slower solution, with highest variability seemingly tied to how fast trough kicks out, suggesting even slower solutions in the ensemble space. While the increase in uncertainty will make pinning down the details a bit tricky, there are a few signals in the data that can provide some guidance for the week ahead. Appears chance for diurnally driven precipitation (i.e. late afternoon/early evening) will be present through much of the period, with chances for more organized precipitation and thunderstorms increasing after Wednesday as closed low system mentioned earlier takes shape. While chance for precipitation will be higher and strengthening shear profiles will provide a better overall pattern for severe weather. That being said, the overall pattern may be one where the warm/dry sector expands eastward rapidly, limiting the actual areas seeing storms develop. Temperatures will be closer to normal than this recent week with highs in the upper 80s to low 90s in general. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 457 PM MDT Fri Aug 13 2021 Both terminals will see VFR conditions through the forecast period with a mix of scattered mid/high clouds. Low chance for VCTS near KMCK after 06z Saturday, but with uncertainty on timing/placement will leave out for now. Winds for KGLD, southeast around 10kts, with gusts to 20kts after 17z Saturday. Winds for KMCK, meandering from east-southeast to southeast around 10kts. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...JN SHORT TERM...JBH LONG TERM...JRM AVIATION...JN
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1002 PM EDT Fri Aug 13 2021 .UPDATE... Issued at 1000 PM EDT FRI AUG 13 2021 SPC has removed the slight and marginal risk across eastern KY, although there will still be some widely scattered showers and storms through the rest of the evening. Made minor adjustments to Pops, Sky, and T/Td. Updates sent to NDFD and web servers. UPDATE Issued at 720 PM EDT FRI AUG 13 2021 Cold front is currently over central IN/OH and will slowly moving south through the evening. Most of the strongest convection has been in the surrounding CWA`s so far this evening where the instability has been better. Despite the widely scattered coverage thus far over eastern KY, didn`t mess with Pops too much overnight as chances for showers/storms will continue overnight as the front gets closer to the area. Still can`t discount an isolated stronger storm, with wind gusts in excess of 40 mph. Updates have been sent to NDFD and web servers. && .SHORT TERM...(This evening through Saturday night) Issued at 432 PM EDT FRI AUG 13 2021 Scattered showers & storms developed late this morning and through the early afternoon across the northern fringes of the CWA and into the higher terrain bordering the Virginias. A few isolated showers/storms have continued to pop up across the heart of the CWA as well. As a result, have bumped up Pops through the midday to better reflect the trends and latest runs in guidance. An upper level wave will continue to traverse through the broad trough that runs across the Ohio River Valley and into Canada. This feature will include a cold front, currently running through Central Illinois and Northern Indiana and is expected to push southeast across the CWA tonight and through Saturday. Guidance has continued to struggle with convection across the region this afternoon, but has shown some improvement in the more recent runs. Shear remains minimal, so storms will likely stay more multicellular/broken and unorganized. Soundings suggest a bed of instability in the 2000-3000 J/kg range through early this evening. This is best along our north and western counties and into Central Kentucky. The GFS and NAM indicate a very moist profile, while other higher-res guidance (namely, the NEST, HRRR and the FV3) suggest a fairly shallow layer of mid-level dry air. With sufficient low-level lapse rates (~7.5C/km), 500 J/kg of DCAPE, and some mid-level dry air, strong to damaging winds will be the main concern through this evening. Additionally, a moisture rich airmass will increase PWATs into the 1.75-2.00+" range, where localized flash flooding can`t be ruled out in training storms. Activity will lesson with the onset of nightfall as instability decreases, but a few chance showers/storms can`t be ruled out as the front progresses south. Some redevelopment, particularly along the higher terrain of the SE will be possible tomorrow afternoon before things dry out overnight Saturday. Showers and thunderstorms can be expected through this evening before activity decreases to chance PoPs overnight. River valley fog and possibly low stratus can be expected to develop with lows in the mid and upper 60s. Highs will be around the norm Saturday with the passage of the front, ranging in the low to mid 80s. Similarly, lows into Sunday morning will be cooler, in the low to mid 60s. .LONG TERM...(Sunday through Friday) Issued at 325 PM EDT FRI AUG 13 2021 The trends in the extended remain pretty much the same; Daily and nightly chances of showers and storms, with the highest precipitation probabilities during the afternoon and evening hours, along with below normal daytime highs and normal to slightly below normal nightly lows. The triggers for any rain we receive around eastern Kentucky will be a surface front associated with an upper level trough, and the remnants of tropical cyclone Fred. Their is still some uncertainty as to exactly what the track of Fred`s remnants will be, but the models continue to bring Fred northward into the eastern Tennessee Valley Monday night and Tuesday. This would do two things. First, Fred`s moisture would flood into the region and would add additional instability and lift to fuel shower and storm development. Fred`s northward movement would also act to slow down a southward moving cold front, and even push that boundary back northward and closer to our forecast area. All that being said, we will repeated chances for showers and storms through out the upcoming work week. Daily highs should top out in the low to mid 80s on average, with a few spots perhaps only reaching the upper 70s during the middle of the week. The latest long range temperatures looked were a bit cooler than the latest NBM numbers, but considering the clouds and precip forecast we are putting out, the slightly warmer, but still lower than normal, NBM min/max temps seemed a bit better than the latest long range MOS, so the NBM was favored. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) ISSUED AT 725 PM EDT FRI AUG 13 2021 VFR to start the 00Z TAF period. Scattered showers/storms tonight and overnight may result in brief flight restrictions. Patchy fog is expected overnight but there is great uncertainty in coverage, but areas that see rain tonight will have the greater chances for seeing dense fog. Cold front crosses the area overnight into Saturday morning, and ceilings may drop to MVFR along and just ahead of the frontal passage. Ceilings improve by late Saturday morning and all locations should return to VFR. Additional afternoon/evening showers and storms may result in brief flight restrictions. Winds will be light and variable this evening and then northerly around 5 kts after the frontal passage on Saturday. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...CMF SHORT TERM...BB LONG TERM...AR AVIATION...CMF
Area Forecast Discussion
National Weather Service Portland OR
251 PM PDT Fri Aug 13 2021 .SYNOPSIS...High pressure over the region will lead to a continuation of the excessive heat and dry conditions through at least Saturday. Temperatures will begin to cool slightly over the weekend before a weak storm system brushes the region Monday bringing with it much cooler temperatures early next week. && .SHORT TERM...Tonight through Monday...Water vapor satellite imagery this afternoon reveals a shortwave ridge over the Great Basin extending northwestward into the Pacific Northwest. An upper level low pressure can be seen spinning well of the California coast. This has resulted in mid to upper level southeasterly flow spreading across northwest Oregon today. An area of mid level instability and lift allowed a few light showers and thunderstorms to fire across southwest Oregon this morning. This area of unsettled weather has now shifted northward into Lane County in the form of primarily just debris clouds and possibly a few sprinkles. Expect this activity to continue to weaken this evening as it shifts northward. Farther south, some surface based instability will lead to a few additional thunderstorms firing over Klamath County late this afternoon. There is still a 15-20% chance of one of these storms impacting far eastern Lane County this evening. Similar to the past couple of KSLE soundings, the 12z KSLE sounding measured an 850mb temperature of ~24C. With little change in the airmass from yesterday was expecting temperatures to eclipse the 100F mark. However, there is enough smoke, particularly aloft, that solar insolation has been reduced enough to hold temperatures down considerably today. We are currently running 3-8F cooler across the Willamette Valley than this time yesterday so high temperatures today appear likely to top out in the mid to upper 90s instead of the low 100s. Given low temperatures should remain unusually warm tonight, and another hot day is expected tomorrow, will keep the Excessive Heat Warning going for now even though we will now be in more marginal conditions for the continuation of it. Additional moisture and instability will likely ride up the Cascades Saturday. However, it appears the west side of the Cascades will largely remain capped based on model soundings. Even if an isolated storm were to fire Saturday afternoon or evening, deep layer westerly flow should result in any storm trying to form to the west of the Cascade crest shifting east of the Cascade crest quickly. As a shortwave trough approaches the region late in the weekend, 500mb heights and cooler air aloft will slowly filter into the region Saturday night into Sunday. This should result in temperatures lowering another several degrees for Sunday afternoon. It will still remain hot, though, with high temperatures topping out in the low 90s. Models are in good agreement the area will see relief from the heat no later than Monday as a weak upper level trough moves across the Pacific Northwest. This will result in a weakening front dropping southeastward into southwest Washington and northwest Oregon Monday. This could possibly bring some light rain to the south Washington and far north Oregon coast some time late Sunday or Monday. NBM PoPs have actually decreased during this time period over the past 24 hours and are now below mentionable thresholds. This appears to be in response to the operational and ensemble data suggesting less and less QPF. Nonetheless, nearly every member of the EC ensemble data suggests light QPF will fall at KAST on Monday so opted to raise PoPs into at least the slight chance category for Monday for the far north Oregon and south Washington coast. Expect temperatures to drop down well into the 80s in the Willamette Valley and Columbia River Gorge on Monday. Finally, smoke from wildfires across the Pacific Northwest is impacting much of northwest Oregon and southwest Washington. The thickest smoke continues to reside in the central Columbia River Gorge around Hood River and across the Cascades stretching from Mt Hood to Oakridge and Willamette Pass where unhealthy air quality values are being observed this afternoon. Elsewhere, visibilities are generally 6 miles or more and should remain at similar levels into tonight. As onshore flow slowly increases over the weekend, expect smoke to gradually shift out of the region. Smoke tends to clear out a bit slower than modeled, but even the latest smoke model guidance suggests significant improvement by either late Saturday or Sunday. Either way, the weather pattern going into Monday will be even more favorable to scoop out any remaining smoke lingering across southwest Washington and northwest Oregon and push it well east of the Cascades. /Neuman && .LONG TERM...Monday night through Friday...A secondary shortwave trough will slide down the backside of the upper level trough Tuesday and keep temperatures near average for the date. Thereafter, models and their ensemble members provide two scenarios for the second half of the week. The first scenario which includes approximately 20-30% of the available model guidance keeps a weak upper level trough over or close enough to the Pacific Northwest that temperatures would remain near to slightly above average for the remainder of the week. The second scenario that approximately 70-80% of the model guidance supports is that shortwave ridging will build more squarely over the northeast Pacific before slowly shifting eastward towards the Pacific Northwest. This would result in a more dramatic warm up and result in another round of hot temperatures towards the end of next week. NBM guidance suggests ~20-30% chance of 100F temperatures returning to the region by next Friday or Saturday and around a 50% chance of 95F. /Neuman && .AVIATION...Shallow marine layer remains over the coastal waters, with patchy IFR/LIFR along the coast. Stratus pulled back from the coast in some areas this morning, but is already starting to return as light to moderate westerly develops this afternoon. Smoke from nearby fires covers the forecast area and is expected to linger through Saturday, but based on the 18z run of the HRRR smoke model conditions should mostly remain VFR at the surface. Some 1-3 SM vsbys or lower possible within 5-10 SM downwind of ongoing fires. Slant-range vsbys on approaches may be impacted by the smoke, and some mountain obscurations are possible within the smoke layer. For detailed regional Pac NW aviation weather information, go online to: https://weather.gov/zse KPDX AND APPROACHES...VFR flight conditions expected to prevail next 24 hours. Smoke layer is expected to remain over the region through Saturday, but surface vsbys should remain 6 SM or better. That said, slant-range vsbys may be impacted on approach due to the smoke. Weagle && .MARINE...Pressure gradients remain weak over the coastal waters this afternoon, thus winds remain generally light. High pressure is expected to strengthen enough offshore the OR/CA border to turn winds more northwesterly along the Oregon coast Saturday afternoon, adding a bit of breeziness south of Newport. This will be short-lived as a weak front approaches from the northwest Sat night/Sun morning, with weak southwesterly flow expected to develop ahead of the front Sunday. Cold front will move across the waters Sunday night/early Monday, bringing a quick transition to northerly winds behind the front. Model guidance continues to suggest a typical summertime northerly flow regime will continue thereafter, most likely through the end of the week. Thermally induced low pressure will reside over northwest CA and far southwest OR during that time, bringing the breeziest conditions to the central Oregon waters with conditions a bit less breezy further to the north. Small craft advisory winds gusting up to 25 kt will be possible over the central Oregon waters Tuesday through Thursday each afternoon and evening. Aside from winds, a west-northwesterly of 3 to 5 ft will prevail through the weekend, before building back to 7 to 8 ft late Monday into Tuesday. Weagle && .PQR WATCHES/WARNINGS/ADVISORIES... OR...Excessive Heat Warning until 10 PM PDT Saturday for Cascade Foothills in Lane County-Cascades in Lane County-Central Coast Range of Western Oregon-Central Columbia River Gorge- Central Willamette Valley-Coast Range of Northwest Oregon- Greater Portland Metro Area-Lower Columbia-Northern Oregon Cascade Foothills-Northern Oregon Cascades-South Willamette Valley-Upper Hood River Valley-Western Columbia River Gorge. Red Flag Warning until 10 PM PDT this evening for Mt. Hood National Forest West of Cascade Crest-North Oregon Coast Range. Red Flag Warning until 10 PM PDT this evening for Central Oregon Cascade Foothills-East Slopes of the Central Oregon Coast Range-Willamette National Forest. WA...Excessive Heat Warning until 10 PM PDT Saturday for Central Columbia River Gorge-Greater Vancouver Area-I-5 Corridor in Cowlitz County-South Washington Cascade Foothills-South Washington Cascades-Western Columbia River Gorge. Red Flag Warning until 10 PM PDT this evening for Eastern Gifford Pinchot National Forest Mt Adams Ranger District- Extreme South Washington Cascades and Foothills. PZ...None. && $$
Area Forecast Discussion
National Weather Service Reno NV
119 PM PDT Fri Aug 13 2021 .SYNOPSIS... Hot afternoon temperatures prevail through early next week before some cooling ensues. Isolated afternoon and evening thunderstorms are expected in eastern CA and far western NV through the weekend with a few lingering storms in Mono and Mineral counties Monday. Wildfire smoke will continue to degrade air quality in many areas. Increased afternoon breezes are forecast for Monday and Tuesday. && .DISCUSSION... An upper disturbance continues to move north across far northern California and northwest Nevada. Last night into early this morning, the disturbance and sufficient mid-level instability initiated nocturnal thunderstorms across Churchill, Pershing, northern Washoe, and far northeastern Lassen counties. As for smoke, denser smoke from the Dixie Fire stuck mostly in northeast CA last night with only a few hour block of worsening air quality for many spots into western NV. Turning to the future, the highlights through the middle of next week are of course smoke but also isolated thunderstorms and hot afternoons through Monday. One other item of note will be an uptick in winds Monday and Tuesday as low pressure moves into the Pacific Northwest. Let`s break it down into individual elements... * SMOKE: Not just one broken record this summer but a whole store of broken records. Anyway, idioms aside, as mentioned the heavier smoke from the Dixie Fire remained in northeastern CA last night with generally moderate air quality readings in western NV. HRRR smoke runs from this morning indicate the heaviest smoke spreading east to Doyle-Pyramid Lake-western Churchill County before midnight before it sags south into Reno and Sparks towards morning. Be prepared for a downturn in air quality tonight and early Saturday; however, not all areas are going to be equally degraded air quality-wise so check with fire.airnow.gov for the latest readings in your area. * THUNDERSTORMS: Isolated afternoon and early evening storms are on tap today for eastern CA and far western NV. However, unlike last night when there was forcing, storms should dissipate by around sunset as daytime heating begins to dissipate. Thunderstorms look to move VERY SLOWLY with little flow aloft so localized moderate to heavy rainfall is likely. This is of major concern for portions of the Tamarack Fire burn scar, especially along and west of Highway 89 in Alpine County and across far southern Douglas County near Highway 395. Those areas could see increased risk of debris flows and flooding from as little as 0.20" of intense rainfall. Saturday, there is widespread simulation support for a reduction in thunderstorm coverage as upper ridging becomes stronger and brings subsidence to discourage deep convection. Still, above normal heat is likely to bring some bubbling up with a few showers or storms possible, mainly in the Sierra south of Highway 50. On Sunday, chances spread back north into northeast CA and far western NV with possible support from a late day zephyr. Monday, drier and more stable air aloft is expected for areas north of Highway 50 with a few residual storms possible south of there before drier air invades by Tuesday. * TEMPERATURES: Remaining hot/above average through the weekend with mid 90s to low 100s for lower valleys before next week`s trough brings a cooldown closer to normal temperatures. This brings good confidence that we will exceed the record number of 100+ for the Reno climate station (20, we are at 19 through yesterday). * WINDS: Generally on the lighter side through the weekend with afternoon thunderstorm outflow being the dominate force for gusty winds (perhaps up to ~45 mph). The impetus for winds becomes more synoptic early next week as low pressure pushes into the Pacific Northwest. This is expected to bring an uptick in winds Monday afternoon/evening, peaking Tuesday afternoon and evening before winds settle back down to typical breezes mid to late next week. The winds will bring fire weather concerns...see below for more information. -Snyder && .AVIATION... Smoke and haze remain widespread over the region due to active wildfires. Slantwise visibility has been heavily reduced in addition to terrain obscuration. Surface visibility is better today than the past few days, but high resolution smoke models indicate smoke potentially worsening overnight both tonight and again Saturday night. Areas immediately downwind of wildfires will see IFR conditions. Thunderstorms will continue this afternoon into the evening, with the greatest chances along the Sierra and eastern Sierra Front. There is a 15-20% chance of a storm within 10 miles of western NV terminals and 20-30% for Sierra terminals. Main threats from storms will be erratic outflow wind gusts over 35 kts in addition to brief heavy rain. Storms may also impact smoke, with improving conditions in some areas and worsening conditions in others depending on outflow speeds and direction. High pressure settling over the region this weekend will limit thunderstorm development. A few spotty storms remain possible, mainly along the Sierra and CA/NV state line south of Tahoe. -Dawn && .FIRE WEATHER... Hot and unstable conditions will lead to a favorable environment for plume dominated fires for the next few days. Increasing moisture may boost pyrocumulus development for the Dixie Fire and open the door for pyrocumulonimbus clouds. Thunderstorms are most likely today and have already initiated along the Sierra. There is a bit more moisture/instability today so expect a better chance of wetting rains and possibly some spot flooding if a slow moving storm passes over a burn scar. Dry strikes outside of rain cores and gusty outflow winds over 40 mph are possible. Thunderstorm potential for Saturday-Sunday may be squashed a bit as high pressure is forecast to center itself over western NV. Best confidence in weekend storms is along the Sierra and CA/NV state line south of Tahoe with coverage rather spotty in nature. Signs are pointing toward increasing winds Monday and/or Tuesday as low pressure moves into the Pacific Northwest. For now the potential for widespread critical fire conditions is low Tuesday with gusts likely to be in the 25-35 mph range. There is starting to be signals for stronger winds on Tuesday, but confidence is lower at this point and will depend on whether or not a trough is able to overcome the ridge and move into the area. Ensembles are hinting at a 40% chance for winds to exceed 40 mph. Increasing winds next week could wake up holdovers from this week`s lightning and the dry breezy conditions may be critical for ongoing wildfires. -Dawn/Brong && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$ For more information from the National Weather Service visit... http://weather.gov/reno
Area Forecast Discussion
National Weather Service Shreveport LA
1010 PM CDT Fri Aug 13 2021 .UPDATE... Raised pops mainly for I-30 overnight and then also spreading better coverage across I-20 early in the daylight hours. && .SHORT TERM.../Tonight through Saturday/ Warm night for most of us with a range of 80s most everywhere. 77 in El Dorado is our coolest as they had a shower. The warmest around is the triple digit winner today at Texarkana with 87 at 10pm. Winds are very light on the surface and lower levels with no desirable low level jet to feed on, just leftover instability with still 3500 J/Kg along and south of I-30. We have likely pops as radar is showing some improvement organization wise. The HRRR takes aim at NW LA by daybreak, but falls apart on arrival. The new NAM is encouraging and is similar to HRRR and does hold together better in NW LA by 12Z. It also has better coverage areawide and thus this update of increase extends into our Saturday. /24/ && .PREV DISCUSSION... /issued 724 PM CDT Fri Aug 13 2021/ AVIATION... For the ArkLaTex terminals, we have increasing chances for convection with a weak cool front on approach that will become stationary in our vicinity late tomorrow. VCTS attm is winding down already, but some nocturnal chances remain possible with activity on models during the overnight and through about daybreak, then a break until heating resumes. Variable winds will become N/NE5-10KT by this time tomorrow. We will be watching and amending with tempos throughout this weekend. /24/ PREV DISCUSSION... /issued 219 PM CDT Fri Aug 13 2021/ SHORT TERM.../Tonight through Saturday Night/ The good news is, better chances for rain are in store for the Four-States region over this short-term period. The bad news is, showers and thunderstorms may interrupt some weekend plans. I personally welcome the idea of some rain cooled air, but I certainly hope no one`s weekend plans are affected. At the upper- level, a small disturbance is moving out ahead of a frontal boundary moving south through the plains. This disturbance will begin to increase shower and thunderstorm chances by this afternoon, a trend that will continue through the weekend. At this time, this activity looks to vary from scattered in nature, to rather organized as the front approaches. Frontal passage appears to occur right at the hand off of the long and short-term desk, which means the best chances for widespread precipitation will occur towards the end of my period, and into the long-term. Unfortunately, we likely won`t see any reprieve from the afternoon high temperatures this short-term. On the other side of that coin, afternoon dew points have not been getting as high as previously anticipated. This means that the Heat Advisory that was previously in place has been canceled, and plans for another one are not in place at this time. Highs tomorrow will range in the low to upper-90s, with overnight lows both tonight and tomorrow ranging in the low to mid-70s. /44/ LONG TERM.../Sunday through Friday Night/ As we move into the second half of the weekend, sfc ridging will continue to retrograde westward into deep southwest Texas due to a broad upper trough located across the Central and Southern Plains, moving into the Ohio and Tenn Valleys. This trough should be enough to pick up Tropical Storm Fred which should be in the NE Gulf of Mexico by Sunday Night and steer him well to our east. Upper forcing due to the vicinity of the trough axis and plentiful low and mid level moisture should result in another period of scattered convection areawide on Sunday, diminishing to isolated to low end chance pop coverage Sunday Night. The trough axis remains virtually unchanged Monday into Tuesday of next week per the 12z ECMWF which again will result in primarily diurnally driven convection each day with the higher pop coverage likely across our eastern half, especially on Monday. The trough finally begins to fill and lifts out during the day Wed with upper ridging beginning to build into our region from the southeast U.S. which will likely result in an downward trend in pop coverage and an uptick in temperatures by the end of the upcoming work week. /13/ && .PRELIMINARY POINT TEMPS/POPS... SHV 76 96 74 90 / 30 50 40 50 MLU 76 95 74 90 / 20 70 40 50 DEQ 72 92 72 87 / 50 40 40 50 TXK 74 93 74 88 / 40 40 40 50 ELD 72 92 71 87 / 30 50 40 50 TYR 75 94 74 89 / 20 50 30 50 GGG 74 94 74 89 / 30 50 30 50 LFK 75 96 74 91 / 10 50 20 50 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 24/44/13
Area Forecast Discussion
National Weather Service Las Vegas NV
745 PM PDT Fri Aug 13 2021 .SYNOPSIS...A strong area of high pressure over the Great Basin and Mojave Desert will lead to above normal temperatures this weekend. Disturbances moving along the southern periphery of the high will interact with monsoon moisture leading to chances for thunderstorms through Saturday. Another disturbance will lead to an upswing in storms Tuesday and Wednesday of next week. && .UPDATE...As of 730 pm, most of the active convection from earlier today, focused across San Bernardino County, has diminished with the loss of daytime heating. Meanwhile, attention shifts eastward with approaching convection moving in from Coconino and Yavapai counties. It`s somewhat unclear how convection will evolve through the remainder of the night. Most CAM guidance and the most recent HRRR runs suggest ongoing storms entering Mohave county will quickly weaken with the loss of daylight. However, the SPC mesoanalysis page suggests 500-1000 j/kg of CAPe remaining in place for a few more hours, and the 00z VEF sounding also showed pretty substancial instability in play. Given the observations, and keeping in mind what occured last night, suspect convection will be slow to wane until late in the evening. I suspect the current activity will likely continue to propagate west, driven by a strong cold pool and develop into at least the eastern half of Mohave county before slowly decaying. Given the instability shown in the VEF sounding this evening, can`t completely rule out storms making a run for the river or even a little further west. Will continue to monitor trends and get a quick evening update out to the forecast grids to account for the latest trends. -Outler- .AVIATION...For McCarran...Southerly winds with gusts to around 15 knots are likely through early evening before diminishing. More of a typical diurnal pattern is expected tomorrow with lesser storm impact potential compared to today. For the rest of southern Nevada, northwest Arizona and southeast California...Best chances for terminal impacts look like KEED/KIFP and this evening, though confidence is low. Another complex of thunderstorms is expected out of western Arizona that could push gusty outflow winds from the east towards the Colorado River Valley, shifting winds to the east late tonight and resulting in gusts over 30 kts. Continued the PROB30 groups from the earlier issuance for these terminals. && .SHORT TERM...through Sunday. Thunderstorms that have started developing over the Clark County mountains will tend to move slowly to the west or northwest due to the influence of the circulation that could be seen on satellite loops moving overhead this afternoon. However, individual cells should have difficulty sustaining themselves as they move off the mountains. Recent mesoanalysis showed mixed layer convective inhibition persisting over the lower elevations through the afternoon around Clark County and Mohave counties. The The main area to watch will be central and southern Mohave County late this afternoon and evening as multiple runs of the HRRR indicate late day thunderstorms over the rim country west of Flagstaff will move toward the west and expand into a complex impacting areas from Peach Springs down to Kingman and the Hualapai mountains. A potentially large cold pool associated with the complex should be enough to overcome the CIN and the storms will propagate fairly quickly to the west limiting the potential for excessive rain over any specific site. Strong winds up to 50 mph will be possible with these storms, but DCAPE values generally less than 1000 J/kg do not indicate extensive severe storm potential. The overall synoptic setup remains fairly similar for Saturday though the circulation overhead will have moved toward the SoCal Coast. The easterly flow in the base of the high centered over Nevada and surrounding states will continue to support westward movement of storms developing over the Mogollon Rim in the afternoon and early evening hours. The HRRR indicates a similar threat of storm impacts for Mohave County late Saturday afternoon and evening. High pressure strengthens and expands southward Sunday which will produce a drier north to northeast flow across our region and should suppress storm development somewhat. Temperatures will continue rising under the influence of the high pressure and the Excessive Heat Watch for Inyo and western San Bernardino counties has been upgraded to an Excessive Heat Warning which for Sunday into Monday. .LONG TERM...Monday through Friday. A pattern transition begins Monday as a broad trough begins to push down from the Pacific Northwest which will push the high over toward the Four Corners and lead to a southerly flow across which will likely bring a moisture influx into our region by Tuesday. The moisture should remain over southern Nevada and surrounding areas through Wednesday. Increasing shear associated with the trough may combine with the deeper moisture to produce more organized thunderstorms. So, Tuesday and Wednesday should be fairly active convective days. A drying trend is indicated Thursday and Friday as the trough progresses over the Rockies. However, there is not a clear indication that moisture will scour out and sufficient moisture may remain for chances of thunderstorms over the mountains of southeast Nevada and northwest Arizona. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ SHORT TERM/LONG TERM...Adair AVIATION...TB3 For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter