Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/24/21

Area Forecast Discussion
National Weather Service Denver/Boulder CO
901 PM MDT Wed Jun 23 2021 .UPDATE... Issued at 851 PM MDT Wed Jun 23 2021 We`re between two areas of very weak lift from passing shortwaves. The diurnal convection nicely filled in the hole so there really wasn`t any clearing, but we got a little enhancement of westerly winds off the foothills this evening that dried the low levels more. Now we have the next area of lift which also marks the beginning of some increase in deep moisture which is currently moving from the San Juans into central Colorado. This should keep the clouds around, and produce some light showers over the central and northern mountains overnight. These clouds will be over Denver in the morning. Whatever rain falls will be very light, but this will be a part of moistening the atmosphere. It will also keep temperatures up overnight. There was less smoke generated by the upstream fires today, likely because of the cloud cover. There is a plume from the Muddy Slide fire but it`s headed northeast. Since the smoke was not lofted as much, there will likely still be some increase in surface smoke overnight in areas north of Boulder, but again the overall volume today was quite a bit less. It will be interesting to see the tradeoff between more moisture and all the cloud cover and cooler surface temperatures tomorrow. CAPE still looks to be quite limited over most of our area, but there could be more light precipitation to drive gusty outflow winds. Still some threat of bigger things over the eastern part of the plains in the evening where there will be more moisture. && .SHORT TERM...(This evening through Thursday) Issued at 216 PM MDT Wed Jun 23 2021 Hot, dry, and smoky conditions will continue this evening with highs gradually falling from the mid to upper 90s. Water vapor satellite continues to show a nice plume of better moisture streaming into the region under south-southwesterly flow, which has led to some very high based shower development during the early afternoon hours. There is some weak synoptic scale ascent around and we should see continued weak convection over the higher terrain, but the main impacts would be from gusty winds and a few lightning strikes. An isolated storm or two will also be possible tonight over extreme northeast Colorado, but trends favor most of these storms to remain north and east of our forecast area. If storms do develop, small hail and gusty winds would be possible. Cloudy, smoky skies are expected overnight tonight with mild overnight lows. HRRR smoke shows increasing near-surface (and total) smoke this evening which is expected to last most of the night. As mentioned before, this will be highly dependent on fire behavior on the Sylvan/Muddy Slide fires this evening, and I wasn`t particularly confident enough to change the smoke grids. Tomorrow will be around 10F cooler or so as a shortwave trough approaches the area and a weak cool front pushes south. Moisture does increase behind the front as well, with PWATs nearing 1 inch. As a result, fairly good coverage of thunderstorms is expected in the afternoon, especially with enhanced lift from the approaching shortwave. Not a whole lot of instability out progged, with around 500 J/kg MUCAPE over most of the area, with better instability in the far northeast. This coincides with deep layer shear greater than 20-30kt, so a few marginally severe storms are possible over most of eastern CO. Over the mountains, better moisture finally makes it west of the divide, and we could see briefly heavy rain across the Front Range and into Middle and North Park. .LONG TERM...(Thursday night through Wednesday) Issued at 216 PM MDT Wed Jun 23 2021 Active period for the first few days of the extended, then things settle down heading into next week. Rex block along the Pacific coast with an upper high centered over southwest British Columbia and low over central California coast. A southwest to northeast oriented trough stretches from the California low to the northern plains. This trough and lower heights over the region will produce...wait for it...daytime high temperature`s as much as 10 degrees below normal through next Tuesday. Thursday`s shortwave trough along with any storms will be departing the northeast corner of the state 00-06z Friday. Meanwhile a second, more vigorous shortwave trough will dig into northern Utah and northern Colorado through Friday, along with a surface cold front. Moisture remains in place across the region, at 1.25" in the northeast to 3/4" in the foothills east of the divide, and 1/2 inch in the mountains. Expect rain to be focused along the front, in the mountains in the afternoon spreading east into the evening. Model soundings show storm motions slow Friday evening, and high moisture levels along with slow storm movements could produce unwanted excessive rainfall over burn area, especially east of the divide. Another wave and chances for rain on Saturday with cooler temperatures. Westerly upslope flow along the divide early Saturday morning into the day may produce some enhanced precip on western facing slopes at high elevations, with some concerns for eastern portions of the East Troublesome burn area and possible high elevation westerly portions of Cameron Peak. From Sunday onward the SW Canada/Pacific NW high shifts slowly east, still a blocky pattern but the ridge comes close enough to have a drying influence over the forecast area and unsettled weather is pushed further south in Colorado. Slow warming trend through this period with temperatures back to near normal on Wednesday. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 851 PM MDT Wed Jun 23 2021 Smoke will remain in the Denver area tonight, though it will not be enough to reduce surface visibilities. More concentrated areas of smoke will remain northwest and west of Denver but may affect northwest approaches to KDEN. Some decrease in the smoke is expected by Thursday morning, and VFR conditions are expected. Scattered high based thunderstorms will likely bring a few wind shifts with gusts to 30 knots after 21z. && .FIRE WEATHER... Issued at 216 PM MDT Wed Jun 23 2021 Near Red Flag conditions are expected through this evening, though winds will likely remain just below criteria. Conditions improve substantially tomorrow with increasing moisture on both sides of the divide. Widespread showers and thunderstorms are likely during the late morning hours, persisting through the evening. Increasing chances for rain on Friday and Saturday with higher levels of moisture in the atmosphere will make prescribed burns more difficult on the one hand, while lowering wildfire risk on the other. From Sunday onward a drying trend with below normal temperatures with excellent RH recovery at night and daytime minimum RH in the 45-60 percent range. && .HYDROLOGY... Issued at 216 PM MDT Wed Jun 23 2021 Limited risk of flash flooding tomorrow for all of our burn areas as scattered thunderstorms are expected across the area. Moisture increases quite a bit compared to today with slow storm motions possible. Briefly heavy rains will be possible through much of the day and into the evening hours. Enhanced risk mainly in Cameron Peak & Calwood burn areas for burn area flooding Friday, with a frontal passage and slower storm movement, and deeper moisture east of the divide. For Saturday there is the possibility that westerly upslope flow on in the northern mountains could enhance rainfall over high elevation areas of the east end of the East Troublesome and west end of the Cameron Peak burn areas. Drying from Sunday onward with little to no flood threat. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Gimmestad SHORT TERM...Hiris LONG TERM...Hanson AVIATION...Gimmestad FIRE WEATHER...Hanson/Hiris HYDROLOGY...Hanson/Hiris
Area Forecast Discussion...UPDATED
National Weather Service Duluth MN
907 PM CDT Wed Jun 23 2021 .MESOSCALE UPDATE... Issued at 907 PM CDT Wed Jun 23 2021 We continue to monitor convective trends across northern Minnesota. A few stronger storms were located in western Beltrami County and southern Clearwater County. Storms farther northeast were mainly elevated and weak with primarily IC and CC detected. Atmosphere remains marginally conducive to thunderstorm maintenance ahead of surface and elevated cold front over northwest Minnesota. Latest 00Z SPC mesoanalysis suggests MUCAPE values over our northwestern zones between 500 and 750 J/kg. Expect MUCAPE to increase from the south with an increase in low- level moisture advection as 850 mb LLJ strengthens over northeast Minnesota and northern Ontario between 03-07Z. Convergence along the elevated frontal surface will increase along the western periphery of the jet after midnight, which should provide enough forcing for showers and storms to become more widespread. The reservoir of greater instability will build from the south and think storm intensities will ramp up around or after 06Z as the convergence pushes southward into central and east-central Minnesota and northwest Wisconsin. The 24.00Z RAP brings 1000 to 3600 J/kg of MUCAPE into an area from near Brainerd to Silver Bay and over NW WI by 08Z. While I think the top end of this range is probably overdone, the increase in instability over this area has been a consistent feature of the guidance throughout the day. Abundant deep layer shear will remain in place with 0-8 km bulk shear of 40 to 55 knots. One or more clusters of strong to severe storms are possible overnight with hail to 1.5 inches in diameter and damaging wind gusts to 65 mph possible. && .DISCUSSION...(This evening through Tuesday) Issued at 417 PM CDT Wed Jun 23 2021 Summary: Mostly clear skies with strong southerly wind have developed this afternoon. Showers and thunderstorms likely this evening into Thursday morning with possible redevelopment Thursday afternoon. Temperatures will be relatively normal for the remainder of the work week. Winds have been out of the south/southwest Wednesday afternoon ahead of our next cold front that is currently over north central North Dakota to northeastern Montana. Due to the strong southerly winds, temperatures across the CWA have reached into the lower 80s with dew points in the low 50s. Severe weather is possible this evening as showers and thunderstorms develop along and west of the cold front as it moves into Koochiching county by 00Z. Convective initiation will be slightly elevated with MUCAPE values of 1000-1500 J/kg and Lapse Rates of 6.5-7 C/km. Bulk shear values are near 35 to 45 knots which favors supercell development. Strong southerly winds will continue to help destabilize the atmosphere therefore 06Z MUCAPE values will increase to around 1300 J/kg based on GFS and 2300 J/kg based on the NAM12. CAMS are indicating that discrete supercells will combine into a line by Thursday morning over northwest Wisconsin. Wind gusts up to 60 mph and hail to one inch are possible with the stronger storms. The cold front appears to become stationary over northwestern Wisconsin leading to additional convective development by Thursday afternoon. MUCAPE values of around 2100 J/kg can be found along the front. There is a slight risk for our far southeastern county in Wisconsin. Some soundings indicate a cap around 750mb which supports the lack of convection with the NAMNEST. After the front moves through temperatures will be closer to normal for the remainder of the work week. Our next chance of precipitation will be towards early next week. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 700 PM CDT Wed Jun 23 2021 A line or two of thunderstorms will move east-southeastward across northeast Minnesota and northwest Wisconsin through 24.14Z along and either side of a cold front. Storms are expected to intensify after 24.03Z in response to a strengthening low-level jet over northeast Minnesota and northern Ontario. Strong low- level winds ahead of the front should keep wind speeds and gusts elevated this evening. Gusts near thunderstorms to 40 knots are possible along with small hail. After the storms pass skies should clear and there will be a potential for some IFR fog at INL and HIB. Fog may develop at BRD and DLH as well, but the later arrival of precip and clearing compared to sunrise and the start of daytime mixing may prevent fog development. && .MARINE... Issued at 952 AM CDT Wed Jun 23 2021 Winds will be out of the south/southwest 10 to 15 knots with gusts to less than 25 knots. A cold front will be passing through this evening into Thursday morning. Showers and thunderstorms will likely develop along and west of the front and move southeastward approaching Lake Superior after midnight. After the cold front moves through the winds will switch to the northwest at 5 to 10 knots. && .PRELIMINARY POINT TEMPS/POPS... DLH 62 80 57 78 / 80 10 10 10 INL 54 79 51 80 / 100 0 10 10 BRD 63 83 57 82 / 80 10 10 10 HYR 64 83 54 82 / 90 50 10 10 ASX 64 78 53 76 / 90 30 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. LS...None. && $$ UPDATE...Huyck DISCUSSION...Eagle AVIATION...Huyck MARINE...Eagle
Area Forecast Discussion
National Weather Service Hanford CA
210 PM PDT Wed Jun 23 2021 .SYNOPSIS...Temperatures will average close to normal over the area through Friday. There is a slight chance of afternoon and evening thunderstorms over the Sierra Nevada Thursday and Friday. Hot temperatures will return this weekend and continue through at least next Wednesday. && .DISCUSSION...WV imagery showing an upper low centered off of the central CA coast near 37N/126W. This system is continuing to push cooler air into our area with temperatures generally running 2-5 DEG F below yday at this time and close to seasonal normals. The low is progged to remain quasi-stationary off the central CA coast on Thursday which will provide for another day of near climo temperatures. Meanwhile, IR imagery is showing a surge of mid-level tropcial moisture streaming northward over southeastern CA with the western periphery of the moisture clipping the Kern County Deserts and the Sierra Nevada from Fresno County southward. Radar composites are indicating some showers and thunderstorms to the east of our CWFA this afternoon. the latest HRRR runs are indicating that the precipitation will remain mainly to the east of our area so precipitation chances for the eastern most portions of our area are minimal at best for this afternoon. On Thursday, the mid level moisture is expected to stream northward further to the east of our area. As a result, Kern and Tulare Counties will remain dry and free of thunderstorms on Thursday. However, some of this moisture might get pulled back by the offshore low and produce showers and thunderstorms over the higher elevations of the Sierra Nevada from Fresno County northward on Thursday afternoon and evening. Latest probabilistic guidance is indicating that Yosemite Valley has a 35 percent chance of picking up measurable precipitation on Thursday. The SREF is indicating that the low will move inland on Friday. While this low is moisture deficient, it will provide for enough lift for another round of afternoon showers and thunderstorms over the higher elevations of the Sierra Nevada from Fresno County. It will also keep temperatures near seasonal normals for another day. The medium range models and their ensemble means are indicating a large upper high pressure center building into the PAC NW over the weekend which will will result in a dry offshore flow over our area during the weekend with temperatures rising back up to well above normal levels by Sunday. The upper high is progged to be centered over the intermountain west region for much of next week which will keep the vary warm airmass in place over our area. Some uncertainty exists on whether or not some high pw moisture gets pulled into our area from a tropical disturbance in the Gulf of Mexico. At this time, have mentioned a slight chance of afternoon and evening showers and thunderstorms in the mountains and deserts for Monday and Tuesday and including more of our area by next Wednesday as mid/upper level RH`s increase. && .AVIATION...Areas of MVFR ceiling with local mountain obscuring IFR in showers and thunderstorms over the Sierra Nevada from Fresno County northward after 18Z Thu. Otherwise, VFR conditions will prevail throughout the central CA interior for at least the next 24 hours. && .AIR QUALITY ISSUES...None. && .CERTAINTY... The level of certainty for days 1 and 2 is high. The level of certainty for days 3 through 7 is medium. Certainty levels include low...medium...and high. Please visit for additional information an/or to provide feedback. && .HNX WATCHES/WARNINGS/ADVISORIES...None. && $$ public/aviation/fire wx...DS pio/idss...BSO
Area Forecast Discussion
National Weather Service Medford OR
839 PM PDT Wed Jun 23 2021 .DISCUSSION...A few strong storms formed this afternoon, but overall the coverage was less than anticipated. This is especially true along the Cascade crest in northern Klamath County. To try and address why this happened we`l first turn to this afternoons sounding and compare it to yesterdays. There was more CIN, negative energy, in the environment, and 5 kts less shear today. The CIN indicates that there needed to be stronger forcing for storms than would have been needed yesterday. Commmon with high CIN values, there was more CAPE today than there was yesterday. Precipitable waters values were nearly the same as well, at 0.90" and 0.92" today and yesterday respectively. So, all things relatively square, other than the increased CIN, what today needed was a stronger forcing mechanism than yesterday. And that was lacking today. In pouring through the latest four deterministic RAP runs, prior to convective initiation, the model data did not show a strong trigger except over the Siskiyou and Marble Mountains. A trigger, aside from orographics, was lacking along the Cascade crest and the east side. This is probably what limited the presence of thunderstorms. Although it`s is worth highlighting that a sounding from Medford and a sounding from east of the Cascades would not have looked identical today, so there is some uncertainty as to why the east side did not see more activity. Also want to note that this is the first instance where the SREF calibrated probability of 100+ lighting strikes busted. It showed a 6% chance for this occurrence, which seems to be the high even for other places in the CONUS, along the Cascades as a distinct bubble from the 4% over Siskiyou County, which came closer to verifying at 64 CG strikes thus far. This is a positive test case and a pragmatic reminder that this tool is contingent on thunderstorms forming in the first place. Having personally only used this tool for three events now, today was a positive learning experience for how best to make use of this tool. In the short term future, stray storms that are very much isolated in nature, will remain possible for the next six hours or so. The latest RAP and GOES-17 mid-and-upper-level water vapor imagery show a wave moving through northern California now. This may be enough to support one or two more small storms during these late evening hours. In fact, two such cells can be observed on satellite trying to get going in northern Klamath and Lake Counties now, with a third in the works. Their storms tops are around 30 kft and are producing some lightning activity now. Can`t rule out an isolated nocturnal thunderstorm tonight in eastern Klamath County and southern Lake county, so have retained them in the forecast. Beyond this, the upper low driving this unsettled weather will begin to return to where it came from to our south. This will shift the area of greatest instability further south and focus storms mainly in northern California. Limited isolated storm potential will still exist in extreme southern Klamath and Lake County. A good description of the uncertainty with these storms was provided in the FireWx section of the previous discussion and here, "Signals are a bit mixed in the models, with some models hitting the Modoc area harder than Siskiyou County and others doing the opposite. Activity also looks as if it could be briefly scattered across southern Lake and Klamath counties. However, some waves of subsidence from building high pressure from the north will be pushing over the area increasing through the day, and this is expected to diminish the vertical extent and general ascent with time. Therefore, we expect convection on Thursday to begin early and then end earlier than normal. With PWATs up around 1 inch, it`s quite possible that the activity will morph into more of an area of rainfall in some areas during the evening. -BTL" And finally, on the weather heading into this weekend from the previous discussion, "As we head into the weekend an Upper level high builds just to the north of the region with an upper low well to the south of us. This blocking pattern will bring near record to record temperatures into the region this weekend. The models remain in near universal agreement in very hot temperatures for all but the coastal areas, and temperatures are very likely to be hotter than they were last weekend. Sunday is the day of highest concern as it`s forecast to be the warmest. In fact, we`re expecting extreme heat risk Sunday in Medford given the latest forecast of 111 degrees for a high and an overnight low that is not expected to drop below 70 degrees. The Excessive Heat Watch has been updated to a warning, and is in effect from Saturday through Tuesday, although with the often stubborn Rex Block pattern, a duration of this event past Tuesday is possible, but confidence is not high enough to extend the warning past Thursday at this time. -Sven" -Miles && .AVIATION...For the 24/00Z TAF Cycle...Along the coast and over the coastal waters...a deepening marine layer has lifted ceilings some, so mainly MVFR cigs in marine stratus will persist north of Cape Blanco and near Brookings into this evening. Later this evening, the stratus will spread into the Coquille and lower Umpqua valleys. The stratus will then erode back to the beaches, and likely clear from Brookings during Thursday morning. Over the remainder of the area...VFR conditions will persist through Thursday, but there will be a few isolated to scattered thunderstorms left this evening, with most storms focused east of the Cascades. Small hail and gusty winds in thunderstorms are possible. Another round of isolated to scattered thunderstorms is expected Thursday afternoon, mainly in northern California but possibly extending into southern portions of Klamath and Lake counties. -DW/Keene && .MARINE...Updated 800 PM PDT Wednesday, 23 June 2021...North winds have begun to increase, mainly south of Cape Blanco with steepening seas. A Small Craft Advisory recently began, roughly beyond 3 nm from shore. The advisory level winds and steep seas will spread nearer shore tonight before spreading northward on Thursday as a thermal trough continues to build northward. These conditions will persist through Friday before the thermal trough expands so far north (into Washington State) that our steep seas and gusty winds subside this weekend. Moderate winds and seas are expected during the weekend with southerly winds developing late Sunday, possibly continuing into Tuesday. On Tuesday, models are beginning to show an incoming northwest swell that could generate conditions hazardous to small craft, but confidence is low in the extended forecast. -DW/Keene && .FIRE WEATHER...Updated 400 PM PDT Tue 22 Jun 2021... Thunderstorm activity today is still expected to be more isolated than it was over the last couple of days, overall, but scattered activity is expected over and near the Marble and Siskiyou Mountains, possibly the Cascades near and north of Crater Lake, and possibly across much of the East Side into this evening. Confidence in significant activity along and east of the Cascades is not high in activity becoming greater than isolated for this evening, however. While most storms will produce rainfall that could be wetting in thunderstorm cores, significant lightning on dry fuels is expected, and isolated dry storms are possible. Models hang onto some instability and moisture sufficient for showers and thunderstorms tonight into the morning over and near the Upper Klamath Basin. While there`s no clear trigger to realize the potential, we`ve kept a slight chance of showers and thunderstorms in for that area overnight into the morning hours. The low will move southward Thursday focusing scattered thunderstorm activity over Northern California. Signals are a bit mixed in the models, with some models hitting the Modoc area harder than Siskiyou County and others doing the opposite. Activity also looks as if it could be briefly scattered across southern Lake and Klamath counties. However, some waves of subsidence from building high pressure from the north will be pushing over the area increasing through the day, and this is expected to diminish the vertical extent and general ascent with time. Therefore, we expect convection on Thursday to begin early and then end earlier than normal. With PWATs up around 1 inch, it`s quite possible that the activity will morph into more of an area of rainfall in some areas during the evening. Still, given the recent dryness and the heat on the way and the expectations of scattered lightning in NorCal Thursday, the Fire Wx Watch has been upgraded to a Red Flag Warning. Very hot and dry conditions are expected Friday through Monday with record high temperatures very likely Saturday through Monday. Record high temperatures are very likely next weekend and all time June records will be threatened. There is about a 25% probability that even all-time record high temperatures could be threatened on or about Sunday/Monday. ~BTL && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Excessive Heat Warning from 11 AM Saturday to 11 PM PDT Tuesday for ORZ023>031. Red Flag Warning until 11 PM PDT this evening for ORZ623>625. Red Flag Warning until 11 PM PDT this evening for ORZ621. CA...Excessive Heat Warning from 11 AM Saturday to 11 PM PDT Tuesday for CAZ080>085. Red Flag Warning until 11 PM PDT this evening for CAZ280>282-284-285. Red Flag Warning until 11 PM PDT this evening for CAZ280. Pacific Coastal Waters...Small Craft Advisory until 11 PM PDT Friday for PZZ350-356-370-376. $$
Area Forecast Discussion
National Weather Service Norman OK
954 PM CDT Wed Jun 23 2021 ...New AVIATION... .SHORT TERM... (This evening through Thursday) Issued at 227 PM CDT Wed Jun 23 2021 A warm night tonight with lows in the 70s. Southerly winds will also stay up a bit tonight. A few showers/storms may develop to the west and northwest and move into NW parts of the fa early Thursday. This development could occur near a sfc trough and may be aided by any subtle disturbance moving in the flow. The chances of anything affecting the area early Thursday is low but several models, including the HRRR and the RAP, show some isolated activity may move into parts of the fa so chances are not zero. Otherwise, hot and humid Thursday with highs in the 90s and 100s. With the hot temperatures and dewpoints in the 60s and 70s, high heat index values will be possible. Heat index values of 105-107 could be possible in parts of north central/central OK Thursday afternoon where the heat advisory criteria is 105-110. There are a couple of mitigating factors to some of the heat impacts with breezy southerly winds expected and cloud cover possible. Will hold off on issuing a heat advisory for now but night shift may need to issue an advisory for parts of the fa. && .LONG TERM... (Thursday night through next Tuesday) Issued at 340 PM CDT Wed Jun 23 2021 A fairly strong low-level jet expected to develop Thursday evening and overnight. Moisture advection within the jet could interact with a short wave digging through our upper ridge producing some non- severe convective storms across far northern Oklahoma. Although both NAM and GFS project QPF, both the ECMWF & Canadian NH keeps our north dry and weakly ridged, so will keep the POPs low for now. Otherwise, expecting breezy south winds under sunny skies to maintain muggy conditions and unseasonably hotter temperatures for Friday afternoon. Expecting to see one last round of triple digit head index values as well before the weekend cooling trend. Adjusted Friday afternoon wind grids a little more windier than NBM with the CONSMOS. Although a capping inversion in place should inhibit any afternoon convective storms, our weak upper ridge is expected to begin breaking down from an approaching negatively tilted trough out of the U.S. Southwest. Meanwhile down at the surface, an elongated area of low pressure will be in place extending across the Central Plains into the Southern High Plains, with a surface boundary/cold front moving across northwest Kansas by the evening hours. With the low-level jet firing up again late Friday and the upper trough starting to come through and a surface boundary approaching, will see POPs for storms return Friday evening across our north. Could see the first round of storms fire up by early Friday evening across northern Oklahoma in association with a mid-level vorticity max. Although mid-level heights are not particularly strong with a weak shear profile, cooling may steepen the lapse rates there for sufficient instability for elevated storms to organize. Although some uncertainty with the frontal timing, at this point could see the surface boundary start pushing across our north after the midnight hours. The NAM remains robust with MUCAPE values 2000-3000 J/kg across our far north, while the latest run of the GFS is trending weaker and more toward the weak ECMWF solution. If the NAM solution holds, then could see a marginal risk for the elevated storms to become severe across far northern Oklahoma, with hail and wind gusts as the main hazards. For now, there is some uncertainty with the severe risk. However, with surface based instability weakening overnight, any severe risk across our far north would more associated with the elevated storms ahead of the cold front. The POPs will increase further south across our entire area during the day Saturday as the cold front continues its push as well as the digging upper trough. Although instability should be sufficient for a few storms, not expecting any it to be severe at this point in time. Should also start seeing a cooling trend start Saturday. Adjusted the warm biased NBM MaxT Saturday and Sunday with a slightly cooler CONSMOS which reflects more toward a trending cooler MEX guidance. Although models suggest the cold front stalling across northern Texas, elevated storms will be possible Saturday evening with periods of storms extending through early next week in associated with the upper trough. The highest POPs for early next week will be across the southern half of our area. By Tuesday, should start seeing a warming trend with temperatures approaching more seasonably average by mid-week. && .AVIATION... (00Z TAFS) Issued at 945 PM CDT Wed Jun 23 2021 VFR conditions will prevail through the period at all TAF sites. An isolated storm may develop or move into far north central Oklahoma by early Thursday morning. The prevailing wind may decrease enough overnight that low level wind shear will be an issue mainly across northern Oklahoma. && .UPPER AIR... Issued at 302 AM CDT Wed Jun 23 2021 An Upper Air flight is not planned for today. && .PRELIMINARY POINT TEMPS/POPS... Oklahoma City OK 76 96 77 95 / 0 0 0 10 Hobart OK 76 100 76 99 / 0 10 0 10 Wichita Falls TX 77 99 76 98 / 0 0 0 0 Gage OK 78 103 76 99 / 10 20 10 30 Ponca City OK 77 97 77 98 / 20 10 10 30 Durant OK 76 94 76 95 / 0 0 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...None. TX...None. && $$ SHORT TERM...25 LONG TERM....68 AVIATION...06
...Update to aviation forecast discussion...

.DISCUSSION... Issued at 345 PM CDT Wed Jun 23 2021 The main concerns with this forecast package are the potential for a round of thunderstorms overnight as well as Thursday night, and excessive heat during the day Thursday. However, there are several moving parts creating quite a bit of uncertainty in the short-term, which will have implications for the end of the week as well. The previously mentioned pressure gradient and lee troughing has kept gusty southerly winds with WAA and moisture advection into this afternoon. This has allowed temperatures to warm into the upper 80s to low 90s with 70-degree dew points starting to move into our area from southern KS. The upper ridge axis is making its way into the Central Plains per water vapor imagery and is expected to flatten into tomorrow as weak perturbations develop around its periphery. These disturbances in the 700-500mb flow look to be just enough to generate thunderstorms in central NE this evening, and tracking this MCS is the first challenge this period as it moves east. Most guidance suggests the better forcing would be along the nose of the LLJ in southeast NE, northern MO, and southwest IA, which is also where the instability gradient should develop. This area is where the HREF tends to focus most thunderstorm activity overnight into early tomorrow morning, although a few of its members do suggest storms could still develop as far south as I-70, with the HRRR being notably the furthest south of the solutions. As such, have kept our highest PoPs north of I-70 overnight through the morning, but have limited them to chance PoPs at this time. Any elevated storms that do hold themselves together and move this far south could have damaging wind gusts with them, but there should overall be a weakening trend into the morning. The evolution of the overnight MCS could then have significant impacts on how Thursday evolves during the day. If we do not have storms in the morning, temperatures would quickly heat up with the thermal ridge overhead and dew points in the 70s area-wide. This could bring heat indices in the 100-107 degree range in the afternoon, and would thus warrant a Heat Advisory. However, given the uncertainty in storm coverage during the morning and the environment left afterwards, will hold off on issuing heat headlines at this time as lingering cloud cover and rain may keep temperatures down for those areas that receive it. Based on the uncertainties mentioned above, we will need to monitor how much the atmosphere will be able to destabilize in the afternoon. The majority of guidance suggests storms will redevelop in the evening with another round of storms through the evening and overnight periods. However, a few models erode the cap soon enough for parts of northeast KS to see redevelopment occur in the late afternoon to early evening. We will also need to monitor the placement of outflow boundaries from the morning convection to get a better sense of where any redevelopment occurs. All this in mind, IF storms develop earlier (during the afternoon), forecast soundings suggest MLCAPE of over 3000 J/kg with veered hodographs, so this does present a window of opportunity for tornadoes to be a potential risk. This is a low-probability scenario, however, as more guidance holds off development until the evening with large hail, damaging winds, and heavy rainfall being the main threats. As mentioned earlier, location of highest storm coverage will depend on where boundaries set up, but at this time the area most favored appears to be far northeast KS into MO, so have held off on a Flash Flood Watch for now. This will be something else for future shifts to consider. Confidence becomes even lower heading into Friday and the weekend as that will depend on how the next 24-36 hours evolve. However, there remains a possibility for additional severe storms on Friday as there could be a surface frontal boundary bisecting the area. Convergence along the boundary doesn`t look incredibly impressive, but instability and shear on the warm side of the boundary could support a hail and wind threat for storms that get going. Models continue to vary on how soon the front moves out, although most appear to have it through the area by Saturday morning except for the ECMWF. In any case, there should be opportunities for breaks in the activity with additional storms possible during the weekend into early next week as a trough moves through the region. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 644 PM CDT Wed Jun 23 2021 Main TAF concerns remain winds and the potential for thunderstorms. Best chance for thunderstorms is late tonight into early tomorrow morning, with storms moving southeast from Nebraska. More storms may develop late in the period, though confidence in timing and location for these is too low to mention. Apart from storms, VFR conditions will prevail. Winds will remain generally southerly at 10-15 kts, with some higher gusts during the evening tonight and again during the day tomorrow. Some marginal LLWS should also develop again tonight as the LLJ restrengthens. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Picha AVIATION...Reese
Area Forecast Discussion
National Weather Service Tulsa OK
1018 PM CDT Wed Jun 23 2021 .DISCUSSION... Latest surface analysis indicates low pressure centered over swrn KS, with a strong pressure gradient across Oklahoma and wrn AR. High cloudiness was spilling over the top of the ridge, which was centered over swrn OK at 00z, some of which should overspread CWA tonight. Additionally, short-term guidance continues to suggest low clouds will be possible late tonight/Thursday morning, with most likely areas of low clouds sern OK and nwrn AR. Guidance suggests convection in wrn KS stays north of the OK/KS border tonight as center of mid level high pressure translates from swrn OK to ern OK overnight. Air mass across ern OK remains moist and unstable with strong low level jet forecast to develop across the area by late tonight. Potential for some of the convection to make it into nern OK is nonzero late tonight, but confidence too low to mention at this time with building heights across the area. All in all, southerly wind and some increase in both high and low cloudiness will result in overnight temperatures quite a bit warmer than this morning most areas. Ongoing forecast elements trending well at this time, with little change needed. && .PREV DISCUSSION... /Issued 717 PM CDT Wed Jun 23 2021/ AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG. Lower than normal confidence forecast this TAF cycle as low level moisture continues to stream into the region on steady south winds through Thursday. Latest NAM guidance has a period of warm advection and more widespread low clouds around daybreak while ensemble guidance and latest HRRR is more limited in development holding low ceilings to the higher terrain of southeast OK and northwest AR. Decided to back off on ceilings across northeast OK terminals given signal for high clouds to spread over the top of the building ridge and limit cooling and cloud development as indicated by the majority of guidance. MVFR ceilings look more probable at KFYV around daybreak with again low confidence of remainder of northwest AR staying VFR. With strong low level jet forecast kept LLWS in northeast OK terminals for a short time Thursday morning. Otherwise, south winds are expected to gust again on Thursday in the 20-30kt range with the exception of KFSM. PREV DISCUSSION... /Issued 221 PM CDT Wed Jun 23 2021/ DISCUSSION... Mid-level heights are expected to rise slowly into Thursday. This should keep precip chances below mentionable levels into Thursday night. Low-level moisture is increasing from west to east across the forecast area is it advects in from the south and the axis shifts east. The GFS could be a little high on dew points tomorrow given the limited rain over the past 7 days, but NBM dew points are not that much lower. So heat index values will jump tomorrow with values ranging from 95F to possibly as high as 110F in a small area in northeast Oklahoma where the dew points should be the highest. We will issue a heat advisory for parts of the river valley of west-central Arkansas and parts of northeast Oklahoma. Some thunderstorm activity could get close to parts of far northeast Oklahoma late Thursday night, but the chances look low at the moment. On Friday, broad mid-level troughing is approaching from the west while a cold front sags toward the area from the north. Thunderstorms are possible in far northeast Oklahoma late Friday. Scattered thunderstorms will spread slowly southeast across northeast Oklahoma and into northwest Arkansas by later Friday night. The south edge of some faster flow aloft will brush the area Friday evening and night. This will support the chance of a severe storm or two. The front will slowly cross the area on Saturday and Sunday, with thunderstorms. High precipitable water values suggest fairly good coverage of 1 to 2 inches of rain is likely, with a few amounts near 4 inches possible. The front will stall in northeast Texas late Sunday, with the weakening frontal zone in the vicinity through early next week. This will keep some precipitation chances in the forecast early next week...especially in the south. The combination of clouds and the broad trough aloft remaining in the area will push out the hotter air. A heat advisory may be needed for parts of the area on Friday. After that a number of days lower temperatures are expected. && .PRELIMINARY POINT TEMPS/POPS... TUL 79 97 80 96 / 10 10 10 10 FSM 73 95 77 96 / 10 10 0 0 MLC 76 93 76 93 / 10 10 0 0 BVO 76 96 78 96 / 10 10 20 20 FYV 71 93 73 93 / 10 10 10 10 BYV 71 93 75 93 / 10 10 10 10 MKO 75 93 76 93 / 10 10 0 0 MIO 75 94 77 94 / 10 10 10 20 F10 76 93 77 93 / 10 10 0 0 HHW 75 93 76 93 / 10 10 0 0 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...Heat Advisory from 1 PM to 7 PM CDT Thursday for OKZ054>056- 059>061-066-067-070. AR...Heat Advisory from 1 PM to 7 PM CDT Thursday for ARZ019-020-029. && $$ SHORT TERM...69 LONG TERM....08 AVIATION....24