Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/19/21

Area Forecast Discussion
National Weather Service Cheyenne WY
522 PM MDT Tue May 18 2021 .SHORT TERM...(This evening through Wednesday) Issued at 155 PM MDT Tue May 18 2021 The upper level trough that has been dominate in the region is expected to get absorbed into the main flow ahead of a Pacific Northwest trough digging towards the southeast early tomorrow morning. This feature is expected to bring a swath of moisture into the region on Wednesday. Most of the stronger moisture conveyor stays a bit further to the west. However, could still see some increased precipitation over the Mullen Burn Scar, with models indicated more upper level diffluence across the Snowys and Sierra Madres. Active pattern remains in place as we transition to the later portion of the week. Current model guidance has an omega blocking pattern setting up over the central CONUS with an upper level closed low developing over the Pacific Northwest. This blocking pattern is expected to limit the movement of the upper level low, as it digs slightly to the southeast, before becoming nearly stationary Thursday night. Guidance from the SREF convective probabilities indicate a 50 percent chance for MLCAPEs values to exceed 1000 J/kg across the Nebraska Panhandle. Combined with some moisture and moderate shear could lead to some stronger thunderstorms development. Models typically put these systems a bit on the drier side for this region. As a result, went ahead and started bumping up the POPs. Will need to monitor this event to determine the likelihood of severe potentials. Nevertheless, the interactions between the upper level high to the east and upper level low to the west is likely to increase the wind speeds Thursday evening into early Friday morning, increasing the impacts along I-80 near our wind prone areas. .LONG TERM...(Wednesday night through Tuesday) Issued at 155 PM MDT Tue May 18 2021 The omega block pattern will continue into Thursday afternoon into early next week affecting our precipitation, temperatures, and winds. Short batches of precipitation will push through our region starting Thursday into next Monday therefore PoPs have increased. Instability, moisture and moderate shear could lead to severe thunderstorm development starting on the I-25 line into the western Nebraska Panhandle. With the assistance of a small amount of helicity in the Nebraska Panhandle, severe thunderstorms could produce moderate hail. This event is still a few days out and will continue to monitor as we move closer this week. The interaction of of an upper level low and a high pressure to our east will cause gradients to tighten which will bring strong wind gusts across our region starting Thursday afternoon into Saturday morning. Additionally, there is another chance of scattered severe thunderstorms Friday into early next week but if the GFS hold true, the low pressure system may move majority of the moisture to our east while the omega pattern finally dissipates. A short ridge pattern is possible mid next week which will clear our skies and increase our temperatures for a small teaser of summer. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 521 PM MDT Tue May 18 2021 Wyoming TAFS...VFR. Wind gusts to 23 knots at Laramie and Cheyenne after 18Z Wednesday. Nebraska TAFS...VFR. Wind gusts to 30 knots until 03Z, and to 25 knots at Sidney after 15Z Wednesday. && .FIRE WEATHER... Issued at 155 PM MDT Tue May 18 2021 Showers and thunderstorms over the course of the week keeps the minimum RH values on the north side of 25 percent east of the Laramie Range tomorrow through Thursday. Main concern exists where some drying out is expected west of the Laramie Range and humidites could drop to the 15 to 25 range. Some breezy conditions are expected Thursday, which may increase critical fire weather conditions. However, the majority of those fuels are still green. Increased change of showers persist through the remainder of the week, decreasing fire weather concerns. && .HYDROLOGY... Issued at 155 PM MDT Tue May 18 2021 Chance for a couple of showers and thunderstorms to develop over parts of the burn scar later today, with the HRRR indicating some popcorn convection possible. These showers may produce brief downpours, but rainfall amounts are still estimated to be less than an tenth of an inch. The more enhanced threat for showers and thunderstorms over the burn scar is still set for Wednesday as the Pacific Northwest trough develops and brings more moisture into the region. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...MD LONG TERM...TJT/AW AVIATION...RUBIN FIRE WEATHER...MD HYDROLOGY...MD
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
742 PM CDT Tue May 18 2021 .UPDATE... The tornado watch has been allowed to be dropped for the I-35 corridor from Williamson to Bexar County as the convective complex producing severe weather, heavy rainfall and flash flooding has advanced eastward into the coastal plains. Tornado watch remains in effect for these areas through at least 9 pm cdt. Additionally, have made grid edits, including PoPs, temperatures, dew points, over the next 6 hours given the latest observational trends and convective short term allowing model guidance. && .PREV DISCUSSION... /ISSUED 659 PM CDT Tue May 18 2021/ AVIATION... /00Z TAFS/ Radar trends and latest model guidance show convective activity staying to the south and east of the AUS and SAT airports for the rest of this evening. KDRT should be clear of any convection as well for this evening as storms over Mexico die this evening and new redevelopment overnight stay well south of the airport. The HRRR and Texas Tech solutions bring new showers and storms around 12Z Wednesday while keeping convective activity through the afternoon hours. As of this writing (23:50Z Wed), all airports are observing VFR conditions. However, cigs are forecast to become MVFR overnight through the morning hours with IFR vsbys as storms move over the terminals. The forecast late afternoon/early evening is a bit tricky as the new round of convection slowly departs the I-35 corridor. PREV DISCUSSION... /ISSUED 307 PM CDT Tue May 18 2021/ SHORT TERM (Tonight through Wednesday Night)... Convection is growing stronger as an outflow boundary moves into our CWA. We expect showers and thunderstorms to become more widespread this afternoon and we have issued a Tornado Watch for most of the eastern half of South Central Texas. There may be sufficient low level shear to produce a few tornadoes this afternoon and evening. The upper level low we`ve been watching for the past few days will move into West Texas tonight and then northeastward to the central Plains. The low levels remain warm and very moist. Rain chances remain high through the short term period. Beyond the Tornado Watch we will continue to have a chance for some storms to be strong to severe with ample instability and deep layer shear. PW values will also be high and locally heavy rainfall will be possible. Models are especially bullish for strong storms and heavy rain Wednesday. The most likely area for heavy rain will be the eastern half of the forecast area. Rainfall totals through Wednesday night will be two to four inches with isolated totals to six inches possible. The highest totals will be east of I-35/I-37. The Flash Flood Watch continues. LONG TERM (Thursday through Tuesday)... As the first upper trough moves away from Texas, another will move onto the West Coast. This will keep rain chances high Thursday over the eastern half of the CWA. An additional 1/2 to one inch of rain is possible during the day. The rain chances will decrease Thursday night, but not end. The heavy rain threat will end as the deep moisture moves farther to the east. The second upper trough will drop down through the west and keep Texas under southwesterly flow. Shortwave troughs moving through this pattern will generate showers and thunderstorms at times through the weekend. The high moisture plume with PW values around 2.0 inches will move back over our CWA and we could see another round of locally heavy rain over the weekend. For the start of next week an upper ridge will push in from the east and force any rain chances to the western part of our CWA. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 67 77 66 80 69 / 50 90 70 60 40 Austin Bergstrom Intl Airport 67 78 65 80 68 / 60 90 70 60 40 New Braunfels Muni Airport 67 78 66 82 69 / 60 90 60 50 30 Burnet Muni Airport 65 75 64 79 66 / 40 80 50 40 30 Del Rio Intl Airport 70 83 67 87 70 / 30 50 10 - 10 Georgetown Muni Airport 66 75 65 79 68 / 60 90 70 60 40 Hondo Muni Airport 69 79 64 83 68 / 50 90 40 30 20 San Marcos Muni Airport 68 78 65 81 68 / 60 90 60 50 30 La Grange - Fayette Regional 70 80 68 81 71 / 80 100 80 70 40 San Antonio Intl Airport 69 77 66 81 69 / 50 90 50 40 30 Stinson Muni Airport 70 79 67 82 69 / 50 90 50 40 30 && .EWX WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch through Thursday afternoon for Atascosa-Bandera- Bastrop-Bexar-Blanco-Burnet-Caldwell-Comal-De Witt-Fayette-Frio- Gillespie-Gonzales-Guadalupe-Hays-Karnes-Kendall-Kerr-Lavaca-Lee- Llano-Medina-Travis-Williamson-Wilson. && $$ Update...Brady
Area Forecast Discussion
National Weather Service Grand Junction CO
545 PM MDT Tue May 18 2021 .SHORT TERM...(Tonight through Wednesday night) Issued at 141 PM MDT Tue May 18 2021 The midlevel circulation is over the CO/NM state line as evident on satellite. Wrap around moisture and frontogenesis on the NW side of the low is supporting a band of showers over portions the central and southern mountains. Despite all of the moisture it may be hindering the instability due to a lack of steep lapse rates. Also, it would appear that there is some midlevel capping that is keeping convection from developing. Persistent heating and lift on the NW edge of this band is the best location for storms later this afternoon. The models are still struggling with how far west this convection will extend. In fact, the HRRR is consistent with showing not much removed from the band itself. The northeastern side of the San Juans and southern Sawatch will see the most precipitation due to the frontogenesis band, upslope and possible convection through the late evening. A few showers and or storms may move over the Grizzly Creek burn scar, but as of now the potential for heavy rainfall is low. Only small concern would be training as shown by some high-res models. Luckily those rainfall amounts are generally below trigger amounts. The precipitation diminishes after midnight as the band weakens and the atmosphere stabilizes. Tomorrow residual moisture will support terrain driven convection over most of the ranges, but focused along the Divide. A subtle wave may also track over the area in the evening, and possibly support additional convection that develops over the higher terrain in eastern Utah before moving eastward. Most of the lower valleys in this region will stay dry, but have the potential for virga showers and strong wind gusts. Temperatures will climb above normal tomorrow as a weak ridge builds over the forecast area. .LONG TERM...(Thursday through Tuesday) Issued at 141 PM MDT Tue May 18 2021 The pressure gradient will tighten as a large low pressure trough dives into the northern Great Basin from the Pacific Northwest by Thursday afternoon. Drier air will advect in from the Desert Southwest ahead of this low with H7 winds in the 30 to 40 kt range out of the southwest. This will lead to the potential for critical fire weather conditions across much of the area, dependent on the fuels status. Either way, it looks to be dry and windy on Thursday with a return to warm, above normal temperatures as highs jump to about 10 degrees above normal. A 100 kt jet streak will rotate around the base of this low into eastern Utah by Thursday night, allowing decent moisture to advect into the Four Corners region heading into the day on Friday. Specific humidities are forecasted to jump upwards of 5 to 6 g/kg with precipitable water values up to 0.7 inches in some areas. Friday appears to be the best chance for more widespread precipitation. Extensive cloud cover coming in Thursday night may limit convective potential for the day on Friday, but still wetting rains will be welcome. The best QPF at this time appears to favor the San Juans. Cooler temperatures will also follow for Friday due to increased clouds and showers. Conditions dry out again by the weekend as the upper low gets closer and moves into Nevada with a 125 kt jet moving overhead. This will again advect drier air by Saturday and Sunday with increasing winds, leading to potential fire weather concerns once again dependent on fuels status and how much wetting rain is received Friday. Daytime heating and instability under the trough will still result in some afternoon convection over the higher terrain both Saturday and Sunday with most lower elevations remaining dry as this trough lifts northeast over the northern Rockies. Our CWA will remain under the influence of the upper level jet at the base of the trough during this time, leaving us on the drier side of things. Monday appears to be a transition day with calmer conditions before the next trough moves into the Pacific Northwest Tuesday. Conditions remain dry Monday and Tuesday with occasional daytime breezes. Temperatures will return to near to above normal levels over the weekend through early next week. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 545 PM MDT Tue May 18 2021 Scattered showers and storms continue this evening, mainly east of a line from KEGE to KMTJ to KTEX to KDRO, including KASE and KGUC. Any shower or storm will be capable of brief reductions in ceilings to ILS breakpoints and visibility to MVFR. Storms can also produce erratic wind gusts upwards of 40kt. Shower and storm activity will wane shortly after sunset with quiet weather to follow overnight. Wednesday will be a drier day for most, but the risk for a pop-up shower or storm will return after 18-20Z, primarily for the eastern mountain terminals. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...KJS LONG TERM...MDA AVIATION...MDM
Area Forecast Discussion
National Weather Service Lake Charles LA
1010 PM CDT Tue May 18 2021 .UPDATE...Another round of storms is inbound. The line is currently passing through the Houston metro. It will advance to the TX/LA line by around 2 AM and to roughly along I-49 by 6 AM. The line is moving, however a quick 1 to 3 inches will be possible. Strong gusty winds may also occur in stronger storms. && .PREV DISCUSSION... /issued 716 PM CDT Tue May 18 2021/ DISCUSSION... For 00z TAF issuance. AVIATION... Satellite imagery/sfc obs show generally clear skies across the area at this time which should continue next few hours. Forecast soundings/time-height sections indicate low clouds returning later this evening in advance of the next MCS getting cranked up over cntl TX. Latest runs of the HRRR have this feature well sited and have followed its guidance as far as precip goes...with the squall line moving into KBPT after midnight, then KLCH/KAEX an hour or so later, and finally the Acadiana terminals just before sunrise. IFR/MVFR ceilings should prevail most of the remainder of the period. Various CAM guidance shows another round of showers/storms moving in for tomorrow afternoon. 25 PREV DISCUSSION... /issued 352 PM CDT Tue May 18 2021/ DISCUSSION... Wx map shows tight pressure gradient continuing between high pressure over the East Coast and low pressure over NM/W TX/OK this afternoon. Had a localized wake low behind the TSRA complex across South Louisiana into the coastal waters. This increased the winds and tides along the coastal parishes, as winds/seas across the coastal waters. The ongoing Small Craft Advisory handled the coastal waters. However, the increase in winds this afternoon, as well as a continued moderate to strong southeast flow, prompted the need for a wind advisory for the coastal parishes and counties through Wednesday evening. The increase in east to southeast winds this afternoon along the coast increased tidal levels to around 1.0 to 1.5 feet above predicted levels, which is at high tide now through this evening. Thus, have a Coastal Flood Advisory for Jefferson, Cameron, Vermilion through 10 PM. Now for the precipitation/rainfall forecast. Radar showing the numerous coverage over Lower Acadiana into the coastal waters, otherwise, no precipitation is occurring for Southeast Texas and only patchy light rain over Central and Southwest Louisiana. This will change later this evening and especially overnight as the next upper level impulse has already ignited the next wave of thunderstorms over Northeast Texas and another batch over Central Texas. This will continue to move east to southeastward this evening and overnight, increasing chances of thunderstorms significantly around late evening/early morning hours over Southeast Texas, and the remainder of the area overnight into Wednesday morning. Will have intermittent breaks by Wednesday afternoon and evening, but appears to be yet another significant impulse to bring widespread thunderstorms with heavy rainfall Thursday. Very challenging to attempt rainfall numbers for now through Thursday afternoon, but latest coordinated QPF numbers will continue the 5 to 10 inches of additional rainfall with locally higher amounts possible. This is stated in the Flash Flood Watch that continues through Thursday evening. For the remainder of Thursday night into Friday, continues to look fairly wet with showers and thunderstorms likely. Will have to address this later this week if the Flash Flood Watch may have to be extended. By the weekend, high pressure at the surface and aloft over the Southeast U.S. likely to build westward over the Central Gulf States, bringing drier air aloft and an end to this prolonged rainfall event. DML MARINE... A moderate to strong onshore flow will continue this week due to the strong pressure gradient between a surface high pressure area over the southeast United States and a surface low pressure area east of the Rockies. The Small Craft Advisory has been extended through Thursday morning. A series of upper level disturbances will move across the region producing additional daytime and overnight showers and thunderstorms over the coastal waters. Some thunderstorms will be capable of producing strong gusty winds, higher seas. && .PRELIMINARY POINT TEMPS/POPS... AEX 69 81 67 80 / 70 80 50 80 LCH 72 82 70 81 / 80 90 80 90 LFT 70 82 70 81 / 60 80 60 90 BPT 71 82 70 81 / 80 70 80 90 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...Flash Flood Watch through Thursday evening for LAZ027>033- 041>045-052>055-073-074. Wind Advisory until 7 PM CDT Wednesday for LAZ052>055-073-074. TX...Flash Flood Watch through Thursday evening for TXZ180-201-215- 216-259>262. Wind Advisory until 7 PM CDT Wednesday for TXZ215. GM...Small Craft Advisory until 7 AM CDT Thursday for GMZ435-450-452- 455-470-472-475. Small Craft Exercise Caution through Thursday morning for GMZ430- 432. && $$
Area Forecast Discussion
National Weather Service Medford OR
248 PM PDT Tue May 18 2021 .DISCUSSION...The weather pattern will shift from a long period of warm and dry to a period of cool and cloudy with some shower chances. Breezy to windy and cooler conditions are expected this afternoon. Temperatures this afternoon will be about 10 degrees lower than yesterday. A broad upper trough is responsible for this change in weather, and an upper low will slowly push south and east over the forecast area through Thursday, lingering just to the east of the forecast area through the weekend. Some of the weather with this low will be impactful, including cold overnight low temperatures, high terrain snowfall, and thunderstorms. First, Wednesday night/Thursday morning low temperatures will be 5 to 10 degrees below morning. This means that some freezing conditions (32F and lower) are possible in Siskiyou County, and generally frost conditions (33-36F) will be possible in some of the colder valleys west of the Cascades. If there were no clouds, temperatures would likely be colder Wednesday night, but some clouds are expected and should keep temperatures from reaching their coldest potential readings. Growing/agricultural interests should stay tuned and take necessary precautions. As the upper low moves overhead Wednesday night, some models (particularly HRRR and GFS) suggest significant late season snowfall in portions of Lake and Modoc Counties. Significant is subjective this late in the season, but we`re highlighting areas where 1-4 inches of snow will be possible, including Highway 299 at Cedar Pass and Highway 140 at Warner Mountain Pass. The Warner Mountains should be the focus for most of the snowfall because of the high elevation and the upslope/enhanced precipitation under northwest flow. Some snowmelt is likely on lower elevation roadways, but visibilities will be low in snowfall. Another effect from the low will be thunderstorm chances. First, some instability in Douglas County Wednesday afternoon brings a slight chance of thunderstorms there. The cold pool of air aloft that could generate storms in Douglas County will move southeast to a location over Modoc and Southern Lake County Thursday afternoon, and there is a slight chance of storms there. Because the low lingers through the weekend, there will be continued chances for thunderstorms east of the Cascades Friday and Saturday afternoons. Precipitation with this low, as can happen during the springtime, will be focused along and east of the Cascades. Data from the National Blend of Models suggests there`s about a 40 percent chance for many areas east of the Cascades to get a tenth of an inch of precipitation in 24 hours on Wednesday, Thursday, and Friday. In contrast, the chances for 0.1 inches of daily rainfall west of the Cascades are much less on these days. So while temperatures will be cool, and there will be some clouds west of the Cascades, we`re not expecting much in the way of rainfall for these areas. As the influence from the upper low wanes late in the weekend into next week, temperatures will moderate with values returning to near or above normal. Of note, there have been previous model run/ensemble indications that upper troughing will return/continue over the forecast area and keep things cool, but the morning suite of model data did not favor this solution. && .AVIATION...For the 18/18Z TAF Cycle...Overall, conditions are VFR this morning west of the Cascades, but higher terrain will likely remain obscured into the afternoon with scattered cumulus clouds in the area. VFR will prevail east of the Cascades and winds will become gusty across the region this afternoon and evening. -Miles && .MARINE...Updated 200 PM PDT Tuesday, 18 May 2021...A change to a more spring-like pattern is expected this week as upper level troughing settles over the Pacific Northwest. This will bring periods of gusty north to northwest winds as well as light precipitation at times. Northwest swell will be increased compared to last week, but is only expected to peak in the 5 to 7 foot range. However, this swell combined with choppy wind seas will result in conditions hazardous to small craft beginning Wednesday afternoon and likely continuing into Friday. At first, conditions hazardous to small craft will be limited to areas south of Gold Beach on Wednesday. Then, as north winds increase across all areas Wednesday night, hazardous conditions are likely to spread across all the waters Thursday into Friday. Conditions improve over the weekend as northerly winds diminish and swell subsides. && .FIRE WEATHER...Updated 230 PM PDT Tuesday 18 May 2021...Winds will remain breezy this afternoon as an upper level low begins to move onshore. Once that low moves onshore, we`ll see temperatures trend lower and humidities continue to trend slightly higher compared to today, Tuesday. There is a 20% chance for some cloud to ground lightning around Douglas County Wednesday afternoon once the low moves onshore. Otherwise, We`ll see breezy winds continue on the afternoons of Wednesday through Friday. && .MFR WATCHES/WARNINGS/ADVISORIES... OR...Winter Weather Advisory from 11 PM Wednesday to 11 AM PDT Thursday for ORZ031. CA...Winter Weather Advisory from 11 PM Wednesday to 11 AM PDT Thursday for CAZ085. Pacific Coastal Waters...Small Craft Advisory from 2 PM Wednesday to 5 PM PDT Thursday for PZZ356-376. Small Craft Advisory from 5 AM to 5 PM PDT Thursday for PZZ350-370. $$
National Weather Service Morristown TN
1009 PM EDT Tue May 18 2021 .UPDATE... EVENING UPDATE. && .DISCUSSION... Still a few light returns on radar mainly to our southwest that have been diminishing as they edge into our area, but a few sprinkles/light showers may make it to the surface over the next few hours so will bump PoPs up to slight chance for our southwest corner. Otherwise, forecast generally looks to be on track so just a few tweaks mainly to temps and dew points. && .AVIATION... 00Z TAF DISCUSSION. There will be varying amounts of mainly high/mid clouds around, along with some scattered cu mainly afternoon/evening hours. Main aviation weather concern looks to be the possibility of fog developing later tonight mainly at TRI. Right now confidence in any fog development is low so will just include a tempo group of fog with MVFR level vsby at TRI for a few hours late tonight. Otherwise, VFR conditions expected for the period all sites. LW && .PREV DISCUSSION... /ISSUED 328 PM EDT Tue May 18 2021/ SHORT TERM...(Tonight and Wednesday) Key Messages: 1. Light showers and isolated thunderstorms dissipate this evening. 2. Heat builds Wed with just isolated thunderstorms mainly over higher terrain areas of the eastern mountains, SW VA, and Plateau. Discussion: Late Afternoon/Evening... Light showers associated with WAA/weak isentropic ascent and lift near the right entrance of a 40-50 kt upper jet streak on the NE side of the building ridge across the Carolinas continue this afternoon. Most of this activity has been confined to the S Plateau and S Valley and has struggled to reach the ground due to low-level dry air, and recent radar loops suggest a diminishing trend. Cloud cover and weak mid-level lapse rates around 5 C/Km per RAP soundings have limited MLCAPE to generally less than 250 J/Kg this afternoon, so convection is unlikely. However, given the aforementioned jet support and weak ascent, kept isolated thunder in the forecast from the N Plateau through NE TN and SW VA through mid evening before dissipating. Tonight and Wednesday... The mid/upper ridge will continue to build across the eastern CONUS through the period as deep mid/upper troughing digs into the Pacific NW, with anomalous H5 height values nearing 590 DAM across the Carolinas and Mid Atlantic by late Wed. These dramatically increasing height and thickness values combined with strong WAA on the west side of a 1030 mb surface high offshore of the Carolinas will allow highs to reach the low/mid 80`s Wed after a mild morning start with lows tonight only in the upper 50`s/low 60`s. The sharpening mid/upper ridge axis poking into the Great Lakes will also shunt the greatest moisture plume westward toward the MS Valley. The best moisture plume shifting W, relatively dry low- levels with Td`s only in the 50`s, and strengthening mid-level capping will greatly limit the coverage of diurnal convection. Despite this, stayed with slight chance PoPs for higher terrain areas of the E TN mountains, SW VA, and the N Plateau in the afternoon since southeasterly low-level flow will produce upsloping that could ignite isolated cells in the terrain. HREF guidance hints at this possibility as well with a few cells depicted forming over western NC/Blue Ridge and drifting west/northwestward. Any thunderstorm will be short lived. Garuckas LONG TERM...(Wednesday Night through Tuesday) Key Messages: 1. Anomalously strong ridging will bring much above normal temperatures from Friday through early next week. 2. Strong upper ridge will keep us dry through the period. Discussion: Surface ridging will be centered across the Southern Appalachians through the Mid Atlantic on Thursday with upper ridging rapidly strengthening across the Southeast CONUS and Midwest. This 591 to 593 dam 500mb ridge will be centered across the Tennessee Valley and Mississippi River Valley on Friday through the weekend. NAEFS forecast data shows that these upper heights are at the maximum of climatological record for this time of year. In addition, low-level heights at 850mb are forecast to be at record high values for this time of year. This will result in strong subsidence across the forecast area with anomalous warmth. Temperatures are forecast to be at least 10 to 15 degrees above normal, and max temperatures may approach record highs in this weekend through early next week. With the strong ridging and subsidence, precip is unlikely through the extended. Due to differential heating along the higher elevations, isolated light convection will be possible late this weekend and early next week; however, it is expected to be too isolated and minor to even mention in the forecast at this time. In addition, guidance is beginning to shift the ridge axis westward late weekend and early next week which would place parts of our area within NW flow aloft along the eastern periphery of the ridge. In this scenario, the short-term forecast would need to be closely monitored early next week for any minor shortwaves or MCVs within the NW flow which could produce more widespread convection across portions of the forecast area. JB && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 63 84 62 86 60 / 20 10 0 0 0 Knoxville McGhee Tyson Airport, TN 61 83 59 85 57 / 10 10 0 0 0 Oak Ridge, TN 60 83 58 86 57 / 10 10 0 0 0 Tri Cities Airport, TN 55 80 54 83 53 / 10 10 0 0 0 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$
Area Forecast Discussion
National Weather Service Topeka KS
557 PM CDT Tue May 18 2021 ...AVIATION UPDATE... .DISCUSSION... Issued at 325 PM CDT Tue May 18 2021 Latest water vapor satellite and profilers show a mid level vort lobe moving northeast out of Oklahoma at 19Z. An area of convection has been moving across south central Kansas and into parts of southeast Kansas. CAMS and HREF members have shown various scenarios through the day with them being split. Now that convection has developed expect it to continue to move northward through the rest of the afternoon and through the evening hours. With PWs remaining high across eastern Kansas and moisture flux continuing through the night, isolated locally heavy rainfall will again be possible which may cause some additional flooding concerns across the CWA. Low end to marginal shear and instability may lead to an isolated strong to severe storm with hail the main hazard tonight. Scattered storms may be ongoing in the morning on Wednesday morning with additional redevelopment in the afternoon and overnight hours as additional lobes move northward into central and eastern Kansas. Again little will change with regards to moisture flux in to eastern Kansas with low level southerly flow off the Gulf into the central Plains. Isolated locally heavy rainfall will again be possible. The trough over the Rockies today will gradually move out across the southern and central Plains through Thursday keeping chances for showers and storms in the forecast. Highs remain in the 70s Wednesday and Thursday with 80s on Friday where chances of precipitation wane. Low end chances for precipitation continue from late weekend into early next week. A frontal boundary may move back into the area which will be a focus for convection once again. && .AVIATION...(For the 00Z TAFS through 00Z Thursday) Issued at 557 PM CDT Tue May 18 2021 Timing TS will be the bigger challenge this evening. A very humid airmass is setting the stage for heavy rain, so when TS impact the terminals brief IFR conditions with restricted VSBY are expected. Will use the consensus of the CAMs to get an initial timing for storms at the terminals. The other concern is low clouds once again. CONSShort is slower to bring MVFR CIGS into the terminals while the RAP is much more aggressive. Given the past several days, am inclined to follow the RAP. But confidence is marginal so will stick with the blend and watch for signs conditions are lowing quicker. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...53 AVIATION...Wolters