Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/21/20


Area Forecast Discussion
National Weather Service La Crosse WI
1030 PM CDT Mon Jul 20 2020 .SHORT TERM...(This evening through Tuesday) Issued at 221 PM CDT Mon Jul 20 2020 Some high clouds will continue to push off to the east this afternoon, with some clearing possible overnight. This should allow temperatures to drop back into the 50s and 60s. With decent radiational cooling, will have to watch out for patchy fog across mainly Wisconsin. 12Z CAMs have backed off on early morning showers for Tuesday and have trended that way, but wouldn`t be totally surprised to see a few scattered showers as warm air advection increases into our area before higher chances for showers and storms in the afternoon. The big question for Tuesday will be severe potential in the afternoon/evening. Kind of an interesting set up, as models suggest the area gets sandwiched between stronger upper level forcing to the north near the main upper level trough, and to the south where a stronger shortwave feature moves through. A cold front should also be approaching from the west during the late afternoon. Latest trend is for showers and perhaps a few storms to pop up by late morning/early afternoon with initial shortwave forcing. 0-6 km shear around 30-40 kts progged to be over our area much of the day, which would be sufficient for storm organization and potentially some strong to severe storms. The big question is how much instability will build into the area. Instability looks rather marginal by the time showers/storms move in during late morning/early afternoon, with values around 500-1500 J/kg MUCAPE depending on the model, but couldn`t totally rule out a stronger storm or two. Models then vary quite a bit on how well instability can build back in ahead of the approaching front for late afternoon. The RAP suggests MUCAPE exceeds 2000 J/kg ahead of the front by late afternoon, while the 20.06Z NAM would suggest sub-1000 MUCAPE and minimal SBCAPE (the 12Z run has a little more instability) - sort of the upper and lower bounds of the possibilities. If cloud cover is extensive during the afternoon, weaker daytime heating could limit instability, whereas clearer skies would allow more instability to build and increase the severe threat. Still lower confidence with all of these caveats, but marginal low/mid-level lapse rates around 6-7 C/km suggest sporadic wind/hail would be possible if stronger storms do develop. In addition, while the storms look progressive overall, precipitable water increasing to 1.5 inches and warm cloud depths approaching 4000m suggest locally heavy rainfall will be possible. .LONG TERM...(Tuesday night through Monday) Issued at 221 PM CDT Mon Jul 20 2020 With the short wave trough coming across the Upper Midwest, some of the convection associated with it is expected to linger into Tuesday night, especially for locations along and northeast of Interstate 94. The potential will still exist for a few of these storms to be on the strong side early in the evening, but it appears that there will be very limited CAPE for them to work with. ML CAPE values only look to be between 500 and 1000 J/kg with 30 to 40 knots of 0-6 km shear. There is also some suggestion that the shear may be out ahead of the CAPE pool with just a narrow corridor of overlap between the two. Once this system moves past the region, upper level ridging is expected to build over the central part of the country. While there is general agreement by the models on this, as usual, there are enough differences that have consequences on the forecast. The 20.12Z GFS is not as robust with the upper level ridging as either the 20.00Z ECMWF or 20.12Z GEM and as a result, short wave troughs running up and over the ridge are shown to track closer to the area with potential chances for showers and storms. For now, will honor the GFS solution with at least some chances for rain starting Wednesday night and continuing through next Monday. If the stronger ridging as shown by the ECMWF and GEM ends up being correct, many, if not most, of these days will end up being dry. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) Issued at 1030 PM CDT Mon Jul 20 2020 Cigs: increasing high clouds overnight, with bkn mid level cigs for the morning and some potential to dip into MVFR for a few hours, mostly during Tue afternoon. Should scatter out later Tue evening. WX/vsby: looking at scattered shra/ts to move east across the area, mostly tied to a cold front in the afternoon, but could see some in the morning, remnants and/or lingering mcv from an ongoing cluster of storms over SD/western MN. Coverage expected to be a bit more widespread to the north and south, associated with pieces of upper level energy. Going to hold with VCSH/VCTS for the moment - refining expectations as scenario becomes a bit more clear. Winds: mostly light southeast tonight, increasing from the south on Tue. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. IA...None. && $$ SHORT TERM...Lee LONG TERM...04 AVIATION...Rieck
Area Forecast Discussion
National Weather Service Columbia SC
1055 PM EDT Mon Jul 20 2020 .SYNOPSIS... The upper ridge will continue to dominate the weather early this week before weakening later in the week as an upper trough moves into the Ohio Valley and Mid Atlantic region. Temperatures will remain above normal and hot with heat indices over 100 degrees. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Convection has mostly dissipated with a few light showers persisting in the northern Midlands and Pee Dee. These showers will end in the next hour or so with debris cloudiness diminishing through the early morning hours. By daybreak expect partly cloudy to mostly clear skies with low temperatures in the low to mid 70s. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY/... High pressure aloft will dominate the weather pattern during the middle of this week. Subsidence underneath this feature will limit thunderstorm activity to the afternoon and evening hours with initiation in the favored areas of the higher terrain of SC/NC and along the sea breeze front. The biggest concern will continue be the heat stress with indices values between 101 and 106 degrees in the afternoons. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... A strong upper level trough moves through New England Thursday Night through Friday with an associated cold front moving into The Midlands and CSRA. This front will enhance shower and thunderstorm activity during this time period. The cold front may push south of the region this weekend which would slightly a slightly drier and cooler airmass to filter into the region with highs in the lower to mid 90s and lows in the lower to mid 70s. High pressure aloft rebuilds across the region early next week with a return to hot and humid weather with diurnal scattered showers and thunderstorms. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... Predominantly VFR conditions expected through the TAF period. With minimal convective activity expected this evening and overnight, there is low risk of restrictions at the TAF sites from showers or thunderstorms. Fog also appears unlikely given the sites have only received, at most, light rain and there will be a 10 to 20 kt LLJ tonight. The HRRR and MOS guidance also support VFR conditions, adding confidence. Tuesday, light southerly winds will pick up by the early afternoon. Upper level ridging will generally suppress convection in the afternoon and limit thunderstorm coverage to isolated or widely scattered. EXTENDED AVIATION OUTLOOK...Restrictions are possible during the afternoon/evening showers and thunderstorms during the extended. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...Heat Advisory from noon to 8 PM EDT Tuesday for SCZ115. && $$
Area Forecast Discussion
National Weather Service Caribou ME
910 PM EDT Mon Jul 20 2020 .SYNOPSIS... A cold front is pushing off the Downeast coast this evening. High pressure will build across the region Tuesday. A weather disturbance will begin to approach from the west on Wednesday and across the region on Thursday. High pressure will build toward the region Friday into Saturday. && .NEAR TERM /THROUGH TUESDAY/... 9:10 pm update: A cold front is now pushing off the Downeast coast. In the wake of the front, a much drier air mass will follow. The dew points are mostly in the upper 50s across far northern Maine, but still a very muggy 71F in Bar Harbor at 9 pm. The 00z Caribou sounding showed the significant drying with the PWAT dropping from 1.88" early this morning to 1.21" this evening. Aside from one lone shower near Grand Manan Island, NB all of the showers have ended. There is a weak post-frontal trough that will drop down into far northern Maine overnight and could touch off a very isolated shower. Previous discussion: A Pre-frontal trof ahead of the cold front was making its way into central areas attm. This boundary is shown by the latest HRRR and RAP to hit the coast later this afternoon. A broken line of tstms have fired up in Washington County where the best CAPE(2000+ joules) and shear resides. Dewpoints in this region were in the lower 70s. A tstm or 2 could contain strong wind gusts and brief heavy rainfall. Otherwise, activity will be winding down by early evening as the drier continues toward the coast. The cold front moving toward nw area attm will continue to press se into tonight. Some clouds associated w/the front as seen on the latest visible satl imagery. Some weak convergence along the front could allow a few showers as the front moves in, but give the upper levels drying out, not expecting than a brief occurrence. WSW winds 10-20 mph attm will be shifting to the W by evening and then NW overnight. The winds are expected to let up later at night as the gradient weakens behind the front. Noticeably difference in the airmass by Tuesday morning w/dewpoints in the low/mid 50s across the n and upper 50 to lower 60s central and downeast areas. Some patchy fog is expected overnight into early Tuesday morning especially in areas where rainfall was observed. Tuesday will be much drier and a bit cooler w/daytime temps near seasonal norms. The NAM and GFS show an upper level disturbance moving across the region and w/the center of high pres still w of the region, there will be a NW wind kicking in by late morning at 10-15 mph. No showers expected as the soundings show it to be dry through the column. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... Tuesday night will feature mainly clear skies as high pressure builds across. Light winds and mainly clear skies will set the stage for some radiational cooling. Lows Tuesday night will fall into the mid to upper 40s in the Allagash and the normally colder valley locations of far northern Maine. High pressure slides east toward the Canadian Maritimes during Wednesday. After a mainly sunny start to the day, increasing cloud can be expected by afternoon as short waves embedded in the mainly zonal flow aloft move toward the region. This leads to the potential for some shower activity as we head into later Wednesday evening and Wednesday night. Thursday will potentially see a more significant short wave approach the region, with more widespread shower activity. Will maintain slight chance for thunderstorms with some surface based cape forecasted. Highs through the period will be near normal for this time of year. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Short wave exits to the east Thursday evening, with any showers or thunderstorms diminishing early Thursday evening. This should set the stage for a couple of fairly quiet weather days both Friday and Saturday. That being said, the upper trof will be in place across the region with Northwest flow aloft. Thus, we will likely see a fair amount of diurnal clouds developing both afternoons, and a stray shower couldn`t totally be ruled out. Another upper level disturbance heads toward the region later in the weekend and early next week, with unsettled weather conditions expected. Temperatures through the extended period will be close to normal for this time of year through the period. && .AVIATION /01Z TUESDAY THROUGH SATURDAY/... NEAR TERM: VFR through Tuesday for all terminals. Some patchy fog overnight could drop vsbys to MVFR for a brief time especially at terminals that received rainfall. WSW winds 10-15 mph early this evening diminishing and shifting to the NW at 5-10 mph overnight. NW winds 10-15 mph for Tuesday. SHORT TERM: Tue Night-Wed...VFR. Light Wind. Wed Night-Thu night...VFR/MVFR in showers. Fri-Sat...VFR. && .MARINE... NEAR TERM: No headlines expected. SW wind 10-15 kt becoming WNW later tonight into Tuesday. Seas around 4 ft tonight subsiding to 2-3 ft on Tuesday. SHORT TERM: Winds/sea generally below SCA levels through the period. && .CLIMATE... So far this meteorological summer is the warmest on record in Caribou, but only ranks as the 24th warmest on record in Bangor. Weather records began in Caribou in 1939, and in Bangor in 1926. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...CB/Hewitt Short Term...Duda Long Term...Duda Aviation...CB/Hewitt/Duda Marine...CB/Hewitt/Duda Climate...CB
Area Forecast Discussion
National Weather Service Cheyenne WY
605 PM MDT Mon Jul 20 2020 .SHORT TERM...(This evening through Tuesday) Issued at 206 PM MDT Mon Jul 20 2020 Latest GOES-E satellite imagery shows pockets of convection this afternoon along the Laramie Range and portions of Converse County. Blended much of the POP/QPF this afternoon towards the HRRR and NAMNEST as model solutions appear to initialize well to the current conditions. Expect further development of showers and thunderstorms further eastward as an embedded elevated shortwave moves through today. Some storms will be on the strong to severe side with best chances out in NE. Wind shear remains a bit lacking this afternoon as values generally between 20 and 35 kts leading to limited storm growth and longevity that will likely limit our severe warned storms till later this afternoon and evening to just a few storms if that. MLCAPE values from 1000 J/kg across Laramie Range to 3000 J/kg across portions of Cheyenne County NE. Some CIN remains along the WY/NE border that may require the outflow from the storm over central Laramie Range to provide the initial lift prior to shortwave arrival. Otherwise, a less heat-stricken day across the region with temperatures falling into the slight-below-normal range as KCYS and other sites are just now reaching past the 80 degree mark. Another chance for showers and thunderstorms, strongest across southeastern Wyoming on Tuesday as frontal boundary begins to eject. .LONG TERM...(Tuesday night through Monday) Issued at 206 PM MDT Mon Jul 20 2020 Pockets of moisture advection as monsoonal flow begins to impact the American West and Southwest with almost near daily chances of precipitation. Some storms may be on the strong side given an above-normal stretch of days ahead. Upper 80s and 90s daytime temperatures expected by the beginning of the Dog Days of Summer through the weekend though additional moisture may add a bit of what we may try to consider a muggy-humid feeling for WY and NE. Biggest concern still remains the passage of mid-layer shortwave with a deeper digging by the GFS vs the EURO into CO that sets up the deeper monsoonal rich atmospheric river into the CWA. 12z runs are coming into some bit of agreement though QPF amounts have some stark difference in terms of coverage and amount that will require some tracking over model cycles as better sampling of system as it comes onshore. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 541 PM MDT Mon Jul 20 2020 All sites from Wyoming to the Nebraska Panhandle remain in VFR. An extreme moist layer will hover through the KCYS site which may lower visibility temporary; overcast skies are included in the KCYS TAF along with thunderstorms until 01Z. Isolated thunderstorms will move across our area from the northwest but will likely affect KBFF and KAIA until 01Z. Cloud ceilings for most sites will trend between SCT and BKN under 5k ft. Next discussion could indicate MVFR conditions for KCYS due to overcast skies and low level moisture. && .FIRE WEATHER... Issued at 133 PM MDT Mon Jul 20 2020 Portions of Carbon County area of main concern for elevated fire weather risk this week. Periods of light rain and gusty winds possible with showers and thunderstorms. Possibility remains for lightning fire starts in the western forecast area where min RH values will remain from the low teens into low 20 percents this week coupled with temps into the 80s and 90s. East of the Laramie Range, fire weather concerns are lessen as min RH values will generally remain above 20 percent. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...None. && $$ SHORT TERM...WM LONG TERM...WM AVIATION...AW FIRE WEATHER...WM
Area Forecast Discussion
National Weather Service Dodge City KS
530 PM CDT Mon Jul 20 2020 ...UPDATE TO AVIATION... .SHORT TERM...(This evening through Tuesday) Issued at 341 PM CDT Mon Jul 20 2020 Typical summer pattern through the Short-term period (Tonight through Tuesday Night) with very weak mid-upper tropospheric flow across southwest Kansas. Residual low level moisture and enhancement from evapotranspiration from all the recent rains have helped keep afternoon temperatures a few degrees below forecast. DDC was still sitting at 86F as of 2015 UTC. There was a mid level weakness rolling very slowly east across southern Kansas/northern Oklahoma as was seen on RAP analysis and satellite today, and this feature had already reinvigorated convection across the eastern TX Panhandle through northwest OK. The latest thinking is that this feature and associated thunderstorm activity will only clip our far southeast CWA (Barber County in particular), so this is where we will keep highest initial POPs (albeit still 40 percent or less). The other area of semi-organized convective activity was starting to develop across portions of eastern Colorado. Latest short-term high resolution models suggest at least a small MCS will develop out of this as it approaches far west central/southwest Kansas later this evening. There should be enough low level MCS maintenance parameters in place after sunset to maintain at least a weak MCS, rolling south-southeast across the far southwest through late tonight. Yet a third area we will be monitoring will be what comes out of southern Nebraska later tonight. A formidable MCS will likely develop up in that region as well, which will move southeast into northern Kansas through the night. This MCS is expected to perhaps clip our far northeastern sections (Ellis County in particular), so that will also need to be monitored. Somewhere in the middle (i.e. around Garden City-Dodge City), there is much lower confidence in any measurable precipitation, but given low level moisture in place and remnant outflow boundaries, we cannot rule out rogue scattered storms developing overnight and/or very early Tuesday morning. On Tuesday, the summer subtropical ridge will continue to be suppressed just enough such that we have to keep an eye out for additional late day/evening thunderstorms just about anywhere, especially in vicinity of remnant outflows. Another eastern Colorado MCS will likely develop Tuesday evening and make a run on far western Kansas. There may be just enough northwest mid-level (cloud- bearing) flow to push an MCS into some of our counties Tuesday Night, so that is something we will continue to monitor as well. .LONG TERM...(Tuesday night through Monday) Issued at 341 PM CDT Mon Jul 20 2020 As we head deeper into the week, the overall pattern will most likely transition toward a drier one for southwest Kansas, as the summer subtropical high expands its influence across our region. Temperatures for the remainder of the week into the weekend will be quite consistent with highs in the lower to mid 90s and lows in the lower 70s. There does not appear to be much indication, as of today, that excessive heat will occur (Heat Indices of 105+) as low level trajectories will actually be more out of the southeastern Great Plains/Gulf Coast region (not a "hot" low level trajectory for us in southwest KS). Increasing subsidence and lack of low level wind convergence will likely lead to gradually lower and lower dewpoints each afternoon, which will also negate development of 105+ heat indices. It is something we will continue to monitor, however, but as of this forecast update, it looks like the rest of the week into the weekend will be fairly tranquil with respect to what is normally experienced the third week of July. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 530 PM CDT Mon Jul 20 2020 VFR conditions will prevail in the vicinity of all TAF sites through Tuesday afternoon. South-southeast winds around 10 to 20kt will persist through early Tuesday morning as a surface low remains anchored in southeast Colorado. && .PRELIMINARY POINT TEMPS/POPS... DDC 68 93 69 92 / 20 20 10 10 GCK 66 92 68 93 / 20 20 20 10 EHA 66 94 67 93 / 30 20 30 10 LBL 66 95 68 94 / 20 20 20 10 HYS 67 90 69 92 / 40 20 30 10 P28 71 92 71 92 / 40 40 10 10 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Umscheid LONG TERM...Umscheid AVIATION...JJohnson
AREA FORECAST DISCUSSION
National Weather Service Kansas City/Pleasant Hill MO
1101 PM CDT Mon Jul 20 2020 .Discussion... Issued at 254 PM CDT MON JUL 20 2020 Key message: Additional storms possible overnight into tomorrow morning with more heavy rain and flash flooding potential. This is a very uncertain forecast with a multitude of mesoscale features, not handled particularly well by any guidance, affecting the forecast. First, there are at least two distinct boundaries noted via satellite imagery. One is across southern KS and MO and progressing southward this afternoon. There is another boundary from north central KS that may extend into west central MO. This showed up well at 925mb, and helped initiate new convection in north central KS, but has been weakening as the low-level flow focuses on the southern boundary. The main synoptic front looks like it`s across northern MO/ southern IA and slowly lifting northward. Any of these boundaries could be a focus for some afternoon/ evening storms. Additionally, there is an MCV along the KS/OK state line that is slowly tracking to the east. With broad/ weak northwesterly flow, there`s subtle shortwave troughs moving through the flow into WY and NE. The morning MCS, residual cloud cover, and new cloud cover from showers/ storms that developed on the 925 boundary, are really inhibiting renewed instability this afternoon, lowering chances for afternoon and evening storms. Given this, the best chances look to be overnight into tomorrow morning again. The RAP has had the best handle, though still not very good, on the features mentioned above and feel that incorporating that more into the forecast may offer the best guidance. With that in mind, several areas of ascent develop overnight that should become the focus for renewed convection. An area of ascent noted on the 305K to 310K surfaces develops over central to eastern KS around midnight that shifts into western MO early in the morning. Another area of ascent, on the same theta levels develops over Nebraska and builds mainly southward. Think that showers and storms will develop over central to eastern KS, possibly into western MO tonight, and persist into tomorrow morning. With precipitable water values at or just over 2" over the area, the main concern will be from heavy rainfall and flash flooding. There could also be some gusty winds, especially areas that begin to surge forward, similar to this morning where 40 to 50 mph winds were observed with the line that surged through the KC metro For the middle portion of this week through the weekend, the pattern remains mostly unchanged. Ample moisture will continue to be present with the upper ridge remaining suppressed to our south. There`s also a weak boundary draped through the region. So it`s hard to find a period of time that looks dry. Rather, there could be afternoon, heat- of-the- day, showers/ storms as well as overnight convective systems that track southeastward along wherever the boundary may be that particular day. The upper ridge builds back north by the end of the week but both the GFS and the ECMWF keep a week boundary in place as high pressure moves into the Great Lakes. This pattern keeps low chances of PoPs going through the extended forecast, even with the upper ridge building northward. The good thing with the potential rainfall and cloud cover would that temperatures would be subdued some. Otherwise, it looks hot and humid through early next week. && .Aviation...(For the 06Z TAFS through 06Z Tuesday Night) Issued at 1101 PM CDT MON JUL 20 2020 We are currently tracking a system in eastern Kansas that has the potential to bring scattered rain showers to our terminals. The last few sets of model runs have been giving little guidance to whether these storms will fizzle out at the Kansas/Missouri border, so we kept the chance for rain showers near our terminals in the early morning hours. Off and on rain chances will continue for the rest of the TAF period until the early afternoon, so it was difficult to nail down a constant dry period before the next round of rain showers. There is still uncertainty in the timing of the late morning round of showers. We kept everything mostly the same with showers arriving by mid-morning, though we did extend the chance for rain farther into the afternoon. VFR conditions are expected into the evening. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ Discussion...CDB Aviation...Klaus
Area Forecast Discussion
National Weather Service El Paso TX/Santa Teresa NM
538 PM MDT Mon Jul 20 2020 .AVIATION...00Z TAF CYCLE VFR conditions expected except during TSRA when MVFR (visibility) may occur. Scattered showers and thunderstorms are expected this evening over much of the area, decreasing overnight but with a few showers lingering until dawn. Winds are expected to be light except during thunderstorm outflows where wind gusts up to 35 knots could occur. Scattered thunderstorms will redevelop after 20Z Tuesday in the lowlands. && 01 .PREV DISCUSSION...235 PM MDT Mon Jul 20 2020... .SYNOPSIS... The typical monsoon pattern is expected to continue through the weekend. Scattered to numerous showers and thunderstorms are expected across the area with the additional moisture in the area. There is also a possibility for locally heavy rainfall with some of this storms. Strong gusty winds and small hail are expected with the strongest storms during the afternoon and evening hours. Temperatures continue to show a downward trend with near normal values in the second half of the week. && 29 .DISCUSSION... .SHORT TERM...Thru Tuesday... We have the humidity. We have the terrain (lift), but thunderstorms appear to be a bit slower to initiate today as compared to yesterday, likely attributed to clouds and shower activity from this morning. The Gila mountains have a few light showers, but the only thunderstorms noted at 1PM were over the Sacramento Mountains. With plenty of sun and dewpoints coming in around 55, CAPE values over 1000 J/kg, and PW values 1-1.2", thunderstorms should continue to develop this afternoon across mountains before moving into the lowlands--very similar to what has been seen the last several evenings though maybe a bit later. Coverage may also be more robust. The NAM-Nest and HRRR are in remarkable agreement (the HRRR has been aggressive lately, but the NAM-Nest has performed well) that we could see scattered to perhaps numerous coverage in storms across the Rio Grande Valley and into much of the lowlands. I did not want to bring up chances to reflect that given how coverage has come in under forecast that past several nights by CAM models, but it could be an active evening with many people getting rain. The main threats would be locally heavy rainfall and maybe some small hail. Storms could have some gusty outflow winds, but DCAPEs less than 1500 suggest a very isolated threat for severe caliber gusts. Activity may last well after dark but should weaken after midnight to just a few scattered showers. Tuesday`s weather looks to repeat today`s weather with little change in the pattern expected. Highs may be a couple degrees cooler, but once again, it appears we will see scattered to numerous mountain storms with isolated to scattered lowland storms. Heavy rain, small hail, and some strong gusty winds will remain the threat again. && 34 .LONG TERM... Broad upper high prevails over most of southern US. This feature keeps a southeasterly flow near the surface which advects moist and warm air into the region. At the same time, an upper trough over northern California will help to reinforce the southerly flow in the area. Both the NAM and the GFS are showing slightly higher PWs with values ranging from 1.25 to 1.6 inches, which is slightly higher than in the previous model runs. Therefore, we are expecting scattered to numerous showers and thunderstorms in the mountains and scattered over the lowlands. The additional moisture increases our chances for observing heavy rain, which will be more predominant in area mountains. The upper high will center itself over the southern plains towards the end of the week. This action shifts the deep moisture plume to the west into Arizona, and western New Mexico. Thus, POPs remain decent through the period in the western portions of our CWA, including the area mountains. In turn, areas east of the Rio Grande will have less chances for precipitation. However, this doesn`t mean that we are not going to see any precip, as isolated chances for storms are still possible through the rest of the week. Over the weekend, an inverted trough will move along the fringes of the upper high from the Gulf of Mexico. This system may be reaching the area by Sunday or Monday, but there is still quite a bit of uncertainty between the GFS and the ECMWF about its trajectory. Regardless, of its final route storm chances remain in the forecast through early next week. Temperatures will continue their slow downward trend. Near seasonal temperatures are expected for the second half of the week and into the weekend. && 29 .FIRE WEATHER... Thunderstorm activity will shift into the lowlands this evening from the mountains with some shower activity possibly persisting into the early morning hours tomorrow, though coverage would be very isolated. Most of today`s activity should end by midnight. Min RH values of 20-25 percent will be common in the lowlands with seasonal highs. Winds will remain light except near thunderstorm outflows. The light winds will keep vent categories within a category of fair. Wednesday will see very similar conditions except that highs will cool a degree or two, bringing slight improvements to min RH values. Otherwise, expect afternoon and evening thunderstorms. Winds will be again be light except around thunderstorms. Moisture may increase further as the week continues, increasing rain and storm chances with modest, daily improvements in min RH values. && 34 && .PRELIMINARY POINT TEMPS/POPS... El Paso 77 97 75 95 / 40 40 40 20 Sierra Blanca 69 92 69 90 / 30 30 30 30 Las Cruces 71 94 69 92 / 30 50 50 30 Alamogordo 73 96 71 95 / 40 50 50 40 Cloudcroft 52 71 52 69 / 40 50 50 70 Truth or Consequences 72 94 71 91 / 40 60 60 50 Silver City 65 89 65 85 / 20 40 40 60 Deming 68 96 68 92 / 30 50 50 30 Lordsburg 69 95 69 92 / 20 30 30 40 West El Paso Metro 77 98 75 95 / 40 40 40 20 Dell City 70 98 70 96 / 20 20 20 20 Fort Hancock 76 98 74 97 / 30 30 30 30 Loma Linda 72 91 71 88 / 30 40 40 30 Fabens 77 97 76 95 / 30 30 30 20 Santa Teresa 73 97 71 94 / 40 40 40 20 White Sands HQ 77 95 75 93 / 40 50 50 30 Jornada Range 71 94 70 92 / 40 50 60 30 Hatch 71 95 70 93 / 40 50 60 40 Columbus 72 97 71 93 / 30 40 50 30 Orogrande 74 96 72 94 / 40 40 50 30 Mayhill 58 83 58 81 / 40 50 40 70 Mescalero 56 82 56 80 / 40 50 50 70 Timberon 55 81 55 80 / 40 40 40 60 Winston 58 86 57 82 / 30 60 60 70 Hillsboro 65 94 65 90 / 30 50 60 60 Spaceport 69 94 68 91 / 40 60 60 50 Lake Roberts 58 88 57 85 / 30 40 50 60 Hurley 63 91 63 88 / 30 40 40 50 Cliff 60 95 60 91 / 20 30 30 50 Mule Creek 67 91 66 88 / 20 30 30 50 Faywood 66 91 65 88 / 30 50 50 50 Animas 68 96 69 92 / 20 30 30 40 Hachita 66 95 66 91 / 30 40 40 30 Antelope Wells 68 94 67 91 / 30 40 50 50 Cloverdale 65 89 66 86 / 20 30 30 60 && .EPZ WATCHES/WARNINGS/ADVISORIES... NM...None. TX...None. && $$ 34-Brown/29-Crespo/01-Fausett
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
732 PM CDT Mon Jul 20 2020 .UPDATE... Issued at 725 PM CDT Mon Jul 20 2020 Short term hi-res models have been all over the place this aftn w/ regards to tstm potential/evolution this eve into the overnight. However, it appears as though the last couple of runs of the HRRR are initializing better (wasn`t doing great early aftn) and doing better with current trends. As such, it`s becoming more and more likely that the tstms near North Platte will become forward propagating over next hr or so, and drop S, mainly W of the CWA. It could be close to Gosper and Furnas Counties 8-11pm, but MCK and points W look more likely for the most intense tstms. That leaves our primary threat for strong to severe tstms dependent on activity currently moving SE through Cherry County. My latest thinking as that this activity may struggle to maintain severity after about 04Z for a few reasons: 1) developing LLJ this eve and into overnight will probably focus further S closer to and ahead of the activity currently near LBF. This would keep the primary WAA and convergence well S of the northern cluster/MCS. 2) Main instability axis currently runs from W KS northward into central and western Sandhills. Without a significant influence from LLJ, will be tough to nudge this axis to the E and more significantly impact/overlap the CWA. 3) Last 30 min or so of radar data suggests more of a Srly vs SErly track, similar to the activity near LBF. If this holds, this second round too would track mainly W of the area. All of this would suggest the severe threat for local CWA is pretty marginal and that going likely POPs for areas along/N of I-80 is overdone. However, not wanting to completely buy into any one solution just yet given very limited capping, weak forcing, and not completely insignificant combination of CAPE and shear. Will continue to monitor trends, but some significant updates may be needed later this eve. && .SHORT TERM...(This evening through Tuesday) Issued at 224 PM CDT Mon Jul 20 2020 Showers and storms last night produced widespread rainfall, with the heaviest rain falling in both the northern and southern parts of our area with Ord seeing 2.22" of rain...with even higher amounts of 2-4 inches falling along the Nebraska/Kansas state line with Hebron tallying 4.06". While we could see a hit or miss shower or storm this aftn in weak warm air advection, better chances for precip arrive later tonight and into the overnight hours. Convection is expected to develop to our west in the Dakotas and western Nebraska in increasing lift in upslope flow...and along a cold frontal boundary associated with a shortwave trough translating across the northern/central plains. High resolution models have trended a few hours slower with this next round of convection later tonight, with timing favored primarily after dark and through the overnight hours with storms organizing to our northwest and rolling through overnight. Model instability progs continue to indicate instability around 2000-3000 j/kg with shear around 30kts and the potential remains for strong to severe storms with the storm threats being damaging winds of 60-70 mph and large hail of quarter size or larger...and our region is outlooked in the SPC Day 1 Slight Risk for severe weather. Rainfall...after heavy rainfall of 2-4" in spots last night, locally heavy rainfall is possible once again tonight in storms given sfc dps either side of 70F and precipitable water values of 1.5-2.0". Another round of heavy rain for areas which already saw several inches of rain could result in some hydro/flooding issues. Fog...models are in decent agreement with the potential for low clouds tonight and SREF probs indicate some potential for reduced vsbys. How much of this is associated with precip or actual fog is more uncertain...but cannot rule out the potential for these low clouds and some fog given moisture/light wind setup and will at least include patchy fog to the forecast. Tuesday...Precip from overnight is expected to depart by Tuesday morning or shortly thereafter...but low clouds look to hold thru at least the first part of the day especially in our eastern zones. Will need to monitor trends of where the front stalls Tuesday...with models placing boundary across northern KS attm. Once the low clouds depart, the daytime on Tuesday is shaping up to be a fairly nice summer day with fairly light winds. Temps north of the front are expected to be in the upper 70s to around 80F...and south of the boundary hotter temps in the upper 80s to near 90F are forecast. .LONG TERM...(Tuesday night through Monday) Issued at 224 PM CDT Mon Jul 20 2020 The stalled boundary will be the focus for another round of convection Tuesday night aided by a weak low level jet, with additional development possible along the high plains in eastern CO/western KS which could organize and move into our region overnight. Our southern zones are currently outlooked in a marginal risk for severe weather which looks reasonable attm. The frontal boundary lifts north as a warm front on Wednesday, with chances for showers/storms continuing in the vicinity of the boundary mainly across portions of south central Neb. Temps trend up by the latter part of the week as the front continues to lift north, with highs returning near or into the 90s by Thursday, with the hot temps continuing thru the weekend and into early next week with a building upper ridge axis. As we heat back up, precip chances taper off mid week on with mainly hot/dry/humid weather expected for several days in the outer periods. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Wednesday) Issued at 648 PM CDT Mon Jul 20 2020 Difficult forecast due to uncertainty on tstm potential/coverage/timing, and whether or not any low clds develop behind convection/frontal boundary. Tonight: Should be mainly VFR for several hrs this eve. Tstms near LBF will likely drop S well W of the terminals, but this may take the LLJ focus further S for late overnight, which casts some doubt on if activity near NE/SD will hold together long enough to make it here. If it does, looks like timing would be around or after midnight, w/ lingering shwrs ending around dawn. Just not enough confidence on tstm evolution to go with a prevailing group at this time. Also uncertain is if low clds will become an issue, as this likely depends on how tstms evolve. Given the uncertainty, didn`t make too many changes other than to shorten the time of IFR cigs given latest trends towards not happening at all. Winds will be SE this eve, but will shift to the N late overnight but remain lgt outside of tstms. Confidence: Low. Tuesday: Continued low confidence forecast in the morning owing to uncertainties in low cld cover evolution mentioned above. If low clds form, should gradually lift and scattered out by late morning, leaving some VFR CU for the aftn. Lgt and vrbl winds during the morning may take on more of a prevailing NE wind, but remain lgt, for the aftn. Confidence: Low. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...Thies SHORT TERM...Fay LONG TERM...Fay AVIATION...Thies
Area Forecast Discussion
National Weather Service Goodland KS
951 PM MDT Mon Jul 20 2020 .MESOSCALE DISCUSSION... Issued at 944 PM MDT Mon Jul 20 2020 Storms are continuing to move south behind an outflow boundary. MLCIN/MLCAPE are still supportive of storm develop. However the environment is more unstable over the eastern part of the forecast area. Effective wind shear remains consistent at 40 kts over the forecast area, which should cause the storms to maintain their intensity. DCAPE is also still high ahead of the line. However as the evening progresses the environment will become more stable and limit the amount of wind reaching the ground. Have already noticed a decrease in the wind speeds where radar has shown winds of 60+ MPH overhead. As the outflow boundary continues to slowly move further from the storm, the storms should weaken due to the lift from the boundary becoming further ahead of the storms themselves. The question is how far south will the storms move before dying out. Based on current guidance, wouldn`t be surprised if they last well into Southwest Kansas. && .UPDATE... Issued at 719 PM MDT Mon Jul 20 2020 A severe thunderstorm watch has been issued for the northern half of the forecast area through 11 PM MT. Main threats are large hail and damaging wind gusts. UPDATE Issued at 608 PM MDT Mon Jul 20 2020 Updated the forecast given the current trends on radar and satellite. Main activity continues to be the storms over Cheyenne County CO. These may spread southeast over the next hour or two. To the north another area of severe thunderstorms is moving southeast toward the forecast area. ETA of storm arrival is roughly two hours away. Behind that round another round of storms may move through the forecast area later on closer to midnight. Not sure how strong these storms will be with the incoming round of storm activity approaching. && .SHORT TERM...(This evening through Tuesday) Issued at 206 PM MDT Mon Jul 20 2020 Satellite imagery and 500 mb RAP analysis showed a broad trough across the northern half of the country this morning. A shortwave exiting the central Plains sparked convection over eastern Kansas and western Missouri. Behind this disturbance, northwest flow prevailed over the region, with areas of high pressure across the desert southwest and southeastern CONUS. At 2:00 PM MT, a cold front was draped from west to east across the center of the region with mostly sunny skies. Temperatures were in the upper 80s to low 90s with east to southeast winds at 10 to 15 mph. A few small storms had developed in western Kit Carson county. The cold front is expected to help trigger thunderstorms this afternoon and evening, as an upper wave passes through the northwest flow. Showers and storms should develop in eastern Colorado this afternoon, and spread east into western Kansas and southwestern Nebraska this evening. There will be enough shear and instability for a few severe thunderstorms. Main threats with these storms are damaging winds, large hail, and locally heavy rainfall. Another area of storms are forecast to form in central Nebraska this afternoon and evening, congeal into an MCS, and track southeast tonight. Depending on how this plays out, we could see another round of thunderstorms across the eastern part of the region during the late evening/overnight hours. However, confidence is low at this time on where this cluster of storms will track. If the line grazes the region, damaging winds and locally heavy rainfall would be the main threats. Otherwise, increased cloud cover is expected tonight, with lows in the upper 50s to mid 60s. Will need to monitor for the potential of stratus developing (and perhaps fog) around sunrise. The region will see a brief break from storm chances Tuesday morning. Temperatures should be slightly cooler behind the front, with highs in the upper 80s to low 90s. Thunderstorms are forecast to develop off of the Front Range and spread into the area in the afternoon and evening. A few strong to severe storms will be possible once again, with threats of damaging winds, large hail, and locally heavy rainfall. Temperatures fall into the upper 50s to upper 60s overnight. .LONG TERM...(Wednesday through Monday) Issued at 149 PM MDT Mon Jul 20 2020 For the extended period the models are showing an upper-level ridge extending from the southern Plains over the Rockies dominating the week with above normal temperatures (middle 90s). Thunderstorms may develop around the periphery of the ridge each day, along the Front Range, and move into northeastern Colorado during the late afternoon/evening hours. Heading into the weekend, the ridge looks to move eastward into the northern Plains region, which may allow some storms to move into northwest Kansas/southwest Nebraska area. Given the weak flow aloft in proximity to the ridge, the chance for severe storms will be low. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 533 PM MDT Mon Jul 20 2020 VFR conditions are forecast for the TAFs. Confidence of storms occurring near KGLD is too low to include in the TAFs. Confidence is higher that KMCK will see storms this evening based on the ETA of storms moving south in Nebraska. Otherwise, KMCK may have ceilings fall close to MVFR around 12z. Latest data seems to have raised the ceiling some from the last TAF issuance, so have the ceiling remaining VFR for now. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ MESOSCALE...JTL UPDATE...JTL SHORT TERM...JBH LONG TERM...BW AVIATION...JTL
Area Forecast Discussion
National Weather Service Indianapolis IN
1136 PM EDT Mon Jul 20 2020 .UPDATE... The AVIATION Section has been updated below. && .SYNOPSIS... Issued at 308 PM EDT Mon Jul 20 2020 A few areas of scattered showers and thunderstorms are possible this evening and tonight, but mostly should be south of the forecast area. Going into the day tomorrow, isolated to scattered thunderstorms are likely during the afternoon hours with the potential for a more organized cluster of storms late tomorrow into the overnight hours. This pattern of isolated to scattered storms will continue later into the week before becoming more dry and hot this weekend into early next week. && .NEAR TERM /Overnight/... Issued at 950 PM EDT Mon Jul 20 2020 Surface analysis this evening shows high pressure in place over the Great lakes. Another high pressure system was found over the southeastern states. In between...a weak front boundary was draped across southern Indiana. Radar this evening shows a isolated showers and even more isolated thunderstorms across the southern parts of the forecast area dissipating quickly and drifting northeast. GOES16 show plentiful cloud cover arriving across Central Indiana from Illinois...associated with earlier convection. Dew points remained humid near 70. HRRR suggests ongoing convection will dissipate with the loss of heating. Confidence in this is high as radar trends reflect this. HRRR also suggests additional very isolated showers overnight as the front slowly lifts north. Confidence in that is rather low...but it cannot be ruled out given our very moist air mass in place. Thus have trended pops toward dry by midnight...but then kept a low chc pops across the southern parts of the forecast area overnight. Again confidence in that is quite low. Given the increasing clouds along with the arrival of a warm front...have trended overnight lows warmer then the NBM...going at or above persistence. && .SHORT TERM /Tuesday through Thursday/... Issued at 308 PM EDT Mon Jul 20 2020 Much of the same weather is expected in the short term period with isolated to scattered thunderstorms likely, especially during the evening and early overnight hours. Confidence in thunderstorm activity is low at any given point due to uncertainty down to the mesoscale level and the impacts of any previous thunderstorm activity. Having said that, upper level forcing does appear to be in place tomorrow evening which should bring a more organized complex of storms to the area late tomorrow into the early overnight hours. A few strong wind gusts will be possible and the potential for flash flooding is there, especially across the areas that received heavy rain last night. Scattered thunderstorms will continue Wednesday and Thursday as upper level vort maxes interact with a nearly stationary surface front. Confidence in the axis of heaviest rain remains low, but areas of 1 to 2 inches of rain look likely between now and Thursday night. Highs will climb into the mid to upper 80s Tuesday and Wednesday. Lows will fall into the upper 60s to low 70s Tuesday and Wednesday nights. && .LONG TERM /Thursday night through Monday/... Issued at 231 PM EDT Mon Jul 20 2020 Some chances for thunderstorms will continue through the day on Friday as a stalled frontal boundary continues to provide a little additional lift and focus for convection. By Friday night, though, the center of the upper ridge that spends most of the week to our west will move into central Indiana. This will serve to increase temperatures and humidity, as well as provide subsidence to make the weather mostly dry. An isolated storm may be possible Saturday afternoon or Sunday afternoon just from the amount of instability, but again, the subsidence from the high should keep coverage from getting any more than isolated. High temperatures should again be in the 90s for the weekend, with heat index values getting into the low 100s, and this should continue into Monday. Monday the upper ridge appears to buckle a bit, and this could allow for more organized convection with better coverage. && .AVIATION /Discussion for the 210600Z Tafs/... Issued at 1137 PM EDT Mon Jul 20 2020 Mainly VFR conditions are expected this taf period. Frontal boundary near the Ohio River is expected to lift north across Central Indiana overnight as a tropical plume of moisture over TX- OK-MO-and NRN IL is expected to sag across Indiana over the next 24 hours. GOES16 shows convective debris clouds over Indiana and Illinois. Isolated showers this evening have continued to dissipate as radar is nearly quiet. Additional showers will be possible as the front lifts north. This is suggested by the HRRR...but confidence for specific timing and any coverage at all is quite low. Thus did not include a mention of that at this time. On Tuesday...forecast soundings are favorable for convection in the afternoon with CAPE over 2000 J/kg along with Pwats over 1.9 inches. Thus expect afternoon tsra development and have opened a large window during peak heating hours to account for this. Confidence for specific locations and timing remains too low for a prevailing mention at this time. Any TSRA that does strike a TAF site on Tuesday may produce brief MVFR to IFR conditions. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...White NEAR TERM...Puma SHORT TERM...White LONG TERM....CP AVIATION...JP
Area Forecast Discussion
National Weather Service Mobile AL
1044 PM CDT Mon Jul 20 2020 .NEAR TERM /Now Through Tuesday night/...Same song different day with this pesky upper level ridge anchored over the eastern US. Luckily this appears the last day for the standard summertime pattern as a weak tropical disturbance moves into the gulf by Tuesday night. Unfortunately, my period only covers up to that point which means same old same old with the seabreeze being the driving factor for showers and thunderstorms during the late afternoon and early evening hours. Like most days, ample cape will be present but with PWATS of 1.7 to 1.9 and not much change overall from today I would not expect much change from Mondays forecast. Convective allowing models don`t have a lot of coverage tomorrow except for the HRRR which typically has too many storms as it did today. I was contemplating keeping isolated storms in the forecast but stuck with scattered over the eastern half of the area. It`s a bold strategy, but we will see how it works out. Per normal, what storms that do develop will have the potential for gusty winds as they spread inland into the evening. Temperatures will be in the low to mid 90s across the area with a few spots possibly getting into the upper 90s. Lows will be in the mid to upper 70s with dewpoints remaining high. A moderate risk of rip currents will continue through tomorrow before increasing later in the week. BB/03 && .PREV DISCUSSION... /issued 634 PM CDT Mon Jul 20 2020/ NEAR TERM UPDATE /Now Through Tuesday night/...Just a little update this afternoon as storms have struggled with dry air across the area this afternoon. Due to this, I trimmed back pops for only isolated storms tonight mainly around the Highway 84 corridor. The good news is that current visible satellite looks good for potential comet Neowise viewing conditions tonight. Be sure to head out about an hour after sunset and look near the big dipper. It might be tough to see in city areas due to light pollution but you should be able to see it with binoculars or a telescope. Temperatures will begin to slowly fall into the mid to upper 70s tonight. BB/03 AVIATION... 00Z issuance...VFR conditions will once again persist through the evening with only an isolated shower along the highway 84 corridor. Winds will become light and variable after sunset tonight. Conditions will persist into the early afternoon with the potential for isolated to possibly scattered thunderstorms developing during the afternoon. BB/03 PREV DISCUSSION... /issued 347 PM CDT Mon Jul 20 2020/ NEAR TERM UPDATE /Now Through Tuesday/...A deep layer ridge of high pressure continues to extend from the western Atlantic through the Tennessee Valley and adjacent southeastern states this afternoon. A light southeasterly flow continues across our region with this pattern. Seasonably hot and humid conditions persist with temperatures in the lower to mid 90s over interior portions of the region and in the upper 80s to around 90 degrees near the coast. Dewpoints in the lower to mid 70s are resulting in heat indices in the 101 to 106 degree range over most places, and even very locally as high as 109 at Mobile Brookley Field. Radar is finally indicating the development of isolated showers and storms along the seabreeze as of 2 PM CDT. With precipitable water values between 1.7 and 1.9 inches and a weak impulse rounding the area on the periphery of the ridge axis, we anticipate that additional isolated to scattered showers and storms will continue to develop through the afternoon and into the evening, with coverage becoming more pronounced over interior portions of the CWA. The hot temperatures and dewpoints in the 70s continue to promote pockets of MLCAPE values between 2000-3000 J/KG, so there is potential for a storm or two to produce very localized strong downburst winds, in addition to frequent lightning and locally heavy rainfall this afternoon into early this evening. Convection should diminish by late this evening and will maintain a dry forecast after midnight. A similar weather pattern will continue across the region on Tuesday. The deep layer ridge will continue to nose west- southwest from the western Atlantic/eastern seaboard through AL/MS. This pattern will continue to support the typical heat and humidity, with highs once again forecast to range in the lower to mid 90s over our interior areas and around 90 degrees near the immediate coast and beaches. Max heat indices are forecast to range between 102-107 degrees over much of the area. Isolated showers/storms should be mostly confined to the marine area early Tuesday morning, and perhaps also dotting portions of interior southwest/south central AL, but more scattered coverage should develop again by Tuesday afternoon, particularly over interior areas. Instability should remain strong enough (2000-3000 J/KG) for there to be concern for locally strong wind gusts and frequent lightning with the stronger storm cells that develop Tuesday. Swell has diminished to 1-2 feet, with periods decreasing to 5-6 seconds, so will allow the HIGH risk of rip currents to expire this afternoon. The combination of 1-2 ft swell and high tidal ranges will support a MODERATE rip current risk through Tuesday night. /21 SHORT TERM /Tuesday night Through Thursday night/...An upper level ridge generally remains to the north of the local area through the week. This ridge briefly weakens as an upper level trough in the northern stream swings across the far northern Plains and across the Great Lakes region on its way toward the East Coast. Low level and surface ridging from the Western Atlantic continues to spill into the Southeast through the week, which will allow winds to be southerly through the day and easterly at night. Looking to our south, a tropical wave cruises to the west-northwest across the central Gulf on Wednesday and reaches the northwestern Gulf later on Thursday. Regardless if the tropical wave strengthens or not as it traverses into a conducive environment in the Gulf, it is forecast to remain south of our area, which will increase the risk for rip currents and higher tides through the short term. We will continue to monitor this tropical wave over the next few days. Deep layer moisture streams into the area on Wednesday and Thursday as the area receives return flow from the surface ridge and the aforementioned tropical wave passes well south of the area. Forecast soundings generally show PWATs of 1.6-1.9 inches on Wednesday increasing to 2+ inches by Thursday afternoon across the southern portion of the area. A diurnal pattern is anticipated for convection each day with storms ramping up across the Gulf waters during the late night and early morning hours before transitioning to the land areas during the late morning hours and concentrating inland through the remainder of the afternoon and early evening. The bulk of the convection during the daytime will remain across the southern portion of the area, generally south of the Hwy 84 corridor, as that is where the deep layer moisture resides. Afternoon highs will top out in the mid to low 90s each afternoon with upper 80s at the beaches. A few spots in southeast Mississippi may struggle to reach 90 on Thursday afternoon due to an increase in cloud cover and rain coverage. Heat index will generally range from 100-105 each day. Lows continue to sound like a broken record as they fall into the low 70s inland each night with upper 70s to near 80 at the beaches. Rip current risk increases to a HIGH Wednesday through at least Thursday night. 07/mb EXTENDED TERM /Friday Through Monday/...The pattern does not change too much through the period as the upper level ridge expands further into the Southeast and Central Plains while the surface ridge remains draped across the Southeast. The local area remains on the southern periphery of the upper level ridge with prevailing easterly flow aloft. A subtle shortwave moves around the eastern edge of the ridge and zips through the area later in the weekend. This feature has the potential to enhance thunderstorm coverage in the afternoons this weekend, but given some timing differences in the operational guidance, we opted not to adjust POPs up just yet. Outside of this feature aloft, light southeasterly flow at the surface will continue with a diurnal convection pattern each day. Subsidence associated with the ridge aloft will likely limit the thunderstorm coverage somewhat. Afternoon highs will generally rise into the mid to low 90s each day with upper 80s at the beaches. Heat index will be slightly higher this weekend with values of 102-107. Low temperatures only fall into 70s each night. 07/mb MARINE...No significant marine impacts forecast through Tuesday night except higher winds and waves near isolated to scattered thunderstorms. Small craft may need to exercise caution Wednesday and Thursday due to increased winds and seas. /21 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...None. FL...None. MS...None. GM...None. && $$ This product is also available on the web at: http://weather.gov/mob
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Morristown TN
926 PM EDT Mon Jul 20 2020 .UPDATE... EVENING UPDATE. && .DISCUSSION... Convection has been able to persist longer into the evening than that last few nights, likely due to the presence of a mid/upper level shortwave trough moving across KY. The 00Z OHX sounding also shows a midlevel layer of steep lapse rates. The forecast will be updated to extend PoPs until around midnight. The widespread coverage of showers this evening makes it more likely that fog will form in many locations, so a mention of this will be added. DGS && .AVIATION... 00Z TAF DISCUSSION. With very little change in the overall weather pattern, the next 24 hours will be very much like the past 24, with scattered afternoon showers and thunderstorms, and a potential for MVFR fog at TRI for a brief period around sunrise. DGS && .PREV DISCUSSION... /ISSUED 256 PM EDT Mon Jul 20 2020/ SHORT TERM (This Afternoon through Tuesday)... Current water vapor imagery and RAP upper air analysis indicates a trough moving to the east across IA/IL/WI. Closer to home, the upper ridge continues to be the main feature but it is a bit weaker today with the trough to the northwest. Temperatures are still elevated across the forecast area with most locations in the upper 80s to mid 90s as of 2 pm. Convective initiation across the region has been sparse so far as updrafts struggle to break through the cap. Continued heating over the next hour or 2 should lead to a bit better coverage. The latest HRRR indicates best coverage across the northern Cumberland Plateau into southwest Virginia. Current radar imagery indicates a decent cluster of storms back to the northwest near the Ohio River. These storms are in the vicinity of a surface front that stretches across the Ohio River Valley. SBCAPE values this afternoon and evening will be in the 1000-2000 J/Kg range with 0-6 km bulk shear values of less than 10 kts. DCAPE values are impressive in the 800-1200 J/Kg range but there is a cap and dry air to overcome. Overall, any storm that does manage to form could produce an isolated damaging wind gusts. Most storms should remain well below severe criteria. Convection should come to an end overnight but a stray shower/storm could linger, especially for areas north of I-40 as the trough passes to the north tonight. Lows will range from the upper 60s to mid 70s. Patchy fog will also be possible again mainly for northeast Tennessee and southwest Virginia, where the slightly higher rain chances will feature this afternoon/evening. The surface boundary currently to the north will nudge just a bit further southward throughout the short-term forecast period. The shortwave trough will move off to the northeast on Tuesday. PW values will actually nudge upward just a bit and the upper level heights may increase slightly as the ridge holds on. Model soundings do not look much different than today except for the slightly higher moisture. Overall, confidence in precipitation coverage may be a bit higher tomorrow than today. SBCAPE values and deep layer shear will be similar to today. Once again, could not rule out a strong to marginally severe storm with an isolated damaging wind gusts but most storms will stay well below severe criteria. High temperatures will once again be in the low to mid 90s with heat indices of 100- 105 in the central and southern Tennessee Valley. MA LONG TERM (Tuesday Night through Monday)... Key Messages: 1. Slightly cooler with fairly widespread afternoon showers/thunderstorms Wednesday through Friday. 2. Hotter and drier trend again this weekend through early next week. Discussion: Tuesday Night Through Wednesday Night... The elongated mid/upper ridge across the S CONUS will undergo its long advertised break down during this period as a significant shortwave trough progresses from the upper Midwest through the Great Lakes with an associated surface low moving into Ontario and dragging a cold front into the lower OH Valley by Wed night. This will lower heights across the TN Valley and S Appalachians with a broad but shallow trough taking shape across the northern tier states. Mid level cooling should leave the region uncapped Wed, and with abundant low-level moisture in place, afternoon instability, and some upper support on the southern periphery of the shortwave, expect convection to develop quickly through the morning and afternoon, so have PoPs increasing to likely during the afternoon. SPC has a marginal risk for severe weather in SW VA in closer proximity to the upper support. This is dependent on how much sunshine we see as clouds will be quite widespread, but at least marginal instability, seasonably high PWATs, and modest deep layer shear could support a few wet microbursts. Decreased PoPs to chance/slight chance Wed night with the loss of heating, but with at least weak upper support and the front reaching the OH Valley, did not want to go dry. Highs will be tempered by the increased clouds and precip with upper 80`s/low 90`s, which is seasonable but better than the heat of recent days. Lows both Tue and Wed nights will remain warm in the upper 60`s/low 70`s. Thursday through Friday Night... Guidance has finally come into agreement that as the aforementioned shortwave moves across the NE U.S. Thursday, the front will temporarily stall across the lower OH Valley and central Appalachians before a stronger shortwave drops through the NE U.S. Thurs night and Fri and pushes the front slowly southward through our CWA. Small timing differences still exist, but consensus is for the front to slowly cross from late Thurs through Fri morning, moving S of the region Fri afternoon. Continued low-level moisture, lower heights aloft, and afternoon instability combined with upper support as the front slowly drops through will yield widespread convection again, with peak coverage in the afternoon and evening. Have likely PoPs all areas Thursday afternoon, but kept likely wording confined to the eastern mountains and SE TN with high chance elsewhere Fri afternoon since the boundary should be moving S. Tapered PoPs to chance/slight chance during the overnights. Flow aloft will still be weak, so generally not expecting severe weather, but continued seasonably high PWATs and sufficient DCAPE as the atmosphere destabilizes could cause an isolated wet microburst and locally heavy rain. Highs Thurs and Fri will continue to trend slightly lower in the mid 80`s to low 90`s, but the warm overnight lows in the upper 60`s/low 70`s will continue. Saturday through Monday... A strong mid/upper ridge is still on track to develop over the central CONUS at the end of the week with a 595-596 DM closed H5 high centering over MO or southern IL this weekend into early next week. This will cause the heat dome to gradually edge back over the region with warming mid level temps reducing convection to mainly widely scattered, diurnal activity over the higher terrain. However, kept chance PoPs each day across the entire area because guidance continues to differ on how far east the core of the ridge builds, which could potentially open the door to weak perturbations dropping around the eastern periphery and periodically enhancing the diurnal convection. Highs will trend back into the middle 90`s. Garuckas && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 75 95 74 93 74 / 10 40 20 70 20 Knoxville McGhee Tyson Airport, TN 74 94 73 93 73 / 20 50 20 70 30 Oak Ridge, TN 73 94 73 93 72 / 20 50 10 70 30 Tri Cities Airport, TN 70 91 70 91 69 / 30 60 20 70 30 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$
Area Forecast Discussion
National Weather Service Shreveport LA
920 PM CDT Mon Jul 20 2020 .UPDATE... Convection has diminished for the remainder of the evening and therefore, had to clean up pops a bit in the grids. Latest 00z NAM and HRRR output suggests we could see isolated convection once again spread north and west across Deep East Texas into West Central Louisiana sometime during the predawn hours so for this reason, have kept slight chance pops across our extreme southern zones which is south of the I-20 Corridor. Areas that saw rainfall earlier are within 5 degrees or so of forecast mins but these areas should stabilize while rain free areas will continue to fall as expected. Therefore, did not make any changes concerning overnight lows. We will continue to see this weak disturbance aloft and increasing PWATs across our region on Tuesday which will result in scattered to numerous showers and thunderstorms that will once again become tied to daytime heating. The forecast for Tue has a pretty good handle on this thinking so no additional changes were necessary. Update out shortly...13. && .PREV DISCUSSION... /issued 723 PM CDT Mon Jul 20 2020/ AVIATION... Convection is quickly dissipating across our airspace this evening but for the 00z TAF package, did carry VCTS across most terminals through 02z or so with TEMPO TSRA given coverage to begin the package. Otherwise, VFR conditions should prevail through the remainder of the evening and overnight hours. Did start VCTS mention a little earlier on Tuesday (by late morning) at our NE TX terminals only given the position of the weakness aloft across our western half which again should be tight to late morning, afternoon heating, elsewhere, kept VCTS tied to the afternoon hours on Tue. 13 && .PRELIMINARY POINT TEMPS/POPS... SHV 76 92 76 93 / 10 40 20 20 MLU 75 95 76 95 / 10 20 20 20 DEQ 73 92 73 91 / 10 20 20 20 TXK 74 91 74 91 / 10 20 20 20 ELD 74 94 74 94 / 10 20 20 20 TYR 74 89 74 91 / 10 60 20 30 GGG 74 90 73 92 / 10 50 20 20 LFK 75 89 75 92 / 20 60 20 40 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...None. LA...None. OK...None. TX...None. && $$ 13/13
Area Forecast Discussion
National Weather Service Tucson AZ
320 PM MST Mon Jul 20 2020 .SYNOPSIS...Above average heat and below average thunderstorm chances to start the week. A more favorable pattern with increasing moisture will set up, with increasing thunderstorm chances the rest of the week. Strongest thunderstorm days are expected to be Thursday and/or Friday. Some storms will generate heavy rain and strong winds. && .DISCUSSION...Isolated showers likely producing virga, sprinkles, or perhaps a few hundredths of an inch of rainfall continued in a north- to-south oriented band across western Pima County at this time. Isolated showers/tstms were also noted across the White Mountains. Otherwise, clouds have decreased markedly during the past 1-3 hours from Tucson eastward, but mostly cloudy to cloudy skies continued across western sections. Several HRRR solutions suggest that the showers across western sections will decrease in coverage during the next few hours. Isolated showers/tstms should also continue mainly near the White Mtns into early this evening, then isolated showers producing very light rainfall should prevail tonight. Expect isolated to perhaps scattered coverage of showers/tstms Tuesday afternoon/evening mainly east to south of Tucson. Most models suggest that much of the Tucson metro area would not receive measurable rainfall Tuesday afternoon/ evening, although the Catalina/Rincon Mountains may be the most susceptible to measurable albeit light rainfall. The various 20/12Z high-res and global models still support the inherited official forecast scenario of an upswing in rainfall chances starting Wednesday afternoon, when scattered showers/tstms are expected across much of this forecast area. As of this writing, the period for the highest rainfall chances/coverage of showers/ tstms appears to exist Thursday through Friday, although Saturday and Sunday during the afternoon/evening hours also favor scattered coverage mainly from Tucson eastward. With increased rainfall chances, there is an increased potential for locally heavy rainfall and gusty winds at times due to thunderstorm outflows. The various models suggest that late night/morning hours Sunday and Monday will likely have minimal if any measurable rainfall across much of the area. Expect scattered showers/tstms mainly from Tucson eastward and southward Monday afternoon. High temperatures Tuesday and Wednesday will be generally a few degrees above normal, then high temps especially Friday and Saturday ranging a few to perhaps several degrees below normal. Daytime temps by early next week should trend closer to normal for late July. && .AVIATION...Valid through 22/00Z. Isolated -SHRA west of KTUS this afternoon, with isolated -TSRA across the White Mountains and the SE portion of Cochise County. Isolated -SHRA may occur across southeast AZ 06Z-15Z then ending late in valid period. Scattered -TSRA/-SHRA east to south of KTUS Tuesday afternoon. Otherwise, FEW-SCT clouds 10-15k ft MSL and SCT- BKN clouds above 15k ft MSL, which will continue through much of the forecast period. SFC winds WLY/NWLY 8-12 kts this afternoon, with higher speeds of 12-18 kts and gusts to 25 kts near KSAD. Winds become light and variable during the evening, returning WLY/NWLY 8- 12 kts tomorrow afternoon. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...Isolated showers and thunderstorms are expected today and tomorrow, favoring the White Mountains and the higher terrain southeast of Tucson. By Wednesday, thunderstorm activity increases area wide. This regime of enhanced precipitation chances will continue each day into the weekend. 20-ft winds are breezy across the Upper Gila River Valley this afternoon, but otherwise less than 15 mph through the period. Thunderstorm gusts of 45 mph or higher will also be possible around the stronger storms. Daytime humidities reach 15 to 30 percent through Tuesday, then generally above 25 percent Wednesday onward. && .TWC WATCHES/WARNINGS/ADVISORIES...None. && $$ DISCUSSION...Francis AVIATION...Howlett FIRE WEATHER...Howlett Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
Area Forecast Discussion
National Weather Service Las Vegas NV
834 PM PDT Mon Jul 20 2020 .SYNOPSIS...Limited mid level moisture moving up from southern Arizona will bring scattered clouds and a few showers and isolated thunderstorms to the area today and Tuesday. This could result in some additional fire starts in the area due to lightning as well as gusty outflow winds. More significant monsoonal moisture may begin to creep into the region toward the end of the work week resulting in thunderstorm chances for at least northwest Arizona and slight chances for southern Nevada. Temperatures should also begin to slowly decline towards the end of the week. && .UPDATE...Have not seen a cloud flash or CG detected by the lightning network in about an hour. However, satellite shows partly to mostly cloudy skies across southern Nevada, as well as Inyo and Mohave County. There has been some IR cloud top cooling across parts of Esmeralda and Lincoln County where a light rain shower or brief thunderstorm could yet occur this evening. Area will remain under the influence of this broad weak cyclonic circulation with several vorticity lobes pivoting around the circulation. Most clearly identifiable circulation early in the day was over southwest Lincoln County which has since moved southwest over southern Nye County. With these features around tonight can not rule out seeing an isolated shower or thunderstorm popping up anywhere over Inyo County, southern Nevada, lower Colorado River Valley or northwest Arizona overnight. Due to the lack of decent instability, Tuesday looks to be a repeat of today with best thunderstorm coverage over the higher terrain. Due to the lack of low level moisture primary concern will be gusty wind and dry lightning. Our Red Flag Warning continues through Tuesday evening. Touched up the POPs/Weather Grids the rest of tonight and Tuesday. && .AVIATION...For McCarran...Most of the overnight period is expected to be quiet with mainly southwest winds around 6 kts and Few to Sct clouds around 15k feet. There is some potential of showers reentering the valley between 10-13z Tuesday morning bringing light rain along with gusty winds, however confidence is low. There will be another chance of seeing isolated thunderstorms Tuesday afternoon along with the potential of gusty outflow winds. Best time for this to occur will be between 18z-02z. For the rest of southern Nevada, northwest Arizona and southeast California...Isolated areas of showers and a slight chance of thunderstorms will occur overnight along with the potential of seeing gusty outflow winds. Shower and thunderstorm chances will again be possible Tuesday afternoon with the main threat being gusty outflow winds between 25-35 kts. Clouds should remain around 14k or higher except near showers where CIGS could drop to as low as 10k feet. && .SHORT TERM...Tonight through Tuesday. This morning`s convection produced frequent lightning across Clark County resulting in at least one fire in the Spring Mountains. Additional development is beginning to occur this afternoon across southern Nevada and northwest Arizona. While isolated in nature, this will continue to be a concern from a fire potential standpoint since low level atmosphere is still quite dry, with this morning`s sounding showing dry adiabatic environment just below 500 mb. CAMs have been handling this convection better than some of the coarser models and have edged confidence towards the HRRR for the short term. As of the 19Z run, elevated thunderstorm potential continues to be maximized along the Sierra as well as Spring/Sheep Range, northern Mohave, Lincoln, and Nye counties. On satellite, we are continuing to note what appears to be a weak MCV just east of the test site. It is worth noting that HRRR/HRRRX does not seem to be capturing this mesoscale feature and thus it`s a bit unclear how much effect this will have on convection the rest of the afternoon. Should convection overachieve this afternoon from CAMs, the biggest concern beyond fire starts will be gusty outflow winds of 40+ mph. Furthermore, noted PV advection looks to wrap back into southern Nevada tomorrow morning as well which could result in another round of showers and storms tomorrow afternoon and possibly as early as tomorrow morning. This PV anomaly does appear in the RAP to exist a bit farther north and east, which should keep the Las Vegas Valley dry but continuing light precip chances for northern Mohave and Lincoln counties. Neighbors have also upgraded their watches (LKN/SLC) for Tuesday, so we have issued a RFW for southern Nevada and northwest Arizona fire zones through Tuesday evening. .LONG TERM...Wednesday through the Weekend. Ensemble output continues to indicated a stronger shortwave trough moving through central California Wednesday night, then across southern Nevada Thursday and Thursday night. Strengthen southerly flow preceding the shortwave will advect `richer` moisture northward up the Colorado River Valley and western Arizona. Some of this will likely leak westward into eastern San Bernardino, Clark and eastern Lincoln Counties. This will form a `sharp` moisture gradient; similar to the southern plains dryline. Forcing will come from a jet streak moving overhead while the `richer` moisture will lead to higher CAPE values. Again, don`t be surprised to see some nocturnal storms Wednesday night. During this period, some thunderstorms could produce brief heavy rain, gusty winds and hail. On Friday and through the weekend some form of a trough will remain intact over the Nevada and California. This should keep most of the area dry and thunderstorm free as moisture is shifted back east into Arizona for the most part. The only exception could be eastern Mohave County where moisture is always difficult to get scoured out so a slight chance of thunderstorms exists each day. Temperatures will be running at or slightly below normal during the period. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && UPDATE...Pierce DISCUSSION...Adair/TB3 AVIATION...Gorelow For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter