Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/30/18

Area Forecast Discussion
National Weather Service Denver/Boulder CO
933 PM MDT Sun Jul 29 2018 .UPDATE... Issued at 922 PM MDT Sun Jul 29 2018 Although there are a few strong thunderstorms moving across southeast Elbert and central Lincoln counties at this time, the threat of tornadoes is low so the tornado watch was allowed to expire at 9 pm. An isolated thunderstorm however could still produce damaging straight-line winds and hail. Have adjusted the pops this evening through Monday morning to lessen the pops north and west of where the thunderstorms are at. Cannot rule out some redevelopment so will keep at least isolated thunderstorms in the grids. Also add patchy fog overnight into Monday morning as well. && .SHORT TERM...(This evening through Monday) Issued at 255 PM MDT Sun Jul 29 2018 Speed max in the northwesterly flow aloft is helping to produce the severe strength and tornado-producing storms currently in southeastern Wyoming. These storms are moving south-southeast to enter our state soon, into the area of Enhanced Risk. Storms further south over the central mountains and Palmer Divide are expected to gain strength soon, though the strongest storms will be further north. The northern storms are expected to continue strong into Weld, Morgan and Logan counties at least into later this afternoon. Forecasted updraft helicities remain high run to run on the HRRR pushing into the northern plains. Will continue to push the tornado threat as well as the very large damaging hail and very strong damaging wind gusts messaging over that area. Cap still remains pretty strong over the central urban corridor out to Denver, as evidenced by the storms dissipating that move over the area, lower surface temperatures and by the ACARS soundings. Will still forecast for little storms in this area until this evenings frontal push. A corridor of thicker smoke also seen on visible satellite is stretched across the northern half of the state may limit much further heating as well. Plenty of shear and CAPE still available this evening when a cold front will push down. This will bring a second round of storms down the plains which will still have the potential of being severe strength, and when the Denver area and central urban corridor may have a better chance of seeing stronger storms. Stratus, rain showers and possibly some fog in the upslope favored areas are expected to fill in behind by midnight. With the speed max aloft, still keeping a slight chance of seeing some thunder overnight. Cold front is also expected to push the smoke out of the area as well. Forecast soundings show the low level moisture and stratus to hang on into Monday morning. Areas along the foothills and Palmer Divide will likely see this as areas of fog, causing low visibilities which may impact Monday morning rush hour. Some lower elevations may see some fog as well. Some areas of drizzle may occur, but some soundings show rain showers remaining as well. Upper trough will pass southeast over the area and high surface pressure over the Great Plains will bring cooler temperatures to the area Monday. as the speed max is over the central plains, may continue to see some rain showers and isolated thunderstorms over the southern half of the forecast area as well as in the mountains where less stability will be above the inversion. .LONG TERM...(Monday night through Sunday) Issued at 255 PM MDT Sun Jul 29 2018 This week`s weather will be dominated by the upper level ridge building back across the region. Tuesday looks like a completely dry day, with no storms expected anywhere in the forecast area. A warming trend will begin Tuesday, and then remain in place through the end of the week with high temperatures warming back into the lower to mid 90s across the plains. Some moisture will eventually build under the ridge, so a few afternoon and early evening storms can be expected from Wednesday onward. Most of these will stay over the mountains, but isolated storms will still be possible on the plains. The majority of these storms would produce just light rain and gusty outflow winds. && .AVIATION...(For the 06Z TAFS through 06Z Monday night) Issued at 922 PM MDT Sun Jul 29 2018 Do not anticipate additional thunderstorm development in the terminals so will not include them in the TAFS, maybe just a brief rain shower or two. MVFR cigs likely overnight, with some IFR restrictions possible if patchy fog develops. Main window for the lowest cigs would appear to be 09-15z, then improving by Monday afternoon. && .BOU WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...Cooper SHORT TERM...Kriederman LONG TERM...Barjenbruch AVIATION...Cooper
Area Forecast Discussion
National Weather Service Caribou ME
952 PM EDT Sun Jul 29 2018 .SYNOPSIS... A cold front will move to the east of the area tonight. High pressure will build south of the region Monday and continue southeast on Tuesday. Low pressure will approach Tuesday night and track west of the state on Wednesday. && .NEAR TERM /THROUGH MONDAY/... 950 PM Update...Temperatures at this hour were ranging from the low 60s across the north Maine Woods to the mid to upper 60s elsewhere across the forecast area. The cold front continues to move east of the region this evening. The air behind the front is somewhat drier, with dew points dropping back into the upper 50s to around 60 degrees across much of northern and downeast Maine. With overnight lows forecast to drop into the mid to upper 50s, this should set the stage for a comfortable sleeping night for a change. Expect mainly clear skies overnight. Will continue the mention of patchy fog late tonight. Only minor tweaks to gridded forecast data base otherwise forecast still looking good. previous discussion Drier air to arrive tonight into Monday. Latest sfc analysis showed drier air working its way into the region as evident of the dewpoints dropping back into the upper 50s and lower 60s. Dewpoints will continue to drop back tonight w/skies clearing out. Radar did show scattered showers around portions of northern and western areas. Activity has been diminishing over the last hr or so and will continue to do so into early evening. Weak high pres is set to move toward the area tonight into Monday w/w winds dropping back below 5 mph overnight. Given the cooling, clearing and moist surface in some locales, decided to add patchy fog for overnight into early Monday morning. The NAM sounding matching w/the RAP point to this potential. Overnight lows will be in the 50s for a majority of the CWA minus the coast as temps will be around 60F. Upper level trof slated to move across the region on Monday. The atmosphere looks to be pretty dry w/some moisture tucked at 850mbs. So, some cu development is expected mainly for the northern 1/2 of the CWA as supported by The NAM and GFS soundings. Steep llvl lapse rates are noted by the NAM and GFS w/some CAPE. The NAM is most robust w/the CAPE of 400-700 joules. This looks overdone given that it appears to high w/its dewpoints. Decided to lean toward the GFS w/less CAPE and moisture. Therefore, kept out and mention of showers. Daytime temps are expected to be in the normal range for late July w/around 80F for northern Maine and low 80s central and downeast areas. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... Monday night will be mostly clear and tranquil as high pressure slowly slides east of the region. Our focus Tuesday into Wednesday will be on a trough digging into the Midwest. This trough will support a low which will track north along the Appalachians Tuesday into Tuesday night and lift up to our northwest on Wednesday. The low will bring increasing clouds Tuesday into Tuesday night with a chance for some spotty showers as it pulls a warm front north across the area. The chances for showers should then increase Wednesday into Wednesday night as the low lifts to our north and pulls a weak cold front south toward the region. This low appears weak and disorganized, but will have lots of moisture to work with, with the help of the subtropical Bermuda high rebuilding to our south and pushing warm humid air up the east coast. Rainfall amounts of generally a quarter to a half inch over the north with less Downeast appear mostly likely at this time, although there is always the possibility for locally heavier amounts where any convective thundershowers form, especially Wednesday into Wednesday evening as the front pushes in. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Showers and perhaps a thunderstorm will be around Wednesday evening as low pressure lifts north of our area and pulls a cold front in. The front will dissipate and stall over the area Wednesday as the strong subtropical high off the Mid-Atlantic coast pushes warm and humid air north. Showers and some spotty thunderstorms will continue to be possible Thursday into Thursday night across our area along the old frontal boundary. Friday`s weather becomes a bit complicated as there will be a subtropical frontal boundary Downeast where moisture is wrapping north around the Bermuda high, and another boundary to our northwest where a weak front will be located. Some showers will be possible Friday, mainly Downeast, with partial sunshine across the north in a corridor of drier air between the two frontal boundaries. The subtropical high will begin to break down on Saturday as the northern front drops down from the northwest and a weak upper trough moves through bringing a chance of thundershowers across the north. Upper level ridging will spring back on Sunday bringing a warm and humid day with some sunshine. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... NEAR TERM: 950 PM Update... VFR is expected at all terminals through Monday. Only exception is the possibility of some late night and early morning patchy fog Monday morning with local MVFR visibilities possible. SHORT TERM: Mostly VFR conditions are expected Monday night into Tuesday. Conditions will likely drop to MVFR then IFR in lower clouds Tuesday night and remain IFR Wednesday into Wednesday night in variable low clouds and showers. MVFR conditions are likely Thursday, although they will likely vary locally depending on where showers occur. && .MARINE... NEAR TERM: No headlines for this term. Patchy fog is possible the intra coastal zone in the early morning. Seas will hold around 3 ft into Monday as the winds w/a westerly component. SHORT TERM: Winds and seas are expected to remain below SCA Monday night through Wednesday. Winds may approach SCA Wednesday night or Thursday. The subtropical ridge will be gaining strength again through the mid week period. Humid air pushing north will likely result in fog over the waters through mid to late week, and an extensive southerly fetch around the high will build seas over 5 ft through mid to late week. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...None. && $$ Near Term...Duda/Hewitt Short Term...Bloomer Long Term...Bloomer Aviation...Duda/Hewitt/Bloomer Marine...Duda/Hewitt/Bloomer
National Weather Service Kansas City/Pleasant Hill MO
1053 PM CDT Sun Jul 29 2018 .Discussion... Issued at 256 PM CDT SUN JUL 29 2018 Afternoon satellite imagery showing abundant cloud cover of the region as early morning shwrs continue to slide east into the lwr Ohio Valley. Expanding out, next upper trough seen on water vapor imagery over North Dakota this afternoon, which with time, will form into a closed low that will slowly meander across the upper Miss Vly Monday and Monday night. Model guidance in general has backed off on precipitation chances tonight as most organize this afternoon`s central High Plains convection into an MCS that is now forecast to slide south through central Kansas. With large- scale support likely remaining west of our region, have knocked down pops to some degree. Some solutions to include the most recent HRRR do show some light shwr activity over our region during the predawn hours, and have left low-end chance pops going to account for this trend. Otherwise expected lows to fall into the lower to middle 60s region-wide. Aforementioned low to slowly slide across the upper Miss Rvr Vly on Monday with our region remaining on the southern fringe of main cold pool aloft during peak heating. Despite this, isolated shwrs and storms will be possible through the afternoon hours before bulk of activity subsides with loss of daytime heating Monday evening. For now, best coverage will be up north in Iowa where coolest midlevel temps and the peak heating cycle will coincide. Temps should be similar to today with upper 70s expected across much of the region. Beyond this, fairly benign weather is expected through late week with shwrs/storms possible by Thursday and maybe into early Friday as a weak boundary approaches from the north. Latest trends show this boundary stalling just north of the region before lifting north again as a warm front by the weekend as height falls occur in advance of the next disturbance progged to track along the U.S./Canadian border. As a result, expect warming temps by late week as southerly flow is reestablished and ridging builds east from the Four Corners region. && .Aviation...(For the 06Z TAFS through 06Z Monday Night) Issued at 1052 PM CDT SUN JUL 29 2018 For the first few hours of TAF period, most people should be VFR with the exception of central MO, who is still experiencing IFR ceilings. Those as far west of the I-35 corridor should see at least MVFR ceilings and visibility as we approach dawn, thanks to the excessive low-level moisture from yesterdays showers. The IFR ceilings should spread west some and might get close to the I-35 corridor, but it still looks like the lower ceilings and visibilities will stay confined to central MO. Conditions should improve to low-end VFR in the late morning for the entire area through the evening. Also during the afternoon and evening, scattered storms are expected as an upper level low moves across the region. This activity should diminish not long after we lose daytime heating. Then, for the end of the TAF period, skies will start clearing. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ Discussion...32 Aviation...Grana
Area Forecast Discussion
National Weather Service Wichita KS
750 PM CDT Sun Jul 29 2018 .SHORT TERM...(This evening through Monday night) Issued at 252 PM CDT Sun Jul 29 2018 Latest satellite and radar imagery show that the complex of showers and thunderstorms which moved through the area overnight and brought some meaningful rainfall totals to the area have made their way east across the Middle and Lower Mississippi Valley. In their wake, it has been a quiet afternoon weather-wise, with just some broken and overcast low and mid-level clouds in central and portions of south central Kansas today. Tonight will mark the final round for chances of showers and thunderstorms for the area through at least the end of the work week. An area of thunderstorms has developed in western Nebraska and eastern Wyoming and is expected to move to the southeast into western Kansas through the afternoon and evening as a mid/upper trough slides to the east. The storms are expected to arrive in the vicinity of central Kansas this evening and then continue pushing southeast across the forecast area into south central Kansas. Regarding chances for strong of severe storms, the greatest instability will be in western Kansas where MLCAPE near 3000J/kg, impressive bulk shear, and steeper lapse rates will be located. Closer to central and south central Kansas, instability is not as favorable, though there will be some potential for strong to severe storms, especially near the southwest corner of the county warning area near the Oklahoma border. The main threats look to be damaging winds, heavy rainfall rates, and large hail in stronger storms. Think the slight risk area in the 1630Z SPC Day 1 outlook aligns nicely with the area most likely to receive strong/severe storms this evening where the greatest instability is expected. There is some degree of uncertainty regarding how long showers/storms will linger into Monday, though the likely scenario appears that scattered showers and thunderstorms will continue through the morning before clearing off to the east by late afternoon. High temperatures over the next couple of days continue to be well below normal due to thick cloud cover and multiple recent rounds of rainfall. .LONG TERM...(Tuesday through Sunday) Issued at 252 PM CDT Sun Jul 29 2018 Once the shortwave trough moves off into the Mississippi Valley by Tuesday, the forecast for central, south central, and southeast Kansas will become much more dry as a surface high settles over the Central Plains by Wednesday. Wednesday will mark the beginning of a gradual warm up, with a return to warmer temperatures (back into the low to mid 90s) by next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 745 PM CDT Sun Jul 29 2018 Less clear cut on storm evolution tonight. Clearly another round of storms will be tracking southeast in upper flow, but 850MB flow is generally from the northeast and not the moisture/warm air advection baroclinc zone of last night. Nod to HRRR early on which did quite well last night which still tracks storms across the area. Did linger clouds a bit longer tomorrow morning as storm complex may not be as well organized with a period of MVFR ceilings possible. -Howerton && .PRELIMINARY POINT TEMPS/POPS... Wichita-KICT 67 82 62 86 / 60 20 10 0 Hutchinson 66 80 61 85 / 70 20 10 0 Newton 65 80 60 84 / 60 20 10 0 ElDorado 65 80 60 84 / 50 20 10 0 Winfield-KWLD 66 82 61 85 / 50 20 10 0 Russell 63 79 58 84 / 70 20 0 0 Great Bend 64 80 58 85 / 70 20 0 0 Salina 66 81 60 86 / 70 20 10 0 McPherson 65 80 59 85 / 70 20 10 0 Coffeyville 67 82 62 85 / 30 30 10 0 Chanute 66 81 61 84 / 30 20 10 10 Iola 65 81 61 84 / 30 20 10 10 Parsons-KPPF 67 81 62 84 / 30 30 10 10 && .ICT WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...TAV LONG TERM...TAV AVIATION...PJH
Area Forecast Discussion
National Weather Service Wilmington NC
1046 PM EDT Sun Jul 29 2018 .SYNOPSIS... An upper trough to the west interacting with the Bermuda High, will stream abundant tropical moisture across the area throughout the upcoming work-week and the upcoming weekend. This pattern will keep showers and thunderstorm chances well above normal each day and night. Heavy rain and ferocious cloud to ground lightning will be the 2 main attributes to deal with from this daily convection. With the slower movements of thunderstorms as well as storms training across the same locations both day and night, FLOODING has now become the main nemesis to deal with for the next 7 days. And we are not just talking about "nuisance" or minor type flooding each day and night, but rather the increasing potential for Moderate or higher type flooding that could result in Damage to Property, Injuries, or even Death. && .NEAR TERM /THROUGH MONDAY/... As of 1000 PM Sunday...Some tweaking to POPs in the 1st 3-5 hrs based on latest 88D trends. The latest fcst has increasing the pre-dawn hr POPs, closer to the coast and the adjacent waters, due to the approach and movement of mid-level s/w trofs from the south. This fcst process still on target and will massage the current updated POPs to this outcome. Will follow suit and keep the "Heavy Rain" attribute to the thunderstorm activity from the pre-dawn Mon hrs thru midday Mon. Have also updated the QPF overnight into daylight Mon with slightly hier amounts given latest WPC guidance. Min temps should run in the mid to upper 70s. However, any thunderstorms or showers themselves, may result in "cooler" temps that is not a reflection of the synoptic temp fcst. Thus, low 70s for mins even at the coast where SSTS are in the 80s, remains a possibility. Previous........................................................ As of 300 PM Sunday...Another day, another active event on radar. Storms this morning along another landbreeze/outflow/residual boundary hybrid produced up to 2" of rainfall across Cape Fear. This eroded before a sea breeze developed which has also produced convection, and is now lifting NW, while other storms develop along a stalled boundary and Piedmont trough inland, and continue to advect over the waters. The concern tonight is once again flash flooding potential. Latest RAP Analysis has 2-2.25 inches of PWAT now entrenched across the entire CWA, along with MLCape of 2000 to as much as 3000 J/kg. There also exists 0.15-0.2 NCape, suggesting very efficient rain processes with embedded heavier convective elements. At the same time, a 60-70 kt upper jet is impinging on the area from the NW, producing at least moderate diffluence within the RRQ of this jet, aiding to enhance lift across the region. Although 0-6km shear remains weak, 10-15 kts, likely precluding significant storm organization, boundary interactions are likely, especially where the NW lifting cells meet the developing Piedmont trough. Thereafter, motion could become erratic or even stall at times, which in this environment supports the potential for flash flooding as storms linger over a small area, or train across the same area repeatedly. WPC has issued an MPD through this evening for flash flood potential. Rain rates of 1-2" per hour will remain possible through this evening, with localized QPF of 3+ inches forecast through nightfall. With loss of heating, instability will wane, but continued deep column moisture, diffluent lift, and elevated CAPE should allow convection to persist well into the overnight, although likely in a weakened form with less coverage. There is an exception to this tonight however. A shortwave lifting across the FL Atlantic coast will push into the area late tonight likely crossing Cape Fear before daybreak. This will enhance rainfall first offshore, and then more significantly into the CWA. Guidance is in good agreement that this feature will lift in this general manner, and have ramped POP up to high-end LKLY for the Cape Fear coastal counties after 2 AM. This could significantly enhance rainfall, especially if the trend of the last few days of a land breeze/outflow spawning convection near the coast occurs again. A secondary shortwave during the aftn may also help convection to increase along the westward advancing sea breeze and any other boundaries. However, the diffluent region of the upper jet shifts away Monday, while increasing southerly flow drives the stalled boundary to the north. For these reasons do not expect coverage of heavy rainfall to be as widespread as today, with the exception being the NE counties of the CWA. Was considering an FFA due to exceptional 14-day rainfall surplus along the coast, but after coordination with neighboring WFOs feel there still remains too much uncertainty into exactly where the heaviest rain will setup for a Watch attm. Localized flooding is certainly possible, but will let the overnight shift take a look at updated guidance to make a determination on any possible watches. Continued very warm and humid southerly flow combined with clouds/storms will minimize diurnal ranges this period. Highs Monday will rise only into the low 80s NE zones, mid to upr 80s far W/SW counties in the Pee Dee. This will climb from overnight lows within a degree or two of 75 all areas. && .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... As of 300 PM Sunday...Longwave trough will be digging and amplifying into the MS VLY this period while an upper low closes off in the vicinity of the Great Lakes. At the same time, stacked high pressure offshore will remain anchored in place. Between these two features will lie the Carolinas, in a regime reminiscent of last week, and once again periods of heavy rainfall are likely across the eastern Carolinas. Deep and increasing southerly flow will develop between these features, enveloping much of the eastern CONUS. This will tap tropical moisture which will stream overhead as evidenced by a PWAT plume of 2-2.3 inches lifting into the area. This deep southerly flow will push a stalled boundary well north of the area as a warm front, which is important to note as there appear to be little in the way of surface features to focus heavy rainfall this period. However, several mid-level impulses rotating through the trough will lift overhead, and although the primary jet dynamics will remain well west of the CWA into Wednesday, diffluence will subtly increase as well as the jet noses into the TN VLY. The environment appears to be very favorable for periods of heavy rainfall, but a complete washout is not expected. Training of storms is likely, so flooding is possible especially in the saturated environment due to antecedent rains of 200-400% of normal in the past 14 days, mostly near the coast. But inland, where rain could be focused, has seen much less this month, so the flooding threat remains uncertain. However, periods of heavy rain are likely, with most guidance suggesting 1-3" of rain on average. Warm southerly flow and increased clouds will keep diurnal ranges relatively low. Highs Tuesday are forecast to be in the mid 80s, with mins both nights 1-2 degrees either side of 75. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... As of 300 PM Sunday...Wet weather is expected to continue through much of the extended range with an upper trough to the west and the Bermuda high the east. By the weekend, the upper trough is forecast to weaken as an upper ridge builds over the area. The result of this will be a decreasing trend in the coverage of showers and storms for the weekend as compared to the Wed through Fri period. Overall, temperatures will slightly below normal for this time of year with maximums in the mid to upper 80s and mid with lows in the low to mid 70s. Max temperatures in the upper 80s to lower 90s are possible for the weekend as the upper ridge builds into the area. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... As of 00Z...The atmosphere has been taxed by the days convection and is now in "rewind" mode getting the atm ready for the next round or bout of showers and thunderstorms. The FA continues to have enough "juice" ie. Cape, for showers and a few tstorms to develop across the FA this evening into the pre-dawn hrs. This due to plenty of boundary collisions going on, mainly from outflows, what`s left of the sea breeze, and the old frontal boundary or sfc trof at this stage of it`s life. The worse convection is by far over-with this evening. Models are in amazingly aok agreement with a few mid-level s/w trofs rotating along the periphery of the Atlantic ridge system. These s/w trofs are located offshore from the southeast U.S. Coast and have begun a more northerly push or turn. As a result, expect convection to blossom over the Atl waters off the SC and NC Coasts during the pre-dawn Mon hrs. This convection will move onshore and affect all 3 coastal terminals basically from 09Z thru 17Z. At this point have indicated VCTS prevailing with a PROB30 convective grouping from 09Z-15Z for MYR and CRE and 10Z-16Z for ILM. The inland terminals will see some of this action push westward across them, with the worse of it occurring between 18z-24Z within a PROB30 grouping. Overnight winds, generally from 090-150 at 3 kt or less except 4 to 7 kt across the coastal terminals due to the slight tightening of the sfc pg complements to the mid-levels s/w trofs. During daylight Mon, winds will veer to 150-180 around 5 kt inland terminals except around 10 kt at the coastal terminals. Extended Outlook...VFR except for bouts of MVFR/IFR from scattered to numerous SHRA/TSRA each afternoon and evening across all sites. The coastal terminals could see early morning convection especially Tuesday and Wednesday. && .MARINE... NEAR TERM /THROUGH MONDAY/... As of 1020 PM Sunday...Only tweaking of the winds by several kts at most. But still looking at Southerly at 10 to 15 kt or just a solid 15 kt given the slight tightening of the sfc pg due to the mid-level s/w trof pushing across late tonight thru atleast midday Mon. Have increased the pcpn coverage overnight and also highlighted the potential for frequent cloud to ocean lightning and near 0 vsby from heavy rain producing tstorms in the HWO. Significant seas in the 2 to 4 foot range still aok with Previous...................................................... As of 300 PM Sunday...S/SW winds of 10-15 kts will persist through Monday across all local waters thanks to a pinched gradient between high pressure offshore and a stalled boundary to the west. There will be little fluctuation in speed or direction through the period. These persistent southerly winds and long duration fetch will keep the spectrum comprised of both a 5-6 sec S wind wave, and an 8 sec SE swell. Together, these will produce significant seas of 3-4 ft through the period. Additionally, periods of showers and thunderstorms are likely, especially overnight into early Monday. These storms have the potential to produce very heavy rainfall limiting visibility, as well as frequent cloud to sea lightning. SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... As of 300 PM Sunday...Gradient will tighten a bit more Monday night and Tuesday, so while winds will remain from the S/SW, speeds will increase to 15-20 kts and then linger there into Tuesday night. These enhanced winds will push the 6 sec southerly wave to 4-5 ft, which combined with an increasing 7 sec S/SE swell will drive seas from 3-4 ft early, to 4-5 ft late Tuesday and Tuesday night. A SCEC will likely be needed for all waters, and it is possible conditions may meet SCA thresholds briefly late this period. As has been the case the past several days, thunderstorms with very heavy rain and frequent lightning will also be possible at nearly anytime through Tuesday night. LONG TERM /WEDNESDAY THROUGH FRIDAY/... As of 300 PM Sunday...S winds of 10 to 15 KT, perhaps 20 KT northern waters, Wednesday will abate to about 10 KT by Thursday and continue into Friday. Seas of 3 to 5 FT Wednesday will subside to 3 FT or less by Friday. Chances for showers and storms with locally higher winds and seas remain through the period. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...DCH NEAR TERM...DCH/JDW SHORT TERM...MJC LONG TERM...RAN AVIATION...DCH
Area Forecast Discussion...UPDATED
National Weather Service Jackson MS
943 PM CDT Sun Jul 29 2018 .UPDATE... Updated for evening discussion. && .DISCUSSION... The last of the rain over the southwest has dissipated. Latest surface analysis shows a stalled boundary across Grenada county southeast across Kemper. Northeast of this boundary a cooler and drier airmass resides. Regional radars showed a few storms over northwest Mississippi and southwest Tennessee that look poised to move southeast along this boundary into our zones later tonight but latest HRRR and other guidance suggests this activity will dissipate just north of our CWA. Also, it appears additional convection from the northwest will not arrive until Monday morning so have removed pops the remainder of the night across the CWA. Heaviest rain occurred in the southwest and cooled temperatures there a little faster than forecast. Have adjusted temperatures curves ti account for this but morning lows still looked good. /22/ Prior discussion below: Tonight and Monday: Subsident area between MCV/shortwave passing off the the southeast and MCS over AR continues to limit convection and cloud cover over much of the forecast area this afternoon. While convection should eventually develop, it should be confined to the south and far west where better low layered theta-e exists and subsidence will be minimized. Convection will diminish by mid evening. CAM guidance showing next upstream MCS getting going around midnight over OK and moving across AR during the predawn/early morning hours, but diminishing as it approaches the MS river near the diurnal convective min time. Various scenarios exist in the guidance, thereafter, with differing spatial and temporal convective development as the outflow from the MCS moves into an increasingly unstable airmass. The best lapse rates and deep layer shear appear to reside over northwest sections, but if the cold pool is strong enough, sufficient forcing could result in strong storms further southeast as well. Because of the model differences and various possible scenarios, have decided to expand the marginal risk of severe storms to include the entire forecast area./26/ Monday night through Tuesday: Beyond any possible storm complex pushing across the area during the daytime Monday, new convection is expected to develop across parts of AR and LA during the night as a cold front continues to approach the region and spread eastward through the daytime hours Tuesday. There isn`t particularly strong model consensus on exact timing, though the best chances for storms by Tuesday look to be mainly south and east of the Natchez Trace. It isn`t out of the realm of possibility for a convective complex to push across the area early on Tuesday and limit rain/storm chances in the afternoon, but confidence is too low to pick up that solution and run with it at this stage. With increasing upper forcing and deep layer shear Monday night through Tuesday, some of the storms could become severe, so we`ll continue to highlight this potential in the HWO and graphics. Increased clouds and precip around the area will likely hold daytime highs well down into the 80s across the bulk of the area Tuesday. Wednesday through next Sunday: The front will stall across the area and gradually lose definition through the remainder of the week into the weekend. Still, it will bring a substantial influx of drier air across most of the area with PW dropping by as much as as inch. This should provide a few cooler nights with temps getting down into the mid 60s in some areas. It should also limit the greater rain chances to the I-59 corridor until moisture begins to creep back north and westward at the end of the week into the weekend. /DL/ && .AVIATION... 00Z TAF discussion: Scattered TSRA wl cont along and south of HWY 84 through 02Z. Convection has ended for the day elsewhere. A brief period 09-13Z Mon of MVFR vsby wl be psbl across se MS with VFR conds this evng cont through Mon morning when TSRA activity comes in vcty of GLH. A greater coverage of TSRA is expected Mon affecting most TAF sites during the aftn. /22/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 71 92 73 83 / 2 51 58 81 Meridian 70 92 73 85 / 5 52 52 81 Vicksburg 71 92 73 85 / 3 50 66 80 Hattiesburg 71 94 74 86 / 6 58 41 80 Natchez 72 92 73 86 / 4 53 52 81 Greenville 72 90 71 84 / 10 56 70 62 Greenwood 71 89 71 84 / 7 49 69 73 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$ DL/22/26
National Weather Service Jackson KY
1156 PM EDT Sun Jul 29 2018 .UPDATE... Issued at 1156 PM EDT SUN JUL 29 2018 Outflow from the eastern Tennessee and southwest Virginia convection has sparked a few showers across far southeastern Kentucky. Consequently, have updated the forecast to include a few hours of isolated showers. Updates have been sent. UPDATE Issued at 1035 PM EDT SUN JUL 29 2018 Skies remain mostly clear across locations generally south of I-64, with thicker high clouds as well as some developing lower clouds to move in gradually past midnight. Have freshened up the sky cover through dawn to account for the latest trends in satellite as well model guidance. Some convection has also fired up across portions of eastern Tennessee and southwest Virginia over the past few hours, as moisture increases across the area. It does not look like this activity will make it into our area, where instability is waning; however, the latest HRRR still shows a hint of convection occurring around dawn across the southeast. Will maintain no thunder at around dawn with slight chance POPs, but would not be surprised to see a few flashes out of anything that does initiate. The current temperatures range from the mid 60s in the cooler valley spots, to the lower 70s on ridges. Given the current rate of drop, forecast lows look on target, so have merely freshened up the hourly temperatures through the overnight to account for the latest trends in observations. Updates have been sent. UPDATE Issued at 657 PM EDT SUN JUL 29 2018 High pressure located just off to our northeast will gradually dampen tonight, with a developing inverted trough/warm front nosing in from the southwest late tonight into the day on Monday. Clouds will likely remain thin enough early on to allow for a good valley drop off once again, as dew points are running only a degree or two higher compared to yesterday at this time. Did tweak a few lows down a notch, with some of the cooler sites nearing around 60 or just slightly below, if thicker clouds can hold off longer. Model guidance is also suggesting some elevated instability available towards dawn. Will maintain some slight POPs with just showers for now and await further trends of some of the higher resolution model guidance, before considering to add some thunder. Updates will be out shortly. && .SHORT TERM...(This evening through Monday night) Issued at 307 PM EDT SUN JUL 29 2018 The short term period should be mostly mild and dry, with high pressure remaining in control of area weather through most of tonight. An area of low pressure, and its attendant cold front, will bring a pattern change to the area late tonight, Monday, and Monday night. Scattered showers and isolated thunderstorms will be on tap for Monday. The rain will become more widespread Monday night into early Tuesday morning, as the front approaches. Locally heavy rainfall will be possible at times Monday night with the strong storms. There is also a marginal risk for severe weather across the area on Monday, so there will be an outside chance for an isolated storm or two to produce damaging wind gusts. We can expect lows in the mid to upper 60s tonight and tomorrow night, and highs in the mid to upper 80s on Monday. These values are all around normal for this time of year. Outside of any showers and storms, winds should be generally light and variable across the area. .LONG TERM...(Tuesday through Sunday) Issued at 307 PM EDT SUN JUL 29 2018 Showers and storms will persist across eastern Kentucky through the middle of the week, as an area of low pressure and a surface cold front move slowly across the area. At this time it appears that the best chance for rain will be Tuesday into Tuesday night. It is also during this time frame when we will see the best chances for locally heavy rainfall across eastern Kentucky. The rain should gradually taper from west to east late Tuesday night and Wednesday, as the upper trough also moves off to our east. Another area of low pressure set to move up the eastern side of the Appalachian Mountains may bring isolated to scattered showers and a few storms to the area Wednesday night through early Saturday night. In general, temperatures in the extended are going to be below normal, with daily highs topping out in the low to mid 80s and nightly lows in the low to mid 60s. Winds will again be generally light and variable outside of any showers and storms. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) ISSUED AT 730 PM EDT SUN JUL 29 2018 VFR conditions will prevail through this evening, as high pressure maintains control to our northeast. Some IFR or worse fog will develop in the deeper river valleys once again tonight, but this will be even more confined, likely not affecting any TAF sites. Mainly high clouds will be seen through around 06z, before a low level deck develops at around 5k feet agl between 06 and 12z. A developing warm front will be nosing in across eastern Kentucky towards dawn. This boundary will gradually shift to the north during the day, allowing the threat of some scattered thunderstorms across the area. Light ENE winds will gradually veer around to the southeast overnight. As the front edges to the north, southwest winds will engage at KSME and KLOZ during the day. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GEOGERIAN SHORT TERM...AR LONG TERM...AR AVIATION...GEOGERIAN
Area Forecast Discussion
National Weather Service North Platte NE
1046 PM CDT Sun Jul 29 2018 .SHORT TERM...(This evening through Monday) Issued at 234 PM CDT Sun Jul 29 2018 Winds aloft at h500mb remain strong at 50-60kt. This feature could still produce a few strong or severe storms this afternoon and evening despite cooler surface temperatures and less moisture. The potential for a "high-caliber" storm producing significant severe weather is very uncertain. This potential would appear to be maximized across sern WY and ern Colo as suggested by SPC. Radar continues to show an area of weak midlevel radar returns across western Nebraska and this could be an area of frontogenesis which could cause lapse rates to steepen. If this is true, then new storms should form in this area this afternoon and move south or southeast through swrn Nebraska. The Black Hills could also be a genesis area for storms as suggested by the HRRR model and there is a disturbance across the Northern Plains which will drop tonight. The HRRR, HREF and RAP were the basis for likely rain chances this afternoon and tonight. Thunderstorm activity should be winding down by late evening with mostly isolated showers and thunderstorms after midnight. Isolated, mostly diurnally forced, showers and thunderstorms are in place Monday. .LONG TERM...(Monday night through Sunday) Issued at 234 PM CDT Sun Jul 29 2018 After that, rain chances vanish and h700mb temperatures begin to rise toward 15C by Friday. Winds aloft are still fairly strong through Thursday (25-35kt at h500mb) but the models show no focus and precipitable water falls to less than an inch perhaps signaling the beginning of dry spell. Moisture could increase sufficiently by Friday night for isolated thunderstorm chances, mainly across northern Nebraska where h500mb winds will be 25-35kts. && .AVIATION...(For the 00Z TAFS through 00Z Monday night) Issued at 1042 PM CDT Sun Jul 29 2018 Severe threat has diminished where thunderstorms have exited southeast. Overnight a few additional showers or isolated thunderstorms may develop. However, visual fight rules will mainly be seen with the potential for patchy fog by sunrise. Clouds will then decrease in coverage through Monday morning. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...CDC LONG TERM...CDC AVIATION...19
...Updated Aviation and Forecast Discussions...

.Forecast Update... Issued at 735 PM EDT Sun Jul 29 2018 Outflow from earlier storms to our northwest is not showing signs of being able to punch through a mid-level cap showing up on RAP soundings. Still cannot rule out an isolated shower in our southern Indiana counties. In addition, hi-res guidance is continuing to hint at an isolated shower farther south into southern KY late this evening into the early overnight, as an interaction between the shortwave coming in from the Bootheel region now and a developing warm front. Decided to throw in a 20 pop for this area. In the wake of that shortwave, we should see a brief lull in new development, but another wave rounding the trough should aid in surface low development and another round of showers/storms Monday afternoon. Latest guidance is favoring areas west of I-65 a little more for coverage, so bumped up pops to the likely range for BWG and Etown areas and points west for the afternoon period. Updated products out shortly. && .Short Term...(This evening through Monday) Issued at 325 PM EDT Sun Jul 29 2018 The latest visible imagery shows plenty of diurnal cu bubbling beneath a thin upper cloud shield. This should continue through the remainder of the afternoon and early evening, with an outside shot at a stray shower popping along or north of the Ohio River. Will keep initial pops silent ~10% as the lack of a trigger and a subtle inversion around 750 mb is noted. Temps peak in the low to mid 80s this afternoon. The cluster of showers over central IL will continue to make slow progress eastward as it combats drier air over our region and central IN. Eventually focus should shift across central IN later this evening as the right entrance region of the mid level disturbance starts to eject out, and the associated weak LLJ response scoots just to our north. Will keep low chances along and north of the Ohio River, but most folks should expect a dry overnight. Look for lows in the mid to upper 60s with upper sky cover mitigating fog potential. The Lake Cumberland region would have the best shot at some patchy fog. ...Conditional Threat of Strong Storms Monday Afternoon/Evening... The baggy upper trough amplifies over the Midwest tomorrow as the exit region of a stronger mid to upper level jet noses into the Ohio Valley. We`ll have plenty of cloud cover through the day, but expect that some destabilization will occur by afternoon. If the destabilization does occur, then a conditional severe threat will exist. The shear profile is actually fairly impressive in the mid and upper levels given a 60-70 knot upper jet and 35 knot mid level jet. However, the low levels (~850mb) lack a notable low level jet. It should also be noted that a weak surface low should develop over the area, with a warm front becoming established through the afternoon. SREF probs suggest a very high likelihood of at least 1000 J/KG of ML CAPE, and a chance of 2000 J/KG. So, given at least modest to moderate instability and the exit region dynamics scattered storms should fire in the afternoon and evening. Some of these could be strong with a heavy rain and gusty wind threat. Given the strong mid and upper shear profiles, and some veering with height, a few supercells can`t be ruled out. At this point, think the lack of a low level jet would be the main mitigating factor to a concerning tornado threat, although one couldn`t be ruled out given the triple point in the region. SPC Marginal Risk looks reasonable, and could see the need for a Slight Risk if the destabilization is realized. .Long Term...(Monday night through Sunday) Issued at 310 PM EDT Sun Jul 29 2018 Monday Night - Wednesday... Numerous showers/storms are expected Mon night into Tues as an upper level trough pushes a sfc front through the region. There is question to the amount of destabilization to occur Mon afternoon due to clouds/AM precip. If instability can build during the afternoon/early evening hours, organized cellular storms could develop and continue into Monday evening posing a damaging wind and heavy rain threat Mon night into Tues morning. Wind shear is definitely favorable. Most models indicate showers/storms will move out late Tues morning although some lingering sct low topped cells could form Tues afternoon on the back side of the main sfc low. Precipitation chances will gradually decrease through Wed as the upper trough axis finally pushes through the Ohio Valley and better moisture exits the region. Temperatures will be mild Tues/Wed with highs in the upper 70s/lower 80s. Thursday - Sunday... The upper trough over the region and main sfc front to our east on Thu will become washed out as we head toward the weekend. These features will result in continued very low POPs (20%) sprinkled throughout the rest of the long term forecast. Temps will rebound toward seasonal norms the latter half of the week. && .Aviation...(00Z TAF Issuance) Issued at 725 PM EDT Sun Jul 29 2018 Seeing a weak outflow boundary push through the HNB terminal this hour. Storms upstream are losing steam as they run into a little drier and more stable environment. Cannot rule out a light VFR shower at HNB overnight, but given drying trend in the model decided against a VCSH for the overnight. Expect showers and storms to try and get going again over our area tomorrow afternoon, as a weak surface low organizes along the Ohio River. This low will make winds variable but any stronger storms could drop down gusty winds and brief restrictions. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...RJS Short Term...BJS Long Term...AMS Aviation...RJS
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
656 PM CDT Sun Jul 29 2018 .UPDATE... Issued at 635 PM CDT Sun Jul 29 2018 Updated to include 00z aviation discussion below. && .SHORT TERM...(This evening through Monday) Issued at 336 PM CDT Sun Jul 29 2018 GOES-16 visible imagery and GLM data shows isolated to scattered convection across the area this afternoon, with the more robust activity and lightning associated with cells in the northern and northeast portion of the area where RAP analysis indicates MLCAPE AOA 500 J/Kg. Things should be much like yesterday, persisting into the early evening hours until instability wanes, then we should clear out for the rest of the night with the exception of some mid/high clouds. Patchy fog will be a possibility overnight given nearly calm winds, especially in river valleys and where rainfall occurs and low level moisture is enhanced. The upper trough and cold pool contributing to enhanced lapse rates and instability will start to move away on Monday, but it appears there will be enough lingering instability for some diurnal convection across a portion of the area again on Monday afternoon. At this point, guidance and trends suggest that will be south/east of the Twin Cities metro area, so only included PoPs for the south/southeast portion of the forecast area. .LONG TERM...(Monday night through Sunday) Issued at 336 PM CDT Sun Jul 29 2018 Main concerns in the long term are timing of a cold front Wednesday and associated precip chances, then attention turns to the end of the week into the weekend, which will feature the return of heat, humidity, and a more active weather pattern. The long term will start with a dry day Tuesday, as building heights ahead of the Wednesday front finally pushes the cold pool aloft that has given us these diurnal showers this weekend southeast east of the upper MS Valley. As for the mid-week front, timing is starting to look less than ideal for us seeing much with it. By Wednesday afternoon, it looks to be already clear of the Twin Cities, with it down near a Fairmont to Ladysmith line by then, which means its southeast MN up into central WI that looks to have the best chance at seeing storms with this front. As a result, likely pops were limited to the Eau Claire area, with chance pops still spread back into St. Cloud and Granite Falls to account for some of the spread we continue to see with guidance. In addition, we do see mid-level lapse rates get above 7 deg c/km, with mlCAPE up between 1000 and 1500 j/kg, so there will probably be at least a marginal risk for severe storms out ahead of where the cold front eventually ends up being. Thursday, we get another refreshing shot of cool and dry Canadian air, but this one will be short lived. The western ridge will have broken down by then and we will be quickly transitioning into zonal flow, with the heat and humidity quickly return Thursday night. This will signal what could be a fairly active weather period starting Thursday night and lasting through the weekend. This far out, it`s hard to pin down details, but we should see a cluster of storms develop Thursday night into Friday morning at the nose of the LLJ in northern MN. That LLJ will will be over the MPX area through at least Friday and Saturday. Friday night has the greatest rain signal between the GFS/ECMWF. After that, models begin to diverge on how the pattern evolves. The GFS is more progressive with the LLJ, pushing largely east of us on Saturday and keeping it there. The ECMWF on the other hand fires it back in here Sunday and doesn`t clear it out of here until Monday night. This pattern will also signal the return of highs near 90 with dewpoints near 70. Given the instability expected, a severe risk would exist with anything we get, though heavy rain may end up being the biggest issue as we will likely see PWats push back up to around 2 inches. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 635 PM CDT Sun Jul 29 2018 Isolated -SHRA/-TSRA will continue across the area until around 02z then skies will become mostly clear this evening through late morning tomorrow. Some patchy fog is again expected during the pre-dawn hours, particularly near sites that had rain today. Additional isolated -SHRA/-TSRA possible tomorrow afternoon but mainly in southern MN into southwestern WI, making KRWF-KMKT-KEAU most susceptible. KMSP...Rather benign TAF for this period. Not expecting any convection to impact the terminal for the rest of this evening, fog looks to stay away during the overnight hours, and any convection on Monday is expected to remain south of MSP. /OUTLOOK FOR KMSP/ TUE...VFR. Variable wind 5 kt or less. WED...MVFR possible chc -SHRA/-TSRA. Wind SW 5-15 kt becoming NW. THU...MVFR possible early. Wind N 5-10 kt. && .MPX WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. && $$ UPDATE...JPC SHORT TERM... LONG TERM...MPG AVIATION...JPC
Area Forecast Discussion
National Weather Service Phoenix AZ
605 PM MST Sun Jul 29 2018 .UPDATE... Updated Aviation discussion. && .SYNOPSIS... Anticipate a familiar Monsoon weather pattern this week with storm activity occurring mainly over the higher terrain of Arizona with only slight chances over the lower deserts. Otherwise, slightly above normal temperatures can be expected. && .DISCUSSION... Tonight... The effects of last night`s storm activity can be seen in the 24 hr trends of surface temperature dew points over the forecast area. Generally speaking, temperatures are down and dew points are up. Those lower temperatures mean more CIN than yesterday. Isolated storms have developed over the higher terrain areas of northern and eastern Arizona early this afternoon. The CAMs by and large have handled that and go on to show new development over Gila County, Yavapai County, and far northeast Maricopa County - but nothing much on the lower deserts (except perhaps portions of Pima County). The exception is the HRRR (and to a lesser extent the HRRRX) which shows strong storms pushing southwestward across metro Phoenix this evening. The HREF doesn`t support that scenario but does suggest significant outflows moving across south-central AZ into southwest AZ. The end result is that we`re looking for a substantially quieter night over the Arizona deserts than last night. But, since the Phoenix area only had noteworthy activity on the periphery last night, it wouldn`t take a lot of activity tonight for there to be a significant difference. Monday through Sunday... Operational models including GFS and ECMWF as well as GEFS ensemble members continue to paint a relatively stable synoptic flow pattern over the region with the mid tropospheric anticyclone center wobbling around the Mohave Desert and AZ. Also, no large inverted troughs being advertised that would have a direct effect. Of note, the GFS and ECMWF do develop a tropical storm next weekend but it`s well south of the southern tip of Baja Mexico. As for moisture, The GFS generally keeps above average precipitable water over the forecast area. However, the GEFS depicts a slow downward trend in precipitable water and CAPE with the GFS being on the upper end of the solutions. That being said, there is a lot of spread amongst the members and the mean value of precipitable water stays well above 1 inch for PHX. Anticipate a bit of warming and lower dew points (compared with the preceding weekend). With the close proximity of the high center, CIN will continue to be a significant factor. That, combined with relatively weak steering flow, will lead to only modest storm chances for the lower deserts. Of course, subtle flow features can have big impacts and thus at least one of the days this week could turn out to be a big night. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL: Winds will remain out of the west at 10 knots with gusts to 20 knots through about 02-03Z with FEW to SCT mid and upper level clouds. Ongoing thunderstorms in southern Gila County will cause a northeasterly outflow boundary that may affect KIWA by 0230Z and KPHX closer to 0330Z. However, this outflow may be too far south to affect the sites and the models that are handling the current situation best like the ARW do not have the outflow making it into the sites. Most models do not show convection developing over Phoenix with these outflows, so we have removed the mention of vicinity thunderstorms with the outflow boundary passage and replaced it with showers. Winds should become light and easterly overnight before becoming westerly tomorrow by early afternoon. Northeasterly outflows will once again be possible tomorrow evening, but with a bit lower chances than today. Southeast California/Southwest Arizona including KIPL and KBLH: Winds should remain southeasterly at KIPL and southerly at KBLH with sustained winds remaining around 10-15 knots with gusts to 20 knots possible for the next few hours. The chance of a thunderstorm outflow from the east making it to the southeast California sites later tonight appears to be very low, so aviation impacts are generally not expected through tomorrow afternoon. Aviation Discussion not updated for amended TAFs. && FIRE WEATHER... Wednesday through Sunday: Anticipate a familiar Monsoon weather pattern this week with storm activity occurring mainly over the higher terrain of Arizona with only slight chances over the lower deserts. Minimum humidities will remain above 15% on the lower deserts (upper teens to mid 20s; mid 20s to mid 30s higher terrain). Overnight recovery will remain good. Apart from thunderstorms, winds will be light except for typical afternoon and evening breeziness. && .SPOTTER INFORMATION STATEMENT... Skywarn amateur radio Nets may need to be activated for this afternoon and evening. Spotters should follow standard reporting procedures. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ DISCUSSION...AJ AVIATION...Hopper FIRE WEATHER...AJ
Area Forecast Discussion
National Weather Service Blacksburg VA
728 PM EDT Sun Jul 29 2018 .SYNOPSIS... East to southeast winds between high pressure to the northeast and low pressure to the southwest will pull in increasingly warm and muggy tropical air back into the mid-Appalachian region for at least the next several days. The threat for showers and thunderstorms will gradually increase through the period as a weak front approaches from the west and then stalls over or near the area. && .NEAR TERM /THROUGH MONDAY/... As of 728 PM EDT Sunday...Been a relatively quiet late afternoon thus far as elongated plume of rich tropical moisture with numerous heavy showers and thunderstorms have been largely to the south and east, extending from around Norfolk VA southwest through the Midlands/Low Country of SC into east- central GA. At least to this point, models have vastly overdone the degree of precip in our area, as this convection has largely robbed better moisture north/northwest - a bias that ironically can be seen in the cold season with weak cyclones coming out of the Deep South. That being said, we are seeing some showers begin to form in two general areas: (1) along the mountains in southeast WV where east upslope and increasing upper dynamics has fostered some deeper convective growth and (2) forced by westward moving outflow across the NC Triad and Triangle regions northward into southeastern VA. It`s been difficult to have much faith in higher-resolution output today, but the HRRR appears to have finally start latching onto the idea of more coverage of storms really in both areas described above, but also drifting into our NC Piedmont counties and into Southside later this evening. Instability should begin to wane with sunset, but increasing upper-level support from the southwest should offset that stabilization to maintain at least a limited/isolated threat of thunder even into the overnight - as weak low/wave over central SC now brings clouds and precip shield back westward during the overnight. How far west is still an unanswered question but appears the best chance is east of the foothills where PoPs are around 40-50%. Clouds should also lower and thicken as well especially across the eastern two- thirds of the forecast area overnight. No changes to lows at this point. So we should be turning a corner toward more unsettled conditions as the rest of the evening progresses. Previous discussion from 200 PM follows... Atmospheric squeeze-play now beginning between surface high pressure to the northwest and low pressure to the southwest resulting slowly veering winds over the Mid-Appalachains and Mid-Atlantic region. Warm and muggy tropical airmass that was displaced out of the area a couple of days ago is again advancing northwestward, which should allow for an existing weak capping inversion over the area to break by mid- late afternoon - supporting the redevelopment of widely scattered showers and thunderstorms. Although some reduction in convective activity is expected this evening as thermodynamic support wanes, approach of weak short wave trof and associated weak dynamic forcing lifting northeast from out of northern Alabama should maintain at least an ongoing low threat for elevated convection throughout tonight. On Monday, southeasterly flow will continue to advect higher moisture and precipitable water into the Blacksburg forecast area. Forecast soundings again show weak instability and Convective Available Potential Energy (CAPE) in 500-1000 J/kg range by mid-afternoon, which should support redevelopment of convective activity as the day progresses - most likely maximized, at least initially, along/near the Blue Ridge, where upsloping and differential heating will help to focus localized upward vertical motion fields. Expansion of coverage into the Piedmont is expected by mid afternoon as yet another weather short wave impulse, currently in MO, dives southeast and then northeast into/through the Blacksburg forecast area. Corfidi Vectors remain relatively weak through the near-term period - supporting slow and likely erratic outflow-dominated storm motion that could lead to localized heavy rain - especially on/by Monday considering increasing precipitable water values back into 1.5-2.0" range. With lack of any significant forcing mechanism or convergence boundary, most heavy rainfall should remain localized enough to not consider issuance of any hydrologic-related headline through Monday - especially since it has been relatively dry the past couple of days, thereby allowing water level to return back to near-normal flow. However, the hydrologic threat may become more problematic as the week progresses. See below for additional details. Overall confidence in this period of the forecast is high, specifically for return to a more tropical airmass and associated slowly increasing threat for rain - both temporally and spatially. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... As of 200 PM EDT Sunday... During this portion of the forecast, precipitation coverage, probability, and amounts will be on the increase. We are anticipating an upper level trough centered over Wisconsin on Monday night, to head southeast during the period and amplify over the Mississippi River Valley by Wednesday. In advance of this system, low level flow will strengthen, all while having its origins from off the eastern part of the Gulf of Mexico. Prevailing around the upper trough, will be a series of weaker shortwave troughs that will progress northeast within this flow across our region, each providing for localized intensification and coverage of the expected showers and storms. Currently, Tuesday night into Wednesday is shaping up to be the most robust in terms of precipitation amounts and coverage. Guidance from the NAEFS Percentile is offering precipitable water, and 850mb specific humidity the V component of the wind all spiking in the 90 to 99 percentile for each of these parameters during this time frame. If rainfall from earlier in the week did not prompt any flooding, but only primed the ground so that it is close to saturation, the Tuesday night into Wednesday time frame would be a good candidate for when flooding potentially may occur. Given the expected generous coverage of clouds and precipitation during this part of the forecast, low temperatures are expected to be slightly higher than normal with high temperatures slightly cooler than normal. Forecast confidence for the above portion of the forecast is moderate to high in regards to the general synoptic pattern and forecast temperature thresholds. Confidence is moderate in regards to the expected trends in precipitation. && .LONG TERM /THURSDAY THROUGH SUNDAY/... As of 200 PM EDT Sunday... This portion of the forecast will continue to be on the wet side, but not at the very high percentage of normal as is expected to be the case on Wednesday. We are expecting a synoptic transition from the stalled upper trough to our east, to one that has the trough washing out with the upper high off the southeast U.S. coast retrograding west. While leading up to this portion of the forecast, the upper trough, and weak disturbances advecting northeast on its eastern flanks across our region, along with plenty of tropical moisture aggressively progressing into the area all combined to yield generous amounts and coverage of precipitation. With the upper trough becoming a shadow of its former self, and the prevailing jet becoming more zonal across the Great Lakes region, our precipitation will develop through somewhat different means. The high working westward will mean the area will still have a decent, although not as impressive, fetch of tropical moisture working its way into the area. However, lost will be the upper level dynamics to support sustained activity into and through the overnight. Our showers and storms will become more diurnally influenced and have their focus near places of weak surface convergence such as near ridgelines or on pre-existing outflow boundaries from the previous day`s activity, or activity earlier on a given day. Temperatures are not expected to fluctuate much day-to-day during this part of the forecast, although there should be a trend towards slightly warmer readings by the weekend as the upper high retrogrades. As a whole during the period thanks to abundant cloud cover and precipitation, low temperatures will average slightly above normal with high temperatures slightly below normal. Confidence in this portion of the forecast is moderate to high in regards to the trends of the larger scale synoptic pattern shift and the trends in temperatures. Confidence is low in regards to specific location and amounts of precipitation given the inherent uncertainty of diurnal convection coverage patterns. && .AVIATION /23Z SUNDAY THROUGH FRIDAY/... As of 728 PM EDT Sunday... VFR conditions at least for the first couple hours of the 00z TAF. Brief/spotty sub-VFR in showers between 02z and midnight, but a more steady deterioration/restricted conditions is expected for the overnight into a good part of Monday from a combination of scattered showers/limited thunder, MVFR-LIFR low ceilings and patchy mist. Coverage of showers this afternoon has been pretty muted, but beginning to see showers/some thunder increase in southeast WV and into the Triad/Triangle areas into southeast VA. Intensity of these should wane with sunset but threat of thunder should remain possible really at any point in the overnight as weak upper disturbance aloft and weak surface low over SC progresses northward. This will spread a greater coverage of rain showers northward at least across the eastern third of the airspace after midnight. NAM-based ceiling progs are quite low and have shown at least MVFR ceilings with temporary IFR ceilings at most terminals after 07z, tending to build northwestward toward the Blue Ridge through early morning. May see areas of mist at times within and east of the Ridge, but the most restricted conditions likely from low stratus ceilings. Improvement in ceilings likely slow to occur after steady rain ends Monday, but any clearing/lifting that occurs in afternoon should fill back in with showers/thunderstorms. Winds light southeast through much of the period. Confidence is high for aforementioned flight restrictions - both temporally and spatially. Confidence is low to moderate on precipitation chances, both spatially and temporally. Extended... Tropical airmass is expected to remain over the forecast area through the longer-range terminal forecast period with widespread flight restrictions often to remain in the MVFR range or lower - especially in/near increasing threat/coverage of showers/thunderstorms as a frontal system approaches from the west and then stalls over the area by midweek. Therefore, any VFR flight is expected to be relatively short-lived, not widespread, and mainly confined to afternoon hours each day outside of any areas of precipitation. Confidence is moderate to high, both temporally and spatially, for the aforementioned flight conditions throughout the extended period. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...WERT NEAR TERM...AL/WERT SHORT TERM...DS LONG TERM...DS AVIATION...AL/WERT
Area Forecast Discussion
National Weather Service Sacramento CA
142 PM PDT Sun Jul 29 2018 .SYNOPSIS... Smoke will help to keep daytime temperatures cooler the next couple of days. Then a gradual decrease in high temperatures is expected later this week but temperatures are expected to remain a little above average. && .DISCUSSION (TODAY THROUGH WEDNESDAY)... Smokey conditions continue to make for a tricky temperature forecast the next few days especially over the north end of the valley where the smoke is thick. The smoke has been keeping temperatures down again today and will likely do the same again on Monday. There is also some high clouds over the Sacramento region which is helping to keep area temperatures cooler as well. They will move to the northeast overnight and should not be a factor for tomorrows forecast. HRRR smoke plume model keeps a similar type of smoke plume again on Monday with smoke moving into the Sacramento and San Joaquin Valleys as well as in the north. Temperatures may be slightly warmer but not much over todays highs. A lot will depend on the thickness of the smoke. Poor air quality can be expected to continue as long as the wildfires are producing an abundance of smoke. Smoky conditions may become worse Monday afternoon over Sacramento if the HRRR smoke model is correct. The Delta breeze will continue remaining weaker during the day and strengthening at night. The marine layer is at around 1200 feet deep and should deepen slightly by Tuesday with a trough of low pressure moving closer to the Pacific Northwest coast. The Delta breeze should pick up a little Monday night and stay stronger into Wednesday to help bring a cooling trend for the valley and lower foothill elevations. Not a lot of change is expected over the higher elevations through Tuesday with only slight cooling on Wednesday. && .EXTENDED DISCUSSION (Thursday THROUGH Sunday) The upper level ridge will remain centered over the Four Corners region of the Desert Southwest through the extended period. A series of shortwave troughs will pass through the Pacific Northwest during this time period, resulting in lower heights and increased onshore flow. High temperatures are currently projected to be a few degrees above normal late this week into the weekend, though that could be impacted if smoke remains prevalent. Dry weather will likely continue through the extended period. Dang && .AVIATION... Widespread smoke and haze from wildfires will likely bring localized MVFR/IFR conditions tonight into Monday. Winds generally less than 10 kt, except gusts up to 30 kt near the Delta. Dang && .STO WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 8 AM PDT Monday for Eastern Portion of Shasta/Trinity NF-Northern Sacramento Valley to Southern Tehama County Line Below 1000 Ft-Southeast Edge Shasta-Trinity NF and Western Portions of Tehama-Glenn Unit. && $$
Area Forecast Discussion
National Weather Service Tulsa OK
912 PM CDT Sun Jul 29 2018 ...UPDATE... .DISCUSSION... Convection ongoing across E CO / W KS will continue to track southeastward and is likely to congeal into a more organized state and be maintained through the overnight hours. HRRR solutions have continued to favor a more westward trend with the strongest convection. The influence from last nights MCS has left a well overturned airmass over much of the forecast area with the zone of strongest moisture upglide now focused from NW OK into SE OK. Furthermore differential water vapor imagery supports an axis of deeper moisture along this same zone thus will align overnight precip chances nearer the HRRR solution/s/. There will likely remain some wind potential as the developing MCS spreads southeastward, though the eastward extent of severe potential is questionable and may well be hampered by the aforementioned influence of the earlier day MCS. Storms will continue eastward through the early morning hours on Monday. && .PRELIMINARY POINT TEMPS/POPS... TUL 69 82 64 86 / 60 50 10 10 FSM 71 82 66 86 / 20 60 20 10 MLC 71 84 65 85 / 80 70 20 10 BVO 67 81 61 85 / 60 50 10 10 FYV 67 78 61 82 / 20 50 20 10 BYV 66 78 62 82 / 20 40 20 10 MKO 70 82 64 84 / 60 60 10 10 MIO 67 80 62 84 / 40 40 10 10 F10 69 82 64 85 / 80 70 10 10 HHW 73 88 67 89 / 60 70 20 10 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && $$ SHORT TERM...07