Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/29/20

Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
640 PM CDT Tue Jul 28 2020 .DISCUSSION...Updated for latest aviation discussion below. && .AVIATION...Diminishing winds and convective cloud debris will prevail for the overnight hours. Tomorrow, another round of showers and thunderstorms may affect the aerodromes with winds at the surface becoming moderate. Overall, VFR will prevail through the next 24 hours. && .PREV DISCUSSION... /issued 407 PM CDT Tue Jul 28 2020/ SHORT TERM (Now through Wednesday Night): The 12Z BRO sounding is still quite moist and unstable with a PWAT of 2.35 inches and an MUCAPE of 3288 J/KG. The latest HRRR run indicates that a sea breeze boundary will the push the sct conv steadily westward clearing through Zapata Co. around 02z. The HRRR then wants to reform some isold coastal conv after 08z with the 12Z NAM showing some more sct conv firing inland Wed afternoon. Currently the KBRO radar is showing the afternoon sea breeze conv moving into Jim Hogg/Zapata Counties. Expect this conv to persist on for a few more hours as the sea breeze pushes west. Considering the saturated conditions in place over the Deep South TX and RGV areas, will maintain the FFA as is until 4 am Wed and will see if it needs to be extended/expanded throughout the overnight hours. Short term NAM/GFS and ECMWF maintains the conv chcs for one more day and then start trending them down Wed Night into Thurs as 500 mb ridging builds over TX and an inverted trough axis over the region shifts westwards. Temps should be on the increase as the cld cover and conv chcs diminish over the region. LONG TERM (Thursday through Tuesday): The subtropical ridge tries to strengthen across the lower Texas coast on Thursday, with slightly drier air, potentially cutting off rain chances finally for Deep South Texas. Unfortunately, a 500mb trough deepens across the eastern half of the CONUS, enhancing the weakness along the coast and brings unstable weather back through the weekend. With the lack of abundant moisture, this may lead to more sea breeze initiated rain chances and less coverage. This may also keep temperatures near to slightly below normal through the period. The mid level trough axis swings east of the coast on Sunday and high pressure builds in from the west, drying things out more for next week. MARINE (Now through Wednesday Night): Surface ridging over the lower TX coastline will maintain a fairly weak PGF over the area. So expect low to moderate SE winds to continue with moderate seas. No SCA conditions expected through Wed Night. Thursday through Tuesday: High pressure slowly retreats eastward as low pressure deepens across the eastern CONUS into Friday, keeping a weak coastal trough across the lower Texas coast. High pressure regains control Sunday into Tuesday. Overall, the pressure gradient may stay relatively weak, keeping favorable marine conditions in place with light to moderate onshore flow. The bay may build to a moderate chop during afternoon hours. && .PRELIMINARY POINT TEMPS/POPS... BAYVIEW/PORT ISABEL 77 89 78 90 / 50 40 20 10 BROWNSVILLE 77 89 78 91 / 50 40 20 10 HARLINGEN 75 90 77 92 / 40 40 20 10 MCALLEN 76 88 78 92 / 40 40 10 10 RIO GRANDE CITY 75 93 77 95 / 40 40 10 10 SOUTH PADRE ISLAND 79 85 81 86 / 50 40 20 10 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...Flash Flood Watch until 10 PM CDT this evening for TXZ248- 252>257-353. GM...None. && $$ This product is also available on the web at: HTTP://WEATHER.GOV/RGV
Area Forecast Discussion
National Weather Service Duluth MN
953 PM CDT Tue Jul 28 2020 .SHORT TERM...(This evening through Wednesday night) Issued at 244 PM CDT Tue Jul 28 2020 A cold front will move south through the forecast area from Canada this afternoon. The front is being aided by upper level short wave energy drifting through the region and some low level frontogenesis. This combination will lead to some scattered showers over the Arrowhead and into northwest Wisconsin. Not expecting any thunder as thermodynamic profiles do not support the mention. After frontal passage, high pressure settles overhead tonight. With a mainly clear sky, expect some fog to form, especially in the typical low lying areas. This fog should erode fairly quickly after sunrise as it should not be too deep. Temps should be near normal. The high remains in control Wednesday and Wednesday night. A weak northwest flow aloft will keep seasonable temps in play. .LONG TERM...(Thursday through Tuesday) Issued at 244 PM CDT Tue Jul 28 2020 The surface high pressure is nearby through Friday. There is a small chance of some light rain showers in the afternoon over the northwestern corner of Koochiching County as a frontal boundary approaches from south central Canada. This lead frontal boundary merges with a cold front following quickly behind it Friday night. The cold front moves slowly through the region Saturday into Saturday evening. There are some timing differences amongst the global models, along with their QPF signals. Regardless, have some pops to cover the frontal passage. Thunderstorms are possible per the model thermodynamic profiles. No severe storms are expected however. High pressure returns for Sunday and Monday. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 646 PM CDT Tue Jul 28 2020 The main aviation hazard is the potential for fog overnight tonight. High pressure will settle into the region, leading to calm to light winds and mostly clear skies. This will allow for ideal radiational cooling conditions and cause areas of fog to develop. Short-range models are still all over the place on how low visibilities may drop, and the HRRR suggests no fog altogether. Anything that forms will likely be patchy with a generally dry low-level airmass. For now, I opted for prevailing MVFR for a few hours between 08 and 13Z. However, conditions may be variable with VFR for most of the night and a few occurrences of MVFR or possibly IFR visibilities for brief periods. Otherwise, VFR conditions expected with high pressure in place through the period. && .MARINE... Issued at 952 PM CDT Tue Jul 28 2020 Quiet conditions expected for the next 48 hours with high pressure in place. Light and variable winds around 5 knots through Wednesday night. Winds will become northeasterly Thursday, which may increase wind speeds to around 10 knots near the head of the lake. && .PRELIMINARY POINT TEMPS/POPS... DLH 54 78 56 80 / 0 0 0 0 INL 53 76 53 82 / 0 0 0 0 BRD 55 80 56 82 / 0 0 0 0 HYR 53 78 53 81 / 0 0 0 0 ASX 56 80 55 81 / 0 0 0 0 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...None. MN...None. LS...None. && $$ SHORT TERM...GSF LONG TERM...GSF AVIATION...JDS MARINE...JDS
Area Forecast Discussion
National Weather Service Goodland KS
511 PM MDT Tue Jul 28 2020 .SHORT TERM...(This evening through Wednesday night) Issued at 330 PM MDT Tue Jul 28 2020 Overview: Small amplitude shortwave energy (situated over southern Idaho and western Wyoming this afternoon) will progress slowly E toward the lee of the WY/CO Front Range tonight, then ESE-SE into the Central Plains Wed-Wed night -- on the northeast periphery of an amplifying ridge over the Desert Southwest and Intermountain West. Through Tonight: With (1) small amplitude waves /DPVA/ anticipated to remain upstream of the region, (2) low-level forcing confined to weak (10-15 kt) southeasterly upslope flow, and (3) a marginally unstable (100-500 J/kg mlcape) weakly capped (25-50 J/kg mlcin) airmass characterized by moist-adiabatic (5.5 C/km) mid-level lapse rates, 10-15C H85 dewpoints, and surface temperatures in the 80s -- in-situ convection is not anticipated this afternoon. Diurnal convection currently developing along the CO Front Range will progress slowly east (via 10-15 kt WSW steering flow) toward Eastern CO this evening (00-06Z).. however.. weak forcing, an unfavorable downstream airmass, and poor diurnal timing (i.e. by the time ongoing convection approaches western Yuma/Kit Carson counties) suggest that said activity is likely to weaken/dissipate with eastern extent this evening. Simulated reflectivity forecasts via the latest runs of the HRRR and NAM NEST support such a scenario -- indicating that ongoing convection will not progress into Yuma/Kit Carson counties until the 01-03Z time-frame -- and that activity will rapidly weaken thereafter, dissipating invof the CO/KS border by ~05Z. Wed-Wed night: As flow aloft veers to the WNW-NW on the northeast periphery of the amplifying ridge -- small amplitude waves will progress ESE-SE from the WY/CO Front Range into the Central Plains Wed afternoon -- while unimpeded insolation (highs approaching 90F), a continued moist low-level airmass (H85 Td`s 12-15C).. and steepening mid-level lapse rates (7.0-7.5 C/km).. are anticipated to yield stronger diurnal destabilization (relatively speaking). Simulated reflectivity forecasts via the HRRR and NAM NEST suggest that convection will (1) develop over and (2) propagate downstream into the Tri-State area Wed aft/eve (both of which appear reasonable, given the pattern) -- mainly in the 20-03Z time frame. A few instances of damaging winds and/or marginally severe hail are possible in association with the strongest/deepest updrafts. .LONG TERM...(Thursday through Tuesday) Issued at 208 PM MDT Tue Jul 28 2020 For the extended period the models are showing an upper-level ridge extending from the southern Plains over the Rockies. Thunderstorms may develop downstream associated with a shortwave trough riding down the ridge over the Tri-State area, only caveat is how far east this shortwave trough manages to get with the NAM slightly quicker than the GFS. With the presence of a stationary front near the Kansas/Colorado border and a surface low coming off the Front Range, I feel there is still the potential for measurable rainfall during afternoon/evening hours on Thursday no matter the placement of the trough. Into Friday the trough will begin to move off to the east, while the upper level ridge begins to dominate over the area. The amount of moisture on Friday is still forecast to be decently high (in the 60`s) so if a surface low can move east off of the Front Range there may be enough moisture present for some isolated storms, confidence in this occurring as of right now is low. The weekend and beginning of the work week, the trough looks to continue its eastward movement towards the Great Lakes region, as stable air associated with the surface ridge is firmly above the region resulting in warm and dry weather for the region. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 508 PM MDT Tue Jul 28 2020 Low ceilings and fog may return once again overnight and early Wednesday morning at both KGLD and KMCK. Air mass remains very moist with low dew point depressions, and saturation likely as temperatures cool. Wednesday afternoon, scattered thunderstorms will develop across the region with brief impacts/reduced flight categories/ possible at either terminal. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...VINCENT LONG TERM...TT AVIATION...024
Area Forecast Discussion
National Weather Service Grand Rapids MI
749 PM EDT Tue Jul 28 2020 LATEST UPDATE... Aviation .SYNOPSIS... Issued at 251 PM EDT Tue Jul 28 2020 - Scattered showers and storms tonight into Wednesday - Seasonable temperatures and dry through Saturday && .DISCUSSION...(This evening through next Tuesday) Issued at 251 PM EDT Tue Jul 28 2020 -- Scattered showers and storms tonight into Wednesday -- Low-level frontogenesis and strengthening winds above 850 mb are occurring in Wisconsin where an upper level shortwave trough rotating around the Ontario low is encroaching on Iowa ridging. The boundary layer in southern Wisconsin to western Lower Michigan is expected to be well mixed and increasingly unstable this evening as elevated convection develops where moisture transport convergence occurs on the nose of an 850-700 mb jet. Convection-allowing model solutions have been pretty consistent in depicting a west to east train of scattered cells crossing Lake Michigan after 6 or 7 pm, moving quickly to the east-southeast into the night as additional weaker convection develops along the rear of the train. The vertical distribution of CAPE according to the HRRR suggests the strongest updrafts will occur in +10 to -10 degree C air, with updraft strength diminishing above that in colder layers. This doesn`t favor the potential for hail, and even lightning could be sparse in some cells. There is north/south disagreement down the county level where exactly convection will set up, but really anywhere between South Haven and Ludington has a chance. The initial arrival of convection in West Michigan may be before too much surface cooling occurs, allowing downdrafts in a nearly inverted-V, 900 J/kg DCAPE environment to easily reach the surface, mixing down 30-45 mph winds from above 850 mb. CAMs have been also showing potential for narrow axes of 0.5 to 1 inch of rain where showers/storms repeat. Some outlier solutions with more robust convection and longer training are painting a swath of 3 inches in SE Wisconsin or W Mich. But for agricultural purposes, most locations will not see the amount of rain desired. Scattered showers or an isolated storm may stick around in southern/southeastern/central sections of the state on Wednesday as the surface front slowly sinks southeast (supposedly) in superposition with the entrance region of the upper jet streak during solar heating. -- Seasonable temperatures and dry through Saturday -- Probably wont hear too many complaints about the weather the next several days as near-normal summer temperatures and fairly comfortable humidity levels (dewpoints around 60) will be in place. The next decent chance of rain looks to be Saturday night or Sunday as a wave from the Southern Plains lifts northeast. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 741 PM EDT Tue Jul 28 2020 There is a band of showers and thunderstorms from offshore MKG west into Wisconsin that will move across the TAF sites tonight. They are weakening a bit as the lake works them over, but lightning will still be possible with them along with wind gusts to 40 mph. && .MARINE... Issued at 251 PM EDT Tue Jul 28 2020 Waves at the Ludington ( and Port Sheldon buoys have been around 2 feet, with 3-4 feet reported at the beaches this morning, so these are generally moderate risk swimming conditions. Showers or storms crossing the lake this evening may produce winds 30 to 35 knots. Low to moderate risk swimming conditions are expected tomorrow with winds more from the north, with the relatively higher waves affecting beaches south of Holland. Will have to watch for upwelling of cold water at the shore the next few days as north to northeast winds drive water below the surface toward the west (Ekman spiral). The water temperatures at the Port Sheldon buoy are in the 70s down to 36 ft depth, and in the 50s below 49 ft depth, so it will be curious to see how big of an effect the upwelling will have on the beach water temperatures. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...None. LM...None. && $$ SYNOPSIS...CAS DISCUSSION...CAS AVIATION...04 MARINE...CAS
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
835 PM CDT Tue Jul 28 2020 .UPDATE... Issued at 835 PM CDT Tue Jul 28 2020 Radar has been pretty lethargic across wrn and north central Nebraska this evening and the HREF and RAP models suggest just isolated thunderstorm coverage overnight. Storm activity will likely occur along or near a warm front across srn SD and a weak Pacific cold front advancing slowly through the Panhandle and northeast Colorado. A forecast update is in place for isolated showers and thunderstorms the rest of tonight across wrn and ncntl Nebraska. && .SHORT TERM...(This evening through Wednesday night) Issued at 330 PM CDT Tue Jul 28 2020 A shortwave moving off the Front Ranges will push into western Nebraska by Tuesday evening. Thunderstorms are expected to develop across the Panhandle by late afternoon (4pm-6pm CDT). Storms will then move east into the eastern Panhandle and southwest Nebraska by early to mid evening (6pm-9pm CDT). Storms are not expected to be severe as instability remains fairly low across the region this evening. Any storms that do develop could be briefly strong but will quickly weaken as they continue to move eastward and encounter increasingly more stable air. The main threats with these storms will be small hail and brief gusty winds. Storms are expected to continue into the overnight hours, transitioning over to more stratiform rain showers by late evening and early Wednesday morning. While rainfall totals through Wednesday night have decreased slightly with this forecast issuance, totals across the central Sandhills and into southwest Nebraska will still be between 1 to 2 inches. With precipitable water values of over 1.5 combined with the possibility of slow moving thunderstorms, heavy rainfall could lead to some localized flooding. Will hold off on any flood headlines at this time, as overall QPF has taken a significant downward trend. In addition to heavy rainfall possible on Wednesday due to stratiform rain, there is also a chance of severe weather Wednesday night. These thunderstorms, supported by a developing low pressure system moving off the Rockies into central Nebraska, will encounter sufficient instability across much of the Panhandle and north central Nebraska. Thunderstorms will develop across southwest South Dakota late Wednesday afternoon and push southeast into northern Nebraska with widespread strong to severe thunderstorms possible. The main threats will be very large hail and strong winds. There is some concern with how earlier thunderstorms and rain showers during the day Wednesday will affect the overall environment for later in the evening. If the environment gets worked over sufficiently, the overall severe potential will be minimal. .LONG TERM...(Thursday through Tuesday) Issued at 330 PM CDT Tue Jul 28 2020 Isolated thunderstorm chances continue on Thursday and Friday afternoon/evening. Confidence in severe storms and the resulting environment is low. Will be continuing to monitor these daily chances over the next couple days and assess severe potential as the event gets closer. Quieter weather will return for the weekend and into early next week as strong upper level ridging occurs across the western US and resulting surface high pressure builds across the central Plains. Plenty of clouds and continued rainfall over the next week will keep daytime high temperatures in the upper 70s to mid 80s. The warmest temperatures will be across the eastern Panhandle and far southwest Nebraska. Nighttime lows will also remain cooler in the mid 50s to low 60s. While both daytime and nighttime temperatures will be cooler than the past several weeks, these temperatures are in line with normal temperatures for this time of year. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 629 PM CDT Tue Jul 28 2020 VFR conditions expected at the KLBF and KVTN terminals the next 24 hours. Scattered to broken high clouds tonight, with any isolated showers or thunderstorms expected to remain west and north of the terminals. On Wednesday, an upper level low pressure system will approach the area, and bring increasing chances for showers and thunderstorms mid to late afternoon. Included a mention at KVTN after 21Z, with no mention at KLBF. TSRA expected to impact KLBF beyond the TAF period. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ UPDATE...CDC SHORT TERM...Kulik LONG TERM...Kulik AVIATION...Roberg
Area Forecast Discussion
National Weather Service Marquette MI
747 PM EDT Tue Jul 28 2020 .SHORT TERM...(This evening through Wednesday) Issued at 141 PM EDT TUE JUL 28 2020 Diurnal cumulus developed right on cue late this morning, highlighting the lake breeze boundaries well. These diurnal cumulus become more agitated through the early afternoon hours, with a few showers and thunderstorms having already developed across the east along the Lake Superior lake breeze and north-central Upper Michigan. Eastern Upper Michigan will remain the focus for better coverage of showers and a few isolated thunderstorms through this evening. Across west and central parts of Upper Michigan a few isolated diurnally driven showers will be possible as well. RAP analysis and forecast soundings show very limited, skinny instability to work with and deep-layer shear in excess of 40 knots. The imbalance between the dynamics and thermodynamics should keep any thunderstorms more isolated as updrafts will likely struggle and quickly become sheared off. Outside of a quick burst of rain with any shower activity, some gusty winds may mix down with any collapsing updrafts due to steeper low-level lapse rates. Tonight, diurnally driven convection gradually diminishes after sunset. Winds become northwest as a cold front currently northwest of the area moves through. This will favor onshore flow tonight for many lakeshore communities along Lake Superior, helping keep temperatures locally warmer (upper 50s) overnight. Elsewhere, lows will fall into the low to mid 50s, with a pocket of mid/upper 40s possible across the interior west. Maintained the dry forecast as moisture looks very shallow along/behind the front with sharply drier air aloft moving in overnight. Given the good mixing in place today, opted to hold off on any fog mentions. Wednesday will be a few degrees cooler behind the front. Lingering shallow moisture will lead to increased cloud cover fairly quickly in the morning as daytime heating increases and favors the development of stratocu. During the afternoon, as increasingly stable air works into western and northern Upper Michigan, north- northwest flow at the surface will favor a gradually clearing trend for those locations later in the day. Strong subsidence overspreading the region as high pressure builds in should keep a lid on any shower development as the subsidence inversion and magnitude of dry air aloft increase throughout the day. .LONG TERM...(Wednesday night through Tuesday) Issued at 311 PM EDT TUE JUL 28 2020 Not much change from the previous discussion as an upper level low will continue to move eastward into Quebec by Thursday. As the low progresses eastward, ridging over the western US will move towards the Upper Great Lakes for late Thursday and Friday. The ridge will retreat back towards the western US by the weekend as another trough will approach the Upper Great Lakes by Saturday which will bring the next chance of some precipitation for the U.P. Troughing will continue into early next week with persistent north-northwest flow with more seasonable temperatures. Outside of the rain chance Saturday, not looking at many rain chances through the forecast period. Temperatures will be more seasonable for this time of year with 850mb temps mostly in the 9-11C range with highs mainly in the 70s inland, cooler by Lake Superior with upper 60s to low 70s. Saturday looks to be the warmest day of the period with 850mb temps reaching 15C resulting in highs reaching the low 80s in spots with upper 70s to 80 elsewhere. Some CAA will fill in across the U.P for Sunday and Monday with highs mostly in the mid to upper 60s to low 70s and some lows potentially reaching the low 40s across the interior west. Enjoy these seasonable temperatures through the forecast period. && .AVIATION...(For the 00Z TAFS through 00Z Wednesday evening) Issued at 746 PM EDT TUE JUL 28 2020 VFR conditions are expected at all terminals through the forecast period. Isolate showers may be possible near KSAW this evening where VCSH was included. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 326 PM EDT TUE JUL 28 2020 Cold front moving across the lake tonight will switch SW winds around 20-25 knots to more NW winds to around 15 knots. Winds should generally be under 15 knots for the rest of the forecast period. Fog still not expected at this time. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Ritzman LONG TERM...JH AVIATION...JLB MARINE...JH
National Weather Service Morristown TN
928 PM EDT Tue Jul 28 2020 .UPDATE... EVENING UPDATE. && .DISCUSSION... Current radar imagery indicates sparse coverage of a few showers across the southern Appalchians. PW values currently range from 1.7-2.0 inches as an upper level trough passes to the north across the Great Lakes. Due to his, have continued with slight chance PoPs into the overnight hours. Expect most locations will remain dry but cannot rule out a few isolated showers during the overnight period. Patchy fog will also develop tonight in the moist boundary layer with surface dewpoints in the low 70s. Any fog should lift shortly after sunrise on Wednesday. Overnight lows will range from the upper 60s to low 70s. MA && .AVIATION... 00Z TAF DISCUSSION. VFR conditions currently across the terminals with a persistent forecast over the next 24 hours. Showers/storms are already coming to an end across the area with a rather limited coverage of showers/storms currently. MVFR/IFR fog will be possible at TRI late tonight into early Wednesday morning. Isolated to scattered showers and storms will develop after 18-20z and continue through the end of the TAF cycle. MA && .PREV DISCUSSION... /ISSUED 319 PM EDT Tue Jul 28 2020/ SHORT TERM...(Tonight and Wednesday)... Upper air water vapor imagery and RAP analysis places deep cyclonic flow across much of the Ohio valley and northeast with ridging extending across the southwest US and western Atlantic and GoM. A subtle perturbation moving across the TN/KY state line has been able to allow isolated to scatter SHRA/TSRA to develop and move generally east early this afternoon. Cloud cover today has generally kept conditions at least somewhat cooler than yesterday. Temperatures as of 18Z range from 90 degrees across the southern valley to the upper 70s across southwest Virginia and northeast Tennessee where stable air from earlier convection and continuous cloud cover has kept conditions cooler. SPC Mesoscale Analysis still indicates CAPE values in excess of 2500-3000 j/kg across the entire area today. Given the relative weak synoptic scale forcing and lack of appreciable surface boundaries, believe coverage of convection remains isolated to scattered at best. Not anticipating a lot of strong convection but cannot rule this possibility out especially given the degree of thermodynamics at play today. Low level front to the north will remain stalled out across the Ohio river overnight and into Wednesday. Coverage of showers and thunderstorms will drop off overnight tonight as the weak upper level perturbation moves east of the area. Cannot rule out an isolated shower or two given the trough to the north, but height rises and lack of lift should keep conditions mostly rain free tonight. Lows will range from the upper 60s to mid 70s. Wednesday, shortwave ridging develops as a shortwave deepens across the Mississippi river valley. Increasing heights aloft and lack of any surface boundaries should inhibit large coverage of showers and thunderstorms. Will continue with chance PoPs for Wednesday but would not be surprised to see extended periods of time tomorrow with rain-free conditions. Highs will range from the mid 80s to near 90 degrees on Wednesday. Diegan LONG TERM...(Wednesday Night through Monday)... The extended fcst period kicks on Wednesday evening amidst cyclonic flow and thus troughing across the east/northeast CONUS with a shortwave further southwest across the Ozarks, while somewhat quasizonal flat ridging prevails across the southeast. At the surface, an old frontal axis looks to be laid out across the TN Valley and southern Appalachian regions, while high pressure prevails northward atop the OH Valley. At fcst initialization, convection along and south of the aforementioned frontal boundary will slowly taper with loss of heating, as heights fall across East TN and southwest VA/NC thanks to the approaching shortwave. This shortwave will traverse the OH Valley on Thursday while a weak surface cyclone prevails beneath, all the while enhancing llv flow and thus moisture advection, per latest moisture flux charts. Given this and the upper support provided by the shortwave, will favor another day of convection on Thursday with pops in the categorical range given vastly improved PWATS exceeding 2.0-2.5 inches regionwide. This will further degrade antecedent soil conditions and work to elevate the flooding threat, especially as the old frontal axis remains stalled in the vicinity of northeast TN and southwest VA. Meanwhile another upper trough will deepen westward, promoting further height falls into Friday across the TN Valley with deep swly flow prevailing. Thus, will keep pops elevated, albeit slightly lower as the initial shortwave will have exited east therefore suggesting weaker upper support overall on Friday. Moving into Saturday, convection will extend eastward along the old stationary boundary which continues to linger, while additional convection prevails along a prefrontal trough extending southward across KY/TN into MS/AL from the parent surface wave beneath the upper trough axis. This surface wave looks to advect northeast across the OH Valley through Saturday, lifting the pesky boundary northward into KY, thus completely uncovering East TN and southwest VA/NC in the warm sector. Expecting convection to be a bit more organized on Saturday given the presence of a deep early August longwave trough (and initial shortwave) and resultant synoptic/mesoscale environments, which all could lead to strong/severe thunderstorms. Moving into Sunday, the initial shortwave will eject northeast as a cold front enters the region (possibly stalling), albeit amidst a more stable airmass behind the surface wave, thus will favor chance pops regionwide. For Monday, starting to focus on a second shortwave traversing the persistent H5 trough centered over the MS Valley which should promote reintroduction of waa amidst a deeper swly flow regime into the southern Appalachians. This combined with approaching height falls from the west suggests the possibility of slightly greater coverage on Monday, however to due to range and model uncertainty, will cap pops at chance levels. All said, the first 72 hours of the fcst will be the most active with flooding threats elevated Thursday into Friday, while strong/severe convection probs increase for Saturday. Temperatures will remain near normal levels. CDG && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 73 88 73 86 73 / 50 60 60 90 70 Knoxville McGhee Tyson Airport, TN 72 90 73 86 73 / 30 50 50 90 80 Oak Ridge, TN 72 90 72 85 71 / 40 50 50 90 80 Tri Cities Airport, TN 68 88 69 85 69 / 20 40 40 80 70 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$