Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/11/20

Area Forecast Discussion...Updated
National Weather Service Billings MT
849 PM MDT Fri Jul 10 2020 .UPDATE... Updated the forecast to add a small chance of showers and thunderstorms to the Beartooth/Absaroka Mountains and adjacent foothills through midnight MDT tonight. Radar and satellite show that a few showers and thunderstorms have developed over the mountains and are moving east/northeastward over the foothills before dissipating farther to the ENE. We think that with the lack of upper air support, a drier air mass, and loss of solar heating, these showers and storms should dissipate later this evening. Otherwise just cleared out PoPs near the Dakota border where activity has ended. Rest of forecast is in good shape. We`re on track for a dry and very warm Saturday. RMS && .DISCUSSION... Tonight through Saturday Night... Line of thunderstorms developed along and ahead of the cold front this afternoon in an area of increasing vorticity advection from the shortwave centered in N central MT. MLCAPE over SE MT was 1500-2000 j/kg and highest shear was over SE Carter County. Given these parameters, supercells were not out of the question mainly over Carter County. HRRR and EC Ensemble were handling the situation well this afternoon and had precipitation exiting the area by 00Z. This seemed reasonable given the line moving E at 30 to 40 mph. Thus went basically dry for tonight. Kept winds gusty early in the evening. Upper ridging then builds over the area tonight through Saturday night with dry weather and temps slightly above normal. Arthur Sunday through Friday... Upper level ridge over the region on Sunday gets crashed by an upper level trof moving into BC. Combination of warmest air aloft and compressional warming ahead of a weak front will bring the hottest day of the week with temperatures of 95-100 in many locations though guidance has begun to slowly back off the highest values a bit. Models indicate as a prefrontal trough shifts east of the area some stronger winds aloft have a chance to mix down so expect some gusty winds in the afternoon. The front pushes through Sunday night and a few thunderstorms are possible over southeast Montana. The upper level trough slowly works across southern Canada Monday through Thursday and this keeps a cooler west northwest flow over the area with a mainly dry pattern. A few showers or thunderstorms are possible as weak disturbances come through this flow but does not look favorable for producing moisture. Temperatures will be 10 degrees below normal for the early part of the week before starting to warm on Friday. borsum && .AVIATION... VFR will prevail tonight. The Beartooth/Absaroka Mountains could be obscured this evening in scattered showers and thunderstorms. Showers could make it to the adjacent foothills and cause brief MVFR conditions there. Shower/storm activity should dissipate by 06z Saturday. RMS && .PRELIMINARY POINT TEMP/POPS... Sat Sun Mon Tue Wed Thu Fri ----------------------------------------------------------- BIL 058/089 060/095 060/080 054/081 055/083 057/085 059/087 00/U 01/U 11/B 22/W 11/U 22/T 22/T LVM 050/088 054/089 053/078 047/079 048/082 050/084 051/085 00/U 01/U 11/B 21/U 11/U 23/T 33/T HDN 055/090 060/097 059/081 054/082 054/085 057/087 058/089 00/U 00/U 11/B 22/W 11/U 11/B 22/W MLS 055/085 060/096 060/080 054/081 055/083 057/085 059/087 00/U 01/U 21/B 32/W 11/U 21/B 22/W 4BQ 055/086 059/098 060/082 054/080 054/084 057/087 058/089 00/U 00/U 10/B 44/W 21/U 11/U 22/W BHK 053/082 055/093 058/080 052/079 052/082 054/084 056/085 00/U 01/U 30/B 33/T 11/U 11/U 32/W SHR 054/089 057/098 056/083 052/081 052/085 054/087 056/089 00/U 01/U 11/B 43/T 21/U 11/U 22/T && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...None. WY...None. && $$
Area Forecast Discussion
National Weather Service Dodge City KS
554 PM CDT Fri Jul 10 2020 ...Updated Aviation... .SHORT TERM...(This evening through Saturday) Issued at 203 PM CDT Fri Jul 10 2020 The main focus for the short term will be convective initiation later today, if at all. A large area of stratus has been mixing out through the day. An area of 850 mb warm advection was located over south central Kansas where clouds have cleared out most efficiently and allowed diabatic heating to ramp up, resulting in temperatures reaching the upper 80s by noon. An inverted trough or outflow boundary was from south central Kansas , nw to around hays. The region located between the edge of this warm advection surge and the boundary would be the general region of convection initiation if the WRF-NMM model is right. The earlier run of the 4km NAM also was producing afternoon convection but has also backed off. The HRRR has just begin to begin to hint at convective initiation, but at this point this afternoon is still unconvincing. If a storm can become sustained, the supercell parameters are not bad with 35 knots of bulk shear and at least 1500 j/kg of MLCAPE, assuming the CIN can be eroded. Next concern will be whether or not the stratus will redevelop overnight. It looks like the best opportunity for stratus redevelopment will be out west of highway 83 overnight, as points east have too low of rh fields despite mainly a strong upslope flow and component. There will be a little better convergence west of Scott city and Garden City. Overnight lows can be far warmer across the Pratt - Med Lodge areas (in the mid 70s) compared to mid 60s forecast around Syracuse. .LONG TERM...(Saturday night through Friday) Issued at 203 PM CDT Fri Jul 10 2020 For day 2 on Saturday, a push of drier air will create light north to northeast winds across central Kansas, reorienting the boundary layer moisture from across western OK and far sw KS to eastern Oklahoma for Sunday. Small chc pops are included for late day Sunday and Sunday evening. likely initiating out in Colorado and moving in late day. An 850 mb high shows up by Tuesday in the ECMWF over the Dakotas which may increase moisture converge from the MissouriValley into central Kansas. Other than that the extended period is one of relatively low confidence in any widespread convective activity. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 554 PM CDT Fri Jul 10 2020 VFR is expected to continue through this TAF cycle. SKC is expected to prevail overnight, with winds trending light and variable. A dry cold front is expected to bring an abrupt northerly wind shift to all airports around 12z Sat. Expect N/NE winds to gust to near 30 kts after 15z Sat. && .PRELIMINARY POINT TEMPS/POPS... DDC 71 95 66 95 / 10 10 10 10 GCK 69 95 64 96 / 10 10 10 10 EHA 71 97 67 98 / 0 10 10 10 LBL 70 100 66 99 / 10 0 10 0 HYS 72 92 64 91 / 10 10 10 10 P28 75 100 68 96 / 10 10 10 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Russell LONG TERM...Russell AVIATION...Turner
Area Forecast Discussion
National Weather Service Des Moines IA
918 PM CDT Fri Jul 10 2020 .UPDATE... Issued at 918 PM CDT Fri Jul 10 2020 The big question this evening is the fate of two convective clusters over NE and SD. The one along the NE/SD border is easily the most significant at this point and should be the dominate player for MO Valley weather later tonight. Effective inflow along the 305-310K surfaces is not great, often 15-25kts, but the associated moisture convergence is expected to intercept the MCS over northeast NE with forward propagating Corfidi vectors suggesting it would do no better than clipping southwest IA. Have kept chance PoPs going overnight for the potential of cells currently west of Aberdeen, which the forward propagating Corfidi vectors would bring into central IA, but have concerns whether this will have much support to mature further due to a lack of low level convergence. It will be entering the persistent MUCAPE axis however with moderate+ effective shear, so there is some conditional strong to severe potential if it can mature somewhat. && .DISCUSSION.../Tonight through Friday/ Issued at 259 PM CDT Fri Jul 10 2020 Overview...Primary concern in the near/short term will be storm chances tonight and again on Saturday afternoon/evening. Beyond this weekend, next chance for storms would come no earlier than late Monday into perhaps the middle of next week. Drier and hotter conditions are expected by late next week or next weekend. Details...GOES-East upper level water vapor imagery shows a shortwave trough moving across the western Dakotas late this morning into this afternoon. Ahead of this shortwave, thunderstorms have been moving eastward in the left-exit region of a 105 knot, 250mb jet. This convection has waned, but has not given up near the Nebraska border as of early afternoon. The area of the western and central Dakotas is the area where strong instability and high deep layer shear will develop by later this afternoon allowing for additional storms to form as another shortwave trough enters the Dakotas toward evening (see recently issued MCD #1171). The storms should eventually grow upscale into more than one mesoscale convective systems (MCS). Current guidance suggests that the stronger of the two MCSs will follow the instability gradient southeastward over eastern Nebraska and western Iowa. This is supported by many convective allowing models (CAMs) as well as most of the global models. The GFS is the farther east among the global models bringing storm chances to near I-35. Further, several runs of the HRRR this morning (13z, 17z) showed the MCS moving into central Iowa and other runs (6z, 12z, 15z) showed a weaker MCS passing through northern Iowa with a strong MCS moving through eastern Nebraska/southwest Iowa after 6z tonight. 10/12z HREF have the bulk of updraft helicity tracks going through eastern Nebraska and far western Iowa with a few streaks toward or into north central Iowa. 16z SSCRAM (Statistical Severe Convective Risk Assessment Model) also would seem to point to eastern Nebraska/far western Iowa as being the main corridor for severe risk with lower risk over northern Iowa. All that stated, what can we expect? The most likely scenario at this point will be a MCS with severe wind gusts moving through eastern Nebraska and far western Iowa perhaps clipping our far southwestern counties. It is possible that another MCS with mainly sub-severe winds moves over northern Iowa late tonight a la the HRRR and NAM. The less probable scenario is the stronger MCS moves through northern to central Iowa with severe wind gusts. After the overnight convection moves through early Saturday morning, there should be a period of recovery assuming the unlikely scenario does not play out. Another embedded shortwave in the northwest flow will arrive by Saturday afternoon and should encounter by that time an airmass characterized by MLCAPEs over 1000 J/kg with 0-6km shear of around 35 to 40 knots. Primary storm mode with fairly straight hodographs will be damaging wind gusts and hail as the storms move southeastward over the northeastern third to half of the state. In the wake of this shortwave trough, drier weather with seasonable temperatures and lower humidity are expected on Sunday. The mid- level ridge stretching from Texas into the southwestern US will be suppressed some early next week as a longwave trough moves ashore over British Columbia on Sunday and across the southern Canadian provinces next week. A lead shortwave trough embedded in the longwave trough with a surface boundary will move across the northern states later Monday into Tuesday. This may bring some chances of storms to the region with the highest chances over northern Iowa into Minnesota later Monday into Monday night. With Iowa on the periphery of the influence of the longwave trough, this may foster additional storm chances into the middle of next week. While current forecast does not veer away from the initial National Blend of Models guidance given lack of clarity on a dry period looking at a variety of global and ensemble models, there will undoubtedly be periods of dry conditions. By late in the week, the mid-level ridge will spread eastward over the south central into the southeastern US and build poleward. This will result in increasing temperatures and decreasing chances of storms as any shortwave troughs will also move poleward. 850mb temperatures push into the middle 20s Celsius by late next week into next weekend, which would equate to highs well into the 90s to challenging the triple digits. && .AVIATION.../For the 00Z TAFS through 00Z Saturday evening/ Issued at 650 PM CDT Fri Jul 10 2020 The primary concern will be convective trends, mainly overnight and again Saturday afternoon. Initially confidence is high in VFR conditions through the evening, but it begins to diminish into Saturday. Clusters of thunderstorms will continue to move across the Dakotas overnight, but there is still some uncertainty on their eventual track. Have only included VFR VCSH wording at more likely spots until trends become more clear. Additional storms are likely to affect NE Iowa later Sat, and have added several hours of VCTS there for a start where confidence is slightly higher, but still not great. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...Small DISCUSSION...Ansorge AVIATION...Small
National Weather Service Kansas City/Pleasant Hill MO
1053 PM CDT Fri Jul 10 2020 .Discussion... Issued at 308 PM CDT FRI JUL 10 2020 Forecast focus is on the MCS expected across western Missouri and eastern Kansas late tonight/early Saturday morning. Broad ridging in place across the northern Plains and Rockies. A short wave trough currently traversing across the Montana High Plains will be a contributor for convective development this afternoon across the Dakotas. Convection will develop along the northern reach of the elongated surface trough stretched across the front range into the Black Hills. As convection evolves through the evening and overnight across eastern Nebraska, the expectation is for it to follow a traditional MCS like trajectory southward, riding along the 1000-500mb thickness gradient into northeastern Kansas/western Missouri. The CAMs have been rather consistent, overall, with the HRRR handling the past few MCS rather well. There is one big caveat in all of this, its the ongoing severe isolated convection in central Nebraska this afternoon. This activity has not been well captured by short range guidance, but continues to maintain itself, supported by decent low level flow from the south and stout surface based instability greater than 3000 J/Kg. This is a tricky situation as this small cluster has left upper 50s and lower 60s dew points in it`s wake. This could have implications for tonight. On water vapor, the wave responsible for this afternoons storms in the Dakotas and overnight tonight for KS/MO is still there. The big question running through the next several hours will be what is the impact of this cluster over central Nebraska. If things pan out the way we anticipate, regardless of the current ongoing activity, the overnight MCS will drop south out of eastern Nebraska and moving into northeastern Kansas through 3 to 5 AM, with remaining storms moving through eastern Kansas and western Missouri, potentially the KC Metro by 5 to 7 AM. Strong to damaging wind would be the greatest concerns. && .Aviation...(For the 06Z TAFS through 06Z Saturday Night) Issued at 1053 PM CDT FRI JUL 10 2020 Looks like VFR conditions will prevail for the next 24 hours. Only issues will be around sunrise Saturday, as a complex of thunderstorms shifts south across central Kansas, with a wind shift to the north later in the morning. && .EAX WATCHES/WARNINGS/ADVISORIES... KS...NONE. MO...NONE. && $$ Discussion...Kurtz Aviation...Cutter
Area Forecast Discussion
National Weather Service Grand Forks ND
1035 PM CDT Fri Jul 10 2020 .UPDATE... Issued at 1024 PM CDT Fri Jul 10 2020 Made slight adjustments for precipitation timing with only light precipitation expected through 06Z. After 06Z, scattered showers and embedded thunderstorms are expected to work eastward through at least sunrise. MUCAPE values will be in the 700 to 1500 J/Kg range with modest shear available. A strong storm or two cannot be ruled out, but widespread severe potential remains rather low. UPDATE Issued at 646 PM CDT Fri Jul 10 2020 Latest CAMs and hi-res ensembles show thunderstorm activity struggling to work eastward into the CWA later this evening. A few stronger storms could make it into the southern portions of the Devils Lake Basin, with the expectation that these storms would become increasingly elevated over time. If storms are able to hold together, hail upwards of one inch could remain a risk into the early overnight hours. The time frame of most concern would be between 05Z and 09Z. && .SHORT TERM...(This afternoon through Saturday night) Issued at 349 PM CDT Fri Jul 10 2020 Monitoring potential for isolated severe impacts this evening in our far west roughly from Devils Lake to southeast ND. Confidence is beginning to decrease that we will see any impacts, but it still can`t be ruled out. Influence of surface high has been keeping dryer more stable air mass in place, with strong cap and limited instability (ML CAPE less than 250 J/KG). RAP indicates minimal increases in our west. Main forcing is still west west over Montana and timing of this wave is favored for later tonight, lowering confidence that we would see initiation locally. That means we are dependent on activity developing into western ND holding together as it moves eastward towards our CWA after 03Z. At that point parameters may not become as favorable, though elevated instability around 1500 J/KG and effective shear 30-35kt may support a strong to marginally severe storm in that narrow corridor of our west for a brief period. HREF has shown UH tracks remaining west/southwest and consensus of latest short range CAMs barely shows any activity making into our southwest. Overall, not a lot of confidence that instability will be high enough for long enough before loss of daylight/stabilization takes place. Late tonight-Saturday night: With mid-upper level shortwave trough passage and linger surface trough axis we may actually see better chances for pockets of showers/thunderstorms late tonight into the morning and then diurnally driven thunderstorms Saturday. ML CAPE generally less than 1500 J/KG with weak shear (0-6km 20kt or less) and decreasing forcing lowers confidence in more that diurnal pulse type sub-severe convection midday Saturday into Saturday afternoon (dry Saturday night with increasing subsidence/stability). .LONG TERM...(Sunday through Friday) Issued at 349 PM CDT Fri Jul 10 2020 Main focus still on severe thunderstorm potential Monday and Monday night, with all severe modes possible depending on timing/evolution of pattern. Large scale pattern dominated by quasi-zonal progressive flow, with most waves less defined, but a good signal for strong mid-upper trough passage Monday-Monday night highlighting one period of higher confidence where there is a stronger consensus from NBM/GEFS QPF over our CWA. Temperatures trends will tend to remain near or a little lower than seasonal averages (highs generally upper 70s to mid 80s). Regarding severe potential Monday: Strong negatively tilted trough is shown to progress across the Norther Plains during the day and evening Monday rounding an upper low over Canada, with a more defined cold front passage Monday night. Strong shear profiles and moderate to potentially high CAPE could support discrete storm development or upscale growth into a stronger organized MCS that would then transition east if things line up correctly. The window for better WAA/instability is narrower with this system though, and at this range it is hard to know ultimately how the finer details/smaller scale surface features line up that would impact evolution of any severe threat. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1024 PM CDT Fri Jul 10 2020 VFR conditions prevail this evening with mid-level clouds remaining persistent across the area. Showers and thunderstorms will gradually work eastward into the KDVL region during the overnight with this activity eventually moving into the vicinity of the Red River Valley as sunrise approaches. While a few strong storms and higher CB are possible, mainly embedded thunderstorms are expected. For Saturday, additional diurnal convection is possible through the day. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. $$ UPDATE...Lynch SHORT TERM...DJR LONG TERM...DJR AVIATION...Lynch
Area Forecast Discussion
National Weather Service Wichita KS
849 PM CDT Fri Jul 10 2020 .MESOSCALE DISCUSSION... Issued at 847 PM CDT Fri Jul 10 2020 The cluster of storms that raced south across Nebraska has ran into a more stable airmass over Kansas and also lost daytime heating. Therefore expect things to remain quiet across Kansas until the late night hours. Latest meso-analysis shows low-level jet/moisture transport feeding complex of storms over northern Nebraska. The low-level jet/moisture transport will lead this complex of storms southeastward across Nebraska into eastern Kansas for late tonight/Saturday morning. The areas greatest at risk for severe weather will be for locations east of a Salina to Wichita line. Damaging winds and torrential downpours would be the main hazards. -Jakub && .SHORT TERM...(This evening through Saturday night) Issued at 334 PM CDT Fri Jul 10 2020 This afternoon, upper level ridging remains established over the Desert Southwest, with fast west/northwest flow aloft from the central/northern Rockies into the central/northern Plains. Within that flow exists a prominent s/w trough moving through Montana, with convection beginning to develop across the NRN High Plains. Elsewhere, a broad zone of WAA exists in the lee of the Rockies from Nebraska south into Oklahoma. Within this zone, a couple of clusters of convection are ongoing (one over northern Nebraska and the other over southern Oklahoma). Like yesterday, visible satellite imagery and SPC meso data appears to show a mid-level baroclinic zone from the OK MCS northwest through central KS and into central Nebraska. With continued WAA through the day and into this evening, a narrow zone of showers/storms may fester during that time. Some short-term guidance try to develop some deeper convection along that baroclinic zone this afternoon, but thinking warm low/mid level temps and a more overturned airmass (in the wake of the early morning MCS) will tend to keep a lid on deeper convection locally in the very near term. Late tonight into Saturday morning, it is likely that one or more convective complexes will traverse the Central Plains/Midwest/Ozarks regions from northwest to southeast. Recent MCS` have generally followed the 12-14C 700mb temp line/mid-level baroclinic zone (mentioned above). That said, some subtle mid-level warming seems plausible tonight as the NRN Rockies wave moves across the NRN Plains and into the Midwest. Additionally, as the LLJ develops, the nose of the stronger elevated moisture transport may tend to be focused a bit more north and east compared to last night. In general, the thinking is that the above-mentioned factors will keep the bulk of the MCS activity focused across the eastern third of Kansas. One potential caveat is the ongoing convection across north- central KS. The HRRR (which has performed well of late) continues to insist that convection will diminish. However, strong heating/destabilization downstream of that area may support some semblance of that activity continuing well into the afternoon/evening as it propagates SSE. That activity seems to be rooted more along the mid-level baroclinic zone that resides across central KS/NE. Should that convection continue, it may survive into parts of KS, with maintenance possibly aided as the LLJ develops this evening. I left some pops in this evening to account for this potential. Otherwise, the focus will remain on convection developing across the NRN Plains, and what trajectory it takes. Model guidance is highly varied (ranging from an MCS moving from Nebraska into Iowa and completely missing Kansas, to something diving more southward through central/eastern Kansas). We`ll keep the higher pops focused across eastern Kansas for now, but leave the door open further west (ie. along the mid-level baroclinic zone). Wherever convection tracks, damaging winds, sporadic instances of hail, and very heavy rain/flooding should be the primary threats. During the afternoon hours Saturday, a SFC trough/cold front will push southeast across central/eastern Kansas. If an MCS dives southeast through eastern Kansas, then the front will probably come through with little fanfare. However, if tonight`s convection stays east of Kansas, then there may be a window for a few storms to develop across SRN KS during peak heating ahead of the front. Martin .LONG TERM...(Sunday through Friday) Issued at 334 PM CDT Fri Jul 10 2020 Models continue to insist that the Southwestern US ridge will expand east across much of the southern US next week. While the trend has been to focus the center of the ridge a bit further south, we won`t escape the building heat. Temperatures should warm well into the 90s, with 100s likely for some. Continued southerly low- level flow will keep higher dewpoints/humidity in place, with dangerous heat likely for parts of the area, especially eastern Kansas. The mid and upper level jet should remain just north of the area, but embedded waves may provide a glancing blow at times with isolated to scattered convection possible (mainly northern Kansas). Martin && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 617 PM CDT Fri Jul 10 2020 VFR conditions will prevail for all TAF sites across central/southern Kansas through the evening hours. Thunderstorms in Nebraska are expected to move southeast during the night time hours, and could affect CNU very late tonight. Otherwise winds will switch around to the east then north as a cold front pushes southward across the region during the day on Saturday. && .HYDROLOGY... Issued at 334 PM CDT Fri Jul 10 2020 Another MCS may impact portions of central or eastern Kansas later tonight through Saturday morning. There remains quite a bit of uncertainty regarding the track of any thunderstorm complexes during this time. The general idea is that the heaviest rain will be focused over eastern Kansas. Flash flood guidance is around 2-3" in a 3 hour period. Should an MCS impact parts of the area, there would certainly be the potential for some heavier rainfall rates and, at least, minor flooding. Martin && .PRELIMINARY POINT TEMPS/POPS... Wichita-KICT 70 94 68 92 / 20 20 0 0 Hutchinson 71 92 66 91 / 30 10 0 0 Newton 72 91 67 90 / 30 30 0 0 ElDorado 72 91 67 90 / 30 30 0 0 Winfield-KWLD 71 95 68 93 / 20 30 10 0 Russell 72 90 64 91 / 20 10 0 10 Great Bend 71 91 65 91 / 10 10 0 10 Salina 74 90 66 91 / 40 20 0 0 McPherson 72 90 65 90 / 40 20 0 0 Coffeyville 70 92 70 91 / 30 50 10 0 Chanute 72 89 68 90 / 40 50 10 0 Iola 72 89 67 90 / 40 50 10 0 Parsons-KPPF 71 91 69 90 / 30 50 10 0 && .ICT WATCHES/WARNINGS/ADVISORIES... None. && $$ MESOSCALE...CDJ SHORT TERM...RM LONG TERM...RM AVIATION...CDJ HYDROLOGY...RM
Area Forecast Discussion
National Weather Service Wilmington NC
859 PM EDT Fri Jul 10 2020 .SYNOPSIS... A weak front will move eastward into the Coastal Carolinas tonight, stalling nearby, before another weak front reaches the area on Monday. Bermuda high pressure will dominate the middle and late part of the week. && .UPDATE... Updated PoP/Wx forecast grids to increase t-storm chances across the upper Pee Dee region over the next couple of hours. The last several HRRR runs indicate there may be a better potential for the convective activity to survive east of I-95 than I earlier thought, perhaps even approaching the coast by 2-3 AM. && .NEAR TERM /THROUGH SATURDAY NIGHT/... Fay is approaching the Jersey Shore this afternoon while its trailing trough lingers off the Carolina coast. Convection has remained isolated thus far, but some increase in coverage is expected primarily across the SC areas later this afternoon and evening. Overall, storms will diminish with the loss of heating later this evening but are expected to develop again during Saturday. The focus Saturday will be the sea breeze front and a weakening surface trough approaching from the west also aided by a mid/upper trough. The Heat Index will increase tomorrow but is expected to remain in the 100-104 range, or just below Heat Advisory criteria. Regardless, the heat/humidity will make it uncomfortable for those outdoors, especially Saturday afternoon. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... Hot weather will continue through early next week. Temps will soar into the 90s. Slightly drier air should work its way into extreme western portions of forecast area through early Sun, but overall, a humid air mass will remain in place with heat index values just above 100 in many spots Sun and Mon aftn. Subsidence and drier air through the mid levels behind exiting shortwave should inhibit convective activity on Sunday, although a weak trough will remain over area and may remain focus for iso convective development. May also see a pop up along sea breeze front Sun aftn. Another shortwave and weak front will approach late Sun into Mon with increasing southerly flow ahead of it. Models show more in the way of mid to high clouds moving through Mon aftn than convection and looks like best chc may come late Mon into Mon night. Overall, do not expect much in the way of shwrs/tstms early next week. && .LONG TERM /TUESDAY THROUGH FRIDAY/... Mid to upper trough will shift off the coast on Tues as mid to upper level ridge builds in behind it. Sfc high will build in from the north, but looks like boundary may linger and remain focus for convection along with sea breeze front through mid week. Bermuda high pressure will dominate the weather by mid to late week. The upper levels should act to limit convection and thunderstorms through the week, though, as ridge builds across the Southeast, but GFS is hinting at trough pushing far enough east on Fri to increase convection. Too far out to tell with much certainty. Hot and humid weather will continue through much of the week with temps typical of summertime and heat index values around 100. && .AVIATION /01Z SATURDAY THROUGH WEDNESDAY/... VFR conditions are expected to continue throughout the next 24 with two possible exceptions. 1: Scattered showers/t-storms moving eastward from the mountains and foothills could affect the FLO airport between 02Z and 05Z tonight. Potential is low, however brief MVFR/IFR visibility is possible in heavy rainfall. 2: New convection will develop Saturday afternoon along the seabreeze front at the coast. Best potential (30 percent) for impact on an airport is expected at ILM and MYR where brief MVFR to IFR visibility is possible. A 20 percent chance or less is expected elsewhere. Extended Outlook...Diurnal convection will continue, especially near the coast, with brief MVFR to IFR conditions expected through the weekend. Increased risk of flight restrictions on Monday, before seeing more of a VFR trend through mid next week. && .MARINE... Trailing surface trough in the wake of Fay will weaken across the adjacent Atlantic waters as another trough moves into the Carolinas and stalls through Saturday night. Southwesterly flow will prevail across the coastal waters with the new trough becoming situated to the west. Speeds around 10 knots are expected initially then temporarily increasing to around 15 knots, especially across the outer coastal waters, by later Saturday afternoon and evening. As the trough nudges closer to the waters very late Saturday night winds speeds should drop back down to around 10 knots or less. Seas will be 2 to 3 ft tonight into Saturday then increase during the late afternoon and evening. Seas will begin to subside again very late Saturday night as the winds diminish. Approach of weak front or trough from the west late Sun into Mon should kick up southerly winds up to 15 kts or so. This will combine with slightly longer period SE-S swell up to 8 sec to push seas up to 3 to 5 ft and around 5 to 6 ft, mainly in the outer waters off NC coast, where Small Craft Advisory conditions may occur. Bermuda high pressure will dominate the local waters through much of the rest of the week with southerly winds around 10 kts or so and slightly longer period SE to S swell mixing in. Winds and seas will spike up a bit each aftn near shore in sea breeze. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS...ILM UPDATE...TRA NEAR TERM...SRP SHORT TERM...RGZ LONG TERM...RGZ AVIATION...TRA MARINE...RGZ/SRP
Updated for 00Z Aviation Forecast Discussion below.

PREV DISCUSSION... /issued 353 PM CDT Fri Jul 10 2020/ DISCUSSION... A hot and dry afternoon across the Mid-South for the first time in awhile. Latest GOES east visible imagery shows a mature MCS near the ArkLaTex, with associated high cirrus spilling into the Mid-South from the west. Temperatures range from the upper 80s across the north to lower 90s further south. Heat index values have remained at 100 or below for much of the day. Northwest winds have advected in a slightly drier airmass across the north, characterized by upper 60s dewpoints. This drier airmass will allow areas across west Tennessee and northeast Mississippi to fall into the mid to upper 60s overnight. Further west, including the Memphis Metro, lows will likely stay in the lower 70s. By late tonight, a MCS is forecast to develop over Missouri and track SSE into the Lower Mississippi Valley by late tomorrow morning. CAMs are still struggling with the exact location of this system as it translates downstream in to our area. Nonetheless, have latched onto the HRRR`s general location and timing of the system for this package. It appears that an MCV or remnant outflow will move into northeast Arkansas as early as 11AM tomorrow and push through the area through the afternoon hours. The instability mass field will vary greatly tomorrow afternoon, as drier air will still reside over portions of west TN and NE MS. However, along and west of the MS River, a hefty amount of CAPE will exist. Values may exceed 3000 J/kg of SBCAPE. Storm mode will be outflow dominant clusters, as only 20 kts of shear will be on hand. If an organized cold pool can maintain, a more widespread risk of damaging winds can be expected. The Mid-South will remain in northwest flow again tomorrow night. The 18Z HRRR depicts another MCS lining up behind the afternoon convection tomorrow evening. This system will also have the ability to produce instances of damaging winds, if it materializes and pushes through our area. All models suggest this solution, but timing will still need to be sorted out for this period. Nonetheless, will add the mention of strong to severe thunderstorms to the HWO for both Saturday and Sunday. The forecast is still on track for a July heatwave next week. The expansive ridge out west will begin to build into the region early next week. Right now, Monday looks to remain the coolest day with highs only in the lower 90s. However, the ridge axis will become nearly centered over the Lower Mississippi Valley by midweek. Preliminary blended guidance suggests highs in the upper 90s to possibly 100F Wednesday through Friday next week. The combination of highs in the upper 90s and dewpoints in the low to mid 70s, will yield heat index values in excess of 105F. Heat advisories will likely be needed for several days. Guidance trends will need to be watched for Excessive Heat. Some weakening of the ridge is possible by next weekend, which could break the streak of excessive heat. Stay tuned. AC3 && .AVIATION... 00Z TAFs Few aviation weather issues tonight, with light winds and VFR prevailing. Main concern remains potential for TSRA arriving from the northwest Saturday afternoon, around the perimeter of the southwest U.S. upper ridge. Model consensus suggests JBR under a more direct path of the TSRA, with MEM along the perimeter in slightly drier air. PWB && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$
...Updated Aviation Forecast Discussion...

.DISCUSSION... Issued at 317 PM CDT Fri Jul 10 2020 Forecast Summary: A good chance for thunderstorms, some potentially severe, remains in the forecast for tonight. Beyond that, a series of shortwaves rolling through generally westerly flow in the Plains will bring off- and-on thunderstorm chances through much of next week. Tonight through Saturday: Northwest mid level flow remained over eastern Nebraska and western Iowa today, along northeast quadrant of high pressure centered over New Mexico. A subtle shortwave was noted rippling through central South Dakota which had spawned scattered convection there and in north central Nebraska. Convective inhibition to the east of this activity had squelched eastward push, with only showers remaining over northeast Nebraska. HRRR had shown this evolution with morning runs. A second and more prominent shortwave was pushing into eastern Montana, and was triggering convection there as of mid afternoon. This activity is expected to increase in intensity this afternoon and evening as it begins a turn to the southeast. This may offer our best opportunity for severe in our area, but will likely arrive after midnight. Short-range convection-allowing models have been all over the place in regards to evolution of storms this evening and tonight. One thing in common is them showing a broken line of wind-producing storms diving southeast through our CWA, but timing into our area is varied from early evening to after midnight. Given current convective trends, expect a later arrival of storms from the western Dakotas. Cold pool development in high instability environment is indicated by various models, so damaging winds may accompany any activity overnight. Another potential for severe is this evening as north central Nebraska storms continue to bubble up and expand south and east as capping gradually weakens. Cumulus field has expanded in central Nebraska where steep mid level lapse rates, MLCAPE near 3000 J/kg, and effective shear near 50kt resides. Will have to watch this activity this evening for potential development. If storms do fire, large hail and damaging winds will be the main hazards with supercellular storms, and mainly affecting areas west of a Norfolk to Lincoln line. Any convection should be exiting to the southeast of our area Saturday morning, though some lingering instability is forecast to lag behind line keeping chance for a few showers or storms to remain in the area through noon or so. Decreasing clouds and temperatures rebounding into the mid and upper 80s should follow. Sunday through Friday: We appear to be getting back to a pattern that will favor periodic thunderstorm chances through the week. Mid level high pressure will remain suppressed to our south as mid level low spins through central Canada. This keeps much of Nebraska and Iowa under influence of westerly mid level flow, with occasional shortwaves agitating environment to trigger storms from time to time. There appears to be some agreement between ECMWF and GFS that a strong shortwave rotating through the Northern Plains will drive a cold front into our area Monday night, bringing a decent chance for thunderstorms then. Wednesday also offers some overlap between models showing convection in our south. Otherwise we will likely see at least small chances for storms each day, with temperatures close to mid-July normals. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 643 PM CDT Fri Jul 10 2020 VFR conditions with light winds, unrestricted visibility and SCT-OVC AOA 7,000 ft AGL should continue through 05Z Saturday. After 05Z Saturday, the potential for thunderstorms will be increasing across the region from northwest to southeast. Any storms between 05Z and 13Z Saturday may produce damaging winds and/or large hail. As always, strong LLWS, up/downdrafts and near zero visibility are possible with the strongest storms. Confidence in storm timing and coverage for the TAFs is low. Suffice it to say, any of the TAF sites (KOMA, KLNK and KOFK) may be impacted overnight. Skies should clear after 13Z Saturday, leaving VFR conditions and breezy north winds (sustained 10 to 18 mph with gusts 20 to 30 kt) Saturday afternoon. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...None. IA...None. && $$ DISCUSSION...Dergan AVIATION...Albright
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Saturday) Issued at 357 PM CDT Fri Jul 10 2020 Main focus for this forecast package has been on the thunderstorm potential late tonight into tomorrow morning. The shortwave that will be the driver of this convection is still in eastern MT/WY and is progged to move southeast through the Dakotas and NE. Plenty of variability still exists across the CAM solutions with respect to timing and track of the resulting clusters of storms as they develop in the Dakotas and NE and progress southeast. Morning CAMs had been showing convection developing ahead of the main line associated with the shortwave, perhaps generating along an outflow boundary, suggesting the potential for multiple rounds to move through the area overnight. Most recent runs of the HRRR, NamNest, GFS, NAM, and ECMWF have all showed a slower trend and as such, have delayed PoPs this evening with the bulk of the activity forecast between 06-12Z, perhaps closer to sunrise Saturday morning. While the greatest likelihood continues to be in the northeastern CWA east of a Marysville to Emporia line (rounding the edge of the upper ridge), cannot rule out expansion of storms further west as has been indicated with multiple rounds and uncertainty of how these clusters may interact. With CAPE between 2500-3500 J/kg and effective shear between 40-50 kts, there appears to be no reason to believe the storms wouldn`t sustain themselves as they dive south from NE, with the primary threats being damaging winds and locally heavy rainfall. Perhaps the biggest caveat to this forecast is the ongoing convection in northern/central NE. The HRRR currently suggests this will weaken and the 18Z NamNest isn`t picking up on it at all, so overall confidence in how short-term models are handling this is low. Will need to monitor this to see if it maintains itself and reaches northern KS earlier this evening. Thunderstorms look to linger across the area through at least part of the morning hours, but drying conditions are expected into the afternoon. Have trended highs slightly cooler in far northeast KS due to the morning activity, and depending on how long clouds/rain linger, could see cooler temperatures overall. But as it stands, highs are forecast to be in the mid 80s toward the KS/NE border to the low 90s further south. .LONG TERM...(Saturday night through Friday) Issued at 357 PM CDT Fri Jul 10 2020 Heading into next week, the upper ridge remains nearly stationary over the southwestern US with northwest flow over the CWA. Another shortwave passes through Monday night into Tuesday followed by a frontal boundary on Tuesday night into Wednesday, which looks to hang around the area with weak disturbances within the flow. Only have low-end chances each day at this point with changes likely to come this far out. Otherwise, heat continues to be the story with temperatures warming back into the 90s across the area and heat indices into the low 100s as we round out the week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 639 PM CDT Fri Jul 10 2020 There remains uncertainty if a thunderstorms complex will affect the terminals through the early morning hours of Saturday. Some of the short-term model guidance shows the complex weakening as it moves southeast across eastern NE, and may remain north and northeast of the KTOP and KFOE terminals. The small complex of storms near Kearney, NE will remain west of KMHK through the evening hours. An outflow boundary will move southwest across the terminals towards 11Z and switch winds to the northeast...again if a complex of storms build south across the terminals, then the northeast winds may be gusty from 11Z SAT through 15Z SAT. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Picha LONG TERM...Picha AVIATION...Gargan