Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/10/19

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
833 PM CDT Fri Aug 9 2019 .UPDATE... Issued at 830 PM CDT Fri Aug 9 2019 Will continue to make updates as threat of severe weather and heavy rain moves off to the east and south this evening. Next issue is whether any convection will reform tnt within LLJ axis over the eastern CWA. Have my doubts, but will hold onto flood headlines for the time being given uncertainty and the fact that HRRR is adamant about more convection. Temperatures are generally okay. && .SHORT TERM...(This Evening through Saturday Night) Issued at 327 PM CDT Fri Aug 9 2019 Severe storms already occurring in central sd this afternoon along a strong warm front. With good deep layer shear, deep instability, good low level turning, and moisture, expect severe storms to continue to trek across the region into the evening hours. A tornado watch has been issued into this evening. Otherwise, the models show a surface low pressure area moving across southern sd with a strong llj impinging on the warm frontal boundary. With this good lift along with deep moisture expect moderate to heavy rainfall with these thunderstorms tonight with some flooding likely to occur. Bufkit soundings also show heavy rainfall ingredients into tonight. LLJ, high precipitable waters, and warm cloud depths point to heavy rainfall possibilities mainly across the east. 1 to 3 inches of rain are expected across much of the region with locally higher amounts. Thus, issued a flood watch earlier for the region through much of tonight/early Saturday. Otherwise, the storms will leave the eastern part of the region Saturday morning with skies becoming mostly sunny. Highs will range from the mid 70s east to the mid 80s west by late afternoon. We may have a return to some storms later Saturday night out west. .LONG TERM...(Sunday through Friday) Issued at 327 PM CDT Fri Aug 9 2019 An upper level ridge will begin the long term on Sunday with mostly dry conditions expected. The in-house pop blend is a bit overzealous, especially compared to the ECMWF, NAM, and Canadian model. Precipitation chances will increase substantially Sunday night into Monday as upper level trough and surface low pressure system crosses the region. As of now, the best instability and LLJ is focused south of this CWA, or closer to the Nebraska border. This system should push east of the region before 18Z Monday with dry conditions possible through Tuesday. A lee of the Black Hills surface low pressure system may develop on Wednesday with WAA and an increasing LLJ Wednesday night bringing the potential for showers and thunderstorms, mainly in the eastern CWA. Increasing upper level heights, along with southerly flow in the lower levels will bring humid conditions into the region by Friday. && .AVIATION...(For the 00Z TAFS through 00Z Saturday Evening) Issued at 615 PM CDT Fri Aug 9 2019 Showers and storms will continue to move east across the region overnight, but the threat of severe weather is waning. Areas of lower cigs are expected to develop across much of the region overnight, along with areas of fog. The fog and low clouds will likely linger through Saturday morning. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...Flood Watch through Saturday morning for SDZ020>023. MN...None. && $$ UPDATE...TDK SHORT TERM...Mohr LONG TERM...SD AVIATION...TDK
National Weather Service Wakefield VA
835 PM EDT Fri Aug 9 2019 .SYNOPSIS... A weakening cold front will move across the local area late tonight, then stall near the North Carolina coast over the weekend. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... As of 130 PM EDT Friday... Latest analysis shows a weak pre-frontal sfc trough in place along the coast from the carolinas into southern New England. A secondary trough was also in place across the piedmont evident by a slight shift ion winds from DC southwest to Farmville and Raleigh. Sct CU and some showers and storms were starting to develop as of 230 pm. Deep layered WNW flow was persisting above 850 mb and this limiting deep moisture and resulting in some inhibition, but not enough to keep activity at bay. The HRRR and ARW remain in good enough agreement that scattered showers and storms will develop and expand some in coverage between 3 pm and 4 pm then move southeast in the NW flow. Question is how widespread will convection be and the trend in the HRRR since 12z has been to slightly decrease storm coverage across eastern and southeast VA. Still maintains 30-50 POPs, but do not intent to go likely at this point. MLCAPE should reach 1500+ j/kg this afternoon mainly near the Bay and across southeast VA and northeast NC. Scattered storms which are able to develop should be able to produce gusty winds and frequent lightning. The weakening cold front will settle just south of the forecast overnight, across NC. Evening convection will decrease from north of south though some lingering showers and storms may continue near the NC/VA border south even late tonight as the front potentially slows. In general drier air will arrive after midnight (w/ dew points falling to the u50s- l60s across the NW). Lows 60-65F N and NW to around 70F far SE. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... As of 130 PM EDT Friday... Still shaping up to be a really nice weekend over much of the area. Some of the model guidance does leave the lingering sfc trough near the Albemarle and Pamlico Sounds Sat- Sun which may mean a bit more in the way of clouds along w/ the potential for ISOLD showers along the Albemarle Sound counties and Outer Banks. Otherwise, not quite as warm w/dew points down at more comfortable levels. Mostly sunny N and central areas both days...partly sunny S and SE. Highs in the m-u80s both days...a bit cooler at the beaches. Clear- partly cloudy Sat night w/ lows in the l-m60s...except near 70F at the immediate coast in SE VA/NE NC. Continued dry but warmer on Monday. Sfc high will settle offshore, shunting weak boundary back north as a warm front. Slightly warmer with highs in the upper 80s to around 90. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... As of 130 PM EDT Friday... The extended forecast period will start out with a warming trend getting rather hot and dry partially due to the zonal flow aloft and upper ridge which builds in Monday and persists into TUE. Humidity increases through next week as an front looks to approach from the NW late Tue into Tue night. An upper wave also drops SE late Tue supporting late day and evening scattered showers and storms. Ahead of the showers and storms highs hit lower 90s on Monday at then middle 90s on Tuesday which should be the hottest day next week. The upper trough hangs up and deepens on Wednesday making for continued unsettled weather with showers and storms. The front also hangs up in the southeast. Expect Wed to see more showers and storms with highs in the upper 80s to lower 90s. A wave develops along the front just off the coast Thu into Fri with high pressures to the NW. This could make for a tricky forecast for the end of the work week, but as of now things look generally drier and cooler for late week. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... As of 830 PM EDT Friday... The surface cold front continues to make slow progress southeastward through NERN MD and NW VA this evening with some scattered convection continuing in SE VA and NE NC. THis front will continue to push SEWD overnight pushing into central NC by Sat morning. Behind the front much drier is pushing southward with sfc dewpoints in the 50s. THis should allow the clouds to clear in most areas and vfr conditions to continue at all TAF sites. Will need to monitor ECG for some possible fog development late as the low levels did see an increase in moisture with an evening storm. But mixing might be enough to keep the fog away. For now have been optimistic with the forecast and kept vfr conditions in place. Canadian High pressure will build into the area by Saturday morning with vfr conditions expected for the entire day. an isolated shower is still possible for NE NC on Saturday afternoon depending on how far south the front goes, but for now have just allow for a developing afternoon cu field with some mid level moisture along and north of the front. OUTLOOK...VFR conditions are expected Sat night into early next week. A cold front is expected Tues into Wed and could produce some MVFR conditions with showers. && .MARINE... As of 400 PM EDT Friday... No headlines in the short term tonight thru Sun. Winds were variable 10 kt or less acrs the waters late this aftn. Waves were 1-2 ft and seas were 2-3 ft. A cold front will approach the waters from the NW this evening, then drops acrs the waters overnight. With fairly robust NW flow aloft, there is the potential for a few strong/severe storms to precede the cold front late this aftn and evening. These storms will bring the chance for winds in excess of 35 kt and locally enhanced waves/seas. The front will become nearly stationary over NC during Sat, then gets pushed farther south Sat night and Sun, as sfc high pressure builds acrs nrn portions of the region and offshore. Mainly SSW winds around 10 kt or less this evening, will become NW then N tonight into Sat morning. The flow becomes less than 10 kt and variable Sat aftn into Sat night, before winds turn NNE again by Sun morning. Onshore winds expected Sun aftn into Sun night, as the high shifts farther offshore. South and southwest winds will increase late Mon into Tue in advance of another cold front. Seas build to 2-3 ft S and 3-4 ft N, with waves 1-2 ft. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...None. NC...None. VA...None. MARINE...None. && $$ SYNOPSIS...MAM/JAO NEAR TERM...MAM/JAO SHORT TERM...MAM/JAO LONG TERM...JAO AVIATION...ESS/JAO MARINE...TMG/RHR
National Weather Service Sioux Falls SD
1055 PM CDT Fri Aug 9 2019 .UPDATE... Issued at 948 PM CDT Fri Aug 9 2019 Convection has generally shifted south of the state line in Nebraska with only a few cells left in south central South Dakota. Lighter rain continues along and south of Hwy 30/34 east of the James River to about OTG and Slayton. The convection has shifted the boundary to the south of the area. CAMs continue to show convection along and north of I90 later tonight as LLJ increases. However, CAMs have struggled with convective evolution all evening - generally being too far north and too slow. So, at this time, expecting that as LLJ increases in the next hour or two, new convection will favor south of I-90 into Nebraska. The only exception would be in there can be a 2-4 hour break until 06-08Z for new convective initiation then the front may be able to shift back north and favor new development into east central SD. At this time, favoring a southern solution with PoPs highest in the Missouri Valley through 06Z. and lowering to 30-60% along/north of I-90 with the highest PoPs in southwestern MN. Have also decreased QPF after 06Z given lower confidence in overall rainfall across the area. As a result we have cancelled the Flood Watch along and north of I-90 but continued it south of I-90 where the threat for heavy rain continues for at least the next 2 to 4 hours. The severe threat has decreased markedly with lack of a significant lifting mechanism. The RAP is likely overdoing MLCAPE given the front is farther north in the model than observed but still expect CAPE around 1000 J/kg over much of the area with 1500 J/kg near the stateline so could see an marginal severe hail if a stronger updraft is able to develop. && .SHORT TERM...(This Evening through Tonight) Issued at 227 PM CDT Fri Aug 9 2019 A very potent severe weather setup continues to build this afternoon across central and western South Dakota. Mid-afternoon surface and satellite analysis showing well defined surface boundary just south of the Missouri River and Pierre southeast towards Chamberlain and approaching Charles Mix county. Isolated surface based convection has already started to develop in the warm sector, along with enhancement of elevated convection across northern South Dakota. This afternoon and evening: Very moist boundary layer air has advected northward south of this frontal boundary, with dew points in the lower 70s. This has allowed for the development of a a large MLCAPE reservoir approaching 2500 J/KG into the western third of the CWA. Isolated surface based convection to our west and northwest should become more numerous through the afternoon as large scale accent arrives from shortwave energy over NE Wyoming later this afternoon. Increasing winds aloft have already pushed effective shear values into the 40 to 50 knot range this afternoon, and this will continue to rise as low-level flow increases this evening. This setup will favor the development of one or more discrete supercells across central South Dakota into the early evening, with eventual cell mergers developing into bowing segments and clusters as storms turn southeast along the edge of the instability gradient and dive towards and across the James River Valley. As far as risks are concerned, soundings show slightly modest mid- level lapse rates and are absent of thick hail growth CAPE profiles, however strong shear should support lofting of hail with potential for 2.5" hail in supercells. Greatest risks this afternoon and evening will arrive from damaging winds and tornadic risks. Eventual advection of dry air in the mid-lvls of the atmosphere will result in DCAPE values approaching 1500 J/KG in the western half of the CWA. This will support wind gusts up to 80 mph in HP supercells along with bowing segments later this evening. More concerning are the significant tornadic parameters showing up this afternoon and early evening along the Missouri River Valley and west of the James River valley. Effective 0-3 SRH values are already approaching 300 M2/S2 near initial development this afternoon near Kadoka, with increasing low-level flow pushing those values towards 500 M2/S2 by early evening towards Chamberlain and Lake Andes. 0-1km shear/SRH values are also very impressive along the frontal boundary, sitting around 150-200 M2/S2 and 20 knots respectively by early evening. LCL heights also fall in the favorable category, lowering down towards 600-750 M AGL later this afternoon. Should discrete cells become anchored to the surface boundary, an extended long track tornado threat could be possible into the James River Valley. However, even smaller bowing segments could be strong enough to produce tornadoes given the environment this evening. Further east, while instability wanes towards the I-29 corridor, it`s possible to have residual MCS complex slide eastward late this evening bringing a strong wind risk. It appears however that the greatest severe weather risk falls along and west of a line from Huron to just east of Mitchell towards Yankton. Heavy rain will also be a large risk this evening and overnight. Slow propagating supercells and any eventual complex will certainly have the potential for flash flooding. Additionally, as the LLJ refocused over MN and far eastern SD after midnight, a secondary area of heavy rain may develop along the Buffalo Ridge. Have issued a flood watch to cover both the large scale and flash flood potential into Saturday morning. .LONG TERM...(Saturday through Friday) Issued at 227 PM CDT Fri Aug 9 2019 Saturday-Sunday: Anticipating rain to linger over the eastern CWA behind this wave well into the morning hours. Residual cloud cover should limit temperatures and have lowered accordingly. Temperatures further south may rebound slightly towards 80 in the afternoon as surface low pressure slides east. A very pleasant day is expected on Sunday as temperatures climb back towards normal and dry conditions continue. Monday-Tuesday: A series of mid-lvl shortwaves arrive late Sunday night with one or more MCS developing off the western Plains and sliding eastward. We won`t really scour out much of the moisture in the atmosphere this weekend, so the antecedent conditions ahead of these waves will be favorable for heavy rainfall. The locations and track of the rain are still slightly in doubt however. While the greatest severe weather risks with these MCS appear to stay south, we`ll certainly need to monitor. Dry air moves in for Tuesday, along with slightly cooler temperatures. Wednesday-Thursday: The middle of the week again favors dry conditions, with gradual warming by Thursday and Friday of next week. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1052 PM CDT Fri Aug 9 2019 MVFR and potentially IFR stratus will attempt to develop on the back edge of the MCS. If stratus develops, could see additional storms develop in uncapped environment. Will be hard to shake the stratus on Saturday, though moisture will gradually thin through the day, possibly leading to breaks in the clouds late day. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...Flood Watch until 7 AM CDT Saturday for SDZ063>070. MN...NONE. IA...NONE. NE...NONE. && $$ UPDATE...Schumacher SHORT TERM...Dux LONG TERM...Dux AVIATION...BT
Area Forecast Discussion
National Weather Service Hastings NE
643 PM CDT Fri Aug 9 2019 .SHORT TERM...(This evening through Saturday) Issued at 425 PM CDT Fri Aug 9 2019 Afternoon upper level pattern consists of a strong dome of high pressure over the southern Plains, with troughs on either side over the eastern CONUS and just offshore the West Coast. A shortwave can be seen over central SD and this will ride SE in the NW flow tonight. A sfc low associated with this trough is located over SW SD, with a lee trough extending southward through the central High Plains. A cold front is noted W of the sfc low over extreme W SD into WY. Locally, current temperatures are in the 80s with dew points in the 60s, pretty seasonable for this time of year. Will continue to see warm and dry conditions through the evening hours as any focus for tstms remains well away from the area. However, after midnight, we may get clipped by the far S end of the SD wave as it crests the top of the ridge and turns SE. The HRRR has been consistent in showing a band of weak convection very close to our far N/NW CWA, so have inserted a slgt chc POP for the 06Z to 11Z time frame. Can`t rule out some patchy fog overnight, but held off on including attm given stronger S winds compared to past few nights. On the other hand, could envision some low stratus once again tonight. Saturday should be dry for most of the daytime hrs. The aforementioned cold front will dive S and likely stall somewhere over the CWA. This could be the spark for a few tstms as early as late afternoon. CAPE and shear is there for severe convection, however the larger scale pattern will feature large scale ridging and weak height rises. So, while the potential for an isolated strong to severe storm exists as early as late afternoon, it is a conditional potential. Expect warm temps ahead of the front across our southern zones. Have increased highs a couple of degrees into the mid 90s. Tds around 70 will yield heat indices in the low 100s for several hrs in the aftn, not far from heat advisory criteria. .LONG TERM...(Saturday night through Friday) Issued at 425 PM CDT Fri Aug 9 2019 The main concern will be multiple rounds of convection and potential for svr tstms and hvy rn. By Sat eve, the upper ridge axis will shift E far enough to turn upper flow to the SW. Several models indicate a weak wave ejecting NE during the eve which should lead to scattered to widespread convection developing over the High Plains during the late aftn and eve. This activity should spread E toward the W CWA during the eve and continue E/ESE overnight, generally along the aforementioned cold front. The NAM develops 40-45kt LLJ over central KS by 06Z Sun, with the nose intersecting this boundary. Aloft, there appears to be decent divergence from the RER of a jet streak over Dakotas/MN. Thus, ingredients appears to be coming together for one or two MCSs Sat night into early Sun, with some severe potential. Heavy rn may be the main threat, though, given PWATs near 2" and good moisture conv along front/nose of LLJ. Held off on a Flash Flood Watch for now for a few reasons: 1) likely still 24+ hrs out before any hvy rain threat, so still plenty of time to get better handle on the potential. 2) models often struggle with placement this far out in this type of pattern and just generally during this time of year. Currently, S zones are most favorable for this activity. 3) S/SW portions of the CWA are quite dry over the past 30 days, so most areas can take a good amount of rain. Overall, I think there will be at least pockets of heavy rn, but confidence on coverage and placement remains low at this time. There`s a pretty decent chance for another round of storms Sun eve into overnight, some of which could once again be strong to svr and produce hvy rn. This wave appears stronger than Sat night`s wave. Biggest thing to watch with this round will be to see if it tracks over or close to any areas that receive hvy rain Sat night as that could incr the flash flood threat. At this time, chcs appear higher across NE zones which is a little further N than Sat night. This would, obviously, be idea and spread the rain out over a large portion of the area. Most areas W of a line from Shelton to Superior could use some rain. Highs Sun range from mid 80s to low 90s, N-S. Otherwise, expect some additional off and on low chances for pcpn Mon-Thu as the upper pattern deamplifies and the main flow sets up just N of the area. This usually results in getting clipped by several low amplitude perturbations of which carry low predictability this far out. As such, expect mainly near to slightly below normal temperatures for much of next week. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Saturday) Issued at 643 PM CDT Fri Aug 9 2019 VFR conditions expected to prevail. Have removed the chance for fog/low stratus in the TAFs this period. Southerly winds look to be strong enough to help keep low levels mixing more and preclude fog development. Something to watch though. South to southwesterly winds expected tomorrow. && .GID WATCHES/WARNINGS/ADVISORIES... NE...None. KS...None. && $$ SHORT TERM...Thies LONG TERM...Thies AVIATION...Billings Wright
Area Forecast Discussion
National Weather Service Goodland KS
554 PM MDT Fri Aug 9 2019 .SHORT TERM...(This evening through Saturday) Issued at 125 PM MDT Fri Aug 9 2019 Cloud cover slowly burned off across much of the region through the morning hours, with a layer of cumulus/stratocumulus developing then dissipating into the afternoon. 500 mb RAP analysis and satellite show and area of high pressure located over Texas with ridging extending north into the Plains and Rockies. Southerly winds were observed throughout the region today at 10 to 15 mph. At 1 PM MDT, temperatures were in the 80s. The tri-state area looks to be on the northern edge of the upper ridge tonight as it begins to gradually shift eastward. A shortwave is anticipated to work its way through the flow from New Mexico to Colorado and towards Kansas through the evening hours. This disturbance should cause storms to initiate along the Rockies which will progress east/northeast into the region. How far these storms make it into the area before dissipating is in question. At this time, the better chances for showers and thunderstorms remain along and west of the Colorado border. Sufficient shear and instability indicate a few strong to severe thunderstorms cannot be ruled out, with hail up to quarter size, damaging winds, and locally heavy rainfall as the main threats. Most thunderstorm activity should end by midnight. Temperatures fall into the 60s to low 70s as cloud cover decreases. Dry conditions are forecast Saturday morning. However, another shortwave is expected to rotate through the ridge and generate another round of showers and thunderstorms from the afternoon through the overnight hours. This precipitation should be more widespread in comparison to today. Saturday`s high temperatures will be in the upper 80s to mid 90s. .LONG TERM...(Saturday night through Friday) Issued at 206 PM MDT Fri Aug 9 2019 Forecast concern be active and wet pattern with some chances for severe but increasingly better chances of heavy rain and flash flooding. Satellite is showing an amplified pattern from the Pacific into eastern North America. Flow highly amplified and even blocky in the central Pacific. Ridge over the country is centered over Texas which is allowing a strong connection to subtropical/monsoonal moisture. Saturday night...Weak shortwave trough will move through the area in weak, mainly southwest flow aloft. In general the models show a boundary over or just south of the area during the period. However, they differ on where to put that boundary. Air mass is moist and unstable with Precipitable water values 1.5 to 2 inches which near to above record levels. As has been the case in this very moist and weak flow/forcing environment, models, especially the high resolution guidance, having a difficult time in deciding where to put the rainfall. Considering the above reasoning believe there will be some heavy rainfall but problematic on where to put it. So raised the chance of precipitation a little. Since we have been dry for a few days and due to the disagreement in the model solutions, decided not to put out a Flash Flood Watch. Upcoming shifts will need to look at this again. Sunday/Sunday night...Upper jet remains to the north of the area. Same general pattern is in place at the beginning of the period, ridge centered over Texas with troughing over the Pacific northwest. However this transitions to a nearly zonal flow by the end of the period. This is due to a couple rather strong shortwave troughs moving through and shoving the ridge further east and bringing better chances of rainfall to the area unless the previous nights convection and associated mesoscale affects mess that up. Forecast blend pops a good chance of precipitation. That looks reasonable and left alone. Depending on how the rainfall goes Saturday night, a Flash Flood Watch may be needed since antecedent conditions will be more favorable and high PWs still remain. Monday/Monday night...It looks like the main shortwave that moved into the area the period before will move through during the daytime hours. So there could be some linger precipitation during the morning and maybe some redevelopment in the afternoon. However, there looks to be no definable shortwave coming during the night. Through the day the jet remains north of the area but gets closer. Weak right rear quadrant moves through the area during the night. Latest forecast blend has the daytime dry with a slight chance to low chance in there during the night. That looks reasonable given the reasoning above. Front is brought through the region and by the end of the period will be south and west of our area leaving the area in a post frontal upslope environment. PWs remain near 1.5 inches. So again locally heavy rainfall will be possible. Tuesday through Friday...Ridging aloft looks like it try to build into the area during the beginning of this period but the strongest portion of the ridge remains well south. During the end of this period the ridge tends to elongate but still remains well south of the area. So general setup/pattern will allow shortwave troughs to move through in the west to southwest flow aloft. This far out those of course will be hard to time out. Main jet looks well north. However, weak jet/axis looks to be over/near the area during this time. Front mentioned above remains to the south and west but moves east from the Front Range a little. During the last two days that front moves across the area as a warm front with a new lee trough settling over the western portion of the area by the end of the period. Precipitable water values gradually lower during the period. They will start out at 1 to 1.5 inches and drop down to 0.75 to 1 inch by the end. Latest forecast blend has the wettest conditions Tuesday and Tuesday night with dry to slight chance pops in the last three periods. Again this looks reasonable and did not change. Also the temperatures look reasonable per reasoning above. This means after a slightly cooler day on Tuesday there will then be a gradual warming trend. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 550 PM MDT Fri Aug 9 2019 VFR conditions are expected through the 00Z TAF period at MCK and GLD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...JBH LONG TERM...BULLER AVIATION...LOCKHART
National Weather Service Jackson KY
1045 PM EDT Fri Aug 9 2019 .UPDATE... Issued at 1045 PM EDT FRI AUG 9 2019 The boundary continues to help fire off and sustain convection this late evening hour. Much of this is rain showers now, but we have seen the occasional cloud to cloud and cloud to ground lightning strike detected by ENTLN. Given this will keep the mention of thunder in the grids and HWO. The trend will be downward with these storms, as inversion sets up and instability wanes. Updates have been sent. UPDATE Issued at 754 PM EDT FRI AUG 9 2019 The latest surface analysis suggests a frontal boundary is draped from west to east across the heart of eastern Kentucky. This is leading to showers and storms developing along and near this feature. While some stronger storms did develop underneath ample shear and CAPE profiles, there seemed to be some kind of CAP aloft leading lack of better development upward. The shear was certainly there as storms that developed across Clark and Powell sent cirrus blow off toward the Virginia border based on GOES-16 data. The CAMs did well portraying the general convection, but did lean toward the HRRR for PoPs. Given this there will be an overall downward trend in the convection this evening and only concern will be fog production through the night. Adjusted PoPs accordingly, but otherwise more minor update overall. && .SHORT TERM...(This evening through Saturday night) Issued at 442 PM EDT FRI AUG 9 2019 A cold front continues to sag south across the area and is currently located across the northern portion of the CWA. Convection in WV has been more vigorous where the alignment of instability and shear has been best so far. MLCAPE should still in the 1000 to 1500 J/kg range over the next few hours with effective bulk shear in excess of 30kt. Lighting has been recently detected in a couple of cells near and just south of the I 64 corridor. Forcing should remain limited as we head into the evening with the cold front sagging south, though given the instability and shear isolated to scattered convection is anticipated in the vicinity of the boundary. A strong storm or two with gusty winds or small hail cannot be ruled out. The boundary should sag south of the area after midnight with showers and storms possible through that point. Once the front sags south of the area and as skies clear and high pressure begins to build in drier air will arrive more quickly in the north. However, dewpoints will be slower to fall further south and fog development appears most likely in valleys south of the Mtn Parkway. High pressure will settle into the OH Valley on Saturday and reach the upper OH Valley late in the period. At the same time, the upper level flow will remain out of the northwest ushering in drier air with gradual height rises through Saturday night. As for temperatures, lows will be a bit colder than this morning with lower 60s in the north and mid to upper 60s in the south. High on Saturday should be well into the 80s and the higher Max T from the NBM and blended guidance was favored as it has been verifying better than MOS recently. Also much of the area has been drier lately thus leading to drier soils and allowing for a bit more heating. The bulk of the region should fall into the lower 60s on Saturday night with a 58 or 59 possible in some of the normally colder northeast valley locations. .LONG TERM...(Sunday through Friday) Issued at 448 PM EDT FRI AUG 9 2019 A strong upper level ridge will slowly begin expanding eastward from the south-central Conus, with increasing heights expected over Kentucky. A strong surface high will also be moving across the Ohio Valley, with abundant sunshine and light winds expected. Temperatures will top out in the mid and upper 80s, but dew points should keep RH values at bay, with Heat Indexes very similar to the temperatures. Things will begin heating up from here. By Monday, the area of high pressure will begin shifting just northeast of the state, with upper level ridging continuing to gain hold. Srly flow in the low levels, though light, will be enough to increase the moisture flow into the region, and with upper level ridging still holding strong, temperatures will rise to the 90 degree range or just above. Humidity increase will cause a spike in heat indexes, making it feel like the mid 90s, and even upper 90s in the southern CWA. Also can`t rule out a bit of afternoon convection, though the GFS, NAM, and newest ECMWF don`t see as on board with this as the NBM. Even still, pops will generally be under 20 percent, and fall off in the evening. Moisture will continue to increase into Monday night as an area of low pressure moves into the Lower Great Lakes and drags a cold front southeastward towards the Ohio River. Southerly flow will continue to increase, with enough moisture and instability entering the region to induce showers and thunderstorms by Mon night, continuing to increase through the day Tuesday as the front passes over and we reach peak afternoon heating/instability. Our highest temperatures of the forecast are expected this day, along with our highest heat indexes. Highs will be in the low 90s, but it will feel like its around 100 degrees. This will be a day to watch as we get closer, both for heat concerns, as well as for high PWATS and convection. The front will pass through late Tuesday night, cutting off precip chances during the first half of the day Wednesday from NW to SE. However, there won`t be much reprieve from the hot and humid temperatures. High will still be in the mid and upper 80s, but it will feel more like the low 90s in many locations. Upper level heights will be on the rise again for Thursday, with mostly clear conditions and similar temperatures as Wednesday. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) ISSUED AT 730 PM EDT FRI AUG 9 2019 We are looking at VFR to the begin the TAF period, but some showers and thunderstorms have developed along a cold front this afternoon. This could lead to quick reductions in CIGs and VIS, but this should be short lived if a site experiences one. We are looking at fog development later tonight around 7Z to 8Z or after for most locations. The dryer air will mitigate fog at SYM, but airport mins are not out of the question elsewhere. We will see this fog lift and/or dissipate through the morning at around 14Z. This will lead to VFR skies for Saturday, with some flat cumulus not out of the question in the afternoon. The winds will remain light through the TAF period, with winds coming out of the north as boundary moves across. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...DJ SHORT TERM...JP LONG TERM...JMW AVIATION...DJ
Area Forecast Discussion
National Weather Service North Platte NE
656 PM CDT Fri Aug 9 2019 .SHORT TERM...(This evening through Saturday night) Issued at 322 PM CDT Fri Aug 9 2019 The thunderstorm forecast late this afternoon and tonight follows a blend of the HRRR, HREF, RAP, NAMdng and the model blend which places isolated to scattered thunderstorm activity from roughly Deuel county northeast to Valentine. The srn storm activity is expected to weaken early this evening which the nrn storm activity may last for several hours as it advances east through nrn Nebraska. POPs for tonight are capped at 30 percent to account for uncertainties in coverage. Some models like the HRRR produce very little storm activity tonight. A significant and potentially major league heavy rain event could develop across parts of western Nebraska late Saturday afternoon through Saturday night. Precipitable water increases to over 1.70 inches with a deep warm layer supporting tropical type rain processes. The problem with the forecast is locating the low level focus for best rain chances. The models may be placing the h850mb front somewhere across KS with swrn Nebraska in an easterly upslope flow. A frontal location near the NE-KS border would favor swrn Nebraska for heavy rainfall. The location of the front will become known later tonight in the wake of the storm activity across the Dakotas. POPs for this portion of the forecast capped at 50 percent and the forecast uses the same model blend as the tonight period. Once again, some models such as the GFS and ECM produce very little rainfall across wrn Nebraska Saturday while the NAM12 places heavy rain centers of 4 to 6 inches over nern Colorado and nwrn Kansas/far swrn Nebraska. The flood guidance across swrn Nebraska is less than 2 inches in an hour which could easily be eclipsed given the moisture available. .LONG TERM...(Sunday through Friday) Issued at 322 PM CDT Fri Aug 9 2019 The atmosphere transitions from quasi-barotropic to baroclinic Sunday as a nrn stream disturbance infiltrates the tropical moisture plume across the cntl Plains. The GEF output places a broad heavy rain center over wrn and ncntl Nebraska and if this verifies, back- to-back heavy rain events will occur. Parts of ncntl Nebraska might be post-frontal with sfc low pressure over swrn KS and nern WY as high pressure builds in to the upper Midwest. The double-barrel sfc low pressure across WY and CO/KS will produce moist upslope east and southeast winds across wrn Nebraska. The NAM and GFS continue precipitable water above 1.70 inches Sunday night. The GFS and ECM favor Sunday for the better rain chance while the NAM and SREF favor Saturday. A cold front will begin to dry out Wrn and ncntl Nebraska Monday with northwest winds developing. Lingering moisture will continue shower and thunderstorm chances Tuesday and beyond but POPs are 30 percent or lower. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 655 PM CDT Fri Aug 9 2019 The main aviation concern will the chance for rain and thunderstorms across portions of north central Nebraska. At this time, the best chance for development will remain across the north, impacting only KVTN. Frequent lightning, erratic winds, small hail, and heavy rain could all be threats with these thunderstorms. Otherwise, VFR conditions will remain across the region through Saturday. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...CDC LONG TERM...CDC AVIATION...Kulik
Area Forecast Discussion
National Weather Service Louisville KY
749 PM EDT Fri Aug 9 2019 ...Updated Aviation Discussion... .Forecast Update... Issued at 646 PM EDT Fri Aug 9 2019 Diurnally-driven convection has consolidated into a narrow band right along the front (running through Elizabethtown and Richmond areas), and this activity is slowing dropping southeast. The cu field has diminished considerably north and south of the boundary, so have updated PoPs to reflect the latest trends. Due to the weak, consolidated nature of the convection, think it will die pretty quickly after sunset. && .Short Term...(This evening through Saturday) Updated at 333 PM EDT Fri Aug 9 2019 Diurnal cumulus field is in full swing across the region this afternoon. As expected, temperatures have warmed into the upper 80s with a few spots in the lower 90s. The cumulus field is a bit more agitated right along the I-64 corridor. This appears to be where a weak front is located. The HRRR still suggests that some isolated- scattered convection may fire along and just south of I-64 over the next few hours. Overall HRRR coverage is slightly less than in previous runs. For now, plan on keeping some 20-30% PoPs south of I- 64 for the next several hours. Surface front is forecast to push southward overnight and we`ll see a switch in the wind flow to the north and northeast overnight. Some patchy fog will be possible mainly across southern KY. Lows will be in the mid-upper 60s with some lower 70s along the KY/TN border region. For Saturday, mainly dry weather is expected across the region. Highs look to warm again into the mid-upper 80s in most locations with a few spots topping 90 again. .Long Term...(Saturday night through Friday) Updated at 250 PM EDT Fri Aug 9 2019 Saturday Night - Tuesday... Dry weather is expected Sat night through Monday morning as sfc high pressure largely controls the region. The next chance of rain looks to arrive on Tuesday as a cold front moves through the region from NW to SE. While organized severe weather doesn`t look likely at this time, some strong storms may be possible. We`ll see a warming trend in temperatures as an upper level ridge works into the Ohio Valley early next week. Temps in the upper 80s to lower 90s on Sun will climb into the lower 90s almost area wide for Mon/Tue. Moisture pooling ahead of front will cause dewpts to rise through the 70s Mon/Tue. 70s dewpts combined with highs in the lower 90s will result in heat index values of 100-105 for Mon/Tue with Tuesday being slightly warmer potentially. Afternoon storms on Tues will provide relief to some areas. Wednesday - Friday... Lingering showers/storms should exit the area Wed morning with the cold front leaving the rest of the week dry. Slightly cooler temps and lower humidity levels can be expected Wed-Fri with sfc high pressure and lower thicknesses in place. && .Aviation...(00Z TAF Issuance) Updated at 749 PM EDT Fri Aug 9 2019 SCT-BKN cu field is now oriented in a fairly narrow band along a cold front stretched west to east across central Kentucky this evening. In addition, we do have some mid-level clouds around 10-12 kft streaming across southern KY. The TAF sites are likely to remain VFR and dry through the remainder of the evening. Scattered convection has drifted south of HNB/SDF/BWG. The lingering showers along the front are likely to diminish after sunset before they have a chance to impact BWG. Skies at the northern TAF sites will remain mainly clear overnight as drier air advects via a north wind. Forecast is tricky for BWG south of the front. Mid-level clouds may be BKN at times between 00- 12z, but should scatter out enough to allow some fog potential after 08z. In general, patchy dense fog will be possible across southern KY early Saturday with plenty of low level moisture and nearly calm winds in place near and south of the boundary. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...None. KY...None. && $$ Update...EBW Short Term...MJ Long Term....AMS Aviation...EBW
Area Forecast Discussion
National Weather Service Tulsa OK
906 PM CDT Fri Aug 9 2019 .DISCUSSION... Earlier convection has dissipated, although modest increase in low-level jet/speed convergence should result scattered convection across parts of eastern OK/northwest AR mainly after midnight. Based on recent HRRR output and 00Z NAM, have increased PoPs a bit across western AR as well as shifting the QPF axis just a bit farther south. Leftover morning convection/debris clouds will impact potential heating on Saturday, so will leave the current Heat Advisory as is. && .PRELIMINARY POINT TEMPS/POPS... TUL 75 94 77 98 / 30 10 0 0 FSM 75 93 77 99 / 40 20 0 0 MLC 76 96 78 98 / 20 10 0 0 BVO 74 92 75 95 / 30 20 0 10 FYV 72 88 74 93 / 40 40 0 10 BYV 71 88 74 95 / 30 40 10 20 MKO 75 94 75 97 / 30 10 0 0 MIO 73 91 74 95 / 30 30 10 10 F10 74 96 76 99 / 20 10 0 0 HHW 77 97 77 98 / 10 10 0 0 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...Heat Advisory from 1 PM to 8 PM CDT Saturday for OKZ049-053-060- 064>067-070>076. Heat Advisory from 1 PM to 8 PM CDT Sunday for OKZ049-053-060- 064>067-070>076. AR...Heat Advisory from 1 PM to 8 PM CDT Saturday for ARZ019-029. Heat Advisory from 1 PM to 8 PM CDT Sunday for ARZ019-029. && $$ SHORT TERM...18
Area Forecast Discussion
National Weather Service Tucson AZ
823 PM MST Fri Aug 9 2019 .SYNOPSIS...Abundant moisture will remain in place through the weekend with a weather system moving north across the area Saturday. This combination will bring occasional thunderstorms to the area with an elevated risk of flash Flooding anytime from late tonight through Sunday night. Scattered thunderstorms are again expected Sunday mainly east of Tucson. Drier and hotter weather is forecast for much of next week. && .UPDATE...Made an update to the forecast to lower rain chances for tonight based on the recent trends and the latest model solutions. The onset of widespread rainfall will be delayed several hours as suggested by the HRRR and recent National Blend of Models(NBM) solutions. However, will keep the Flash Flood Watch going with the caveat that the bulk of the rain and heavy downpours will commence after 15Z Saturday. && .DISCUSSION...Skies have cleared over the area with thunderstorms developing to the south much as expected this afternoon. With plenty of moisture available there is a small threat for locally heavy rains. This activity should die down this evening. Then attention turns to the easterly wave that is moving up the back side of the upper ridge that will bring about some interesting weather this weekend. Plenty of moisture will be in place with PWs in excess of 1.5 generally late tonight through Saturday. As that wave slowly drifts north through tonight through Saturday it will be the force triggering convection over the area. With the forcing and moisture, some of the thunderstorms are likely to produce excessive rains that could lead to flash flooding. This is not a widespread steady rain event, rather scattered to numerous thunderstorms from early Saturday morning into Saturday night. Most thunderstorms will be good rainers and some slow movers our overly frisky ones could produce strong winds and flooding rains, especially if the same area gets hit more than once. Considering the forcing, the flood threat will not be just confined to the daytime periods as scattered nighttime convection is possible. While we occasionally get local flash flooding on a monsoon day, the watch is issued when the threat is elevated "above normal" over a significant area. Given the inconsistencies in the models, pin pointing areas of highest threat within the watch areas is challenging, especially with convection. However, at this time it looks like the enhanced risk will start near the southern border up to Tucson during the early morning (pre-dawn) hours, then move north through the day to encompass much of the forecast area during the daylight hours, then gradually moving north during the evening into central and northern AZ. The watch area encompasses the area and times of greatest threat at this time and that could be adjusted through the event. As a result of the precipitation and clouds temperatures will remain below normal. Sunday will be a transition day with lingering moisture but a drying SW flow developing. This pattern provides for the potential for increased shear which if thunderstorms develop, they could make use of that and be quite strong. At this time storms look to be from Tucson eastward but a lot will depend on how the next 24-36 hours pans out. High temperatures look cooler than normal once again. Then for next week we are in a drying pattern with temperatures quickly jumping above normal once again. Much the same as has happened several times in this fickle monsoon season. && .AVIATION...Valid through 10/00Z. Isolated-scattered SHRA/TSRA is expected across SE AZ into this evening with the potential for gusty outflow winds and localized MVFR CIGS/VSBYS possible, particularly along the International Border. SCT-BKN clouds 10-20K FT AGL will continue a chance of SHRA/- TSRA possible during the overnight hours as well. More widespread SHRA/TSRA is possible Friday afternoon into the weekend. Expect gusty and erratic surface winds near any TSRA with reduced visibilities possible. Aviation discussion not updated for TAF amendments. && .FIRE WEATHER...The daily cycle of mainly afternoon and evening showers and thunderstorms will continue through the forecast period with coverage becoming a bit more widespread by Friday evening into the weekend. Min RH values will rise to the 25-35 percent range by the Friday evening with continued very good to excellent RH recoveries through the weekend. Some of the storms that develop over the weekend may become severe in nature and produce strong outflows and heavy rain. A drying pattern is expected in the beginning half of next week with monsoon activity diminishing temporarily. Aside from gusty erratic winds from thunderstorm outflows, wind trends stay light and terrain driven. && .TWC WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch from 1 AM MST Saturday through late Saturday night for AZZ502>515. && $$ PUBLIC...Cerniglia AVIATION....Powell FIRE WEATHER...Powell Visit us on Facebook...Twitter...YouTube...and at