janetjanet998 Posted February 16, 2019 Share Posted February 16, 2019 Tennessee Valley Authority 53 mins · The River Forecast Center is tracking significant rainfall with numerous rounds of heavy rain beginning as early as Monday and continuing through the week. Most of the heavy rain is expected Tuesday through Thursday. We are preparing by increased releases from the tributary reservoirs like Norris, Douglas, and Cherokee to create as much storage space as possible. On the main stem Tennessee River, reservoirs are being pulled down to below winter pool to have some storage and handle local inflows. We continue to work with the US Army Corps of Engineers to help reduce flooding on the Ohio and Mississippi Rivers. This rain event could result in high river flood stages, especially in Alabama and below Pickwick in the Savannah to Johnsonville areas. River stage info: Chattanooga, TN: http://tva.me/XehH50lyZqL South Pittsburg, TN: http://tva.me/8XyT50lyZqK Whitesburg, AL: http://tva.me/ZM9T50lyZqP Florence, AL: http://tva.me/lpmw50lyZqN Savannah, TN: http://tva.me/Eam150lyZqO Clifton, TN: http://tva.me/7Bkb50lyZqM Perryville, TN: http://tva.me/vNt650lyZqQ 3 1 Link to comment Share on other sites More sharing options...
janetjanet998 Posted February 16, 2019 Author Share Posted February 16, 2019 Wolf Creek Dam increasing releases to drawdown Lake Cumberland NASHVILLE, Tenn. (Feb. 15, 2019)– The U.S. Army Corps of Engineers Nashville District plans to increase releases at Wolf Creek Dam in Jamestown, Ky., as soon as conditions allow in an effort to drawdown the water level at Lake Cumberland. Water managers at the Nashville District headquarters in Nashville, Tenn., said Wolf Creek Dam is currently discharging water at a rate of 28,000 cubic feet per second, but plan to increase to 35,000 cfs as soon as conditions allow. The current elevation at Lake Cumberland is the highest observed since April 25, 1998 when the pool crested at 742.44 feet. The pool of record is 751.69 set in May 1984. In 2019 inflows are averaging 33,270 cfs and the lake has risen 19 feet Wolf Creek Dam last discharged water at a rate of 35,000 cfs in March and April of 1997. The flow of record from Wolf Creek Dam is 40,000 cfs in January 1974. River View Road had not been developed at that time. https://www.dvidshub.net/news/310958/wolf-creek-dam-increasing-releases-drawdown-lake-cumberland Local dams to release less water, hope to reduce flooding impact downstream (KY lake and Barkley into OH river) As the Ohio River reaches its peak, Looney says less water will be released out of the dams, causing lake levels to rise above typical summer levels. He says that should also help reduce the impact of flooding downstream. https://www.wpsdlocal6.com/2019/02/14/local-dams-to-release-less-water-hope-to-reduce-flooding-impact-downstream/ 1 1 Link to comment Share on other sites More sharing options...
TellicoWx Posted February 16, 2019 Share Posted February 16, 2019 Picked up 1.01" overnight, with a rise of 1.2' on the Tellico River. Currently at 3' (Flood stage is 9') some of the banks start topping a little sooner. One of the interesting things was how long it took to recede, continued rising 5 hrs after the rain stopped. Normally it takes a little less than an hour for the graph to begin falling, shows how much runoff is coming down the mountain. Link to comment Share on other sites More sharing options...
TellicoWx Posted February 16, 2019 Share Posted February 16, 2019 MRX AFD: Main flooding concern starts late Tuesday and Tuesday night. Strong upper jet becomes established over the Ohio and Mississippi Valleys with strong upper divergence over the area from Tuesday night through Wednesday night. The direct circulation around this jet enhances the fronto-genetic forcing over the area and intensifies the 850mb southerly jet pulling in unseasonably high moisture. PWs increase to 1.4 to 1.5 inches which is above the daily climatology maximum. Another concern is that freezing heights are quite high which are also well above the daily climatology maximum. Layer above freezing will be greater than 10kft over much of the area helping to produce high rainfall rates. End result, another round of heavy rainfall over already saturated ground/high stream flows will set the stage for the potential of serious flash flooding concerns, especially over the Plateau, central-southern Tennessee, and southwest North Carolina. Will highlight this concern in the Hazardous Weather Outlook and Hydrologic Outlook. The persistent southwest flow continues through the end of the week with the potential of additional moderate to locally heavy rains for Thursday through Saturday. Overall, a very wet pattern with flooding concerns continuing. River flooding looks to be a major problem as well from mid to late next week, possibly into the next weekend. Link to comment Share on other sites More sharing options...
jaxjagman Posted February 16, 2019 Share Posted February 16, 2019 Hydrologic Outlook Hydrologic Outlook TNC003-015-021-027-031-035-037-041-043-049-055-061-081-083-085- 087-099-101-111-117-119-125-133-135-137-141-147-149-159-161-165- 169-175-177-181-185-187-189-172045- Hydrologic Outlook National Weather Service Nashville TN 234 PM CST Sat Feb 16 2019 ...More heavy rain and flooding possible across Middle Tennessee next week... A very active weather pattern is expected to continue affecting Middle Tennessee through next week into the following weekend, with frequent storm systems bringing rain almost every single day. The next round of rain will arrive tonight and continue into Sunday night. After another brief drying out on Monday, particularly heavy rain is forecast from Tuesday through Thursday of next week, and even more heavy rain is possible next weekend. Although the forecast remains uncertain on which parts of Middle Tennessee may see the heaviest rainfall next week, current indications are that total rainfall amounts could reach anywhere from 3 inches northwest to 9 inches southeast. Due to the frequent and well-above normal rainfall that has already fallen across Middle Tennessee this month, grounds are saturated and many rivers, creeks and streams are already running high. The forecast heavy rainfall over the next week has the potential to cause significant flooding along area rivers, with flooding of some area roadways, low lying areas, and other poor drainage locations also possible. Residents across Middle Tennessee should continue to closely monitor the potential for heavy rainfall and flooding next week. For the latest forecast updates and river forecasts, visit our website at weather.gov/nashville. Link to comment Share on other sites More sharing options...
dwagner88 Posted February 16, 2019 Share Posted February 16, 2019 I don’t think I can remember ever seeing this much rain forecast with so little convection. Of the roughly 10” qpf at KCHA forecast next week, only 1.50” is convective on the 12Z GFS. Probably means the likelihood of totals busting high or low is minimal. 1 Link to comment Share on other sites More sharing options...
janetjanet998 Posted February 16, 2019 Author Share Posted February 16, 2019 well yesterday it was reported flows would be reduced from Kentucky lake and Barkley into the OHIO river...so far outflows from the combined dams have only dropped from a combined 323,000 cfs to 280,000 cfs which is still a huge amount they also are still releasing 177,000 from Pickwick I (was 114K 2-14) into basically the start of Kentucky Lake...and the downstream hydrography suggest they may increase it? plus another 10K from buffalo and Duck the Cumberland river into Barkley is at 74,000 bfs at Dover, so a combined 261,000 cfs plus local runoff going into Ky lake and Barkley) ...180,000 out the OH river will crest soon at Cairo at 52 feet, the 20th highest on record (61.7 2011) and hold steady for 5- 6 days before falling that is WITHOUT most of next weeks rain factored in.....which is creeping more north into more of the OH valley ,,,each run... you can bet they are heaving heated discussions on what to do with all of the water...I suspect they will store it in Kentucky and Barkley to a point until the OH river crest passes... Kentucky lake level 353.9 and slowly rising now,,,normal summer pool is 359 I think the record is 372 or something in 2011 when they stored It until the OH crest passed.. ----- lake Cumberland 736.90. looks like it crested at 736.94...with 28,100 cfs outflow ...as of yesterday they were going to increase that to 35,000 after they build flood walls (record 40K) Dale hollow, just downstream is releasing 5,000 cfs the max combined allowed release is 40K I think.... note: Nashville needs 5.55 inches to break the monthy record 1 Link to comment Share on other sites More sharing options...
Windspeed Posted February 17, 2019 Share Posted February 17, 2019 Uptick QPF a bit further on the 00z. I hope this busts. 1 Link to comment Share on other sites More sharing options...
dwagner88 Posted February 17, 2019 Share Posted February 17, 2019 49 minutes ago, Windspeed said: Uptick QPF a bit further on the 00z. I hope this busts. That far NW corner of north Georgia is in the south chickamauga creek watershed. That creek represents the largest flood threat to the Chattanooga metro. It was impounded with levees after the 1973 floods. The last time they were tested was May 2003. We could have a comparable crest to that event next week. 2 Link to comment Share on other sites More sharing options...
janetjanet998 Posted February 17, 2019 Author Share Posted February 17, 2019 10 minutes ago, dwagner88 said: That far NW corner of north Georgia is in the south chickamauga creek watershed. That creek represents the largest flood threat to the Chattanooga metro. It was impounded with levees after the 1973 floods. The last time they were tested was May 2003. We could have a comparable crest to that event next week. info on the 2003 event The Major to Record Flooding of May 2003 across East Tennessee During the four day rain event (beginning at midnight on May 5th and ending at midnight on May 8th), a bull’s eye of over twelve inches of rain was reported in McMinn County, TN at both Etowah and Athens. The heaviest rains fell during the first 35 hours (midnight May 5th through 11:00 P.M. May 6th), where 11.6 and 11.1 inches fell at Etowah and Athens, respectively. Storm total rainfall of greater than six inches fell somewhere in each county south of a Sevier to Morgan County line. In the Little Tennessee River and Hiwassee River basins, greater than nine inches fell during the entire event. All of this water drained into Watts Bar and Chickamauga Lakes, which eventually flowed down to Chattanooga. https://www.weather.gov/mrx/may03flood 1 Link to comment Share on other sites More sharing options...
jaxjagman Posted February 17, 2019 Share Posted February 17, 2019 1 hour ago, dwagner88 said: I don’t think I can remember ever seeing this much rain forecast with so little convection. Of the roughly 10” qpf at KCHA forecast next week, only 1.50” is convective on the 12Z GFS. Probably means the likelihood of totals busting high or low is minimal. Not sure about 10".But i'm going by the Euro and not GFS.There's more convection shown.Also the DP depression would most certainly be fog and rain . 12Z FEB16 2 M SFC SFC 6 HR 6 HR 6 HR 500 1000 TMP DEW CAPE QPF CVP NCP HGT 500 (C) (C) J/KG (IN) (IN) (IN) (DM) THK SAT 12Z 16-FEB 5.9 5.4 1 561 553 SAT 18Z 16-FEB 11.1 4.7 1 0.00 0.00 0.00 564 555 SUN 00Z 17-FEB 8.8 5.0 0 0.00 0.00 0.00 565 556 SUN 06Z 17-FEB 6.3 4.2 13 0.01 0.00 0.00 566 557 SUN 12Z 17-FEB 8.4 7.9 16 0.16 0.13 0.03 567 558 SUN 18Z 17-FEB 11.7 10.8 21 0.08 0.01 0.06 569 560 MON 00Z 18-FEB 12.0 11.9 120 0.13 0.04 0.09 570 562 MON 06Z 18-FEB 10.7 10.6 17 0.71 0.15 0.56 570 559 MON 12Z 18-FEB 4.4 3.8 0 0.15 0.06 0.09 569 553 MON 18Z 18-FEB 11.3 -0.3 0 0.00 0.00 0.00 572 552 TUE 00Z 19-FEB 6.9 -2.2 0 0.00 0.00 0.00 574 553 TUE 06Z 19-FEB 2.2 -2.8 0 0.00 0.00 0.00 577 552 TUE 12Z 19-FEB 1.3 -3.7 0 0.00 0.00 0.00 577 551 TUE 18Z 19-FEB 5.3 1.8 0 0.07 0.05 0.02 579 554 WED 00Z 20-FEB 3.9 3.8 13 0.52 0.18 0.34 579 556 WED 06Z 20-FEB 4.5 3.6 121 0.36 0.20 0.16 579 561 WED 12Z 20-FEB 5.7 4.8 4 0.06 0.02 0.04 579 562 WED 18Z 20-FEB 10.4 8.5 128 0.10 0.07 0.03 579 564 THU 00Z 21-FEB 9.7 9.6 326 0.50 0.38 0.13 578 565 THU 06Z 21-FEB 11.5 11.5 526 0.48 0.38 0.09 577 565 THU 12Z 21-FEB 12.3 12.1 233 0.54 0.37 0.17 576 564 THU 18Z 21-FEB 14.0 13.4 238 0.24 0.11 0.13 576 563 FRI 00Z 22-FEB 9.5 9.0 38 0.58 0.32 0.26 576 561 FRI 06Z 22-FEB 7.9 7.4 1 0.14 0.05 0.09 577 561 FRI 12Z 22-FEB 8.0 7.6 1 0.05 0.01 0.04 577 560 FRI 18Z 22-FEB 9.7 9.6 144 0.25 0.09 0.16 579 561 SAT 00Z 23-FEB 10.2 10.1 407 0.39 0.24 0.15 579 562 SAT 06Z 23-FEB 12.4 12.4 430 0.40 0.30 0.10 579 562 SAT 12Z 23-FEB 12.3 11.9 80 0.26 0.23 0.03 579 563 SAT 18Z 23-FEB 17.2 14.9 181 0.04 0.02 0.02 578 564 SUN 00Z 24-FEB 16.6 15.6 194 0.06 0.04 0.02 576 565 SUN 06Z 24-FEB 16.7 16.7 310 0.35 0.07 0.28 571 564 SUN 12Z 24-FEB 9.4 2.7 0 0.28 0.05 0.24 568 556 SUN 18Z 24-FEB 7.1 -7.1 0 0.00 0.00 0.00 565 547 MON 00Z 25-FEB 4.2 -7.2 0 0.00 0.00 0.00 566 547 MON 06Z 25-FEB 0.2 -7.6 0 0.00 0.00 0.00 567 546 MON 12Z 25-FEB -2.0 -8.6 0 0.00 0.00 0.00 567 546 MON 18Z 25-FEB 6.9 -8.8 0 0.00 0.00 0.00 568 546 TUE 00Z 26-FEB 5.7 -3.2 0 0.00 0.00 0.00 566 547 TUE 06Z 26-FEB 2.1 -4.5 0 0.00 0.00 0.00 566 546 TUE 12Z 26-FEB -1.2 -6.4 0 0.00 0.00 0.00 566 544 Link to comment Share on other sites More sharing options...
Holston_River_Rambler Posted February 17, 2019 Share Posted February 17, 2019 EPS with aims the highest QPF mean into N. Alabama as of 12z today. 8-9 inch mean into N. Alabama and 7 - 8 inch mean into N. GA. Link to comment Share on other sites More sharing options...
janetjanet998 Posted February 17, 2019 Author Share Posted February 17, 2019 00z NAM NW with the first wave.(well second wave if you count tomorrow as the first)..max of 3.25 inches or so in southern KY thru 84 hour still 1.5 to 2.5 over much of eastern TN very little of it falls outside the OH valley watershed (aka south of TN river) and more over KY near the river itself Link to comment Share on other sites More sharing options...
weathertree4u Posted February 17, 2019 Share Posted February 17, 2019 I thought that I saw someone posting in here yesterday that they saw a pattern change in the extended. I am not seeing it, am I looking in the wrong place? By end of the week, I would think the region would be uniquely positioned to be experiencing flooding, not sure we are to 2010 levels yet but we have got to be getting close. Link to comment Share on other sites More sharing options...
janetjanet998 Posted February 17, 2019 Author Share Posted February 17, 2019 Hunstville ... AS ONE WOULD EXPECT FROM GUIDANCE 3+ DAYS OUT, THE PERIOD OF HEAVIEST RAINFALL NOW APPEARS TO BE LATE WEDNESDAY INTO EARLY THURSDAY DUE TO THE STALLING FRONT. AN ADDITIONAL 2-3" OF RAIN WILL FALL IN THIS PERIOD WITH LOCALLY HIGHER AMOUNTS POSSIBLE. THE STALLED BOUNDARY WILL BRIEFLY MOVE SOUTH AND EAST OF THE AREA LATE THIS WEEK, WHICH MAY INTRODUCE ANOTHER BRIEF PERIOD WITHOUT RAIN. RAIN TOTALS FROM TODAY THROUGH NEXT FRIDAY WILL BE WIDESPREAD 5-8", WITH ISOLATED AREAS POTENTIALLY 10"+. IT IS ALSO NOTEWORTHY THAT MODEL SOUNDINGS INDICATE 200-500 J/KG OF CAPE THROUGHOUT THE WEEK, INTRODUCING THE POSSIBILITY OF ISOLATED TO SCATTERED THUNDERSTORMS WITHIN THE HEAVY RAINFALL. STRONGER CONVECTION WILL LEAD TO ISOLATED HIGHER RAINFALL TOTALS. ALL GUIDANCE IS AGAIN ABNORMALLY CONSISTENT WITH ANOTHER WAVE EJECTING OUT OF THE WESTERN US TROUGH, BRINGING ANOTHER ROUND OF HEAVY RAINFALL NEXT WEEKEND. THIS WOULD CAUSE THE COLD FRONT TO RAPIDLY RETREAT AGAIN OVER THE TN VALLEY AS A WARM FRONT. WITHIN THE WARM SECTOR, THERE IS THE POSSIBILITY FOR STRONG STORMS NEXT SATURDAY INTO SUNDAY. ESTIMATED ADDITIONAL RAINFALL TOTALS FOR NEXT WEEKEND WOULD BE 1-2" ON TOP OF WHAT WE EXPECT THIS WEEK. CURRENT ANALOGIES BEING USED ARE THE FLOODING EXPERIENCED ON CHRISTMAS IN 2015, AND POTENTIALLY AS BAD AS THE SPRING FLOODS OF 2003. Link to comment Share on other sites More sharing options...
Holston_River_Rambler Posted February 17, 2019 Share Posted February 17, 2019 0z Euro still with widespread 6 - 7.5" through TN and Ohio watersheds. Some areas 8+. WPC basically sums it up. And that discussion above as well. Just amazing how wide the 7 - 10 inch field is. Weathertree I think janetjanet mentioned that a run of the GFS yesterday broke the pattern down, but (janetjanet can correct me if wrong) I took that as just a hopeful mention of what that model depicted as a way out of this awful pattern. 6z GFS is back to this; Basically GFS think we are one of the most soaked places on earth over the next 15 days. Good news is that it's just one run of the GFS. That being said, the 0z Euro really flattens the jet after day 7-8 and that would help a lot. Maybe not totally shut off precip, but at least stop this training mess. The Euro control (Euro itself run at slightly lower resolution), keeps it coming though, but with a slightly more suppressed flow. 1 Link to comment Share on other sites More sharing options...
janetjanet998 Posted February 17, 2019 Author Share Posted February 17, 2019 3 hours ago, Holston_River_Rambler said: 0z Euro still with widespread 6 - 7.5" through TN and Ohio watersheds. Some areas 8+. WPC basically sums it up. And that discussion above as well. Just amazing how wide the 7 - 10 inch field is. Weathertree I think janetjanet mentioned that a run of the GFS yesterday broke the pattern down, but (janetjanet can correct me if wrong) I took that as just a hopeful mention of what that model depicted as a way out of this awful pattern. 6z GFS is back to this; I think the GFS and GEFS had a NW flow for a few runs after next weekend for a bit yesterday,,but seems more flat now..and in end of the run is back tiothe same pattern 1 Link to comment Share on other sites More sharing options...
Holston_River_Rambler Posted February 17, 2019 Share Posted February 17, 2019 Yeah the bad part about this is that out current forecast period ends when a pattern like this is starting to become climatologically (at least in my experience) favored for this area. Link to comment Share on other sites More sharing options...
weathertree4u Posted February 17, 2019 Share Posted February 17, 2019 1 minute ago, Holston_River_Rambler said: Yeah the bad part about this is that out current forecast period ends when a pattern like this is starting to become climatologically (at least in my experience) favored for this area. Exactly! That is what I am concerned about. Personally moved from winter tracking a few days ago but knowing what I know about Spring in the TN Valley, we could be entering uncharted territory. For example, last Spring, the area just to the north of where I am got 5"- 6" of rain in a thunderstorm - May I believe - within a half hour, the large creek near me - Upper Station Camp, that flows into Old Hickory Lake - was out of its banks. Now, throw that same storm into the area this May and I honestly do not know what would happen! Link to comment Share on other sites More sharing options...
Holston_River_Rambler Posted February 17, 2019 Share Posted February 17, 2019 Big blocks being advertised by the Euro to develop across the N. Hemisphere. Hopefully if that happens they can effect some change in the pattern. But, as with all things this winter, 8 - 10 days. Looks like it might be snowy in N. Africa though. 1 Link to comment Share on other sites More sharing options...
weathertree4u Posted February 17, 2019 Share Posted February 17, 2019 1 minute ago, Holston_River_Rambler said: Big blocks being advertised by the Euro to develop across the N. Hemisphere. Hopefully if that happens they can effect some change in the pattern. But, as with all things this winter, 8 - 10 days. Looks like it might be snowy in N. Africa though. Something off the modeling this Winter or maybe it is just me or a little of both. 2 Link to comment Share on other sites More sharing options...
jaxjagman Posted February 17, 2019 Share Posted February 17, 2019 National Weather Service Nashville TN 533 AM CST Sun Feb 17 2019 .UPDATE... FOR 12Z AVIATION DISCUSSION. && .DISCUSSION... ...Heavy Rainfall and Flooding Likely This Week... A very wet pattern will be in place this week with several rounds of rainfall, heavy at times. Our latest total QPF through the next 7 days ranges from 5 to 10 inches of rainfall in Middle Tennessee. The biggest problem is exactly where the heavier amounts will occur. Each wave that moves across the area could set up a narrow axis of especially heavy rainfall, and the position of each could vary significantly or could repeatedly focus over one area. Models are varying with qpf axis, so it is important that we not focus on just one area for flooding potential. The pattern and expected rainfall will present a threat for flooding across the entire Mid State. This includes flooding of streets, low lying and flood-prone areas, streams, and the major rivers. Scattered showers and a few rumbles of thunder were ongoing at 3 AM CST. We expect a this wave of showers and isolated thunderstorms to move across the area this morning with one tenth to one half inch of rainfall, then a second wave this afternoon and evening will impact mainly the southeast half of the area with another quarter to half inch. Other than brief ponding on roads, there should not be any flood problems today. Temperatures will warm into the 50s. Showers will taper off tonight with a dry day Monday- probably the only dry day this week. For Tuesday through Wednesday, a big system will move slowly out of the Southern Rockies, setting up deep southwest flow into Tn and surrounding states. This flow will bring in upper level tropical moisture and a series of disturbances. The Gulf of Mexico will open up with development of a 40-50KT LLJ transporting abundant low level moisture directly to the Tn Valley. A surface trough will set up over Mid Tn, becoming a focus for potentially excessive rainfall. Repeated episodes of heavy rainfall are likely from late Tuesday through Wednesday with the upper flow being parallel to the low level trough axis. The rainfall intensity may ease up a bit for Thursday and Friday, then models show another surge of heavy rainfall by next weekend. Too soon for any watches today- we will continue with a Hydrologic Outlook (ESF) and heavy rain / flood potential messaging through social media. We ask local media to place emphasis on the hydro message - possible major flooding- for the entire area. 1 Link to comment Share on other sites More sharing options...
janetjanet998 Posted February 17, 2019 Author Share Posted February 17, 2019 12z NAM another inch NW bump on the "tuesday night" wave 3+ inches over central KY..most of guys about an inch edit GFS too (in thru 69 hr) Link to comment Share on other sites More sharing options...
TellicoWx Posted February 17, 2019 Share Posted February 17, 2019 SWS just issued for tonight from MRX: Heavy rain forecast for today and tonight... Showers leading to heavy rain across eastern Tennessee and SW North Carolina for Sunday and Sunday night. Up to an inch and a half is possible especially across the southern Tennessee valley and the Smokey Mountains with possibly heavier local amounts. Due to the saturation of the ground from previous rain events, most of the rainfall is expected to result in excessive runoff with some areas of localized flooding possible. Stream flooding, roadway flooding, ponding of low level areas and potential mud slides are all possible. Lesser amounts are expected for the central valley region and more northern areas of the forecast area, including the Cumberland plateau. Due to saturated soils and rainfall from the last 24 hours, some local flooding could occur in the northern areas of the forecast area as well. Link to comment Share on other sites More sharing options...
TellicoWx Posted February 17, 2019 Share Posted February 17, 2019 Picked up 0.11" so far today, and the gauge is already beginning to rise. There is zero water being soaked into the ground here, everything is going straight into the river. If we get anywhere close to 2003 level on the gauge, swift water teams will be deployed. Link to comment Share on other sites More sharing options...
TellicoWx Posted February 17, 2019 Share Posted February 17, 2019 Just had a message from Polk Co swift water team, deployed 3 hrs ago for two people submerged in a creek..unfortunately 1 fatality. 2 Link to comment Share on other sites More sharing options...
janetjanet998 Posted February 17, 2019 Author Share Posted February 17, 2019 small slight risk added for today Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 1008 AM EST Sun Feb 17 2019 Day 1 Valid 15Z Sun Feb 17 2019 - 12Z Mon Feb 18 2019 ...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE SOUTHERN APPALACHIANS... ...Tennessee Valley/Cumberland Plateau/Southern Appalachians... The 12Z hires model suite suggests multiple rounds of moderate to heavy rainfall over the next 12 hours as multiple shortwave impulses embedded within strong deep layer southwest flow advance off to the northeast this afternoon and evening. In fact, the 12Z NAM and recent runs of the HRRR guidance support a low level jet reaching as strong as 50 kts and nosing in across the southern Appalachians by around 00Z. Strengthening frontogenetical forcing, backing mid/upper level flow aloft (favoring strong deep layer jet-aided ascent) and enhanced moisture transport/convergence with PWATs increasing to near 1.25 inches should favor an axis of moderate to heavy rain across the TN Valley and adjacent areas of the southern Appalachians. A relatively broad Marginal Risk area has been highlight across these areas given concerns at a minimum over locally wet antecedent conditions. However, the heaviest rainfall amounts which may exceed 1.5 inches, through 06Z tonight should be focused over southeast TN, far northern GA and southwest NC where the best nose of the low level jet and at least some modest instability will favor heavier rainfall rates and also working in tandem with stronger orographic forcing. Given the expected rainfall, and wet antecedent conditions, it is expected that ongoing runoff concerns will be further enhanced and become more widespread. also older day 3 outlook Excessive Rainfall Discussion NWS Weather Prediction Center College Park MD 326 AM EST Sun Feb 17 2019 Day 3 Valid 12Z Tue Feb 19 2019 - 12Z Wed Feb 20 2019 ...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF THE SOUTHERN U.S. AND TENNESSEE VALLEY ON WEDNESDAY... Heavy rainfall will begin Tuesday afternoon and continue beyond the end of the Day 3 forecast period on Wednesday morning...with much of the 17/00Z guidance showing an axis of 2 to 5 inches of rainfall by the end of the Day 3 forecast period at 12Z Wednesday. Given expected rainfall rates and training of cells/repeat convection, WPC hoisted a Moderate Risk of Excessive Rainfall. A system moving out of the Southern Rockies and adjacent High Plains will induce falling surface pressure over the southern tier of states on Tuesday. Low level winds become southerly along the Gulf Coast and accelerates to between 45 kts and 60 kts by Wednesday morning. The low level jet and the associated moisture transport vectors are expected to peak between 4 and 5 standardized anomalies ahead of the system...and maximum precipitable water values increasing to near 1.75 inches along the Gulf Coast. Rainfall is expected to become more widespread with rainfall rates increasing Tuesday night due to increase low level moisture in addition to mid level shortwave energy sweeping in from the west. Aloft, the entrance region of a 160 kt to 180 kt jet will set up increasing amounts of divergence/difluence by the end of Day 3...with increasing threat for flash flooding from either cell training or multiple rounds of convection at any given spot. WPC QPF opted for a position a bit east of the 16/12Z ECMWF moisture/QPF axis (and certainly more east of the 17/00Z ECMWF run)...but not as far east at the 17/00Z operational run of the GFS largely based on the bias of each model. The idea to not be as far east as the 17/00Z GFS was supported by the 17/00Z run of the GFS-FV3 which tended to offer more support to the 16/12Z ECMWF idea. Over time, the system becomes increasingly convective and the axis of heaviest rainfall pivots from a southwest-northeast orientation on Tuesday morning to one more south-north early Wednesday morning. This is the beginning of a prolonged period of heavy to excessive rainfall event which is expected to continue well beyond the end of the Day 3 forecast. For precipitation forecasts for Thursday and beyond, refer to graphics and dicussions from the WPC Medium Range section. 1 1 Link to comment Share on other sites More sharing options...
Math/Met Posted February 17, 2019 Share Posted February 17, 2019 In addition to the flooding threat, there could also be a mountain wave event Tuesday night into Wednesday as a strong LLJ develops over the region with a favorable wind profile. With the saturated ground, these strong winds along the mountains could cause some problems as well. 1 1 Link to comment Share on other sites More sharing options...
janetjanet998 Posted February 17, 2019 Author Share Posted February 17, 2019 well the 1-3 precip updates on WPC are in so are the 4-5 days and 6-7 but the total day 5 and day 7 not updated yet.(the sum of the above)..both should be interesting to say the least..plus that doesn't include precip before 00z this evening right now weak thunderstorms training up the cumberland river watershed... so far they haven't increased outflow at lake cumberland to the 35,000 planned...lake level down only an inch since the peak yesterday over 3/4 inch at nashville so far today no2 over 7.5 for the month...should break the FEB record with ease now (11-12ish forgot the exact amount)] Link to comment Share on other sites More sharing options...
1234snow Posted February 17, 2019 Share Posted February 17, 2019 This morning’s rains have already brought .75 to over an inch for much of SWVA. Link to comment Share on other sites More sharing options...
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