Last spring, 6 forecasters from both WFO Raleigh NC (RAH) and Peachtree City GA (FFC) participated in the Phased Array Radar Innovative Sensing Experiment (PARISE). The project was motivated by the potential use of phased array radar (PAR) in the future. Phased array radar (PAR) may have update times of a minute or less which would likely be of great benefit to meteorologists during rapidly evolving weather, especially convection. PAR would also bring some potential issues with the higher-temporal resolution of the radar data which could make information management an issue during the warning decision making process. The 2013 experiment built off previous experiments in 2010 and 2012 which all had the goal of determining the extent that higher-temporal resolution radar data can be effectively used during severe weather. Results from that experiment were shared at the 30th Conference on Environmental Information Processing Technologies in February 2014 – Katie A. Bowden, CIMMS/Univ. of Oklahoma, Norman, OK; and P. L. Heinselman, D. M. Kingfield, and R. P. Thomas. The experiment found that traditional verification numbers including POD, FAR, and lead team were all better with the PAR when compared to the traditional radar products currently available to forecasters . Additional information is available at the links below:
Links to an abstract, a recorded presentation, and manuscript:
Another presentation on the project:
Project web page:
On Wednesday, May 28, 2014, beginning with the 1200 UTC run, NCEP will upgrade the High-Resolution Window Forecast System (HiResW). The upgrade includes changes to the model components, increases in horizontal and vertical resolution, changes in parameterized physics, product fields, and more.
Here are a few of the highlights:
- The WRF-ARW model horizontal resolution will increase from 5.15 km to 4.2 km (CONUS) and change to WRF Version 3.5 code.
- The WRF-NMM model horizontal resolution will increase from 4.0 to 3.6 km (CONUS) and will be replaced by the Nonhydrostatic Multiscale Model on B-grid (NMMB).
- The number of vertical levels will increase from 35 to 40 in both the new WRF-ARW and NMMB systems.
- The WRF-ARW will change from the use of WRF Single Moment 3-Class (WSM3) microphysics to WRF Single Moment 6-Class (WSM6) microphysics.
- Ferrier microphysics used with WRF-NMM will be updated to the Ferrier-Aligo microphysics in NMMB.
- The new CONUS domain interpolates an initial condition from the Rapid Refresh (RAP) model, with boundary conditions generated from the Global Forecast System (GFS) model. The current West and East domains are initialized using North American Mesoscale (NAM) model conditions for initial and lateral boundary conditions.
More complete details on the model changes can be found in the Technical Information Notice at: http://www.nws.noaa.gov/om/notification/tin14-16hiresw.htm
Matt Pyle of EMC has set up a website to include plots of output from the parallel (future ) HiResW compared to that of the production (current) HiResW. Note that the production HiResW is using ARW and NMM, whereas the parallel is using ARW and NMM-B. The web site may be viewed at: http://www.emc.ncep.noaa.gov/mmb/mpyle/hiresw/ while shortcuts to the pages are shown below. These links will also be added to the NWS RAH High Resolution NWP Reflectivity Comparison web page which can be viewed at: http://www.erh.noaa.gov/rah/hiresnwp/
00Z ARW Simulated radar reflectivity (dBZ), 1000 m AGL
00Z NMMB Simulated radar reflectivity (dBZ), 1000 m AGL
12Z ARW Simulated radar reflectivity (dBZ), 1000 m AGL
12Z NMMB Simulated radar reflectivity (dBZ), 1000 m AGL http://www.emc.ncep.noaa.gov/mmb/mpyle/hiresw/conus12/combonmmb.refd1000_animate_1h.html
00Z ARW and NMMB Multiple fields
12Z ARW and NMMB Multiple fields
The severe weather event that unfolded in central NC during the evening hours of March 29, 2014 was notable for several reasons. Although diurnal destabilization in central NC was severely limited by widespread cloud cover, intermittent showers, and weak mid-level lapse rates during peak heating, strong synoptic ascent /layer-lifting/ in the presence of a convectively unstable airmass (associated with a drier mid-level airmass advecting atop an unseasonably moist boundary layer) resulted in an atypical thermodynamic setup in which marginal to moderate destabilization (500-1000 J/kg mlcape) occurred after peak heating during the early evening hours. This in of itself is worth another post, as I think it highlights some of the inherent limitations in convective parameters and the necessity of performing a thorough environmental analysis using data from a variety of remote sensing platforms, observations, and short-term model guidance.
The animated GIF below shows a 4-panel loop of REF, SRM, VEL and CC from 0.5 to 2.4 degrees of the 0111Z volume scan from KRAX. This is an excellent example of a subtle tornadic debris signature associated with a supercell observed within several miles of an 88D. Note that the ‘hole’ in CC (values 0.60 to 0.90) is co-located precisely with both the velocity couplet and the reflectivity ‘ball’ within the hook. Vertical continuity (including a down-shear tilt) of this feature from 0.5-0.9-1.3-2.4 degrees and the lack of such a feature prior to when the supercell arrived or after it departed provide compelling evidence for a tornadic debris signature. A weak (EF-0) tornado was indeed confirmed at this precise location/time in southeastern Wake county (see damage survey PNS below).
0.5,0.9,1.3,2.4 degree 4-Panel Loop of REF,SRM,VEL,CC at 0.5,0.9,1.3,1.8 degrees on the 0111Z March 30, 2014 Volume Scan at KRAX
In case the aforementioned radar loop did not attach properly, you can also find it at:
March 30, 2014 0111Z 1.3 deg 4-Panel from KRAX with subtle tornadic debris signature
...TORNADO CONFIRMED NEAR GARNER IN WAKE COUNTY NORTH CAROLINA...
LOCATION...GARNER IN WAKE COUNTY NORTH CAROLINA
ESTIMATED TIME...0908 PM EDT
MAXIMUM EF-SCALE RATING...EF0
ESTIMATED MAXIMUM WIND SPEED...80 MPH
MAXIMUM PATH WIDTH...75 YDS
PATH LENGTH...1/8TH OF A MILE
* THE INFORMATION IN THIS STATEMENT IS PRELIMINARY AND SUBJECT TO
CHANGE PENDING FINAL REVIEW OF THE EVENT(S) AND PUBLICATION IN
NWS STORM DATA.
THE NATIONAL WEATHER SERVICE IN RALEIGH NC HAS CONFIRMED A
TORNADO NEAR GARNER IN WAKE COUNTY NORTH CAROLINA ON 03/29/2014.
PER EYEWITNESS AND A DAMAGE SURVEY...A WEAK EF0 TORNADO OCCURRED
SHORTLY AFTER 9 PM AT THE INTERSECTION OF TREBOR DRIVE AND CROSS
POINTE LANE. A RESIDENCE SUSTAINED PARTIAL ROOF DAMAGE WITH A
COUPLE OF WINDOWS BROKEN AND A COUPLE OF TREES DOWN.
Based on feedback, Dr Parker at NC State updated and expanded the online model plots of SHERB recently.
Some of the improvements include:
1) SHERBS3 is now only shaded where MUCAPE>0 J/kg and/or MULI < +6 K
2) The SHERBE is now available
3) A new “compare” link allows you to loop through images with SHERBS3 and SHERBE side by side
4) RAP data has been extended to 12 hours. GFS/NAM imagery is available at 3 hour intervals through 36 hours, then 6 hour intervals through 84 hours.
5) The color scheme for SHERB has been improved to emphasize resolution in the 0.5-1.5 range
6) There is now a full archive of all images available online (the link is available by request)
In case you’ve misplaced them, the relevant links are:
Real-time RAP – http://storms.meas.ncsu.edu/users/mdparker/rap
Real-time NAM – http://storms.meas.ncsu.edu/users/mdparker/nam
Real-time GFS – http://storms.meas.ncsu.edu/users/mdparker/gfs
We have a pretty dynamic set up coming into the southern part of the study area on Sunday. Looking at 18Z Saturday run of the 12km NAM, the model is hinting at a comma-shaped MCS moving through southern Georgia. These images show surface pressure, winds, and model simulated surface reflectivity starting at 18Z Sunday every 3 hours.
SHERB values are quite high, but instability is poor over the northern half of the region of interest. These images show the SHERB along with the surface-based CAPE during the same time frame.
The darker green shading indicates SHERB values greater than 1.
It seems as though the strongest “bullseye” of SHERB values stays just north of the surface-based CAPE (in this model, of course) tomorrow afternoon and evening, at least in relation to the CHS CWA. It’s going to be close, though, and makes for an interesting forecast. We could see some pretty good rotations to the west of the area on radar with those kind of values, making the radar operator a little nervous, even though the instability will be minimal.
The project entitled “Improving Understanding and Prediction of High Impact Weather Associated with Low-Topped Severe Convection in the Southeastern U.S.” will be led by Drs. Matthew D. Parker, Gary M. Lackmann, and Lian Xie of N.C. State University in collaboration with nearly a dozen WFOs in the Southeast along with the Storm Prediction Center. The three-year project is being funded as a part of the NOAA/NWS Collaborative Science, Technology, and Applied Research (CSTAR) Program. This project will build off of previous collaborative research between N.C. State and the NWS which have had very successful research to operations results along with the integration of students into NOAA and the NWS.
Severe convective storms in environments with large vertical wind shear and marginal instability (so-called “high-shear low-CAPE”, or “HSLC” events) represent a significant short-term, high-impact forecasting and warning challenge, particularly in the Southeastern and Mid-Atlantic states of the U.S. Such environments account for a substantial fraction of severe wind and tornado reports in the region, and they are present for many hours each year. The long-range goal of the research is to improve predictions and warnings for hazardous weather in HSLC environments.
The research will be conducted through a set of complementary collaborative research studies including:
(i) The project intends to advance the understanding and interpretation of HSLC radar imagery by performing idealized simulations of HSLC convective storms, within which we will study the dynamical processes at work and compare them to pseudo-radar measurements of the simulated storms.
(ii) The project also intends to improve short range prediction and situational awareness of HSLC scenarios by evaluating a suite of convection-allowing hindcasts of notable HSLC events and nulls and testing the sensitivity of these hindcasts to grid spacing and model configuration.
(iii) The project hopes to improve short-to-medium range prediction and situational awareness of HSLC scenarios by applying dynamically-based statistical downscaling techniques in order to exploit the information available from operational model ensembles.
(iv) Finally, the project intends to improve operational “best practices” in HSLC environments by coordinating an assessment of a number of experimental HSLC diagnosis and forecast products within NOAA.
The threat of severe weather across the Mid-Atlantic and Southeast has been well advertised with the initial threat noted in the “Day 5″ portion of the SPC 4-8 Day Severe Weather Outlook issued on 17 February. Today’s potential for severe weather is focused on damaging wind gusts while brief QLCS events could result in short episodes of an increased tornado threat.
For multiple days the SHERB parameter has highlighted the potential for an enhanced severe weather threat associated with a High-Shear Low CAPE (HSLC) environment on the northern periphery of region of more favorable surface-based instability located across southeastern NC and SC. The SHERB parameter was developed as a part of an NC State-NWS CSTAR project. You can learn more about it in a PDF version of a presentation entitled Improving Forecasting of High Shear, Low CAPE Severe Weather Environments.
SHERB guidance from multiple runs of the NAM and other NWP sources have shown an enhanced HSLC threat across northeastern NC and southeastern NC this afternoon, centered around 18 UTC, with SHERB values greater than 1 (see the first image below). These locations are forecast to have an air mass characterized by SBCAPE values of around or possibly a little more than 500 J/Kg and MUCAPE values of close to 1000 J/Kg, meaning they are a borderline HSLC case (see 03Z SREF forecast for KRDU valid 18z in the second image below). Despite the more limited surface based instability in these regions than locations further south, the SHERB highlights this region as especially susceptible to severe weather which is consistent with the 12 UTC SPC Severe Weather Outlook.
Realtime NAM – http://storms.meas.ncsu.edu/users/mdparker/nam/
Realtime RAP – http://storms.meas.ncsu.edu/users/mdparker/rap/