ALY: First Warning of the Day

A three-body scatter spike and strong indications in the dual-pol data have led the decision to a severe thunderstorm warning for hail in southern Herkimer County, NY.

KENX Reflectivity, Velocity, ZDR, and CC valid 2012-05-16 1920 UTC
KENX 0.5-degree Reflectivity, Velocity, ZDR, and CC valid 2012-05-16 1920 UTC

Neither MRMS nor 3DVAR are as impressed with the storm.  Updraft intensity fields in the 3DVAR are rather weak, but there were indications of strong 10km (storm-top) divergence (greater than 9.5 s^-1) starting at 1915 UTC.

3DVAR Analysis Reflectivity Composite, Updraft Composite Maximum, Max Updraft Track, and 10km Divergence valid 2012-05-16 1915 UTC
3DVAR Analysis Reflectivity Composite, Updraft Composite Maximum, Max Updraft Track, and 10km Divergence valid 2012-05-16 1915 UTC

MRMS MESH has peaked under 1″ and had just a 38% POSH.

MRMS MESH & POSH valid 2012-05-16 1924 UTC
MRMS MESH & POSH valid 2012-05-16 1924 UTC

FL-LDAR domain: Lightning Jumps & HWT 3DVAR and Tor Warnings

Lightning activity has been prevalent in the FL-LDAR domain today and the ltg jump alg has detected multiple jumps in range of the domain.  Scale_0 seems to be the most stable at keeping the storms ID’s unique while scale_1 seems to be dealing with lots of mergers/splits.

In the past half hour (2230-2300 UTC) at least 3 jumps have been detected at scale_0:  cell IDs: 31025 @ 2242 UTC, 31107 @ 2245 UTC, and 31184 @ 2248 UTC (additional jumps likely occurred prior to this time).

Storm clusters at scale_0 at 2242 UTC. Cell 31025 was the primary storm of interest in the testbed.

The main cell of interest for forecasters in the HWT operating in the MLB domain has been #31025.  3DVAR products depicted increases in max updraft and vorticity as early as 2230 when the domain was re-centered over the storm.  The storm maintained its strength through over the next half hour and the forecaster opted to continue the warning at 2256 UTC (the first TOR warning issued in the HWT was at 2225 UTC, see the forecaster post associated with these warnings for more info).  The screenshots below from AWIPS2 include lightning, 3DVAR, MRMS & KMLB radar data for this event:

AWIPS2 screenshot 2245 UTC. Top left: 3DVAR max updraft composite; Top right: MRMS Refl @-10C, pGLM lightning flash extent density, & 1-min NLDN CG data; bottom left: MRMS MESH; bottom right: 3DVAR updraft helicity and 2 km winds

At the time the tor warning was issued in the HWT:

AWIPS2 screenshot.
AWIPS2 screenshot @2257 UTC: Top left: pGLM flash extent density and 1-min NLDN CG data; top right: pGLM flash initiations & Tor warning; bottom left: refl @-10C; bottom right: KMLB 0.5 deg refl

Even as the clusters have become a bit more muddled, the storm tracking algorithm has seemed to maintain a good handle on individual clusters at scale_0, though some of the cell ID’s have changed…

WDSSII image at 2324 UTC: Left: Refl at lowest altitude and lightning flash contours; right: scale_0 storm clusters overlaid on pGLM flash extent density.

SHAVE is also operational today over this same area… current reports include 1 in hail and high wind:

SHAVE data between 2200 and 0000 UTC in the Kennedy Space Center domain. Gray H circles correspond to no hail, green H circles 1 in hail, and blue W circles severe wind. Reports include 1 in hail piled against side of house & dents to truck.

Technical difficulties of note: the KML images are not currently updating on the webpage, but should be back up in the next day or two; it is also possible that cron job notification of a python script stopped running mid-day on 2 May 2012 and data between 2 May and 14 May, may need to be reprocessed to assure that jumps occurred within the network range.

-K. Calhoun

MLB: tornado warnings north of Cape Kennedy

A storm cell over Volusia County, Florida apparently ran over a sea-breeze front and developed a lot of rotation.  A hook echo on the reflectivity and strong gate to gate shear was quite evident on Melbourne’s radar.  We had been monitoring MRMS data including reflectivities at -10C and -20C.  Looking back at Convective Initiation, there was a strong signal at 2154z.

Twenty minutes later the satellite picture and NLDN lightning data looked like this:

MRMS data at 2224z showed 57 dbz echoes at the -10C level.

By 2225z, velocity data from Melbourne’s radar compelled us to issue a tornado warning.  Time from the first Convective Initiation signal to issuing the warning was 30 minutes.

After issuing the warning, we got the 3DVAR domains set up properly and here is a screen capture of the 2km vorticity and winds for the storm of interest.

Here is a four panel of various 3DVAR data for the storm at 2230z.

At the top of the hour, the storm was still quite organized, and a second tornado warning was issued.


20120515 – 2125z update 1st warning of the week

The first warning of the week was issued by the MLB team for a storm just northwest of MLB.  The MRMS and 3dVAR shows some indication of rotation with that storm between 3 and 6 km.

Updraft helicity and merged azimuthal shear layers and units are different.  How does one compare between the two?

Jim LaDue: EWP week 2 coordinator

Monitoring & Forecasting DVN Convection

Despite strong indications from the NSSL-WRF SimuSat imagery, convection in the DVN CWA has stayed rather benign.  The NSSL-WRF appears to have overestimated the low-level prefrontal moisture.

SimuSat Imagery at Top, IR Imagery at Bottom, valid 2100 UTC 2012-05-15
SimuSat Imagery at Top, IR Imagery at Bottom, valid 2100 UTC 2012-05-15

The GOES-R NearCast Theta-E Low vs. Mid-Level Theta-E image indicates very little destabilization ahead of the front (in fact, it actually indicates increased stability).  This is consistent with surface dewpoints in the 30s and 40s reported ahead of the front.

GOES-R NearCast valid 2030 UTC 2012-05-15
GOES-R NearCast Theta-E Difference valid 2030 UTC 2012-05-15

There have been a few cloud-to-ground lightning strikes just to the northeast, and the 3DVAR and MRMS data have helped to monitor the convection across multiple CWAs and on the edges of multiple radars.

3DVAR Analysis valid 2120 UTC 2012-05-15
3DVAR Analysis of Reflectivity, Updraft composite, 30 Minute Updraft Accumulation, and 1km/10km Divergence, valid 2120 UTC 2012-05-15
MRMS Surface Merged Reflectivity, -20C Reflectivity, VIL, and MESH valid 2114 UTC 2012-0515
MRMS Surface Merged Reflectivity, -20C Reflectivity, VIL, and MESH valid 2114 UTC 2012-0515

Weak Convection in the RNK CWA

We are monitoring convection in the RNK (Blacksburg, VA) CWA this afternoon, but so far the development has been rather weak.

The 3D-VAR analysis has been useful for monitoring updraft intensity and anticipating possible stronger updrafts (top-right indicates instantaneous updrafts, bottom-right indicates 30-minute updraft history).  However, none of the strong updrafts have maintained themselves beyond one “scan”.

RNK 3D-VAR valid 1900 UTC 2012-05-15
RNK 3D-VAR valid 1900 UTC 2012-05-15

The convective initiation algorithms have struggled due to all of the cirrus blanketing the northwestern half of the RNK CWA, but some clearing in the southeast has produced some CI from the UAH algorithm.  Using the new Strength of Signal output, nothing has gotten above ~50 (the included sample is just 46 in the south-central portion of the CWA), and indeed there has been little significant development in those areas.  Nothing has triggered the UW Cloud Top Cooling algorithm yet in our area as of 1902 UTC.

Convective Initiation Algorithms valid 1845 UTC 2012-05-15
Convective Initiation Algorithms valid 1845 UTC 2012-05-15


While most of the action is currently taking place south of the Border, it is close enough to be detected on radar and simulated by the 3DVAR WoF model. The Simulated Composite Reflectivity image (lower left) did a nice job of depicting the actual reflectivity (lower right) for the same time.

3DVAR: Corpus Christi 1940-1950 UTC

3 training supercells are currently moving across the northern counties of the CRP CWA.  Ryan & Jeffrey have issued TOR warnings on all 3 of the storms & have been interrogating a number of 3DVAR products and integrating them with base CRP radar data.

The maximum updraft product has quickly become a go-to for situational awareness and quickly evaluating which storms strengthening/weakening…

4 Panel 3DVAR at 1940 UTC
AWIPS2 forecaster display at 1940 UTC. Maximum Updraft (TL); Vorticity (TR); Refl at -20 deg C (BL); MESH (BR).
4 panel 3DVAR/MRMS at 1940 UTC
AWIPS2 4-panel display of 3DVAR and MRMS products at 1940 UTC: Updraft Helicity (TL), Max Low-level (1-3 km) Vorticity (TR), Merged AzShear (BL); 30 min track LL Vort (BR)
4 panel vorticity at 1950 UTC
AWIPS2 4-panel display of vorticity at 1 km (TL), 2 km (TR), 4 (BL) & CRP 0.5 deg reflectivity (BR) at 1950 UTC.

Local storm reports and trained spotters have reported a number of funnel clouds and a couple of tornadoes with the storms over the past hour.

-Kristin C.