June 2 — Timing from Flash Density to CG Ltng (CYS CWA)

While monitoring the 1-minute satellite and NLDN data, noted that the Surface Flash Density product begins to show in increase in in-cloud density about 2-3 minutes before noting CG lightning strikes.  Check out the comparison on Figure 1.

Fig 1.  NLDN Lightning Plot at 1937 UTC (L) and Surface Flash Density at 1934 UTC (R)

This appears to give a short fused indicator of CG strikes close to the flash density areas, especially as they increase. Expect to see increasing flash densities and CG lightning as the boundary moves NE through this afternoon.

CoonieCatEye

"Surface Flash Density" here refers to the Pseudo Geostationary Lightning Mapper (PGLM) Flash Extend Density product, which is showing Total Lightning (IC and CG) information from Lightning Mapping Arrays processed to an 8 km grid, similar to what we will see from the GOES-R GLM. -BL

ProbSevere on BLX storm

The ProbSevere algorithm had a notable jump on the convection NW of BLX, despite it moving into an area that may not be as hospitable for severe weather. There were two ProbSevere clusters at 1920z; the northern one had a value of 23% and the southern at 73%.

At 1926z, the two were combined into one with a ProbSevere of 66%. Since it was maturing, ProbSevere may have moved past its prime usefulness.

Jason Williams

individual cells merge into linear system near Billings

Discrete cells which showed modest growth west of Billings merged into a linear complex very close to Billings.  CIMSS prob severe model shows high degree of confidence of embedded severe potential within the line as it sweeps over the radar site. Dime size hail was reported near Billings as of 1945Z.

John Pendergrast

Bismarck, ND Discussion

Synoptic Discussion

Little synoptic change over 24 hours.  Main upper level trough remains over the PacNW with broad SW flow aloft over the BIS CWA.  Fig 1 in the top right panel shows an associated surface low slowly progressing east. This is producing  south low-level flow ahead of the low that is producing moisture advection primarily over the eastern CWA. Currently surface dewpoints are in the mid 60 east of Bismarck so cloud breaks are allowing for instability to develop. Moisture and instability are in place and trigger mechanism looks to be associated with diabatic surface heating and eroding the low-level CAP.  Surface convergence will also come in play in the surface trough areas associated with the sfc low. These are located through the central Dakotas and extending into Montana and Wyoming. By 00z Wed a secondary forcing provide by a weak vorticity center may allow for already developed convection to rapidly develop. The HRRR (fig 2)also seems to initiate convection with the small perturbation around 20Z.  Overall will focus on eastern CWA for most potent and organized convection. --Cattywampus

Fig 1:

Fig 2:



Mesoscale Discussion

The CIMSS Layer CAPE and LI products show that instability has increased over the last few hours. CAPE and LIs are highest in the south central portion of the FA with values up to 1900 J/kg and -7 respectively. The CIMSS Layer PWAT is most favorable across the eastern half of the FA with values up to 1.35 inches. The SPC mesoscale analysis shows wind shear values up to 35kts in the south central portion of the FA, so believe convection will be organized. Large hail and locally damaging winds appear to be the main threats. CIMSS

-Helen Hunt

SRSO data vs. RAP

Convection was ongoing across the area today in CYS.  This lead to a quick assessment of the weather.  Wanting to use the new data, I asked to use the 1 min srso wind data as well.  This shows that there is a weak 50kt + jetlet moving across the cwa.  This suggests that deep layer shear is larger than previous suggested by the RAP.  As storms move to the east across the cwa, I’m expecting the storms to become more organized.  With dewpoints in the 60s across this area, would not be surprised if we start getting some severe weather soon.

MacGyver

LAP and Montana convection

GOES-derived LAP products indicate a swath of higher instability across the southwestern part of the BYZ CWA. A storm cluster is moving northeast out of this zone of higher instability. Per the LAP products, I would expect the storms to diminish in intensity. Will provide an update on whether or not that occurs.

Jason Williams

Environmental setup for eastern Montana this afternoon

A review of the Sounding from GGW shows an elevated unstable layer with sufficient moisture for ongoing storms through the afternoon.  It looks like the primary threat from convection will be the possibility of some coin size hail and high convective wind gusts in the strong or severe cells which develop.  Current radar shows scattered multi-cellular storms west of Billings will be moving through the region with a general increase in coverage expected through mid-afternoon.

Pendergrast/Jason Williams

Daily Summary: Week 4, Day 1 (June 1, 2015)

After a week off, the EWP Spring Warning Project resumed in the Hazardous Weather Testbed. With much of the first 3 weeks of activities taking place in Texas, it is refreshing to have a change in the weather pattern, taking us north this week. Today, we had our 3 pairs of forecasters operate in the Bismarck, Pocatello, and Pendleton CWA’s. It is beneficial to have the algorithms evaluated in a variety geographic regions, so today’s northwest convection was welcomed. With a slow start to convection, participants had ample opportunity to become familiar with all of the GOES-R and ENTL products under evaluation. By the end of the day, as convective activity amped up, participants were comfortable using the products to issue short-term forecasts and warnings.

Tomorrow’s activities will begin at 1 pm, and will likely make a slight shift eastward with the most active convective weather.

– Bill Line, SPC/HWT Satellite Liaison and Week 4 EWP Coordinator

Forecaster comments from debrief:

GOES-R LAP products
- It was useful in the pre storm environment, looking for most likely areas for convection to fire.
- It was a nice SA display.
- At first there weren’t much in terms of trends, convection didn’t go till late, we did notice one area in ND Montana border that was persistent with instability, that’s where we focused,
- It showed LL PW increasing, southerly flow advecting moisture.
- I liked having the 3 layers of moisture, especially being out west

NUCAPS
- Looked at 19z pass, mid afternoon, sampled clear areas in east Pocatello, confirmed elevated convection. PW fairly low. Good representation of current state of atmosphere
- Give you a general idea of how the atmosphere has evolved  since the morning.
- Edited for sfc temp and dp, gave us pretty good cape,
- Color code dots to highlight good/bad profiles (QC)

GOES-R CI
- Never got high probabilities in Bismarck. When you looped you could kind of see a trend. There was a lot of cirrus so that could have led to some contamination. So we weren’t too thrilled with it.
- In Pocatello, you saw increasing probs on leading edge of convection, and that's where stuff developed, did good job of indicating development
- I was impressed with how well the ci product was able to pick out individual cloud elements, and track those.
- We had convection ongoing when we sat down, but looking at ci further west, and had values that helped.

- Convection east of Bismark developed and had no ci at all

ProbSevere
- One we warned on, it went from nothing to 90% within a few scans, really good indicator that storm was strengthening fast
- Couldn’t get long lead time, it was good to look at to draw attention to strongest cells
- One convo we had, in typical short lived multi cell events ~ usually issue for 30ish minutes. Using prob severe, you should go out longer with warning cause you are getting more lead time. After first warning, we wrote longer
- Good in triage situation, with lot of cells on radar, in picking out the most noteworthy ones.
- Would be good to use in southeast for popcorn convection, when you have little time to make decision, prob severe could increase lead time and pinpoint storms
- Yesterday, popcorn convection in Bismark, very low probs, but drew us to the storms
- Case where there was a tbss showed up same time probsevere jumped over 50%, having probsevere match with this gave extra confidence that something else was showing this too.
- Unobtrusive display, easy to read, easy to put on combo rotate, doesn’t take away form viewing other data
- I like the sampling associated with cursor readout
- Weren’t getting glaciation because of cirrus deck
- Were using mesh from readout to decide what size hail to go with. Nice having it there in display

SRSOR
- Using super rapid scan, could see bubbling
- Loved it, cause you could see the cells bubbling up, it was smooth and continuous, rather than 15 or 5 min imagery
- Looking at cu fields evolving quickly, prepares you for what to see on radar
- From broadcaster perspective, waiting 15 min for vis sat to update, if we were to have 1-min updates, to be able to pick out where cu field is bubbling up more, is something we’d absolutely love to see and use
- Easier to see the trends.
- If you can see the way things are evolving before they evolve, before issuing warnings, could increase lead time to calling someone in, or holding someone over
- Last week in my office, one of the guys said this is probably the first time I used sat in warning ops, and it was great … davenport
- Especially out west, we have radar void areas. Seeing this, seeing it evolve and live, that catches your eye.
- Already being used in real life warning ops
- Not just weather porn, it is actually useful
- Sea breeze fronts
- Extremely important for fire weather, picking up fires.
- Out west, lots of dust storms, seeing that come

- We could see this being useful every day, in many situations

Lightning jump
- Using base data and DP, we had a good idea for storm, looking at it after the fact it agreed. Definitely a confidence booster.
- We used it quite a bit, to help direct us to the strongest storms, interesting to compare lightning jump to probsevere... some cases where lj jumped, and probsevere after, and opposite
- Display with different sigma, I don’t see what point of showing dark objects with -999
- 11 sigma jump with smaller scale, nothing with smaller scale
- In SC, would be good during summer for SVS

ENI compared to LJ

I’ve noticed a few cases today where the Lightning Jump Algorithm and ENI polygons and time series data do not line up as I might have imagined. Lightning jump is based on radar data whereas the ENI polygons and time series data use the Earth Network lightning data. Beam blockage due to the terrain in the Pocatello CWA may have affected the radar data going into the lightning jump which may account for some of the differences.

In the example below, the lightning jump algorithm shows a value of 6 sigma at 2301Z whereas the ENI time series shows only a relatively small increase in lightning activity at this time.

-Helen Hunt

6/1/15: 1st Severe TS Warning

We issued our 1st SVR at 2246Z. This decision was based on a combination of basic base data interrogation. Solid core of 50dbz with 65+dbz at 0.5 degrees. Dual-Pol showed signs of a TBSS in ZDR and CC radially behind the core.

In terms of experimental tools we noticed the Sigma Jump of 2 at 2237Z, then next scan showed an 11 Sigma. This can be seen in the gif loop below.

Figure: Gif Loop of reflectivity and Sigma for lightning

Fig 2: Plot of the the ENI lightning jump near the time of the warning.

It is interesting to note that the ENI lightning jump plot showed this rapid jump as well (fig 2). At this time the rapid jump could have also demonstrated a cell merger in conjunction with intensification of the southern cell which also demonstrated a low level mesocyclone along with a POSH/POH of 80/100 and MESH of 1.25″ (fig 3).

Fig 3: 2246Z, Low level circulation and hail indicator on the HC plot.

Forecasters: Cattywampus/CoonieCatEye