PHS Reflectivity Forecast Helping Out with DSS

The Panda Ceremony was held at the Jackson, MS Zoo on the evening of Wednesday, Jun 14, 2023.  Strong to severe storms were forecast throughout the afternoon and evening hours and the event coordinator requested DSS for lightning and any severe weather with as much lead time as possible.  Using the 14.16z initialization of the PHS reflectivity was useful in providing some timing details to the event coordinator (See Figure 1). It suggested a fairly robust storm to roll through the Jackson area by around 00z with the forecast reflectivity ranging from 50-65 dBz directly over the event site.  

The reflectivity forecast did well with depicting a fairly large storm to move across southern Mississippi but was a bit too north on the location.  Overall, the product was very useful in boosting the forecaster’s confidence in the convection timing to impact the event. See Figure 4 for a look a the verification.

Figure 1: Loop of the 14.16z PHS layer reflectivity had a large storm over Jackson, MS, and impact the event (black range ring) by 00z.

Figure 2: A DSS Graphic was issued shortly after 3 p.m. to highlight the timing and potential impacts of the Panda Ceremony.  The original image had the animated GIF above with the PHS reflectivity forecast.

Figure 3: This was the first of 3 graphics created for the event and this graphic highlighted the severe weather threat and timing.  Overlaid is the MRMS reflectivity greater than 35 dBz and OCTANE Winds.

Figure 4:  A loop of MRMS with ProbSevere and LightningCast shows some verification of the PHS reflectivity forecast shown above. This loop ends at 2232z.   

– Podium

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Day 3 Review of Products & Operational Applications

I took on the warning forecaster role during the operational period today. A supercell was underway at the start of the period, so I began by issuing a Severe Thunderstorm Warning. ProbSevere was (unsurprisingly) indicating a slam dunk for severe wind and large hail (Figure 1) but I noticed when sampling the ProbSevere data that MESH was slow to pick up on just how large the hail was with this storm. A broadcast meteorologist passed along a report of 5-inch hail at 2000z, but MESH did not indicate 4+ inch hail until 2020z.

Figure 1

I also noticed that PHS composite reflectivity was much too slow with the progression of convection across the SHV CWA. Below are a screenshot of PHS progged composite reflectivity at 21z and a screenshot of the radar 0.3 degree reflectivity at 21z. PHS expected the supercell of interest to still be located over the northeast portion of SHV (Figure 2) while in reality the supercell was about to exit the easternmost fringes of the CWA (Figure 3).

Figure 2

Figure 3

Once the aforementioned supercell exited the SHV CWA, we pivoted to the LZK CWA to monitor the ongoing convection there. I decided to interrogate the OCTANE products because I hadn’t looked at much satellite imagery thus far.

OCTANE was especially useful in two ways today:

  • OCTANE Speed indicated a storm split underway as two speed maxima can be seen in the red-orange hues (Figure 4, top left panel)
  • I tweaked the AWIPS colormap for OCTANE Direction to better depict the storm-top divergence occurring (Figure 4, top right panel)

Figure 4

– Vort Max

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6/14/23 HWT – SHV

Operational window encompassed ongoing severe storms at the start of the period which moved eastward out of the CWA by mid afternoon. The resultant outflow boundary / cold front intersection to the west of the CWA become the focus regions for potential for renewed storm development.

NUCAPS 6/14/23 19z sounding south of the outflow boundary of interest compared to nearby surface observation showed a large discrepancy in observed surface conditions (90/72 at nearby ASOS). This raises considerable questions on how these soundings are to be best utilized in operations.

OCTANE was useful in monitoring the attempted updrafts along the outflow boundary. It seems to show updraft growth more clearly than the day cloud phase product. I would like to see these data incorporated into the LightningCast model as this product is also very good at highlighting potential areas for CI.

OCTANE output was also viewed  in a region of a splitting supercell across western AR. Good conversation with developers on further development of the wind retrievals with observational data constructed hodographs being an operational request.

Utilized LightningCast to highlight the region of concern for new storm development. The storms did develop but it was a more gradual evolution. The highlighted region did verify as the region of development.

ProbSevere did a great  job as a safety net for radar warning operations. The element trend window is a helpful addition.  Talked with the developer on potential marking times along the time series where the element changes ID or grows in area to show when ProbSevere has merged or separated elements as this impacts resultant probabilities.

PHS model output from the 16z run was viewed online and compared to the corresponding HRRR. At the time of the exercise conclusion its solution had verified better on composite reflectivity than did the HRRR. A product in AWIPS highlighted regions where the fusion data is different than a zero hour model output would be beneficial for situational awareness and potentially for model output utilization.

– jbm

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PHS Blog Post AMA 6/13

PHS today was interesting given some of the local convective parameters. The main one that caught my attention was the lesser 0-6km bulk shear that it was giving just ahead of an incoming storm in the Oklahoma Panhandle. The PHS was around 20-30 knots whereas other guidance and SPC Mesoanalysis was showing 50+ knots. I did look at other parameters such as MUCAPE and SBCAPE for example and they were in the ballpark of other guidance including SPC Mesoanalysis.  If the PHS was correct then the storm mode would feature more multicell with some organization vs more of a discrete supercell mode so it was going to be interesting to see what would occur. 

What wound up occurring was a persistent long track supercell along with other convection which was anticipated given the PHS wind shear.  Overall, I was impressed with the PHS wind shear forecast as that tailored away any thinking that there may be additional supercells as additional updrafts would interfere with the intensification of other cells. The PHS however was around 1-2 hours slow with convection moving into the AMA CWA, however the composite reflectivity forecast did show more of a cluster of storms developing. The PHS was also showing a corridor of stronger 0-3 and 0-1 SRH which in reality the intense cell did move through and actually wound up producing a few tornadoes. The ProbTor was also showing tornado potential as high as 40% as it was moving through this corridor.  Overall, I was impressed with the PHS today and think that it could create good DSS messaging opportunities along with being skillful in Mesoanalysis.

PHS showing the lesser values of 0-6 bulk shear in contoured form

SPC Mesoanalysis depicting the 0-6km bulk shear at the same time

How the radar wound up turning out at 2130Z with the multiple cells

– Tor Nader  

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DFW and TAE HWT Feedback for 6/13

General question overall, can the units be displayed in fraction form instead of with a (-1 or2)?  Such as m/s instead of m*s-1?

PHS

Can temperature units be in F or even C instead of K?

Is 0-1 KM bulk shear AGL?

Could the bulk shear be in knots instead of m/s?

Can the bulk shear vectors and mean cloud wind vector (or 850-300mb wind) also be plotted?  This can help with determining storm mode. 

The PHS had storm coverage well matched with radar when simulation started.  However it was about 3 rows of counties too far north than what actually was happening.  This led me to believe that all the other data with PHS was also shifted north for what was actually happening.

Could mixed layer CAPE/CINH be added to the stability menu?  I think SPC’s mesoanalysis page defaults mixed layer to 100mb.  We use mixed layer CAPE quite frequently at our office.

Having DCAPE as a viewable product would be very helpful to diagnose a severe wind threat from supercells.

Noticed the PHS surfaced based CAPE/CINH matched quite well with mesoanalysis except for the CAPE/CINH just north of FL.  Both images are from 21z.

LightningCast

Helped maintain awareness about the overall threat for lightning, especially on the outskirts of the storm.

NUCAPS

Noticed the ML CAPE was much further east than what happened.  Of course this was from the morning overpass, not the afternoon one.

Did notice that the ML CAPE was lower than the surface based and MU CAPE.  Was going to look at a NUCAPS sounding to determine why that may have been the case.  However was not able to do that due to no data aside from the morning run. ML CAPE is on the left, MU CAPE is on the right below.

Prob Severe

Is there a way to highlight which storm Prob Severe is showing the trends for?  When I am looping the radar with multiple storms on it (example image below), I quickly lose track of which storm I had the trend graph displayed for.  Really like the ability to look at the trends graphically through AWIPS instead of having to go to the webpage to do so.

Noticed the readout only displayed above the pointer, not below.  The right image is what happened when I tried to sample the Prob Severe data.

Could there be an option to select the different fields we want Prob Severe/Hail/Tor/Wind to show?  There is a lot of data there, good data, but at the same time too much to look at during storm interrogation.

Does ProbTor calculate QLCS tornado probability?  This would help build confidence for issuing these kind of tornado warnings because the environment can change so rapidly from one radar scan to the next.

OCTANE

This helped me really see the updraft divergence of the cells.  This was in deep layer shear environment of 20 kts.  Neat to see the divergence weakening on the middle bottom cell in the upper left pane weaken as the cloud top temperatures warmed for that cell, confirming that the updraft was weakening.

– Rainman

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6/13/23 EWP Blog Post – SHV

Active CWA assignment today. Warning issuance followed by the log form entry was somewhat cumbersome and time consuming but I understand the reasoning. 

Great interaction with the subject matter experts and their insight and comments were much appreciated. 

Good discussion on the potential uses of the OCTANE data. My CWA partner mentioned constructing real time hodographs that could be sampled. This is a good idea. The mental exercise to visualize the wind profiles from the height / direction/ and magnitude data is taxing to me and I think would be too time consuming in operations. 

Developer stepped through the awips imaging method to highlight specific layer winds and I found this very helpful. A layered wind four panel procedure would be helpful. Also good discussion on reaching for storm scale signals in the wind fields and whether wind speed data bins could be higher resolution than radar at high elevations and distance from radar. An intense left moving storm during this exercise window across NW LA into far SE OK showed strong anvil level divergence that persisted for an extended period.

Screen capture of the ice machine and intense three body scatter spike that persisted for close to an hour at least. Probsevere was very good especially once the tracking element was assigned to just the primary updraft. I issued several warnings during the exercise window and utilized probsevere on each one. The time trend window is great and I hope it gets to the operational version soon.

The PHS idea of better utilizing sampled profiles seems good to me. I would prefer it not be solely validated by WRF model output. I like the idea of showing where the fusion data senses departure from model initial conditions similar to shown on  this website:   cas.hamptonu.edu/~adinorscia/InteractiveMap/FusionMap.html

NUCAPS data today  was from the previous run with the 10-12 hour forecast near the exercise valid time. I compared the 11 hour NUCAPS forecast to the zero hour RAP analysis for MUCIN across the exercise domain. There was a large discrepancy between the two. Due to convection that had spread across this region earlier in the day I discounted the NUCAPS data. In this instance the NUCAPS forecast would have been viewed as suspect and likely would not have been used.

– jbm

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Assessing Potential for Additional Severe Convection in ABQ June 12, 2023

Our group role played as ABQ on June 12, 2023, where severe convection was already underway in the northern third of the CWA during the early to mid afternoon. Rather than interrogating ongoing storm strength and hazards, we were curious as to whether or not additional severe convection was possible south of the current convection. In essence, we were performing tasks of a mesoanalyst.

The synoptic environment was composed of upper troughing over the Great Basin region, with a stout, unseasonably strong mid to upper level jet at its base overspreading New Mexico, and a shortwave trough pushing out of the Four Corners into southeastern Colorado as well as northern New Mexico. GOES-16 mid level water vapor imagery showed the location of the bulk of synoptic forcing through steadily cooling brightness temperatures (not associated with deep convection). Overlaying NAM 500mb geopotential heights helped illustrate where strongest height falls associated with the shortwave trough were located. In this case, strongest height falls/cooling brightness temperatures were located within southern Colorado into far northern New Mexico, and was driving the ongoing severe convection in northern ABQ. However looking south and upstream within central New Mexico, there were still cooling brightness temperatures within water vapor imagery, just not as robust relative to the north. This implied there was still some synoptic forcing for ascent to overspread areas like San Miguel, Guadalupe and De Baca counties, the counties we were most interested in for additional initiation.

Another display we referenced to assess low level moisture content was GOES “Clean LWIR 10.3um – Dirty LWIR 12.3um” Split Window Difference sandwiched with visible imagery to show current areas of Cu development/maintenance. This showed low level moisture pooling up nicely along higher elevation of the Sangre de Christo Mountains southward to the higher elevations along the western flanks of the southern High Plains, along with agitated Cu at the terminus of these moisture gradients. Additionally, local areas where there were easterly pushes of the moisture gradients suggested dryline dynamics were at play, potentially providing additional forcing for ascent.

After assessing the current state of the environment, we referred to PHS Layer Composite Reflectivity, which is simply just simulated reflectivity offered by the WRF that runs within PHS environment that incorporates latest hyperspectral sounder information on thermodynamics via polar orbiting satellites while merging it with the motion and high spatiotemporal resolution of GOES ABI . The 18Z model run indeed sparked additional convection off of the higher terrain within Guadalupe County.

So in the eyes of this model, the potential was still there. It was also nice to compare current radar (in this case MRMS Composite Reflectivity) in the same display as PHS reflectivity to see how the model was performing in this aspect thus far.

But let’s not take this for face value as this is modeled convection. We desired other datasets to help provide insights on the thermodynamic environment that may play a role in allowing additional convection, or lack thereof. With this, we referenced other datasets within PHS:

This display shows MRMS Composite Reflectivity and surface observations overlaid with PHS thermodynamic parameters in the top and right halves, and shear parameters in the lower left. Focusing on the two right panels, PHS suggested moderate instability (~1500 – 2500 J/kg) lee of the southern Sangre de Christo Mountains into the southern High Plains of northeastern New Mexico, with perhaps slightly lower instability within Guadalupe and De Baca counties. More interestingly was the stark increase in LCL heights within these counties compared to the environment just to its north. This raised a yellow flag, leading us to to think thermodynamics may not be as favorable as the area with current convection. Perhaps relatively drier air may be located in this area of interest compared to that currently driving convection? We referred to other satellite-derived datasets like NUCAPS soundings, Gridded NUCAPS and NUCAPS-Forecast (not shown) to assess upstream mid level moisture (namely 700 mb RH) advecting into the area, of which reveals a well developed and strong EML with notably strong inversion nested around 700 mb. We also referenced PHS CIN (not shown) which exposed a relatively higher area of capping in this same area where LCLs were higher.

It was nice having the high spatial and temporal resolution offered by PHS when performing mesoanalysis, and in my opinion had an advantage over objective analysis (e.g. SPC Mesoanalysis), with its higher resolution and ability to step forward in time on an hourly basis.

Here is the full loop of this PHS display between 18 UTC to 23 UTC:

Within our area of interest, the considerations of relatively higher CIN, strong EML advecting over this area, relatively weaker forcing compared to points north, we had some concerns that sustained convection would develop, but we still didn’t discount the possibility should enough subtle forcing via synoptic (DCVA/height falls) and mesoscale (dryline) lift contribute together to overcome locally higher capping likely in place. Ultimately, we gave around a 20-30% chance of additional severe convection within Guadalupe and De Baca counties in the next 1-3 hours starting at 21Z.

Just before today’s HWT window closed, OCTANE hinted at attempts of deep convection within central San Miguel County via the warming colors collocated with agitated Cu turned orphaned anvils behind exiting deep convection. This was advantageous as it caught our eye perhaps faster than Day Cloud Phase Distinction RGB indicated for attempts at deep convection.

Ultimately, deep convection did not occur within Guadalupe and De Baca counties.

– OSMBLSN     

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Comparing PHS Data with SPC Mesoscale Analysis and MRMS Data

The first day was slightly overwhelming with all the different products to test out this week. I decided to focus on one of the products I was unfamiliar with and that was PHS data. I compared PHS SBCAPE/MUCAPE values from the 12.14z model run to the latest SPC Mesoscale Analysis data. At first glance, the PHS SBCAPE/MUCAPE values depicted were generally higher over southern Colorado and northern New Mexico than the SPC data. However, I did notice a small bullseye of CAPE minimums in south-central Colorado and was curious about why that was depicted (See Figure 1). The SPC data was not as detailed with the gradients and had no mention of the minimum in south-central Colorado (See Figure 2). Thankfully, one of the developers was in the room and mentioned that the model might be depicting storms in that location. I loaded up the composite reflectivity from PHS (See Figure 3) and sure enough, PHS was suggesting storms in south-central Colorado.

Figure 1: Top image shows PHS SBCAPE at 20z with a minimum in south-central Colorado.

Figure 2: The bottom image is the SPC Mesoscale Analysis at 20z.

The composite reflectivity had the right idea with convection near that location compared to MRMS data. It was slightly further north with the maximum dBz values, but for an 8-9 hour forecast, it depicted the convection fairly well IMO.  The PHS did much better with the convection over the northern portions of PUB CWA as it showed a decent line of storms at 22z which matched up well with MRMS.  For obvious reasons, this model could certainly be helpful in providing higher confidence in convective storms for various NWS partners and DSS events.

Figure 3: top loop showing the PHS layer composite reflectivity.  This is the 12.14z model initialization.

Figure 4: MRMS loop of the composite reflectivity for the hour of 20:00z to 21:00z.

– Podium

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Day 1 Review of Products & Operational Applications

OCTANE-Direction

  • Distinguish different air masses when they are characterized by different advection regimes
    • Stable cloud streets in magenta (Figure 1)
    • Agitated Cu and deep, moist convection in yellow/green (Figure 1)
  • Locate boundaries
    • Identify areas of convergence based on the depicted flow directions
  • Suggestion: it would be great to be able to sample the cardinal direction (i.e. NW, SE) in AWIPS in addition to the direction already given in degrees

Figure 1

NUCAPS & PHS

  • Attempts at convective initiation failed over Guadalupe County and De Baca County… but why? Isobaric analysis revealed supportive dynamics for ascent south of the already-occurring convection.
    • 700 mb relative humidity and 850 mb humidity data (Figure 2) reveal a sharp moisture gradient across northeastern New Mexico
      • SPC 850 mb Td mesoanalysis verifies this (Figure 3)
    • Dry air was already moving across both counties from the west and was progged to continue over the next few hours, thus hindering convective initiation

Figure 2

Figure 3

– Vort Max

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6/12 Observations from ABQ CWA

OCTANE

Have knots abbreviated as “KTS” instead of “KN”

Change direction of movement from to lettered degrees instead of a numerical value

This product does help me become more aware, in realtime of the winds vertically.  However, not entirely sure how to adapt this into my forecasting routine yet.

NUCAPS

Great to see the better sampling/readout of the data compared to what it was 2-3 years ago

The parcel count is a great way to help me gauge the validity of the data (confidence in how accurate it is)

Overlaying a NUCAPS forecast field with the parcel count allows me to sample what the field has and what the parcel count is so I can have more of less confidence in the data

No less than six hours for operational needs.  9 hours might be the perfect duration.  I usually don’t use hourly data much beyond 9 hours due to my lack of confidence in the reliability of the data.

Hourly data is very nice.  Half hour spacing is a bit too much data for that duration.
-Something to consider is could there be half hour spacing in the data for the first three hours?  However I don’t know if that would be enough of a benefit to use.

I would use the 700-500mb lapse rates, ML CAPE, temp and dew point, and parcel count most often.

PHS

Very easy to look at; very smooth data

Didn’t have much time to look at the data

Lightningcast

Noticed on a well defined supercell the lightning probability is not over 80% despite lightning ongoing.  Does the program cap at 75-80%?
-Have GLM ligthning data displayed too

Otherwise this does help draw my eye to where lightning could occur in the near future.

Prob Severe

Didn’t have time to look at it much. Did notice the storm in eastern CWA had higher values for version 3 than for version 2

– Rainman

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