Convective Initiation Spikes

As convection begins developing in the Lubbock WFO vicinity, monitoring of CI reveals mostly fields of CI 0-20% and Severe CI 0-1%.  Noticed some random spikes from such low levels up to 89/69% and then back to those lower levels on the next update.  The most extreme example I saw was at 2057Z:

CI with radar below.  Example above is seen at the southern boundary of Lubbock WFO, bordering MAF and SJT (just below the exact center of the image).

Animation below shows other smaller magnitude spikes in the same general area:

-Forrest

Upcoming Polar Orbiting Passes in AWIPS

The information for when the various polar orbiting satellites (MetOps A/B, NUCAPS, NOAA-20) pass over specific spots can be found online.  However, forecasters don't always have the time or the interest to look up this information.  It would be very helpful to show upcoming/future passes and locations in AWIPS.  The image below could be a potential example.

The polar orbiter imagery can show the current image in color (green/yellow/red).  But then it could also show the upcoming/future passes.  They could display the same way in the future (with dots over the approximate location).  But they could be in a different color (blue?) to indicate it's an upcoming/future pass.  It could also give the time the pass is expected to be completed.  Perhaps having upcoming/future passes for the next 12 hours would be useful.

-Kevin

Polar Orbiting Time Stamps

The polar orbiting data is very nice.  However, the time stamp is confusing.  In the image below, the NUCAPS improved latency product has a time stamp of 19:41Z.  However, it shows that for ALL of the points. In reality, each point has a different time stamp as the satellite moves across the Earth.

In the experiment at this time, I was concerned with Wyoming.  The pass occurred at 19:49Z (per the NPP SSEC orbit site).  But the time labeling gave the appearance it was at 19:41Z.  Each point should have the approximate time the pass occurred, ideally in the Skew-T.

-Kevin

RGB Composites and Channel Difference Labeling Suggestion

There are lots of RGB Composites and Channel Difference products being introduced with the GOES-R series.  They are very useful.  However, with more and more of these products being created, it's getting very difficult for operational meteorologists to memorize what each one means (including the color scales).

The quick guides that are being created are very helpful.  But it's not easy to view these quick guides in AWIPS.  It's also not always easy to view these guides online, especially if convection has already initiated.  As a result, some forecasters are limiting how many satellite products they view because they can't keep track of what each one stands for.

It would be very helpful to have the guides built into the products.  How?  The image below shows cloud phase distinction.  When the sampling option is turned on it gives more information about the image.  However, it displays Red/Green/Blue information.  This information is useful for developers, but useless for operational forecasters.

The quick guides created for each product display RGB interpretation.  If you view the quick guide for cloud phase distinction, the color orange (in the image above) is labeled in the guide as "Thin high-level clouds with ice particles (red-orange)."  This information should be built into the product.  In fact, it's already being done for radar.  Below is a Hydrometeor Classification image for radar.

Notice how all of the colors are labeled.  In the example above, the light blue is dry snow.  This same methodology can be used for the RGB composites and Channel Difference labeling.  It would make it much, much easier for operational forecasters to understand and remember each product.

-Kevin

First Thoughts - GLM Integrated Time Options

The only integrated time option available at this time for GLM is one minute.  Many of us like to look at at least a five minute integration time, perhaps with one minute updates, to see better coherence of stronger updrafts and prolific lightning production.  My anticipation based on my limited understanding is that densities will look more pixelated today when lightning does start to get picked up.  Then again, we are in uncharted territory, so we'll see....

-Forrest

Improve GLM Menu

The location for GLM data in AWIPS is under too many submenus (see image).  Given the expected importance of GLM, it should be in the first drop down menu of satellite.

-Kevin

ProbSevere at HWT Spring 2018 Experiment

The NOAA/CIMSS Probability of Severe (ProbSevere) model is being evaluated by forecasters at the 2018 Spring Experiment at the Hazardous Weather Testbed (HWT).  For 2018 forecasters are evaluating an improved version of ProbSevere known as ProbSevere AllHazards.  The existing ProbSevere model provided the probability a thunderstorm would produce any severe weather (severe hail, severe wind and/or tornado) in the 0-90 minute timeframe.  Based on feedback from previous experiments, ProbSevere All Hazards provides probabilistic forecasts that thunderstorms will produce specific hazards--severe hail, severe wind, and tornado--in addition to the overall probability of severe (which is the maximum of the 3 hazard models).  Starting in January 2018 ProbSevere, both the version feeding NWS WFOs and the experimental ProbSevere All Hazards version are using GOES-16 data over the entire CONUS.  GOES-17 data will be incorporated into ProbSevere for the western US in late 2018.

Today forecasters are becoming familiar with the experimental products they will evaluate and developing AWIPS procedures they will use all week.  The initial WFOs of interest today are Lubbock, Texas and Cheyenne, Wyoming.  I will provide some examples of ProbSevere All Hazards via blog posts, in addition to characterizing some discussions with partipicants related to ProbSevere All Hazards.

-J. Sieglaff

2018 Spring Experiment Underway

The 2018 Satellite Proving Ground Spring Experiment is underway at the HWT in Norman. A great group of forecasters are here this week to provide feedback on current and future satellite related products. Today's groups will be operating in the Cheyenne, Wyoming and Lubbock, Texas CWAs.

-Michael Bowlan

Severe storm outbreak in the Mississippi and Ohio River Valleys

A potent shortwave forced severe storms across the middle of the U.S. yesterday, wreaking havoc from Texas to Ohio. Below is the 850mb analysis from 00Z 04/04/2018 (Figure 1), showing well-defined warm and cold fronts emanating from the low, centered on Lake Michigan. We also see that moisture was well-established in the warm sector and the flow at 850mb was quite strong (30-40 kts).

Figure 1: 850mb analysis from 00Z 04/04/2018.

The NOAA/CIMSS ProbSevere model is experimenting with hazard-specific models: ProbHail, ProbWind, and ProbTor. The ProbHail model did fairly well to capture the initial hail threat along the cold front, with numerous storms exhibiting strong satellite growth from GOES-16.

These storms produced numerous hail reports between 1" and 1.5" in and around the Mark Twain National Forest.

Figure 2: ProbHail for storms in eastern MO, with MRMS MergedReflectivity and NWS severe weather warnings.

With sampling turned on in AWIPS2 (Figure 3), users of ProbHail can see the constituent predictors. Here, the strong satellite growth rate, high MRMS MESH (1.5"), and high Earth Networks® total lightning flash rate (40 fl/min) contributed to a ProbHail of 96%. NWP predictors of effective bulk shear, CAPE between -10C and -30C ("hail cape"), precipitable water (PWAT), and the lowest height of the wetbulb 0C isotherm are also used as inputs in ProbHail.

Figure 3: ProbHail readout for storms in eastern MO, with MRMS MergedReflectivity and NWS severe weather warnings.

Due to very favorable kinematics, the tornado threat was rather high, with the Storm Prediction Center issuing a wide swath of 10% probabilities for tornadoes within 25 mi of a location for their 2000Z outlook (Figure 4).

Figure 4: SPC tornado outlook and verification for 20Z and 12Z, respectively.

A storm that produced numerous reports of significant wind damage in the Dayton, OH metro area also produced a tornado east of the metro. ProbTor captured it's development well (Figure 5).

Figure 5: ProbSevere, MRMS MergedReflectivity, and NWS severe weather warnings for southwest OH.

The time series of this storm's attributes demonstrate that very high MRMS 0-2km AzShear (>20 * 0.001 /s), along with SRH of 300-400 m2/s2 in the 0-1km layer helped spike the ProbTor value to over 90%. In this case, the tornado report came slightly after the time of peak ProbTor. Several wind reports in the Dayton area were significant (e.g., "large debris cloud", "structural damage to homes"), around 20Z when ProbTor was in the 30-50% range. Thus, it's possible there may have been a tornado earlier (a NWS survey should confirm the presence or lack thereof).

Figure 6: Time series of ProbTor (red curve) for this storm with its predictors. The bottom axes show NWS warnings and reports.

The "ProbSevere" value simply uses the maximum of ProbHail, ProbWind, and ProbTor. For this long-lived storm, each model was the maximum at different times. Regardless, the ProbSevere values were mostly over 70% when there was reported severe weather. The MESH and lightning (pink and green curves) show the cycling of this storm nicely. The storm produced hail and wind reports in the Columbus, OH metro and later east of the metro.

Figure 7: Time series of ProbSevere (red curve) for this storm with its predictors. The bottom axes show NWS warnings and reports.

Storms later evolved into big wind-producers, evidenced by these storms in the Nashville, TN area. There were many reports of trees and power lines down in the metro area around 0200-0230Z.

Figure 8: ProbWind, MRMS MergedReflectivity, and NWS severe weather warnings for storms affecting the Nashville metro.

 ProbWind was in the 50-70% range for these storms, owing to a strong MeanWind in the 1-3km layer and moderate 0-2km MRMS AzShear. Note that the ProbWind readout in AWIPS2 now has a "weak", "moderate", and "strong" designation tag for the MRMS AzShear fields (e.g., Figure 9)

Figure 9: ProbWind readout for a storm south of Nashville.

At the end of each day, we make an "accumulation" product, plotting the centroids of storms colored by their ProbSevere value (or ProbTor value), along with the NWS severe weather warnings and SPC preliminary reports. From Figure 10, we see that ProbSevere corresponded with severe weather warnings and reports quite well in MO, AR, IL, IN, OH, KY, PA, and TN, and parts of TX and LA. However, many wind reports were missed (at the 50% threshold) in MS, AL, and GA. Many of these storms had meager reflectivity and lightning flash rates, and no discernible satellite growth. ProbWind was largely 10-30% for these storms, a small improvement over the legacy "all-in-one" ProbSevere product, which had < 10% for most of these storms. We are still working to improve upon probabilistic prediction of storms in this regime, and are open to ideas from the field.

Daylight Savings storms

As we mindlessly set our clocks ahead one hour, storms raged on in the southern U.S. A shortwave in the polar jet stream plunged southward over the Plains to force strong convection along a 500mb jet streak in eastern Oklahoma and western Arkansas. The NOAA/CIMSS ProbSevere model is moving toward hazard-specific statistical models using MRMS, GOES-ABI series, lightning, and NWP data. ProbHail, ProbWind, and ProbTor will be evaluated for a second year at the NSSL Hazardous Weather Testbed.

This storm northwest of Fort Smith, AR, shot up in ProbSevere value (the probability of severe is simply the maximum of the ProbHail, ProbWind, and ProbTor values) between 21:30Z and 21:40Z, going from 18% to about 50%. Golfball sized hail was recorded at 21:40Z. The increasing MESH (though still less than 1.0") spiked the ProbSevere value, while a jump in the total lightning flash rate increased the ProbSevere value from 65% to over 90% later on (see a time series of this storm's attributes in Fig 2). Interestingly, the 3-6km AzShear was very high before the lightning or MESH really took off, indicating strong mid-level rotation. The storm later recorded 2.0" hail east of Fort Smith. ProbHail had the highest probability for any of the models throughout the duration of the storm.

Fig. 1: ProbSevere contours, MRMS MergedReflectivityComposite for a storm in eastern OK / western AR. NWS severe weather warnings are also plotted.

Fig. 2: Time series of ProbSevere (max of ProbHail, ProbWind, and ProbTor) for the storm in OR/AR, with a subset of contributing predictors.

During the daylight savings time switch, another set of storms forced by a strong subtropical jet stream and moist southerly return flow from the Gulf of Mexico made their way from eastern Texas into Louisiana. The monster supercell in Figures 3 and 4 had a strong normalized satellite growth rate (4.1%/min observed by GOES-16) prior to 03:00Z. The growth rate brought the probability to about 20%, where the MESH and flash rate catapulted the ProbHail value from 20% to 90% in about 20 min. The storm had ProbHail and ProbWind exceeding 85-95%, recording numerous hail and wind reports, while ProbTor peaked at 20% (there were no tornado reports).

Fig. 3: ProbSevere, MRMS MergedReflectivityComposite and associated NWS severe weather warnings for a storm in east TX.

Fig. 4: Time series of ProbSevere (max of ProbHail, ProbWind, and ProbTor) for the supercell in east TX, with a subset of contributing predictors.