Waiting for cirrus to dissipate

Considerable overnight and ongoing convection over the upper midwest on August 2nd has left a large cirrus shield over Wisconsin. The UW Convective Initiation (UWCI) product does not detect convective development in regions where significant ice clouds already exist. The 'ice mask' -- where UWCI cannot be computed, can be displayed in AWIPS, and it shows the extent of the ice cloudiness over Wisconsin. A small gap has developed over the extreme southwest part of the state. If this region expands with time, then UWCI might be able to detect incipient convection over the upper midwest later this afternoon.






A MODIS Cirrus Channel image (1.38 micrometers) from 1710 UTC on 2 August shows that cirrus persists over the upper midwest.














Submitted by Scott Lindstrom (UW CIMSS) and Denny VanCleve (NWS-MKX)

Using NearCast vertical theta-e differences on a Warm Humid morning

Note the outflow boundary that is moving southward (in the 1512 UTC radar composite to the left) into the MKX WFO, arcing from northern Sauk County (south of the Dells) through central Columbia County. (The convection that has spawned this outflow is in the northern strip of counties of the WFO to the west of Fond du Lac) What are the chances that convection will fire along this outflow boundary? Are there products that could help you decide if the convection will continue, or will redevelop as the outflow boundary moves south?






The NearCast forecast of Theta-e differences valid at 1530 UTC shows a region of stronger stability over the MKX WFO -- suggesting that any convection that moves into southeast Wisconsin will struggle to develop. Convection might pop -- and it did over northeast Dane County at 1627 UTC (see below) -- but that convection was short-lived.










NearCast output suggests the convection over Dane County will not persist. The highest tops were to 20-25000 feet, and no lightning occurred. (Radar image at left from 1627 UTC)
















Posted by: Scott Lindstrom (CIMSS) and Denny VanCleve (MKX)

Fog/Stratus over Lake Michigan

Above is the 11-3.9 Low Cloud/Fog product from1101Z that shows an extensive area of stratus and fog over portions of Lower Michigan and Southern Lake Michigan.

The GOES R IFR probability from 1115Z shows over 80% probability of IFR ceilings over much of Lower Michigan and parts of Southern Lake Michigan. While surface obs can tell a forecaster the IFR ceilings over land, the GOES R product adds confidence that IFR conditions with stratus and fog were occurring over lake Michigan.

Below the Visible image from 1515Z confirmed the existence of fog and stratus over Southern Lake Michigan. The GOES R IFR probability showed values of IFR ceilings over 40% over much of the Fog/stratus layer over Lake Michigan. There is uncertainty on whether this is fog or stratus, but web cam images showed mainly fog. The GOES R IFR probabilities are lower over Southern Lake Michigan during the daytime.

Steve Hentz
WFO MKX

Using NRCAST Vertical Theta-e Diff

A 5 hour NRCAST vertical theta-e difference is shown to the left. The gradients between unstable values (greens, yellows, and reds) and stable values (blues) are marked by the white lines. The stronger gradient is along the solid line as a weak cold front pushed southward through the area. A weaker gradient extends to the south.

Observed radar is shown to the left along with the 5-hour theta-e gradient forecast. Note that the stronger storms formed generally along the gradient, rather then in the middle of the unstable area. Additionally, showers were generally confined to the unstable areas. If a general convective initiation time is known, this gradient forecast could be useful in locating the areas where storms will fire. With virtually no precip in the stable areas, this product would also be useful in short term precip probability forecasts.

Denny VanCleve NWS/MKX

Robert Aune NOAA/ASPB, Jordan Gerth UW/CIMSS

NSSL 4km WRF Simulated Satellite imagery

Advanced Baseline Imager bands 8 through 16 are available for the NSSL 4km WRF output.

In this example a 16 hour forecast of band 9 (6.95 um, top image) is compared with the current WV imagery (bottom image) depicting an upper low over the Northern Great Lakes. Band 9 correctly depicts the location and orientation of the upper low and the associated dry slot and cloud regions. Farther to the south over AR, TN, and MS, band 9 is slow in the evolution of a MCS. The various bands of the WRF would be beneficial to forecasters to assess the model evolution of the environment and aid the forecaster in the progression as well.

Mark Gehring NWS/MKX

Justin Sieglaff UW/CIMSS

Fog/Stratus California Coast

The GOES-W MVFR Fog Probability 4km does a fairly nice job assigning high MVFR probabilities to stratus and fog off the coast of CA but also depicts the clearer area over Channel Islands National Park. It does assign only low probabilities to the MVFR-IFR conditions along the coastline however. Could this possibly be due to a thinner depth to the stratus field, assuming it is actually thinner? Farther to the west beyond the various islands the Fog Probability shows an area of "no data" due to clear areas that are present and sct-bkn cloud cover versus the bkn-ovc cloud cover to the east.

Mark Gehring NWS/MKX
Justin Sieglaff UW/CIMSS

CIMSS-MKX Local Area Testbed Beginning Soon

This summer the Hazardous Weather Testbed concept will be expanded to the National Weather Service forecast office in Sullivan, Wisconsin (MKX). Cooperating with the Cooperative Institute for Meteorological Satellite Studies (CIMSS) and Advanced Satellite Products Branch (ASPB), this Local Area Testbed will focus on evaluating GOES-R Algorithm Working Group (AWG) cloud type and mask products, fog probabilities, and simulated ABI longwave bands weekly.

Stay tuned to this blog for exciting posts on how NWS forecasters envision these new products will be used in future forecast operations to improve our assessment of the atmosphere.

J. Gerth

End of the experiment...

Well, the 2011 Spring Experiment is now officially over. Ironically I just made some major facelifts to the blog, including a "follow by email" tool on the right-hand side. I would encourage everyone to follow this blog throughout the year as it is likely to be used by the UW-CIMSS local testbed with the Milwaukee/Sullivan WFO. We may also have an informal late summer experiment here in the HWT regarding fire weather that may have some interesting results.

I would like to thank everyone that visited this year and participated in our activities. Without visiting scientists, the feedback gained and interactions with the forecasters would have been greatly reduced. I would also especially like to thank everyone who helped set up and run the Spring Experiment this year. There are too many to list here, but without their efforts the Spring Experiment would not have happened.

Thank you all!
-Chris Siewert

EWP end of week debrief... 10 June

Today marks the last day of the last week of the experiment. As is tradition, we debriefed the EWP visiting forecasters on their experiences throughout the week...

Convective Initiation

- (Thursday event - N.E.) Cloud-top cooling products seemed to work in diagnosing the strength of storms on the southwest edge of the line that were newly developing.

- Even though CI didn't always occur... false hits were useful in identifying clouds trying to break the cap.

- Forecasters not interested in seeing a binary yes/no output.

- "There were instances where similar looking clumps of Cu that one would flag for CI but the other wouldn't... so I wasn't sure how to interpret that other than maybe this area was more conducive to further development."

- There are lots of products that provide you lead time on CI, the real question would be on the consistency of the output.

- "I would definitely look at this in my WFO... especially the cooling-tops product gave me a lot of information on the relative strengths of the storms."

- "If both groups could work together and come up with a probabilistic product that combined the strengths of the UAH and the UWCI products, that would be very useful."

- "I think from a purely public forecast perspective, especially this time of year where we get convection every day, it would help you identify when exactly CI will occur."

- Would be very valuable for nocturnal CI.

Nearcast

- (Thursday event - N.E.) "I didn't see a whole lot of trend in terms of gradients developing, but all the sudden on the back side of the squall-line we lost data rapidly, probably due to cloud cover... compared to the other days, I didn't see any real patterns."

- (Thursday event - KS/OK) Showed an arch of destabilization between 2200-0300 across the eastern halves of OK and KS... storms formed on the western edge of this gradient and forecaster did not expect the storms to diminish anytime soon and thus increased warning confidence... stronger wording regarding hail/wind potential in warning was issued.

- There seemed to be small scale features in the fields, areas of relative maximum that were moving around... would be nice to compare to radar evolution and see how those areas affected the storm structure.

- Helped understand why convection occurred and where it would occur... definitely the 1-6 or 1-9 hour timeframe was the most useful aspect of it.

- Having a 4-panel set up of the individual layers in addition to the difference field to help increase the understanding of the product.

- The color-table in AWIPS was poor... Also, the values were reversed from those in NAWIPS and on the web. The individual layers of PW were also not available in AWIPS.

Would it be useful to extend the Nearcast another 3 hours, even if that meant smoother fields?

- "I like the high resolution out to whenever we can have it... it seemed that there was definitely information within the gradients... of course if you add 3 hours, we will definitely take that."

Would you have used the observations without it being advected forward?

- Wouldn't have been as useful... It helped determine the evolution of the environment... The forecast parts tended to build areas of increased instability that helped provide guidance on what was going to happen later on.

Overshooting-top / Thermal Couplet

- (Thursday event - KS/OK) None were detected when forecasters expected to see detections, so was not used, especially with the rapid updates of radar data.

- Need to remember to turn icon density to "MAX" within AWIPS or some detections will be lost.

- Looked at pretty much every day... for the most part, operator identified OTs occurred before the algorithm did.

Pseudo-GLM

- (Thursday event - OK) Some of the storms to the east had higher flash rates, but this was an artifact of the LMA network's detection efficiencies.

- (Thursday event - OK) Flash rates would pick up a short time before increases in reflectivity.

- Was useful for diagnosing lightning danger... get a lot of calls from the public regarding that within the WFO.

Overall

- Would definitely help to have some pre-configured procedures before forecasters arrived... forecasters used the "ultimate CI" procedure heavily and liked to see what we think they should be combining to help enhance the utility of the products. Forecasters can then adjust the color-scales for their own preferences.

- "I liked the morning/evening shift idea... that was nice... got to experience something different everyday."

- Sometimes the forecasters would get to tied into warning operations mode and forget to look at the experimental products... would be nice to make sure that the forecasters understand that there is no real pressure and to take their time to examine all of the experimental stuff.

- Would have been useful to provide the forecasters with the training via visitview prior to arrival, as well as some cases that the forecasters could use to get familiar with the products and decrease spin-up time... This would have to be done very far in advance.

- Interaction with the EFP CI desk was not done because there were so many participants over in the area.

- EFP/EWP daily briefing was seen to be repetitive between all the groups and not very "brief" as one forecaster stated. Also, the information being provided was more academic than pure weather discussion.

- WE NEED MORE CHAIRS!

Overshooting-top/thermal couplets over Wichita, KS not detected

AWIPS 4-panel with satellite IR window (top left), visible (top right), overshooting-top detection (bottom left) and NLDN lightning detection (bottom right) for 2345 UTC on 9 June 2011.
EWP forecasters are in the act of warning on storms across KS and OK. One of the more notable storms this evening formed west of Wichita, KS and began moving east towards the northern part of the city. The storm had a very nice hook echo and many reports of funnel clouds and large hail. The forecasters were asked to examine the overshooting-top / thermal couplet products while they were making their warnings. Unfortunately no overshooting-tops were detected... which means there was no chance of detecting a thermal couplet because it requires an overshooting-top detection. Starting from top left and moving clockwise the image above shows the standard IR window, visible, overshooting-top magnitude and NLDN lightning detections within the 4-panel AWIPS D2D display. While it is fairly clear in the IR window and visible imagery at 2345 UTC that there is an overshooting-top, as well as a nice wake signature in the visible, no overshooting-top was detected. At the time of this blog post the storm still has not had an overshooting-top detection.

It was hypothesized that initially the minimum IR brightness temperature requirement for the overshooting-top product was not reached early on. Then once the storm continued to grow, the spatial tests to identify isolated areas of relatively cold cloud tops associated with an overshooting-top failed because cold cloud top temperatures were too close together. These problems are likely due to the relatively poor spatial resolution of the GOES-13 imager and the product would be much improved if resolutions were similar to what will be available on ABI.