SPoRT is planning an assessment of Total Lightning products with several existing and new collaborators from WFOs, CWSUs, and National Centers, ranging in locations from southern Florida to New Mexico and Colorado. From May 15 – July 15, 2014 operational forecasters will evaluate the application of total lightning to support severe storm, public safety, and aviation weather warning responsibilities. To prepare, SPoRT is holding tele-training sessions with collaborators during the week of April 21 and has provided users several training modules as well as a Total Lightning Quick Guide. These can be found via SPoRT’s Training Page and on the NOAA LMS. Experience with total lightning data will prepare users for the GOES-R GLM as well as provide feedback from operations to researchers regarding the types of products users desire.
Here at the Huntsville National Weather Service Forecast Office (NWSFO), we’ve been using various SPoRT LIS parameters, namely absolute and relative soil moisture and skin and soil temperatures, for situational awareness purposes for some time now. Specifically, I’ve been using soil moisture data to help with drought monitoring application and subsequent feedback to the U.S. Drought Monitor for a few years. But, we’ll leave that particular use for another post. Today, I wanted to post about the relevance of these data on the far other end of the hydrologic spectrum, that is, flooding. Let’s take the most recent example here in Alabama and adjacent areas of Mississippi and Florida. I’m going to start with a graphic of precipitation over the region during the 24 hour period ending at 12UTC 7 April 2014.
As shown in the graphic above, some locations on the south side of the Birmingham metro received around five to six inches of rain in about a 12 hour period. This lead to significant flash flooding across parts of the metro where some water rescues were even necessary. Rainfall amounts here in northern Alabama ranged from around one inch in the far northwestern part of the state to about 3.5-4 inches in parts of north central and northeastern Alabama.
Now, let’s investigate the antecedent soil moisture conditions before heavy rainfall moved across the region. Let’s begin by taking a look at the shallow layer (0-10 cm) relative soil moisture produced by the SPoRT LIS.
Relative soil moisture values generally south of Birmingham, and in particular in the “black belt” region of Alabama, a region characterized by rich, black topsoil, but underlying less permeable chalks and clay soils, were around 75% to 90%. So, even before widespread heavy rains of three or more inches moved across the region, soil moisture values were relatively high. Note here in northern Alabama however, that values were lower, at around 50%. The combination of lower antecedent soil moisture conditions and similar to lower rainfall led to less incidence of flash flooding in northern Alabama. In fact, only two flash flood warnings were issued for the event and were for the same location: encompassing parts of DeKalb, Jackson and Marshall Counties in northeastern Alabama. Incidentally, soil moisture values were higher in the Big Wills Valley in DeKalb County where most of the flash flooding occurred. Although, other factors should be considered there such as the narrow and steep-walled drainage basin characteristics.
Now, let’s take a look at the deep layer (0-200 cm) antecedent relative soil moisture conditions across the region (below).
In this image, the solid darker green indicates relative soil moisture values around 60% or higher, while blue shades indicate values in the 70s-90s%. Notice that values were this high or higher across much of Mississippi and central and southern portions of Mississippi. Next is a map of flooding locations as of this morning (April 11th…unfortunately, I don’t have one from earlier).
Streams and rivers with orange and red boxes indicate locations of minor and moderate flooding, respectively. Notice that many of these are located where rains were heaviest, but also where antecedent soil moisture values were highest. The main take away item here is that while rainfall values of this magnitude can occur in this part of the country, importantly, soil moisture values must be included to make a more complete assessment of the threat for flooding. We certainly have had higher rainfall amounts in the region with much less flooding. Such was the case with the passage of Tropical Storm Lee in September 2011, especially here in northern Alabama.
Here at the Huntsville NWSFO it has taken some time, but we have noticed that when deep layer (0-200 cm) relative soil moisture values exceed about 60%, we are at a greater risk for longer term flooding on local stream and river basins when we receive a “typical” synoptic rainfall event totaling around 2-3 or more inches. Values in northern Alabama before this event were generally under 60%, with the exception of the Big Wills Valley in DeKalb County and in some small portions of the Paint Rock Valley in Jackson County. Incidentally, in addition to the flooding along the Big Wills Creek in Fort Payne, minor flooding occurred along the Paint Rock River in Jackson County here in northern Alabama. This was one of the locations with some indication of relatively wet antecedent soils (relative soil moisture values ~60%). Thus, once again, we received further confirmation in these rough thresholds. These two locations contain streams that are particularly prone to flooding, but it has been difficult to gauge what rainfall amounts are necessary. This is because an important component of that assessment was lacking until the advent of LIS soil moisture data into our operations beginning over a year ago.
Thanks to the SPoRT team, we now have these data back in AWIPS (II) and can overlay other important data, such as QPF from the Weather Prediction Center. Although these flooding threat analyses are mostly qualitative and subjective at this point, the plan is to undertake a more objective study of soil moisture and rainfall thresholds in our more problematic drainage basins to have a better understanding of threats for flooding in the future.
A fantastic post by Satellite Liaison Michael Folmer about the use of SPoRT and CIRA RGB products for examining the very rapid development of Tropical Cyclone Hellen in the Indian Ocean
Originally posted on Satellite Liaison Blog:
Now on to this week’s storm of interest. . .
Tropical Cyclone Hellen formed in the northwest Indian Ocean between Mozambique and Madagascar on 03/28/14. Hellen rapidly intensified from a 60 kt (70 mph) tropical storm to a 130 kt (150 mph) Category-4 tropical cyclone in 18 hours (satellite-based)! Since the Atlantic hasn’t shown us a strong hurricane (Category 3+, but…
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This was one of those storms that people will talk about for years, especially those that were directly affected by it. It all started with three separate shortwaves that all phased together once off the Mid-Atlantic coast, far enough offshore to limit any direct effects save for some unusual late season snow and gusty winds the next day. The highest impact area included Cape Cod, Nantucket, Nova Scotia, and New Foundland. I’m sure any ships that were in the vicinity were not happy with this situation!
The evolution of the nor’easter can be seen in the GOES Sounder RGB Air Mass animation above. A southern stream system originating in the Gulf of Mexico moved east of Florida while two other shortwaves dropped southeast out of Canada. All of the pieces combined near the North Carolina coastline, but the explosive deepening took place as the combined system moved northeast away from the Mid-Atlantic. There appears to be a few stratospheric intrusions, but the most impressive intrusion occurs with the final shortwave as noted by the dark oranges and reds that appear at the end of the day on 03/25. When models are forecasting a phasing situation, this product can be quite useful in identifying the features and observing the stratospheric drying seemingly “bleed” from one shortwave to the other.
The two MODIS RGB Air Mass products above show the nor’easter near peak intensity. Notice how distinct the gradient between oranges and greens is in this image, almost as though you can see the upper portion of the frontogenesis, well behind the actual front. The intensity of the stratospheric intrusion is quite evident by the dark pinks near the center of the cyclone. The second image shows the wind field overlaid from ASCATB. Notice the large area of hurricane force winds (red wind barbs) near the bent-back front, in the comma-head of the cyclone. This area of wind affected parts of Southeast Massachusetts, including Nantucket where winds gusted from 60-85 mph. Nantucket recorded a wind gust of 82 mph and about 10″ of snow. Meanwhile, Nova Scotia bore the brunt of this beast with wind gusts of 129 mph at the Bay of Fundy and 115 mph in Wreckhouse. Waves were equally impressive with altimeter readings between 40-50 ft and a buoy report of 52.5 ft.
Another interesting aspect of this storm was the two distinct areas of thunderstorms that erupted. I overlaid the OPC and TAFB offshore zones for reference. Notice well east of the Bahamas there are possible supercell thunderstorms associated with the southern shortwave energy. Meanwhile, as the strong northern stream shortwaves exit the NC coastline, two areas of thunderstorms developed with the easternmost storm exhibiting supercell characteristics. Although the lightning was not as intense with this northern area, I would speculate that the storms were associated with very strong wind gusts due to the dry air associated with the stratospheric intrusion.
I’ll finish this entry with two VIIRS Visible images above showing the majestic beauty of this nor’easter. The 18 UTC OPC surface analysis depicts the storm at a maximum intensity of 955 mb, after a 45 mb drop in 24 hours! This qualifies as one of the most explosive cyclones on record. Another tidbit. . .this was the strongest storm in this part of the Atlantic since Hurricane Sandy (2012).
Thanks for reading!
Originally posted on TFX-shoptalk:
A fast moving shortwave trough is forecast to bring snow through central Montana this morning. The radar has been active (Fig. 1), but snow is not yet being reported at area stations except at Havre, where its only just began. It’s night, and only a few web cams are illuminated. The nightime microphysics RGB (Nt-micro) adds some value to the situation (Fig. 2). At 0448 UTC the Nt-micro image shows widespread red-orange-purple colors across the state. These are best interpreted as optically thick mid to high level clouds. Ceilings above 6000 feet AGL are consistent with this interpretation. The radar has been active in these areas for much of the night in clear-air mode, so likely picking up on ice crystals within the cloud. Four hours later, the scene has changed (Fig. 3). Notice the introduction of bright yellow clouds in southern Alberta, just sneaking into northern Glacier County. These…
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The severe to extreme drought conditions in the Colorado, Kansas, Oklahoma, Texas, and New Mexico regions surrounding the panhandle of Oklahoma (see U.S. Drought Monitor: http://droughtmonitor.unl.edu/) served as a source region for a large-scale dust event impacting these five states. The VIIRS and MODIS RGB Dust imagery shows this dust event well with MODIS providing an early indication of the event prior to obvious dust signatures in current GOES imagery. See the “Real-Time Data” tab on the NASA/SPoRT webpage: http://weather.msfc.nasa.gov/sport/.
At 1807 UTC MODIS imagery (see below) indicated two areas of blowing dust in the afore mentioned region. At this time the GOES visible imagery was hinting at the dust region in southeast Colorado but the GOES imagery was not clearly showing the dust in Texas. By the 1947 UTC VIIRS Dust RGB imagery (second image below), both the GOES visible and IR imagery showed the two large dust regions, but VIIRS Dust RGB imagery provided a more clear definition of the dust plume impacting north TX, originating in eastern NM. By 2202 UTC the dust plume from Colorado had fanned out and could be well seen in the GOES visible imagery (see below) impacting NM, OK, and TX while the dust from the eastern NM source region had spread across north TX and into OK. I’m sure we’ll see many photos of this extreme event over a wide area; feel free to post them to this blog.
Jonathan Case of NASA/SPoRT and Dr. Ashutosh Limaye of NASA/SERVIR traveled to Nairobi, Kenya this week to collaborate with the Kenya Meteorological Service (KMS; see figure below). The goals of this visit were to learn more about KMS operations, transition the SPoRT-Model Evaluation Tools (MET) verification scripting package for operational use at KMS, and to demonstrate initializing the Weather Research and Forecasting (WRF) model with high-resolution Land Information System (LIS) land surface fields. Mr. Case and Dr. Limaye worked closely with Mr. John Mungai and Mr. Vincent Sakwa of KMS to install and test the SPoRT-MET scripting package during the course of the visit. Installation and testing of the SPoRT-MET scripts were successful for generating surface point and gridded precipitation verification statistics, including the generation of graphical “quick plots” using embedded Perl utilities. Mr. Mungai and Mr. Sakwa indicated the high utility that this verification system will provide KMS to improve operational efficiency through routine, automated verification of WRF model forecast accuracy, as well as other models the KMS uses in-house for which they have access to GRIB files. SPoRT and SERVIR will continue collaborating with KMS representatives to ensure automation of SPoRT-MET capabilities, and to offer additional enhancements to the KMS-WRF, such as future real-time vegetation data to improve LIS and WRF simulations.