Plenty of Fresh Powder for Paralympic Winter Games in PyeongChang: Three Snowstorms in Eight Days

Plenty of Fresh Powder for Paralympic Winter Games in PyeongChang: Three Snowstorms in Eight Days

The 13th Paralympic Winter Games are set to begin officially in PyeongChang on March 9th, and the mountainous Olympic venues in eastern South Korea have had no shortage of snow in the last week.  Three major winter storms have affected the Korean Peninsula since 28 February 2018, helping to recharge the snowpack for the Paralympic Winter Games.  Figure 1 shows 24-hour simulated snowfall totals from SPoRT’s real-time NASA Unified-Weather Research and Forecasting (NU-WRF) model for the three recent snowstorms on 28 February, 4 March, and 7-8 March.  SPoRT is continuing to generate 24-hour forecasts of NU-WRF model runs, updated four times per day as part of the research field campaign known as the International Collaborative Experiments for PyeongChang 2018 Olympic and Paralympic Winter Games (ICE-POP).



Figure 1.  Simulated 24-hour accumulated snowfall (in cm) from NU-WRF simulations of the snowstorms occurring over the Korean Peninsula on (a) 28 February, (b) 4 March, and (c) 7-8 March 2018.  The region depicted is the inner-nested NU-WRF model grid with 1-km horizontal spacing.


The Korea Meteorological Administration’s surface analysis on 0300 UTC 28 February shows a potent low pressure approaching the Korean Peninsula from the southwest (Fig. 2), which eventually intensified to less than 970 mb near northern Japan the next day.  A picture taken of the NASA Precipitation Imaging Package after the 28 February storm (Fig. 3) shows the substantial snowpack resulting from the ~40 cm (~16 inch) snowfall that occurred at the research station labeled “DGRWC” in the NU-WRF simulated snowfall plots of Figure 1.



Figure 2.  Surface analysis from 0300 UTC 28 February 2018, courtesy of the Korea Meteorological Administration (KMA).




Figure 3.  (top) Photograph taken of the NASA Precipitation Imaging Package (PIP) at the NASA instrumentation site in South Korea, following the snowstorm of 28 February. (bottom) NASA PIP and disdrometers observe a large number of 2.5+ cm diameter snowflakes/aggregates during 28 February.  Photograph at top taken by Mr. Kwonil Kim, Ph.D. student at Kyungpook National Univ.  Bottom image provided by Larry Bliven, NASA GSFC/Wallops Flight Facility.


Perhaps the most interesting of the three events is the latest storm from 7-8 March.  The NU-WRF model simulated composite radar reflectivity at 30-minute intervals (Fig. 4) shows a shield of moderate to heavy synoptic precipitation associated with the low pressure tracking to the south of the Olympic venues.  As the precipitation shield pulls away after ~0600 UTC 8 March, surface winds increase from a northeasterly direction over the Sea of Japan and push residual moisture inland against the mountains oriented parallel to the coastline.  This leads to a prolonged band of shallow, but moderately intense snowfall in the mountains as the moist onshore flow is forced upward by the topography.  Consequently, snowfall amounts are enhanced along the east coast of the Korean Peninsula.  Finally, the evolution from deep synoptically-driven snowfall to the shallower forced uplift snowfall is captured nicely by NU-WRF time-height cross sections at the various Olympic venues.  Figure 5 shows one of these time-height sections at the Alpensia site (location labeled in Fig. 1 panels), depicting the deep snowfall mixing ratios until ~0600 UTC 8 March, followed by a transition to much shallower, episodic snowfall for the remainder of the time period through 1800 UTC 8 March.



Figure 4.  Twenty-hour hour animation of NU-WRF simulated composite radar reflectivity (dBZ) at 30-minute intervals from the model run initialized on 1200 UTC 7 March 2018.



Figure 5.  Time-height cross-section of simulated precipitation microphysics in the lowest 2000 meters above ground level at the Alpensia Olympic venue, from the NU-WRF model run initialized on 1800 UTC 7 March 2018.

Shallow Snow and High Wind Event of 14 February during the PyeongChang2018 Winter Olympics

As the Winter Olympics come to a close this weekend, NASA/SPoRT continues its involvement in the International Collaborative Experiments for PyeongChang 2018 Olympic and Paralympic Winter Games (ICE-POP) through the gathering of field campaign observations and numerical weather prediction (NWP) model data.  The ICE-POP campaign extends through March to support the Paralympic Games, and obtain more event data to set the stage for future research activities.  During the first week of the 2018 PyeongChang Winter Olympics, another weather event worth highlighting is the shallow snow and high wind episode that disrupted downhill skiing competition at Jeongseon Hill on 14 February.  On this day, a potent shortwave trough embedded in strong northwesterly flow approached the Korean Peninsula (Fig. 1), which led to a relatively short-lived, but potent snow event accompanied by strong winds in the mountains, occurring mainly between 0000-0600 UTC 14 February.


Figure 1.  Animation of NASA Unified-WRF model 3-hourly 500-mb geopotential height (dam) and wind speed (m/s), valid between 1200 UTC 13 February to 1200 UTC 14 February 2018.

An animation of Himawari 10.4-micron infrared imagery from 1200 UTC 13 Feb to 1200 UTC 14 Feb (Fig. 2) shows enhanced cold cloud tops northwest of the Korean Peninsula associated with the shortwave.  However, between 0000-0600 during the snow event, we see relatively warm cloud top temperatures over the Korean Peninsula, indicative of the shallow nature of the snow.  Himawari visible imagery between ~0000-0800 UTC 14 February (Fig. 3) shows the presence of the low clouds that dissipate rapidly in coverage after 0600 UTC.  Experimental ICE-POP disdrometer measurements of hydrometeor size distribution confirm the timing of the snow event between 0000-0600 UTC (Fig. 4), showing predominantly small diameter hydrometeors (most likely snow).  However, the vertical “spikes” seen in Figure 4 between 0000-0200 UTC indicate some larger diameter snow aggregates associated with the more intense snow activity. Cloud profiling radar data (not shown) confirmed a shallow a nature to the precipitation, generally under 2 km depth.


Figure 2.  Animation of Himawari 10.4 micron infrared imagery between 1200 UTC 13 February and 1200 UTC 14 February 2018.


Figure 3.  Animation of Himawari visible imagery between 0000 and 0800 UTC 14 February.


Figure 4.  Experimental ICE-POP distrometer measurements, showing the concentration and size distribution of hydrometeors as a function of UTC hour on 14 February 2018.

The experimental NASA Unified-Weather Research and Forecasting (NU-WRF) model simulations being provided to South Korea during the Olympics captured this event fairly well.  Simulated composite radar reflectivity on the 1-km nested grid from the 1200 UTC 13 February model initialization (Fig. 5) shows a region of enhanced precipitation occurring between ~0000 to 0600 UTC 14 February, around the time of the observed snowfall.  The experimental NU-WRF run also depicts strong 10-m wind speeds during this time (orange shades exceeding 20 m/s, or ~45+ mph), particularly along the axis of higher terrain in the eastern Korean Peninsula (Fig. 6).  Finally, a time-height cross section of the NU-WRF simulated precipitation microphysics at Jeongseon Hill (Fig. 7) shows the precipitation episode timed between ~0000-0600 UTC 14 February, quite consistent with observational data.  The model also captured the shallow nature of the event, with the most substantial snow and graupel mixing ratios being primarily at or below ~1500 m above ground.

The combination of these experimental observations and NWP model data being collected during the Winter Olympics will serve as a foundation for future research to improve our understanding of snow processes in complex terrain.  Additionally, hydrometeor size distribution data from Fig. 4 along with other observations can help refine NWP model microphysical parameterization schemes to determine the proper distribution of precipitation species produced by the model.


Figure 5. SPoRT/NU-WRF simulated composite radar reflectivity (dBZ) every 30 minutes on the 1-km nested grid centered on the ICE-POP Olympics venues, for the model run initialized at 1200 UTC 13 February 2018. Valid times are from 1200 UTC 13 February to 1200 UTC 14 February.


Figure 6.  Same as in Fig. 5, except for the maximum 30-minute interval 10-meter wind speeds.


Figure  7.  Time-height cross section of SPoRT/NU-WRF model simulated precipitation mixing ratios (g/kg) from the 1-km nested grid, valid between 1200 UTC 13 Feb and 1200 UTC 14 Feb 2018 at the Jeongseon Hill Olympics site for the lowest 2 km above ground.

High Winds Impacting Olympic Events Captured by NASA/SPoRT Model and Satellite Products

High Winds Impacting Olympic Events Captured by NASA/SPoRT Model and Satellite Products

As summarized in a previous blog post, NASA/SPoRT is providing one of many numerical weather prediction (NWP) model solutions to South Korea during the 2018 PyeongChang Winter Olympic and Paralympic Games during February and March.  The field campaign is known as the International Collaborative Experiments for PyeongChang 2018 Olympic and Paralympic Winter Games (ICE-POP). In combination with the suite of radar, satellite, and in situ observations during the field campaign, the SPoRT configuration of the NASA Unified-Weather Research and Forecasting (NU-WRF) will serve as a benchmark for future research to improve our understanding of snowfall in complex terrain, our ability to estimate snow using satellites, and for improving prediction models that parameterize these intricate processes.

A key component of the Olympics field campaign is to improve forecast models through comparison to observations and satellite retrieval products.  The constellation of passive microwave imagers being assembled in support of the Integrated Multi-satellitE Retrievals for the Global Precipitation Measurement mission (IMERG) precipitation dataset also provide information on near-surface meteorology necessary to estimate the surface turbulent fluxes. Algorithms designed to retrieve surface temperature, humidity, and wind speed are used together with bulk-flux algorithms to estimate the latent and sensible heat fluxes over the ocean surface. These fluxes are a source of energy and moisture for the overlying atmosphere.  One of the research goals of ICE-POP is to improve heat and moisture fluxes in prediction models through assimilation of these retrieval products.

During this past weekend, the Men’s Downhill Alpine was postponed until Thursday, and the Women’s Giant Slalom Qualifiers were canceled due to high winds that impacted Jeongseon Hill.  Figure 1 shows a 24-hour animation of NU-WRF simulated maximum 10-m wind speeds in 30-minute intervals on 11 February, on the 1-km nested grid centered on the Olympic venues.  We can see a substantial maximum in wind speed impacting the mountains along the eastern Korean Peninsula as well as offshore in the Sea of Japan.  Simulated wind speeds reached 15-20+ m s-1 (~35-45 mph) in the vicinity of Jeongseon and other mountain Olympic locations.  Wind speed observations at nearby Daegwallyeong (north-east of Jeongseon; not shown) peaked around 13 m s-1 (~30 mph) on 11 February, but speeds were most likely stronger in the higher terrain around Jeongseon.  In this particular situation, the higher resolution of the 1-km grid was critical to resolve the fine-scale variations in wind speeds within the complex terrain.


Figure 1.  Twenty-four hour animation of NU-WRF simulated 10-m maximum wind speeds in 30-minute increments, valid from 0000 UTC 11 February through 0000 UTC 12 February 2018.

Meanwhile, the 10-m wind speeds, sensible, and latent heat fluxes are shown in Figure 2, comparing the 9-km model grid simulation with the satellite flux retrievals produced by NASA/SPoRT.  In Figure 2, the retrievals are hourly-averaged composites produced for the ICE-POP campaign, derived from swaths of the constellation of passive microwave satellites.  As the bitter cold Siberian air mass flows over the warmer open waters of the Sea of Japan, Yellow Sea, and western Pacific Ocean, substantial heat and moisture fluxes are directed from the sea surface to the atmosphere.

The 10-m model and retrieved wind speeds both depict a similar broad pattern of high wind speeds up to and exceeding 15 m s-1 across favored corridors downwind of the Korean Peninsula, China, and Russia (Figs. 2a and b).  The model sensible heat flux on the 9-km grid valid at 0600 UTC 12 February (panel c) has a broad pattern similar to the retrieval composite (panel d), but with an axis exceeding 500 W m-2 from the east coast of the Korean Peninsula to central Japan, and a broader amplitude between ~200-400 W m-2, generally higher than the retrievals values  The model latent heat flux (panel e) shows a similar pattern, except for a larger coverage of values exceeding 500 W m-2 between the Korean Peninsula and Japan, and offshore of central and southern Japan.  The maxima offshore of Japan show good agreement between the model and retrieval patterns (panels e and f).

The NU-WRF flux amplitudes are generally higher than that of the retrieval, likely due to several factors such as the retrieval being an hourly-averaged composite compared to instantaneous model fluxes, differences in product resolution, input sea surface temperatures, and model errors in simulated wind speed, and near-surface temperatures and moisture.  Following the Olympics, additional research as part of ICE-POP will involve examining the viability and benefits of assimilating the surface meteorology retrievals into the model for improving the predictions of oceanic heat and moisture transports into the atmosphere and their attendant impacts on air-mass modification.


Figure 2. Comparison between NU-WRF 6-h forecast and passive-microwave hourly-averaged composite retrievals of 10-m wind speed (m s-1), sensible, and latent heat flux (W m-2) valid 0600 UTC 11 February 2018. (a) NU-WRF 10-m wind speed, (b) 10-m wind speed retrieval, (c) NU-WRF sensible heat flux, (d) sensible heat flux retrieval, (e) NU-WRF latent heat flux, and (f) latent heat flux retrieval.

NASA/SPoRT Providing Real-time Numerical Weather Prediction Guidance for 2018 Winter Olympics

The NASA/SPoRT Center has developed a real-time numerical weather prediction (NWP) configuration that is being provided to forecasters in South Korea in support of the 2018 PyeongChang Olympics and Paralympic games.  The real-time modeling solution is part of a broader initiative known as the International Collaborative Experiment for the PyeongChang Olympics and Paralympic Winter 2018 Games (ICE-POP), which focuses on the measurement, physics, modeling, and prediction of heavy orographic snow in the PyeongChang Region of South Korea from January to March, 2018.  ICE-POP is led by the Korean Meteorological Administration (KMA) as a component of the World Meteorological Organization’s (WMO) World Weather Research Program (WWRP) Research and Development and Forecast Demonstration Projects (RDP/FDP).

The overarching ICE-POP goal is to gain a better understanding of orographic frozen precipitation processes, with the expectation that ICE-POP activities will also improve real-time weather forecasts and KMA-led decision support during the 2018 Winter Olympics. A coordinated array of surface, air and ship-borne meteorological instrumentation, radars, and NWP tools from numerous international partners (including NASA) support the ICE-POP objectives.  NASA’s participation in the ICE-POP RDP/FDP involves Marshall and Goddard Space Flight Centers collaborating as a team on a variety of common forecast and research goals.  The outcome of NASA’s involvement in ICE-POP will be the contribution of observational and modeling data that, as part of the larger ICE-POP dataset, will provide a more comprehensive understanding of orographic snowfall processes — a necessary step for improving and/or developing satellite-based snowfall retrieval algorithms and improved snow microphysics in NWP models.

For the real-time NWP solution as part of the ICE-POP FDP, SPoRT has configured the NASA Unified-Weather Research and Forecasting (NU-WRF) modeling framework to generate 24-hour forecasts four times per day, with initialization times at 0000, 0600, 1200, and 1800 UTC.  The model physics suite features the advanced 4-ice microphysics and short- and long-wave radiation parameterization schemes developed at Goddard Space Flight Center.  The NU-WRF grid setup consists of a triple-nested domain at 9-km, 3-km, and 1-km horizontal spacing, and 62 terrain-following vertical levels, covering regions spanning eastern Asia (9-km grid), the Korean peninsula and surrounding waters (3-km grid), and the eastern Korean peninsula centered on the Olympics venue (1-km grid; Fig. 1).  Initial and (lower) boundary conditions are provided by the NCEP Global Forecast System model and SPoRT’s own 2-km resolution sea surface temperature composite product.


Figure 1. Depiction of the triple-nested grid configuration for the real-time NU-WRF forecast guidance, consisting of 9-km (upper-left), 3-km (right), and 1-km (lower-left) mesh grids.

Model fields are output every 3 hours on the 9-km grid, and every 30 minutes on the 3-km and 1-km grids.  The high-resolution output from the 1-km nest centered on the Olympics venue is being delivered in real time to South Korea forecasters for decision support during the games. SPoRT is sending full grids as well as point forecasts of model fields of interest at each specific game site.  Additionally, numerous graphics of temperature, moisture, winds, precipitation, snowfall, etc. are produced for each grid and hosted to a live model web page, accessible to the public.  The SPoRT/NU-WRF model output along with other models from participating international organizations will provide unique forecast guidance for advanced decision support during the Winter Olympics.  For more information and access to all the SPoRT modeling and remote-sensing products being served for ICE-POP, please link to the SPoRT ICE-POP project page.

Finally, an examination of the SPoRT/NU-WRF model guidance initialized at 1200 UTC 7 February offers a preview of anticipated conditions for the opening ceremony on 8 February.  A weak low pressure is forecast to move southeastward across the Yellow Sea, as indicated by the simulated mean sea level pressure and composite reflectivity from the 3-km grid in Figure 2.  However, this system should not impact the Korean peninsula, so the Olympic venues are forecast to remain free of precipitation.  Temperatures will be seasonably cold, as they are expected to remain below freezing at the venues for the next 24 hours (Fig. 3 animation of forecast 2-meter temperatures on the 1-km nested grid).  Visibility looks good, as it is forecast to remain above 10 km (Fig. 4 animation) with little to no low-level cloud cover being simulated by the 1200 UTC initialization of NU-WRF (not shown).  Enjoy the games and be sure to visit the SPoRT/NU-WRF modeling page often for short-term forecast weather conditions during the 2018 Winter Olympics!


Figure 2.  Animation of 30-minute mean sea level pressure (hPa), 10-m winds (m/s), and composite reflectivity (dBZ) from the 3-km nested grid of the SPoRT/NU-WRF simulation initialized on 1200 UTC 7 Feb 2018.


Figure 3.  Animation of 30-minute 2-m temperatures (deg C) and 10-m winds (m/s) from the 1-km nested grid of the SPoRT/NU-WRF simulation initialized on 1200 UTC 7 Feb 2018.


Figure 4.  Animation of 30-minute surface visibility (km) and 10-m winds (m/s) from the 1-km nested grid of the SPoRT/NU-WRF simulation initialized on 1200 UTC 7 Feb 2018.

Lightning’s Reach

Over the weekend of October 22, thunderstorms moved through eastern Texas.  One feature that stood out was the number of flashes that extended well behind the main convective line of storms.  The image below shows where lightning was observed for one minute at 1258 UTC.  The overall Geostationary Lightning Mapper (GLM) event density display shows the lightning activity in a broken line from just west of Austin, Texas eastward towards Lake Charles, Louisiana.  Overall, the lightning remained fairly close to the parent storm.

The image is much more dramatic one minute later at 1259 UTC.  Here, GLM observes lightning extending from Austin, Texas all the way to Bryan and Waco, Texas and continuing northeast of Tyler, Texas.  Just from Bryan to Tyler, Texas this extends approximately 145 miles!



NOTE:  NOAA’s GOES-16 satellite has not been declared operational and its data are preliminary and undergoing testing. Users receiving these data through any dissemination means  (including, but not limited to, PDA and GRB) assume all risk related to their use of GOES-16 data and NOAA disclaims any and all warranties, whether express or implied, including (without limitation) any implied warranties of merchantability or fitness for a particular purpose.


Comparison of Soil Moisture Response in Hurricanes Harvey and Irma

Comparison of Soil Moisture Response in Hurricanes Harvey and Irma

After a record [nearly] 12 years between landfalling major hurricanes [cat 3 or higher], the United States has now experienced two major hurricanes making landfall less than three weeks apart from one another.  Hurricane Harvey brought exceptional record rainfall to southeastern Texas and southwestern Louisiana because it stalled shortly after landfall due to a lack of atmospheric steering currents.  Less than 3 weeks later, Major Hurricane Irma made landfall twice in Florida: once in the Lower Keys and again near Marco Island on the southwestern coast.  A long-lived cat 5 hurricane prior to landfall, Irma had a very large wind field which resulted in far-reaching impacts along the Florida East Coast, up to Charleston, SC, and inland to Atlanta, GA, with millions of households and businesses without electricity and/or water.

Here at the NASA SPoRT Center, we have been closely monitoring these two hurricanes through numerous social media and blog posts of unique satellite products and through SPoRT’s real-time instance of the NASA Land Information System (“SPoRT-LIS”).  This blog post serves to compare the soil moisture responses to hurricanes Irma and Harvey rainfall, as depicted by the real-time SPoRT-LIS output.  The Relative Soil Moisture (RSM) variable is shown throughout this article, since it takes into account the variations in soil composition by scaling the moisture availability between the wilting point (plants cannot uptake moisture) and saturation point (soil cannot hold any more water).  The SPoRT-LIS runs the Noah land surface model, which estimates soil moisture through 4 layers: 0-10, 10-40, 40-100, and 100-200 cm depth.  We first examine the response during Irma in the top 0-10 cm layer, followed by 0-100 cm layer for both storms, and then compare the total column (0-200 cm) values relative to historical values from a climatological database spanning 1981-2013 (33 years).

Figure 1 compares the weekly rainfall accumulation primarily from Hurricane Irma over the Southeastern U.S. to the August monthly rainfall total over Texas/Louisiana, primarily contributed from Hurricane Harvey during the final week of August. Rainfall from Irma was quite substantial in the Florida peninsula up to coastal South Carolina, where numerous locations measured over 10″ of rain in less than 2 days. Rainfall of 3-5″ extended inland to northern Georgia and central South Carolina, with lesser amounts generally below 3″ across eastern and northern Alabama (Fig 1, left panel).  The highest totals were along the southwestern and eastern Florida coasts.  This rainfall still pales in comparison to the widespread 20″+ that fell across a huge part of southeastern Texas and western Louisiana, albeit over a 5-6 day span.  Highest totals exceeded 50″ near Beaumont/Port Arthur, TX!


Fig 1.  Comparison of weekly rainfall estimate associated with Hurricane Irma (left), and August monthly rainfall estimate associated with Hurricane Harvey (right).

The 0-10 cm RSM animation in Fig 2 for hurricane Irma shows how quickly the top soil layer responds to incoming rainfall within the Noah land surface model in SPoRT-LIS.  The heavy rainfall rates up to 4″ per hour or more led to a quick saturation during 10 September across the Florida peninsula, eventually extending up to coastal Georgia and South Carolina on the 11th.  Similarly, as rainfall ends we can see the 0-10 cm RSM quickly decrease from south to north as the moisture infiltrates into deeper model layers and/or evaporates back to the atmosphere.  We also see that the top soil layer does not completely saturate across interior Georgia and Alabama, likely due to lower rain rates, drier initial soils, and different soil composition compared to the fast-responding sandy soils across Florida.


Fig 2.  Hourly animation of SPoRT-LIS 0-10 cm relative soil moisture (RSM) and Multi Radar Multi Sensor (MRMS) quantitative precipitation estimates (QPE) from 0000 UTC 10 September through 1200 UTC 12 September 2017, associated with Hurricane Irma.

Meanwhile, the RSM averaged over the top 3 layers (0-100 cm; Fig 3) takes a longer time to moisten up during the heavy rainfall of Irma. We do see values approaching saturation across southwestern, central, and particularly northeastern Florida near the end of the rainfall event as the deeper soils have had an opportunity to recharge.

Over southeastern Texas and Louisiana (Fig 4), the 0-100 cm RSM animation shows how the prolonged, training heavy rainfall led to near saturation of the top meter of the Noah model, despite dry antecedent conditions (especially west of the Houston metro, where the RSM transitioned from less than 10% to nearly saturation!).  The much longer rainfall duration with hurricane Harvey led to sustained higher values of soil moisture in the top one meter.


Fig 3.  Hourly animation of SPoRT-LIS 0-100 cm RSM and MRMS QPE from 10-12 September 2017, associated with Hurricane Irma.


Fig 4.  Hourly animation of SPoRT-LIS 0-100 cm RSM and MRMS QPE from 25-30 August 2017, associated with Hurricane Harvey.

Finally, the total column 0-200 cm layer can require months or years to respond to rainfall events (or lack thereof), depending on the soil composition.  However, with major rainfall events like hurricanes Harvey and Irma, the total column RSM does respond dramatically and subsequently can depict substantial wet anomalies.  To that end, the SPoRT-LIS has a daily, county-based climatological database of modeled soil moisture from 1981-2013 from which current conditions can be compared to depict anomalies via percentiles relative to the 33-year distribution.  Fig 5 shows these percentiles color-coded to depict dry anomalies (less then 30th percentile) or wet anomalies (greater than 70th percentile) according to the scales beneath the figure.

Following hurricane Irma, we see that portions of southwestern and northeastern Florida have 0-200 cm RSM greater than the 98th percentile, as well as parts of west-central Georgia (Fig 5; left panel).  In general, the extreme wet percentiles are fairly spotty across the domain.  However, following hurricane Harvey (Fig 5; right panel), the 0-200 cm RSM percentiles are “off the charts” high, with dozens of counties experiencing soil moisture exceeding the [33-year] historical 98th percentile.  In fact, the soil moisture was SO anomalously moist following hurricane Harvey that the average daily value across all of Jefferson County, TX (Beaumont/Port Arthur) exceeded all values in the entire 33-year database by the end of August!  This unusual condition is highlighted in Fig 6, which shows a daily animation of historical 0-200 cm RSM histograms for Jefferson County, TX, with the current 2017 county-averaged values in the vertical dashed line.  We see that by the end of hurricane Harvey, the vertical dashed line is well above any values from the 33-year historical distribution, thereby quantifying how exceptionally unusual this rainfall event was in southeastern Texas.


Fig 5.  SPoRT-LIS 0-200 cm RSM percentile, valid at 1200 UTC on 12 September 2017 (post-Irma; left), and 30 August 2017 (post-Harvey; right).


Fig 6. Animation of daily distributions of 0-200 cm RSM for all SPoRT-LIS grid points residing in Jefferson County, TX (Beaumont/Port Arthur) during the month of August 2017.  Gray bars are the frequencies of 0-200 cm RSM from the 33-year SPoRT-LIS climatology; colored vertical lines are reference percentiles according to the legend in the upper right; and the bold vertical dashed line is the county-averaged value for the present day in August 2017.

Passive Microwave Views of Three Atlantic Hurricanes This Morning…

Below are 89 GHz RGBs (composited) of the three hurricanes affecting the Atlantic basin this morning.  Notice a decent eye structure is observable in all of the storms, including Hurricane Katia in the SW Gulf of Mexico.  This was noted in the 4 AM CDT discussion about the hurricane from the National Hurricane Center (NHC), “Enhanced BD-curve infrared imagery and a GPM microwave composite image indicate improved banding over the western portion of the circulation and the earlier ragged eye presentation has become much more distinct.”  SPoRT helped with the implementation of the passive microwave data into the AWIPS platform at the NHC several years ago, which has aided forecasters there with the diagnosis and analysis of these systems.

For the latest, best up-to-date information regarding the hurricanes, please refer to the NHC website.


89 GHz RGBs from the GPM constellation of the three hurricanes affecting the Atlantic Basin this morning.  Approximate times for passes over the respective hurricanes are noted in the image.