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The Albuquerque NWS recently began receiving an updated NESDIS snowfall rate (SFR) product from NASA SPoRT. We were anxious to see how the updated product performed during our most recent winter storm. A fast moving upper level trough and associated Pacific Front blasted into western New Mexico on the afternoon of Saturday, December 13. The upper low deepened and closed off over New Mexico with wrap around snow impacting northeast New Mexico through mid-day Sunday, December 14.  Ahead of the system, temperatures were very warm with Albuquerque reporting a high of 61 and Santa Fe reporting a high of 57 on Saturday.  The RGB snow-cloud product from 2045Z on Sunday depicts snow cover following the event. Four areas in the state were impacted – the western high terrain, the San Juan and Sangre de Cristo Mountains (mainly west slopes) in north central New Mexico, and extreme northeastern corner of New Mexico. Four yellow ovals mark areas to be discussed in this blog entry. Strong westerly, downslope flow on the backside of this storm system resulted in the snow-free region along the eastern slopes between Taos and Raton.
SnowCloud121414_2045Z

In the loop below, the 0.5 reflectivity mosaic and surface observations show the surface front moving into western New Mexico (left most oval in the snow-cloud product) during the period from 1942Z to 2318Z. In the first image, the winds have shifted to the northwest in Farmington (FMN) and rain is reported as temperatures are too warm to support snow. Note that throughout the loop the Farmington area, especially west and north of the site, there are no radar returns. The Four Corners area has poor to no radar coverage and it is an area where we hope the SFR product will help us. Snow was reported at Gallup (GUP) by 2030Z.

0.5 Reflectivity 1942Z to 2318Z

The SFR product was limited during this initial period, with only one swath covering New Mexico at 2034Z (shown below). This image (obtained from the SPoRT product page) shows that snow is detected in northeast Utah and northwest Colorado, but not in northwest New Mexico.  The Gallup area ended up with about one inch of snow while higher terrain south of Gallup reported two to three inches. While only rain was reported at the Farmington ASOS, the snow-cloud product shows some snow just to the east of Farmington where reports of one-half to an inch of snow was reported.

SPoRT_SFR_121314_2034Z

The next SFR product with coverage over New Mexico had a timestamp of 0338Z (14 December 2014), and is compared to the composite reflectivity image of 0336Z in the image below. Reflectivity is strongest just west and northwest of the Albuquerque ASOS (ABQ), which is reporting rain. The cold front however was moving quickly from west to east toward the ABQ metro area. The strong reflectivity returns to the northwest of Albuqurque are actually bright banding as rain began changing over to snow. The dual polarization hydrometeor classification algorithm showed the rain/snow line shifting quickly eastward. Fifteen minutes prior to this image, rain transition to snow was reported in Rio Rancho, just northwest of Albuquerque. The higher terrain just east of Albuquerque, the Sandia and Manzano Mountains, did receive snow accumulations of two to four inches and the SFR product highlights that area with light rates (blue) of about .02 inches/hour. The Santa Fe area (SAF) is not reporting snow at this time, but is highlighted with the max values of SFR, though snow reports in the Santa Fe area were generally less than 2 inches.  Recall that afternoon temperature were quite warm, making it difficult for snow to accumulate. The SFR product also depicts rates up to .05 inches/hour over the Sangre de Cristo mountains north and east of Santa Fe, where accumulations of 4 to 8 inches were reported. Interestingly, the SFR product is estimating precipitation around Santa Fe when the radar reflectivity pattern and observation do not indicate rain or snow. A portion of this area to the immediate northeast and east of ABQ is beam-blocked by the Sandia Mountains (yellow oval southwest of SAF).

mosaic_Comp_Ref_20141214_0336_SFR_0338Z

A similar comparison is shown for 13 hours later, or around 1655Z on December 15. (Another image was available around 08Z, but is not discussed in the post.)  Note that the SFR product depicts accumulating snow, albeit light, from eastern Taos through all but extreme southern Colfax County. Two stations (KAXX and KRTN) are reporting snow, but radar composite reflectivities do not extend over either location. Snow did accumulate at KAXX, but not at Raton (KRTN) where temperatures hovered right above freezing.

mosaic_Comp_Ref_20141214_1642_SFR_1645Z

Snow that is evident in extreme northeast New Mexico occurred after mainly 16Z and was associated with persistent wrap around precipitation (a SFR product was not available). The SFR product was not used in near real time for this event but was re-examined only a short time thereafter. However, the product did validate that we will indeed be able to complement radar void coverage areas in an operational forecast environment using polar-orbiting satellite imagery. This example will also serve to highlight potential product applications, advantages, and disadvantages for forecaster training prior to the upcoming NESDIS evaluation period.

Last winter, SPoRT collaborated with NESDIS to perform an evaluation of the a passive microwave snowfall rate (SFR) product.  The impact of the product on the operational process was very large, and a tremendous amount of feedback was generated.  This feedback was used to improve the product in 3 ways:

  1. Product latency has been reduced through use of direct broadcast datasets over CONUS
  2. Algorithm modifications have been performed to drop the limitation of cold air at the surface from 22F to 7F, meaning more snow will be detected in colder air masses
  3. The minimum threshold of detected snowfall was reduced from 0.1 to 0.04 mm/hr (liquid equivalent)

These modifications were based on direct feedback on limitations to the product noted by WFO participants last winter.

Because of the operational impact of the data of the first product iteration, and the great responsiveness by the product developers at NESDIS, SPoRT is again working with NESDIS and the WFOs to assess the next iteration of the SFR product.  An assessment is ongoing in Alaska and a CONUS assessment will begin in mid-January.

To whet everyone’s appetite about this upcoming assessment, we received the following input from Sheldon Kusselson, at the Satellite Analysis Branch, who is a strong forecaster advocate for the SFR product and has been an active participant in assessment of the SFR product:

A small success with low rates/small area of 0.04″/hr over the northern Sierras…Plumas/Sierra County  with SFR pass of I believe 2230z…and relayed that to the WFO Sacramento.  They responded, that they had some reports of snow down to 3200′ in Plumas County. A little south of Sierra County in Placer its around 5000′.  Then they came back 03z and mentioned 4″ of new snow at 3800 ft in Plumas County.  Noted a new 0010z pass that had max rates of 0.08″-0.09″/hr centered over the Plumas, Tehama, Butte, Sierra-Plumas County border area.   So this appeared to work out well for a small, but intense area in elevations above 3000′.

NESDIS SFR Product valid at 0057Z on 12 December 2014.  The navy blue coloration indicates over water regions where the SFR product will not be retrieved.  Notice the small-scale, high-intensity snowfall that is detected over NE California.

NESDIS SFR Product valid at 0057Z on 12 December 2014. The navy blue coloration indicates over water regions where the SFR product will not be retrieved; the grey coloration indicates the area of the satellite swath where no snowfall was detected. Notice the small-scale, high-intensity snowfall that is detected over NE California.

Thanks to Sheldon for pointing out this great example of the SFR product in elevated terrain where radar overshoot and beam blockage makes detection of falling precipitation challenging!

I’ve written about the operational utility of Day-Night Band (DNB) RGB imagery several times in the SPoRT blog, and here I’m going to take the chance to do that again.  First, just some brief background information in case you’re not familiar with this type of imagery.  The DNB RGB is composed of a long wave IR channel (~10.8 µm), which is assigned to the blue color component of the RGB recipe, while the DNB channel (0.7 µm) is assigned equally to the red/green colors of the RGB.  SPoRT produces two DNB RGB products: Radiance and Reflectance.  I typically prefer the Radiance RGB for operational uses since it is composed of the raw data (emitted and reflected light) from the sensor.  Sure, cities are quite bright in the imagery, but the cloud features also stand out better compared to the reflectance product, where the data are normalized by the available amount of moonlight. Below are a few observations from the Suomi-NPP VIIRS instrument during this most recent full moon cycle.

First, take a look at the images below from the SE half of the CONUS on the early morning of December 7th.  The top image (Image 1) is a Nighttime Microphysics RGB at approx. 0736 UTC, while Image 2 is a DNB Radiance RGB valid at the same time.  While this type of imagery is far superior to legacy IR imagery (even enhanced with fanciful color curves), there are proper operational forecasting/analysis applications that one has to consider.  The Nighttime Microphysics RGB is generally more useful for distinguishing different cloud types (e.g., low stratus vs fog, thin cirrus vs thick cirrus, etc).  After at least a year of viewing the DNB imagery, I think perhaps the best application of these types of imagery (at least with respect to operational forecasting) lies in the ability to view low clouds through cirrus at night.  No other imagery available to forecasters offers this capability currently.  Take for example these first two images below and pay close attention to the cloudy regions stretching from the central Plains into the lower Mississippi Valley.

Image 1.  Nighttime Microphysics RGB 0736 UTC 7 Dec 2014

Image 1. Nighttime Microphysics RGB 0736 UTC 7 Dec 2014.  Ceiling and Visibility observations from some ASOS and AWOS stations also shown in cyan.

Suomi-NPP VIIRS Day-Night Band Radiance RGB 0736 UTC 7 Dec 2014.  Ceiling/Visibility observations are shown in cyan.  Notice that details of the extensive deck of low clouds can be seen more easily than in the Nighttime Microphysics RGB.

Image 2.  Suomi-NPP VIIRS Day-Night Band Radiance RGB 0736 UTC 7 Dec 2014. Ceiling/Visibility observations are shown in cyan. Notice that details of the extensive deck of low clouds can be seen more easily than in the Nighttime Microphysics RGB.

Notice that in the Nighttime Microphysics RGB the expansive deck of low stratus across much of Kansas, southwestern Missouri and Oklahoma is almost entirely obscured by the cold cirrus clouds.  Of course, this is only realized upon looking at the DNB imagery.  Details in the low stratus can also be observed in the DNB imagery, such as the cloud banding stretching SW-NE across much of northern Louisiana and Mississippi.  Since the cloud bases in this imagery were mostly at MVFR and IFR levels with respect to aviation forecast concerns, knowledge about the details and characteristics of the low clouds are very important.

The next series of images from the New England region in the early morning hours of December 9th again demonstrates this application of the DNB imagery.

Image 3.  Suomi-NPP VIIRS IR (~10.8 u m) 0658 UTC 9 Dec 2014.  Ceiling/visibility observations from regional ASOS/AWPS are shown in cyan.

Image 3. Suomi-NPP VIIRS IR (~10.8 µm) 0658 UTC 9 Dec 2014. Ceiling/visibility observations from regional ASOS/AWPS are shown in cyan.

Image 4.  VIIRS Nighttime Microphysics RGB 0658 UTC 9 Dec 2014.  Ceiling/visibility observations shown in cyan.

Image 4. VIIRS Nighttime Microphysics RGB 0658 UTC 9 Dec 2014. Ceiling/visibility observations shown in cyan.

Image 5.  VIIRS DNB Radiance RGB 0658 UTC 9 Dec 2014.  Ceiling/visibility observations shown in cyan.

Image 5. VIIRS DNB Radiance RGB 0658 UTC 9 Dec 2014. Ceiling/visibility observations shown in cyan.

In the images above, notice that the extensive low cloud deck across the region that spans from Maine to at least as far south as northeastern North Carolina cannot readily be observed either in the legacy IR (10.8 µm ) imagery or in the Nighttime Microphysics RGB.  However, more details about the low clouds can be discerned from the DNB imagery.  Sure, cirrus clouds are optically thick enough to prevent viewing of any low clouds in the NY metro area.  Nevertheless, the advantages of the DNB imagery for detecting low clouds beneath thin cirrus can clearly be seen.  Again, as expressed earlier, this type of imagery certainly offers application for aviation forecasting, in particular.

Lastly, here are some observations from just this morning (Dec 10th) over the Rio Grande Valley region.

VIIRS color-enhanced IR (10.8 u m) image 0819 UTC 10 Dec 2014.  Ceiling/visibility observations are shown in cyan.

Image 6.  VIIRS color-enhanced IR (10.8 µm) image 0819 UTC 10 Dec 2014. Ceiling/visibility observations are shown in cyan.

Image 7.  VIIRS DNB Radiance RGB 0819 UTC 10 Dec 2014.  Ceiling/visibility observations are shown in cyan.

Image 7. VIIRS DNB Radiance RGB 0819 UTC 10 Dec 2014. Ceiling/visibility observations are shown in cyan.

In the VIIRS IR image (Image 6) just as in previous IR imagery the cirrus clouds obscure the presence of any clouds beneath.  However, the patchy low clouds in eastern New Mexico can be much more easily seen in the DNB imagery.  In the area between Midland, TX (KMAF) and Fort Stockton (KFST), a forecaster might have made the assumption that the low clouds were continuous based on the observations alone and without the aid of the DNB imagery.  Yet, what becomes noticeable in the DNB imagery is that a gap exists in the low cloud deck.

Of course, with all of this said, the availability of the imagery severely limits its application for operational forecasting and analysis.  Generally, only one or two passes are available over a given location on any night.  Also, due to moonlight limitations, the imagery are only available for about half of the month…at best.  I can only lament that the DNB imagery will not be available on a geo-stationary platform (at least anytime soon).  Nevertheless, understanding the limitations of the imagery while also appreciating its advantages can offer operational utility when applied properly to a forecast challenge.

The inaugural Orion flight test successfully lifted off from Space Launch Complex 37 at Cape Canaveral Air Force Station aboard a Delta IV Heavy rocket the morning of 5 December (Fig. 1), following a scrubbed launch attempt the previous day. Orion is designed to take humans beyond Earth orbit into deep space, including missions to an asteroid and eventually Mars.

Fig 1. A Delta IV Heavy rocket lifts off from Space Launch Complex 37 at Cape Canaveral Air Force Station in Florida carrying NASA's Orion spacecraft on an unpiloted flight test to Earth orbit. (photo credit: NASA)

Figure 1. A Delta IV Heavy rocket lifts off from Space Launch Complex 37 at Cape Canaveral Air Force Station in Florida carrying NASA’s Orion spacecraft on an unpiloted flight test to Earth orbit. (photo credit: NASA)

The Applied Meteorology Unit (AMU) operated by ENSCO, Inc. at the Cape Canaveral Air Force Station, Florida has transitioned a high-resolution configuration of the Weather Research and Forecasting (WRF) numerical weather prediction (NWP) model to support ground and launch operations at the Eastern Range (ER) and Wallops Flight Facility (WFF). The AMU-WRF runs a nested modeling domain with the highest-resolution nest (1.33-km grid spacing) centered on the ER launch facility (Fig. 2) and uses two initialization datasets from NASA/SPoRT: (1) Land Information System soil moisture and soil temperature data, and (2) the high-resolution (2-km) northern hemispheric sea surface temperature product.

Figure 2.  Grid setup of the AMU-WRF model as transitioned into operations at the 45 WS.

Figure 2. Grid setup of the AMU-WRF model as used by the 45th Weather Squadron.

The ER and WFF require high-resolution numerical weather prediction model output to provide more accurate and timely forecasts of unique weather phenomena that can affect NASA’s Space Launch System, Launch Services Program, and Ground Systems Development and Operations Program daily operations and space-launch activities. Global and national-scale models cannot properly resolve important mesoscale features due to their horizontal resolutions being much too coarse.

Daily and weekly weather forecasts issued by the 45th Weather Squadron (45 WS) are used as decision tools for their day-to-day and launch operations at the ER. The 45 WS and vehicle Launch Weather Officer (LWO) use NWP models as a guide for these weather forecasts. Forecasters have found the AMU-WRF model performance quite useful. It has frequently been the preferred model to help accurately identify complex, small-scale boundary interactions. Of particular note, its rapid hourly update capability adjust to dynamic changes in weather features, aiding the LWO during sensitive ground and launch operations that require specific timing accuracy.

During the Orion launch operations on 4 and 5 December 2014, the LWO relied on AMU-WRF low-level wind, fog and precipitation output variables as part of their forecasts leading to a successful launch. Figures 3 and 4 show five-hour forecast AMU-WRF output of 10-m wind gust and forecast radar reflectivity as displayed in the AWIPS II at the 45 WS, valid at the beginning of the launch window (1200 UTC 5 December). The forecast radar reflectivity image (Fig. 4) suggested that the rain shower activity would be primarily south and west of the launch complex at the beginning of the launch window, which corresponded fairly well with the validating Melbourne, FL radar image in Figure 5. The combination of shower activity movement from northeast to southwest and little indication of forecast precipitation upwind of the launch complex suggested a favorable weather outcome for launch.

Figure 3.  AMU-WRF 5-hour forecast 10-m wind gusts as displayed in the 45 WS AWIPS II, valid 1200 UTC 5 December 2014 (7 am EST).

Figure 3. AMU-WRF 5-hour forecast 10-m wind gusts as displayed in the 45 WS AWIPS II, valid 1200 UTC 5 December 2014 (7 am EST).

Figure 4.  AMU-WRF 5-hour forecast radar reflectivity as displayed in the 45 WS AWIPS II, valid 1200 UTC 5 December 2014 (7 am EST).

Figure 4. AMU-WRF 5-hour forecast radar reflectivity as displayed in the 45 WS AWIPS II, valid 1200 UTC 5 December 2014 (7 am EST).

Figure 5.  Validating radar reflectivity at 1207 UTC 5 December 2014 (7:07 am EST), approximately corresponding to the time of the Orion launch aboard the Delta IV Heavy rocket.

Figure 5. Validating radar reflectivity at 1207 UTC 5 December 2014 (7:07 am EST), approximately corresponding to the time of the Orion launch aboard the Delta IV Heavy rocket.

A strong cold front is ushering in markedly colder air for much of the central and eastern U.S. over the next several days.  The cold front today is highlighted by extreme temperature contrasts over the Southern Plains, with high winds and blowing dust along and behind the front as it surges southward through Colorado and Kansas.  Figures 1 and 2 show the VIIRS dust RGB images over the Plains at 1906 to 2049 UTC, respectively.  One can easily identify the increase in dust coverage (given by the darker pink colors) by 2049 UTC over southeastern Colorado as the front propagates southward.  A corroborating surface analysis valid at 2043 UTC in Figure 3 depicts visibility reductions at Lamar, CO (LAA; 2 miles), La Junta, CO (LHX; 1 mile), and Pueblo, CO (PUB; 3 miles) in southeastern Colorado.  Notice temperatures in the 80s across the Oklahoma and Texas Panhandles, while temperatures are in the 20s and 30s across northeastern Colorado and northwestern Kansas.  Quite the contrast!

Figure 1.  VIIRS dust RGB image valid at 1906 UTC 10 November 2014.

Figure 1. VIIRS dust RGB image valid at 1906 UTC 10 November 2014.

Figure 2.  Same as Figure 1, except valid at 2109 UTC 10 November 2014.

Figure 2. Same as Figure 1, except valid at 2049 UTC 10 November 2014.

Figure 3.  Surface analysis valid 2043 UTC 10 November 2014.

Figure 3. Surface analysis valid 2043 UTC 10 November 2014.

Expanding D0 in Central NC Utilizing 0-200cm RSoM in Conjunction with 30-90 Day Precip Deficits

Introduction

The North Carolina Drought Management and Advisory Council (NCDMAC) has a teleconference each Tuesday afternoon to discuss drought conditions and submit recommended changes to the U.S. Drought Monitor (http://drought.gov/drought). A variety of data are considered, such as streamflows, reservoir and monitored well levels, and agricultural reports. Relative soil moisture fields from NASA’s Short-term Prediction Research and Transition Center (NASA/SPoRT- http://weather.msfc.nasa.gov/sport), are newer datasets which have been introduced and evaluated over the past few months.

A Case from 10/28/2014

Below are 30, 60, and 90 day rainfall deficits, as well as the 0-200 cm relative soil moisture (RSoM) product from NASA/SPoRT. The circled area in each image corresponds to the area designated as ‘abnormally dry’ (D0) for the previous week. The RSoM (using a rather subjective 25% threshold) shows very strong correlation to rainfall deficits in the longer time frames (60 and 90 days), which are the fields typically used to help delineate low base flow in areas where reliable streamflow data is more sparse. The high resolution of the RSoM (which is more evident than can be seen in the downsized image), allows for sub-basin and sub-county scale delineation of areas of concern.SPoRT

 

Southerly expansion of D0 conditions were recommended (below), with the RSoM’s weighing heavily on the decision to do so. The U.S. Drought Monitor author for the week, Brian Fuchs, was on the call and requested information concerning the NASA/SPoRT product suite. He was provided LIS  links and information.

dm

NASA SPoRT has developed a real-time application of the NASA Land Information System (LIS) that runs over much of the central and eastern United States. The LIS produces several products, including a suite of soil moisture products that can be used to help assess drought and flooding potential. There are four LIS soil moisture products that are made available to WFO Raleigh forecasters in AWIPS-2 and which are available online for the Southeast and for North Carolina.

A fairly significant rain event occurred across central North Carolina on 15 and 16 October 2014 as a cold front and a wave of low pressure moved across the region. Two day precipitation totals across the WFO RAH CWA (Fig. 1) indicated between 0.75 and 1.25 inches of rain fell across the western Piedmont with much more significant amounts generally ranging between 1.5 and 3.0 inches across the eastern Piedmont and Coastal Plain of North Carolina. The heaviest rain occurred across Franklin, eastern Wake, northern Johnston, and western Nash Counties.

Fig. 1. Analyzed two day two day precipitation totals across the WFO RAH CWA on 15 and 16 October 2014.

Fig. 1. Analyzed two day two day precipitation totals across the WFO RAH CWA on 15 and 16 October 2014.

One of the SPoRT-LIS fields that forecasters have found quite useful during the assessment is the one-week change in total column relative soil moisture (RSM, 0-2 m). The RSM is the ratio of the current volumetric soil moisture between the wilting and saturation points for a given soil type, with values scaling between 0% (wilting) and 100% (saturation). The one-week change product valid at 12 UTC on 14 October, just prior to the rain event, is shown in Fig. 2 with the RAH CWA outlined in red. This product indicates that much of the southern and eastern portions of the RAH CWA have experienced a relative soil moisture decrease during the previous week, while locations near the Virginia border, especially across the northern Piedmont have had a relative soil moisture increase.

Fig. 2. The one-week change in total column relative soil moisture valid at 12 UTC on 14 October 2014 with the RAH CWA outlined in red.

Fig. 2. The one-week change in total column relative soil moisture valid at 12 UTC on 14 October 2014 with the RAH CWA outlined in red.

This rainfall produced significant rises on many rivers and creeks across the northeast Piedmont and the Coastal Plain of North Carolina. Figure 3 shows the gage height on the Swift Creek at Hilliardston which had an uncharacteristic rapid response and the gage height on the Neuse River at Smithfield which exceeded flood stage.

Fig. 3. Gage heights for the Swift Creek at Hilliardston (left) and the Neuse River at Smithfield (right).

Fig. 3. Gage heights for the Swift Creek at Hilliardston (left) and the Neuse River at Smithfield (right).

It was noted that the locations that experienced the most significant rises along with some flooding where in the river basins that had a notable overlap of the one-week increase in total column relative soil moisture prior to the event and the basins which experienced the most significant rainfall as shown in the composite image in Fig. 4.

Fig. 4. Composite chart of the one-week change in total column relative soil moisture valid at 12 UTC on 14 October and the analyzed two day two day precipitation totals on 15 and 16 October 2014 along with the locations of the gages for the Swift Creek at Hilliardston and the Neuse River at Smithfield.

Fig. 4. Composite chart of the one-week change in total column relative soil moisture valid at 12 UTC on 14 October and the analyzed two day two day precipitation totals on 15 and 16 October 2014 along with the locations of the gages for the Swift Creek at Hilliardston and the Neuse River at Smithfield.

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