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A unique weather event is unfolding this week as Hurricane Odile, now a tropical storm, is impacting Baja California Sur, bringing heavy rain and high winds to the region and causing tourists to evacuate resorts. The National Hurricane Center reports that Odile ties Olivia (1967) as the strongest hurricane to make landfall in the satellite era in Baja California Sur**. NASA SPoRT provides specialized satellite products to National Weather Service Forecast Offices as well as National Centers such as the National Hurricane Center to aid forecasting high impact events such as Hurricane Odile.

Below is an example of Passive Microwave RGB imagery created from the NASA Global Precipitation Measurement (GPM) mission as part of The Core Observatory satellite launched on 27 February 2014. The images are in N-AWIPS (National Centers for Environmental Prediction Advanced Weather Interactive Processing System) format and are an example of products available to forecasters at the National Hurricane Center.  Forecasters use the 89 GHz RGB product to look for areas of strong convection which show up as deep red as seen in Fig. 1 which captures Hurricane Odile a few hours before landfall.

89 GHz RGB 0121 UTC 15 September 2014. Areas of deep convection appear red and can be seen surrounding the eye wall and within the rainbands of Odile in this image a few hours before landfall.

Figure 1. GMI 89 GHz RGB 0121 UTC 15 September 2014. Areas of deep convection appear red and can be seen surrounding the eye and within the rainbands of Hurricane Odile in this image a few hours before landfall.

The 37 GHz can additionally be used to distinguish areas of deep cloudiness (light blue) from more active convection (pink) as well as open water (green) or land (cyan).  Note the areas of pink or active convective in Fig. 2 surrounding the eye and within the rainbands.

odile_37RGB1

Figure 2. GMI 37 GHz RGB 0121 UTC 15 September 2014. Areas of active convection appear pink and can be seen surrounding the eye and within the rainbands of Hurricane Odile in this image a few hours before landfall.

Figure 3 and 4 show similar observations from the legacy NASA Tropical Rainfall Measurement Mission (TRMM) as Hurricane Odile made landfall near Cabo San Lucas around 445 UTC 15 September. TRMM is expected to run out of fuel by February 2016 and will no longer be available to collect valuable observations. We are well prepared for a replacement with GPM in orbit and already collecting observations.

TRMM 89 GHz RGB 0307 UTC 15 September 2014

Figure 3. TRMM 89 GHz RGB 0307 UTC 15 September 2014.  Areas of deep convection appear red and can be seen surrounding the eye and within the rainbands of Hurricane Odile in this image a little over one hour before landfall.

TRMM 37 GHz RGB

Figure 4. TRMM 37 GHz RGB 0307 UTC 15 September 2014.  Areas of active convection appear pink and can be seen surrounding the eye and within the rainbands of Hurricane Odile in this image a little over one hour before landfall.

Additionally the Visible Infrared Imaging Radiometer Suite (VIIRS) Day-Night Band Radiance imagery from the next generation NASA Suomi National Polar-orbiting Partnership (NPP) satellite shows an impressive picture of Hurricane Odile approximately one day before landfall (Fig. 5). Note the city lights that can be seen through the clouds in Fig. 5 as well as lightning within the area of convection in the rainband. This imagery can be used to support disaster response and help emergency managers identify the areas where conditions have caused power outages. Local knowledge of city light patterns can allow users to identify where the most significant power outages are and determine where to begin relief efforts.

VIIRS Day-Night Band Radiance

Figure 5. VIIRS Day-Night Band Radiance 0904 UTC 14 September 2014. City lights and lightning observed approximately one day before Hurricane Odile made landfall.

As the community transitions from legacy instruments such at TRMM and MODIS, NASA SPoRT will continue to develop unique products from Next-Generation missions such as GPM and Suomi NPP to aid National Weather Service Forecast Offices and National Centers in forecasting high impact events such as Hurricane Odile.

**see archived National Hurricane Center forecast discussion at http://www.nhc.noaa.gov/archive/2014/ep15/ep152014.discus.021.shtml?

Kevin Fuell:

Here is an excellent satellite imagery interpretation by Paul Nutter of the Great Falls WFO regarding the Nighttime Microphysics RGB. As Paul demonstrates with his ability to describe this image and support its value based on current imagery, training and continued experience can lead to efficient use of RGB-type imagery.

Originally posted on TFX-shoptalk:

A strong early season cold front pushed through Montana from Alberta on 9 September 2014. The front produced several layers of cloud cover that appeared richly on the Nighttime Microphysics RGB imagery. This provides an excellent case for a study of capabilities we expect to have available on the GOES-R platform.

WPC Daily Weather Map valid 12 UTC 9 Sept 2014

WPC Daily Weather Map valid 12 UTC 9 Sept 2014

SPoRT VIIRS Night-time Microphysics RGB valid 0844 UTC 09-Sep-2014.

SPoRT VIIRS Night-time Microphysics RGB valid 0844 UTC 09-Sep-2014.

Table 1. Wavelength Band or band difference contributions to the RGB triplets and their physical interpretation used within the Nighttime Microphysics RGB composite imagery.

Color Band / Band Diff. Physically Relates to: Little contribution to composite indicates: Large contribution to composite indicates:
Red 12.0 – 10.8 Optical Depth Thin clouds Thick clouds
Green 10.8 – 3.9 Particle Phase and Size Ice particles;
Surface (i.e. cloud free)
Water clouds with
small particles
Blue 10.8 Temperature of surface Cold surface Warm surface

Violet colored…

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Kevin Fuell:

Here is a posted application of the VIIRS Day-Night Band by the NWS Forecast Office in Great Falls. It was posted on their local blog.

Originally posted on TFX-shoptalk:

Clear skies and a bright moon in the early morning hours on September 12th 2014 allowed for good view of the extent of recent snowfall on the VIIRS Day-Night Band Reflectance imagery. At 1km resolution it’s about as detailed as a GOES visible image during daylight.

-Bob

VIIRS_DNB_ref_201409120930z_state_snow


Image1: Note Calgary’s location (bright city lights) on the eastern flank of the snowfield. east of the Canadian Rockies.

Viirs_snow_tfx

Image 2: Closer look at the TFX CWA

VIIRS_snow_RMF

Image3: Good detail of the extend of snowfall along the Rocky Mtn Front.

View original

A cold front will sag slowly southward across the mid-South and Mid-Atlantic during the upcoming weekend, and will likely stall over the Carolina Piedmont region as a couple of waves of low pressure move along the front. The broad scale lift of the moisture-laden airmass ahead of and over the shallow front will be capable of producing moderate to heavy rainfall in the Carolinas through early next week. Recently, the Raleigh NWS forecast area experienced heavy rainfall (see recent blog post from the Raleigh NWS office) which lead to the moistening of soils and some instances of flooding. If the heavy rains in the latest forecast by the Weather Prediction Center (WPC) materialize, then current soil moisture levels suggest the risk for flooding will be increased. Take a look at the SPoRT LIS 0-200 cm Relative Soil Moisture (%) analysis below from 12Z this morning (Image 1).

Figure 1.  SPoRT LIS 0-200 cm Relative Soil Moisture (%, RSOIM), valid 12Z 11 Sep 2014.  An area with RSOIM values around 50-60% is circled in black centered on the eastern part of the Raleigh forecast area.

Image 1. SPoRT LIS 0-200 cm Relative Soil Moisture (%, RSOIM), valid 12Z 11 Sep 2014. An area with RSOIM values around 50-60% is circled in black centered on the eastern part of the Raleigh forecast area.

The area circled in black indicates portions of the Raleigh NWS forecast area where 0-200 cm Relative Soil Moisture (RSOIM) values exceed 55%. Here in the Huntsville area, subjective analysis of several synoptic rainfall events suggests that when 0-200 cm RSOIM values exceed this threshold, the risk of flooding of basins and rivers in our area is increased substantially. Next, let’s take a look at the latest 5-day precipitation graphic produced by the Weather Prediction Center (WPC, Image 2).

Image 2.  WPC (HPC in label) 5-Day Total Precipitation ending 12Z 16 Sep 2014.

Image 2. WPC (HPC in label) 5-Day Total Precipitation ending 12Z 16 Sep 2014. The region with relatively moisture 0-200 cm soils is circled in black.

In this latest update from the WPC, precipitation amounts totaling around two to four inches are forecast for portions of the Raleigh NWS forecast area. Of course, these totals are likely to be adjusted over the days ahead. Additionally, some of the precipitation during this period is likely to be convective in nature, which will make the resulting precipitation in the region more heterogeneous, and it may fall in several distinct episodes, reducing the overall average rainfall rate. Nevertheless, since soil moisture levels have now exceeded a seemingly critical threshold, this particular area may bear watching for potential flooding if the rains materialize.

The Raleigh WFO together with the Huntsville and Houston WFOs are participating currently in a more formal assessment of several SPoRT LIS variables. Although this and other soil moisture variables have demonstrated utility for assessing both drought and flood risk in the Huntsville forecast area over the last few years, this is the first formal assessment to evaluate the utility in different environments simultaneously.

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.  WFO Raleigh is currently evaluating these soil moisture products.

A significant rain event occurred across central and eastern North Carolina on 08 and 09 September 2014 as surface low moved northeast along a stalled cold front that was located in the Coastal Plain of the Carolinas. Radar estimates which match fairly well with surface observations indicated a large area of 2 to 4 inches of rain fell across eastern NC with several locations receiving between 6 and 8 inches of rain (Fig. 1).

Fig. 1. The 48 hour precipitation estimate for North Carolina for the period ending at 12 UTC on 9 September 2014.

Fig. 1. The 48 hour precipitation estimate for North Carolina for the period ending at 12 UTC on 9 September 2014.

This heavy rain resulted in a significant increase in the 0 to 10cm below ground Relative Soil Moisture (RSM) as noted in the animation of RSM from 12 UTC on 7 September through 00 UTC on 09 September, 2014 shown below (Fig. 2). The 0 to 10cm RSM product provides the ratio of the water content per total soil volume between the wilting and saturation points for a given soil type, expressed as a percentage. The RSM product provides information about the soil saturation state. Since this RSM product highlights the moisture in a very shallow layer between the surface and about 4 inches below ground, the values change quickly as the heavy rain begins and diminishes.

Fig. 2. An animation of the LIS 0 to 10cm below ground Relative Soil Moisture product from 12 UTC on 7 September through 00 UTC on 09 September, 2014.

Fig. 2. An animation of the LIS 0 to 10cm below ground Relative Soil Moisture product from 12 UTC on 7 September through 00 UTC on 09 September, 2014.

The previous blog post made by the NWS forecast office at Raleigh, NC (WFO RAH) illustrated the decrease in LIS total column relative soil moisture over North Carolina (NC) associated with the recent lack of rainfall through 1 September.  Despite receiving some nominal precipitation up to 0.50″ during the previous week, portions of eastern NC experienced the greatest amount of soil drying compared to central NC where practically no rain fell.

This response in the Noah land surface model within the real-time SPoRT-LIS is related to the disparate soil composition across NC as seen in Figure 1.  The soils consist of mostly sand or sandy loam composition across eastern NC compared to silty loam in central NC.  The movement of water in lower porosity, sandy soils is dominated by capillary action (upward movement of water against gravity) and thus readily release its water at higher soil moisture values.  Meanwhile, higher porosity soils (i.e., clay/silt with numerous smaller pores) retain water for longer time periods and tend to dry out more slowly at higher values of soil moisture (google “water retention curve” for more details).  Thus, despite the modest rainfall over the sandy soils of eastern NC, the soil actually dried out faster than over central NC where less rainfall was observed.

soilType_nc

Figure 1. Soil texture classifications used in the SPoRT-LIS runs of the Noah land surface model, centered over North Carolina.

NASA SPoRT has developed a real-time configuration of the NASA Land Information System (LIS) that runs over much of the central and eastern United States at 3-km grid spacing.  The LIS produces several products, including a suite of soil moisture products that can be used to help assess drought and flooding potential.  WFO Raleigh is pleased to be participating (along with WFOs Houston and Huntsville) in an assessment of these products from August through October.

Central North Carolina has been in a short-term relative dry spell of late, with much of the area having seen little to no rainfall in the last week (Fig. 1). One ramification of this lack of rainfall is the soil drying evident in the 1-week difference in column relative soil moisture imagery (Fig. 2), which shows marked drying over all of Central NC in the last week. Interestingly, in coastal sections of NC that actually have seen some rainfall in the last week, the soil drying has been even more pronounced. Reasons for this are unclear, but it may have to do with the soil type over Eastern NC.

7dayrainfall.ending12z20140901

Fig. 1. Seven-day rainfall over North Carolina, for the period ending at 8 am EDT 1 September 2014.

1weekdiffinsoilmstr.ending00z20140901

Fig. 2. One-week difference in column relative soil moisture (%) over North Carolina, for the period ending at 8 pm EDT 31 August 2014.

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