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Archive for the ‘GOES-R Proving Ground’ Category

It is said that a picture says a thousand words…well in this case let’s just say 434 words, as are contained in this post. Anyway, I’d like to point out six features in this morning’s Nighttime Microphysics RGB.  The image below (MODIS Nighttime Microphysics RGB) showed several features of varying degrees of operational relevance.

MODIS Nighttime Microphysics RGB with annotations valid 0755 UTC 16 July 2014

MODIS Nighttime Microphysics RGB with annotations valid 0755 UTC 16 July 2014

 

A myriad of cloud features can be observed, including fog in the valleys of central Appalachia, deep convective clouds along the Florida coast, patches of thin and thick cirrus over north-central Alabama, and low stratus clouds in Missouri…to name just a few.  Sure, this isn’t an exhaustive list of the potential cloud features to observe, but showcases the ability to contrast effectively between different cloud types.  Of perhaps significant interest is the ability to see the contrasting airmasses displayed across the Southeast region.  Notice the  pinkish colors north and west of the yellow curved line that stretches from central Louisiana to southern Virginia.  This represents a lower relative contribution of blue color, or lesser longwave radiation at the 10.8 µm wavelength, which is indicative of cooler temperatures.  To the south and east of this line, much more blue is apparent, which is thus indicative of warmer temperatures.   Surface observations valid at about the same time have been overlaid with the RGB image to provide temperature data context.  Air and dew point temperatures are around 10 degrees F cooler behind the line/front, but notice that the northerly wind shift is still on the south/east side of the line at such locations as Montgomery, AL and Columbus, GA.  At those locations, dew point temperatures were still 70 and 71 F, respectively, with air temperatures at 72 F.  So, the gradient in temperatures still lingered behind the surface front and is well depicted in the RGB imagery.  This type of information can be valuable to forecasters, as temperature, moisture, and wind characteristics are often complex in the vicinity of surface fronts.  Thus, while wind shifts may be observed initially, as in this case, the imagery shows the location of the temperature gradient much better.

The importance of this type of imagery is that it offers a much more effective assessment of meteorological phenomena than existing GOES imagery.  The only problem currently is the limitation of available imagery to forecasters, since these are from polar-orbiting platforms (Terra, Aqua, Suomi NPP), and thus provide just a few snapshots per night over a given location.  Nevertheless, the imagery form the VIIRS and MODIS instruments offer added value to existing GOES imagery and serve as valuable teaching and preparatory aids for future GOES-R and JPSS missions.

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I wanted to point out a couple of operational advantages of total lightning data offered by current LMA networks scattered across parts of the CONUS, but also the advantages forthcoming with the GLM in the future GOES-R era.  While viewing the data today in conjunction with radar and NLDN data, two great examples were noticed.  First, let’s consider the situation where a cell becomes electrically active (intracloud lightning), but never produces a cloud-to-ground strike.  The first image below shows KHTX 0.5 reflectivity overlaid with LMA Flash Extent Density.

Image 1.  KHTX 0.5 reflectivity (dBZ) overlaid with North Alabama LMA Flash Extent Density valid 1735/1736 UTC 25 June 2014

Image 1. KHTX 0.5 reflectivity (dBZ) overlaid with North Alabama LMA Flash Extent Density (pinkish-white shaded area) valid 1735/1736 UTC 25 June 2014

 

Notice the small area of lightning detected by the North Alabama LMA in the central part of the image.  This cell never actually produced a ground strike.  So, using NLDN data alone, a forecaster would not have known that this cell was electrically active, and capable of producing lightning/thunder.  True, CG lightning was never observed by the NLDN network, but this is rather rare.

Next, let’s look at a situation where intra-cloud lightning preceded a CG strike as a cell was approaching an airport location.  Image 2 below, shows a cell that has just become electrically active as it was approaching the Tuscumbia/Muscle Shoals area around 1750 UTC.

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Image 2.  KHTX 0.5 reflectivity (dBZ) overlaid with North Alabama LMA Flash Extent Density (pinkish-white shaded area) valid 1749/1750 UTC 25 June 2014

Notice in the image above that the first lightning detection by the LMA was during the 1749-1750 two-minute interval.  Now, we’ll take a look at an image just a little later, which shows the first incident of cloud to ground lightning as detected by the NLDN.

Image 1. KHTX 0.5 reflectivity (dBZ) overlaid with North Alabama LMA Flash Extent Density (pinkish-white shaded area) valid 1735/1736 UTC 25 June 2014

Image 3. KHTX 0.5 reflectivity (dBZ) overlaid with North Alabama LMA Flash Extent Density (pinkish-white shaded area), including CG strike (small cyan line) as indicated by NLDN  valid 1757/1758 UTC 25 June 2014

The image above (Image 3) shows the first CG strike, indicated by the small cyan line, which was about 7-8 minutes after the first intra-cloud flash.  Notice also that this cell was approaching the Muscle Shoals ASOS to the east, for which the HUN office has airport weather warning responsibilities.  These responsibilities include the issuance of warnings for CG lightning with 5 SM of the airport. So, not only do the total lightning data alert to the presence of lightning when a cell never even produces a CG strike, but intra-cloud flashes will often precede CG strikes.  In fact, research has shown this to be by about 5 to 10 minutes.  Forecasters here at the HUN WFO have been privileged to use these data in operations for over 10 years now.  These and future GLM data will be a boon to operations, allowing for earlier lead times in some warning and forecast situations.

 

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I didn’t have a chance to make this post last week when the imagery were more time-relevant.  Nevertheless, I wanted to point out another example of the usefulness of MODIS and VIIRS imagery over current GOES imagery and show the usefulness of exciting products and imagery to come!  First, let’s take a look at the color-enhanced GOES-IR image below from the morning (0715 UTC) of June 20th.

Color-enhanced GOES-IR (11um) image valid 0715 UTC 20 June 2014

Image 1.  Color-enhanced GOES-IR (11 µm) image valid 0715 UTC 20 June 2014

 

I’ve placed the yellow circles in the image for a reason, which you’ll see below.  Further down, I’m going to show areas of fog displayed in the MODIS and VIIRS imagery, and granted, this is not the standard GOES channel difference (11-3.9 µm) typically used for making fog assessments.   However, this post is meant to show current (MODIS / VIIRS) and future capabilities (GOES-R / JPSS) that will make fog detection and cloud differentiation much more easy for the operational forecaster.  So, in the image above, fog is nearly unidentifiable as it was in the 11-3.9 µm channel difference image that morning (not shown).  Mainly high cirrus clouds can be observed scattered across the region.  Now, let’s take a look at the MODIS “fog” product, or channel difference (11-3.9 um) product valid at about the same time (Image 2).

Color-enhanced MODIS 11-3.9 u m product valid 0718 UTC 20 June 2014

Image 2.  Color-enhanced MODIS 11-3.9 µm image valid 0718 UTC 20 June 2014

Notice that in the same areas we can now begin to see low clouds (indicated by yellow colors) scattered around the valleys of the southern Appalachian region.  While the GOES-East imager is capable of detecting larger scale fog often in the valleys in the eastern circle, fog in the valleys in the western circle present challenges for the current GOES-East instrument, and is often not shown very well (even in the standard 11-3.9 µm channel difference).    Next, let’s take a look at a VIIRS Nighttime Microphysics RGB valid at about the same time.

VIIRS Nighttime Microphysics RGB valid 0723 UTC 20 June 2014

Image 3.  VIIRS Nighttime Microphysics RGB valid 0723 UTC 20 June 2014

In the RGB imagery it is much easier to detect the extent of the fog, making the operational forecast process much more effective.  Notice also that it is possible to see the fog through the higher clouds around the TN/GA/NC border region.  Not only does the resolution of the VIIRS and MODIS instruments allow for superior fog detection, but the RGBs in particular offer tremendous operational advantages.  As a user of RGBs for about 2 years now, I am convinced that this type of imagery has a relevant and needed place in future operational forecasting.  Of course, it will take time for forecasters to become accustomed and adjust to the new imagery, but it will happen.

 

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Shortly after arriving for my evening shift today, I was called by a representative from an organization hosting an outdoor event in downtown Huntsville.  She was inquiring about the chances for shower or thunderstorm development into the early evening hours during the outdoor event (movie in the park night).  As I have grown quite accustomed to loading the GOES-R CI and total lightning products to be used for situational awareness, especially during the convective season, I referred to those to help with my assessment…in addition to radar data of course.  The image below shows GOES Visible channel imagery overlaid with GOES-R CI, total lightning data, and NLDN (the latter of which may be hard to see).  The location of Huntsville is labeled, and cloud motion is analyzed in the image.  Notice that the GOES-R CI product indicates generally low probabilities of convection in the area of clouds to the northwest (and upstream) of Huntsville.  The blue colors indicated CI probabilities of around 10-40%.

GOES Vis imagery overlaid with GOES-R CI, Total Lightning, and 15-min NLDN, approx. 2015 UTC June 13, 2014

GOES Vis imagery overlaid with GOES-R CI, Total Lightning, and 15-min NLDN, approx. 2015 UTC June 13, 2014

The next image shows lightning data overlaying the GOES Vis imagery…

GOES Vis imagery overlaid with KHTX 0.5 reflectivity (dZB) ~2015 UTC June 13, 2014

GOES Vis imagery overlaid with KHTX 0.5 reflectivity (dZB) ~2015 UTC June 13, 2014

 

Notice that only a few showers were located to the NW of Huntsville, but the GOES-R CI suggested further development was not likely and the total lightning (available from the North Alabama LMA) suggested these were only showers and thus not electrically active (I had looked over the previous ~20-30 mins).   Notice that lightning activity was relegated mainly to the South and East of the area.  This was a situation in which the GOES-R CI and total lightning data both served to provide a more complete assessment of the situation, allowing for a better forecast for one of our customers.

By the way…my forecast to her?  Well, based on the evidence from the observational imagery/data…I said very small chances for any shower activity, so let the show go on!  No showers ended up impacting the downtown area.

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Author: Emily Berndt

This week NASA SPoRT began producing and disseminating real-time Cross-track Infrared and Microwave Sounding Suite (CrIMSS) ozone products to the Ocean Prediction Center, Weather Prediction Center, and Satellite Analysis Branch. CrIMSS retrievals are a combination of retrievals from the Cross-track Infrared Sounder (CrIS) and Advanced Technology Microwave Sounder (ATMS) instruments aboard the NOAA/NASA Suomi NPP satellite which is our Nation’s next generation polar-orbiting operational environmental satellite system. Since CrIS is an infrared sounder its ability to detect atmospheric variables through cloudy regions is limited, therefore the retrievals are combined with ATMS retrievals to view atmospheric variables in partly cloudy regions. Despite the use of microwave retrievals, retrievals are still degraded or blocked by thick clouds, similar to AIRS. Recall AIRS infrared retrievals are also combined with microwave retrievals from the Advanced Microwave Sounding Unit (AMSU) to overcome this limitation of the infrared sounder.

Expanding the ozone products to included CrIMSS retrievals will provide National Center forecasters with additional retrievals to evaluate for identifying stratospheric air related to forecasting rapid cyclogenesis and high-wind events.

While the CrIMSS algortihm differs from AIRS, the creation of ozone products using CrIMSS is the first step to expanding SPoRT’s ozone products to the next generation instrumentation aboard the Suomi NPP satellite. There are slight variations in the retrievals, but decent agreement in ozone concentration is observed between AIRS and CrIMSS retrievals. Retrievals processed via The NOAA Unique CrIS/ATMS processing System (NUCAPS) are planned for release this summer. NUCAPS is a version of the AIRS Science Team Algorithm. Once SPoRT has access to the NUCAPS retrievals the CrIS ozone product will be updated. The advantage of the NUCAPS retrievals will be the the ability to directly compare the AIRS and CrIS/ATMS ozone retrievals across satellite platforms/instruments and provide forecasters with greater spatial and temporal coverage.

The four images below are an example of consecutive AIRS and CrIMSS ozone retrievals now available to forecasters in N-AWIPS format.

1400 UTC 14 May 2014 AIRS Total Column Ozone

1400 UTC 14 May 2014 AIRS Total Column Ozone

1500 UTC 14 May 2014 CrIMSS Total Column Ozone

1500 UTC 14 May 2014 CrIMSS Total Column Ozone

1600 UTC 14 May 2014 AIRS Total Column Ozone

1600 UTC 14 May 2014 AIRS Total Column Ozone

1700 UTC 14 May 2014 CrIMSS Total Column Ozone

1700 UTC 14 May 2014 CrIMSS Total Column Ozone

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MODIS Air Mass RGB Imagery with limb correction applied to the water vapor and ozone channels.  1859 UTC, 13 May 2014

MODIS Air Mass RGB Imagery with limb correction applied to the water vapor and ozone channels. 1859 UTC, 13 May 2014

The Air Mass RGB imagery product via MODIS has often appeared to lack “green” coloring near the edge of the swath and there have been noticeable differences between the channels from Aqua and Terra used within the RGB.  Forecasters from the Great Falls, MT and Albuquerque, NM WFOs applying this experimental data noted these issues.  The above image is a limb and bias corrected version of the Air Mass RGB.  The water vapor and ozone channels tend to “cool” near the swath edge as they pass through more atmosphere and the differences in satellite instrument quality result in physical characteristics between the images having different coloring.  SPoRT has worked to develop a non-linear function to correct much of the limb cooling as well as a bias correction, both through comparison of the MODIS instruments to the EUMETSAT SEVIRI instrument.  Annotations to the image attempt to classify the various features indicated by the resulting composite color during a MODIS pass from 1859 UTC on 13 May 2014 when a cold air mass was moving into the upper Midwest.  Simple interpretation guides can be found via SPoRT’s Training page or EUMETSAT. For comparison, additional plots of GOES Water Vapor,  and NAM 500mb Temperature, Humidity, and Height 0-hour analysis and 6-hour forecasts are provided below for reference. There is also a single image of the Hybrid GEO/LEO Water Vapor / Air Mass RGB product that loops GOES Water Vapor imagery and inserts the MODIS Air Mass RGB swath as it is available because the RGB is largely made up of water vapor channels.  Both the Hybrid and single-swath MODIS files are available in netCDF format for use in AWIPS I or II as well as KML format.

This new limb/bias corrected Air Mass RGB product is credited in large part to graduate student work being done at the University of Alabama Huntsville in conjunction with NASA/SPoRT. Primary contributors are:
Nicolas Elmer (UAH graduate student)
Dr. Emily Berndt (NASA/SPoRT Post-Doctoral Scientist)
Dr. Gary Jedlovec (NASA/SPoRT PI)

Additional contributors include:
Frank LaFontaine (Raytheon, Data processing and analysis)
Kevin McGrath (Jacobs, Product code development and real-time processing)
Matthew Smith (UAH, Data processing and product code development)
Dr. Andrew Molthan (NASA/SPoRT, RGB code development and research science)

g13.2014133.1845_US_wv

GOES Water Vapor Imagery at 1845 UTC, for 13 May 2014

 

 

 

 

NAM 500mb, 0-hour forecast valid 1200 UTC, 12 May 2014 of Temperature, Humidity, and Height via

NAM 500mb, 0-hour forecast valid 1200 UTC, 13 May 2014 of Temperature, Humidity, and Height via NCAR RAL website

NAM 500mb, 0-hour forecast valid 1200 UTC, 13 May 2014 of Temperature, Humidity, and Height via NCAR RAL website

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NAM 500mb, 6-hour forecast valid 1800 UTC, 13 May 2014 of Temperature, Humidity, and Height via NCAR RAL website

NAM 500mb, 6-hour forecast valid 1800 UTC, 13 May 2014 of Temperature, Humidity, and Height via NCAR RAL website

CAR RAL website

Example: SPoRT Hybrid GEO/LEO Water Vapor and Air Mass RGBimagery

Example: SPoRT Hybrid GEO/LEO Water Vapor and Air Mass RGBimagery

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This week I am privileged to be a part of the Experimental Warning Program at the Hazardous Weather Testbed in Norman, OK.  Here, forecasters get a chance to test, in an operational style setting, some of the latest experimental warning products as a part of the GOES-R Proving Ground and Risk Reduction projects.

 

Image 1.  An NWS forecaster evaluates the Convective Initiation (CI) product at the HWT.

Image 1. An NWS forecaster evaluates the Convective Initiation (CI) product at the Hazardous Weather Testbed.

 

This GOES-R product, being evaluated by the NWS forecaster in the image above,  is created by researchers at UAH, but transitioned to operations by the SPoRT team.  The CI, which is a probabilistic tool, can alert forecasters to areas where convective initiation is likely or unlikely, in about a 0-2 hour window.  During the evaluation today, the product has performed favorably over a rapidly developing cumulus field in north central Texas.  The forecaster above noted large probabilities for convective initiation, which subsequently verified.  Yesterday, results with the CI were more mixed, with CI performing generally well late in the afternoon and early evening with lower based convection, but suffering earlier in the day with high-based convection (generally over 700 mb).

The next image below showcases a feature of the Tracking Meteogram (TM) tool, developed collaboratively by researchers at NASA SPoRT and the NWS Meteorological Development Lab.  Here, the tool also demonstrates success of the CI, which showed high probabilities for convective initiation before the cell showed corresponding rapid increases in reflectivity.  Although the TM tool is still undergoing some changes and development, feedback here at the HWT has been instrumental in some necessary updates this week before the tool moves on to the Operations Proving Ground later this month.

GOES-R CI, GOES Visible, and NEXRAD reflectivity left pane, with meteograms of each parameter as tracked by the Tracking Meteogram tool.

Image 2.  GOES-R CI, GOES Visible, and NEXRAD reflectivity (left), with meteograms of each parameter (right) as tracked by the Tracking Meteogram tool.  Notice the increase in CI (over 90%) before reflectivity values near 40 dbZ were present with this cell.

 

 

 

 

 

 

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A strong cold frontal boundary that surged south across the high plains of Colorado, New Mexico, Oklahoma and Texas April 29, 2014 was forecast to produce widespread strong winds and blowing dust.   The presence of cloud cover is a key limitation of observing important surface features from satellite imagery.  The following series of imagery illustrates how the availability of the Dust RGB composite product can improve analysis of dust through clouds even when compared with other high resolution satellite imagery.  The 500-meter Visible valid at 2026 UTC over west Texas shows exceptional detail of the cloud field over the area however based on surface observations it is difficult to see verify any dust.  The 1-km True Color image valid at the same time also shows various cloud structures as well as the background appearance of the land surface.  Again, it is still difficult to discern any dust in the imagery.  Finally, the Dust RGB at 2026 UTC details precisely where the location of the main dust field exists beneath the cloud cover.  Source regions are even visible over southeastern Colorado.  A sharp boundary along the southern extent is also evident over the Permian Basin.  This area of dust surged west into eastern NM through the morning of the 30th and even produced visibility reductions in the Rio Grande Valley around Albuquerque.

MODIS-VIIRS 500-meter visible image valid at 2026 UTC April 29, 2014.

MODIS-VIIRS 500-meter visible image valid at 2026 UTC April 29, 2014.

MODIS-VIIRS 1-km True Color image valid 2026UTC April 29, 2014.

MODIS-VIIRS 1-km True Color image valid 2026UTC April 29, 2014.

MODIS-VIIRS 1-km Dust RGB image valid 2026UTC April 29, 2014.

MODIS-VIIRS 1-km Dust RGB image valid 2026UTC April 29, 2014.

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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.

Total lightning (left) in a source density product form and radar reflectivity near the mixed phase level.  Higher values of total lightning correspond to regions where strong updrafts result in numerous particle collisions and charge separation.

Total lightning (left) in a source density product form and radar reflectivity near the mixed phase level. Higher values of total lightning correspond to regions where strong updrafts result in numerous particle collisions and charge separation. This image is from the NASA/SPoRT Quick Guide Training.

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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!

GOES-Sounder RGB Air Mass animation valid 03/24/14-03/26/14.

GOES-Sounder RGB Air Mass animation valid 03/24/14-03/26/14.

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.

MODIS RGB Air Mass product valid at 1540 UTC on 03/26/14.

MODIS RGB Air Mass product valid at 1540 UTC on 03/26/14.

MODIS RGB Air Mass product with ASCAT winds overlaid valid at 1540 UTC on 03/26/14.

MODIS RGB Air Mass product with ASCAT winds overlaid valid at 1540 UTC on 03/26/14.

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.

GOES-13 Infrared imagery with the GLD-360 30-minute lightning density product overlaid.

GOES-13 Infrared imagery with the GLD-360 30-minute lightning density product overlaid.

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.

VIIRS Visible image valid at 1719 UTC on 03/26/14.

VIIRS Visible image valid at 1719 UTC on 03/26/14.

VIIRS Visible image with the 18 UTC OPC surface analysis overlaid.

VIIRS Visible image with the 18 UTC OPC surface analysis overlaid.

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!

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