Pacific moisture plume and strong jet

October 3rd, 2008 |
AWIPS images of water vapor composite

AWIPS images of geostationary satellite water vapor channel data

AWIPS images of geostationary satellite water vapor channel data (above) showed a long moisture plume moving across the Pacific Ocean toward the west coast of the US on 02-03 October 2008. A comparison of GOES-11 water vapor channel data with POES (AMSU) and SSM/I Total Precipitable Water (TPW) products (below) revealed that TPW values were as high as 50-60 mm (2.0-2.4 inches) within this moisture plume. The MIMIC TPW product suggested that this moisture plume originated over the western Pacific Ocean, southeast of Japan.

AWIPS images of POES TPW products and GOES water vapor channel

AWIPS images of POES TPW products and GOES water vapor channel

This moisture plume was associated with a strong polar jet stream, as seen by an overlay of hourly MADIS atmospheric motion vectors on GOES water vapor channel imagery (below).

GOES water vapor images + MADIS winds

GOES water vapor images + MADIS winds

The 18 UTC GFS model fields were forecasting maximum winds in the core of the jet to reach 170 knots (below) — there were a few MADIS wind vectors with speeds of 177-181 knots around that time (and a MADIS wind vector with a speed of 191 knots was seen at 21 UTC).

GFS winds + MADIS winds

GFS winds + MADIS winds

Water vapor imagery: upper level vortices and jet streaks

September 13th, 2006 |

GOES-12 water vapor animation

A QuickTime animation of GOES-12 imager 6.5 micrometer (“water vapor channel”) imagery (above) reveals an interesting vortex associated with a cutoff upper-level low which was migrating eastward from Illinois to Ohio on 13 Sepember. Several pulses of convection can be seen developing along the periphery of the vortex. In addition, GOES-12 sounder total column ozone values were slightly elevated within the core of the vortex (~350 Dobson Units, compared to the background of ~300 DU), suggesting that some stratospheric air was also present.

Also of interest were the subtle indications that the structure of the jet stream (within the southeastern quadrant of the upper low circulation) was very complex — note the “streaky” appearance on the water vapor images across the Tennessee and Ohio River Valley regions, especially evident on the 1km resolution MODIS water vapor channel (below, upper right panel), but also apparent on the 10km resolution GOES-12 sounder water vapor channel (below, lower left panel). The relatively smooth NAM 300mb wind speeds simply indicated a broad jet streak core oriented SW-NE from Mississippi to Virginia, with a 500mb jet streak axis located farther to the northwest. The striated appearance of the water vapor imagery suggests that the broad jet core region may have been comprised of multiple jet streaks (likely existing at different altitudes).

The lower right panel below is the CRAS model forecast of the GOES water vapor channel, close to the time of the actual satellite images in the other 3 panels; while the CRAS model was unable to resolve the fine mesoscale structure associated with the multiple jet streak cores, it did offer a good prognosis of the “3-pronged structure” of the leading edge of the dry slot.
AWIPS water vapor channel comparison

Hurricane Force low off the US East Coast

April 2nd, 2019 |

GOES-16 "Red" Visible (0.64 µm) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed a cluster of deep convection just to the north of the center of a rapidly-intensifying midlatitude cyclone (surface analyses) off the coast of North Carolina on 02 April 2019. In addition, convection was later seen developing along the north-south cloud band marking the leading edge of the cyclone’s cold front. The rapid deepening of this hurricane force low easily met the criteria of a bomb cyclone — its central pressure dropped 20 hPa in just 12 hours (from 1004 hPa at 18 UTC on 02 April to 984 hPa at 06 UTC on 03 April).

The primary convective cluster began to exhibit a large amount of lightning after 1830 UTC, as seen in plots of GOES-16 GLM Groups (below). To the east of this intensifying convection, one ship report at 18 UTC included winds from the east at 50 knots — in addition, a moderate to heavy shower of hail was being reported and their surface visibility was restricted to 1.25 miles (18 UTC surface analysis).

GOES-16 "Red" Visible (0.64 µm) images, with GLM Groups and surface wind gusts plotted in red [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) images, with GLM Groups and surface wind gusts plotted in red [click to play animation | MP4

There were several factors pointing to the development of a sting jet with this storm, as discussed here and here. GOES-16 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (below) revealed distinct areas of warming/drying (darker shades of yellow to orange) that possibly highlighted rapidly-descending air associated with a sting jet (for example, on the 1946 UTC images).

GOES-16 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images [click to play animation | MP4]

GOES-16 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images [click to play animation | MP4]

After 23 UTC, GOES-16 “Clean” Infrared Window (10.3 µm) images (below) portrayed the formation of a large eye-like feature indicative of a warm seclusion (00 UTC surface analysis). Lightning activity remained very high during that time.

GOES-16 "Clean" Infrared Window (10.3 µm) images [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images [click to play animation | MP4]


A comparison between 1-km resolution Terra MODIS Infrared Window (11.0 µm) imagery at 0237 UTC with an Aqua MODIS Sea Surface Temperature product at 1755 UTC on the following afternoon (below) showed that the storm intensified and formed the large eye-like feature over the northern portion of the axis of warmest Gulf Stream water (where SST values were in the 70-76ºF range).

Terra and Aqua MODIS Infrared Window (11.0 µm) images from 0237 UTC and 0649 UTC, along with the Aqua MODIS Sea Surface Temperature product at 1755 UTC [click to enlarge]

Terra MODIS Infrared Window (11.0 µm) image at 0237 UTC, along with the 1755 UTC Aqua MODIS Sea Surface Temperature product [click to enlarge]

With a nighttime overpass of the NOAA-20 satellite at 0651 UTC, the eye-like feature was apparent in VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) images (below). Although the Moon was in the Waning Crescent phase (at only 8% of Full), that illumination with the aid of airglow was sufficient to provide a useful “visible image at night” using the Day/Night Band; a streak of bright pixels was due to intense lightning activity within a line of thunderstorms just ahead of the cold front. Note: the NOAA-20 images are incorrectly labeled as Suomi NPP.

NOAA-20 VIIRS Infrared Window (11.45 µµ) and Day/Night Band (0.7 µm) images [click to enlarge]

NOAA-20 VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) images, with an overlay of the 06 UTC surface analysis [click to enlarge]

Intense central US midlatitude cyclone

March 13th, 2019 |

GOES-16 Air Mass RGB images [click to play animation | MP4]

GOES-16 Air Mass RGB images [click to play animation | MP4]

An unusually deep midlatitude cyclone — which easily met the criteria of a “bomb cyclone”, with its central pressure dropping 25 hPa in only 12 hours (surface analyses) — developed over the central US on 13 March 2019 (WPC storm summary). GOES-16 (GOES-East) Air Mass RGB images from the AOS site (above) showed the large size of the cloud shield — and the deeper red hues over the High Plains indicated the presence of ozone-rich air (from the stratosphere) within the atmospheric column as the tropopause descended. A preliminary new all-time low surface pressure of 975.1 hPa occurred at Pueblo, Colorado just after 13 UTC; to the east of Pueblo, a 970.4 hPa minimum pressure recorded at Lamar (plot) possibly set a new state record for Colorado.

On a map of NWS warnings/advisories valid at 14 UTC (below), Blizzard Warnings (red) extended from Colorado to the US/Canada border. South of the Blizzard Warnings, High Wind Warnings (brown) were in effect to the US/Mexico border.

Map of NWS warnings and advisories at 14 UTC [click to enlarge]

Map of NWS warnings and advisories at 14 UTC [click to enlarge]

GOES-16 Mid-level Water Vapor (6.9 µm) images (below) displayed a hook-like signature resembling that of a sting jet, which developed over the Texas/Oklahoma Panhandle area after 11 UTC. At 14 UTC an interesting burst of surface wind gusts occurred at 3 sites — Burlington CO, Goodland KS and Colby KS — which may have been related to the downward transfer of momentum along the leading edge of the sting jet flow. The corresponding 7.3 µm Low-level Water Vapor animations are also available: GIF | MP4.

GOES-16 Mid-level Water Vapor (6.9 µm) images [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images [click to play animation | MP4]

The MIMIC Total Precipitable Water product (below) showed the northward surge of moisture from the Gulf of Mexico.

MIMIC Total Precipitable Water product [click to play animation | MP4]

MIMIC Total Precipitable Water product [click to play animation | MP4]

During the afternoon hours, the strong surface winds began to create plumes of blowing dust across parts of southeastern New Mexico and western Texas — a blowing dust signature first became apparent on GOES-16 Split Window Difference imagery as plumes of yellow, but then became more obvious on “Red” Visible (0.64 µm) images as the afternoon forward scattering angle increased (below). Blowing dust reduced the surface visibility to 1-2 miles at Snyder (KSNK) and Lubbock (KLBB).

GOES-16 "Red" Visible (0.64 µm) and Split Window Difference images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) and Split Window Difference images [click to play animation | MP4]

The blowing dust signature (lighter shades of brown) was also easily seen in late-afternoon GOES-16 True Color RGB images (below) — the dust plume reached southwestern Oklahoma by the end of the daytime hours, restricting the visibility to 5 miles at Frederick (KFDR). The blowing dust was also evident in True Color imagery from GOES-17, as seen here.

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 True Color RGB images [click to play animation | MP4]

Not long after the cyclone reached its lowest analyzed surface pressure of 968 hPa at 18 UTC, an overpass of the Suomi NPP satellite around 19 UTC provided a swath of NUCAPS soundings covering much of the storm (below). The air was very dry and stable near the near the center of the surface low in eastern Colorado (TPW=0.29″, CAPE=0 J/kg), in western Texas (TPW=0.31″, CAPE=0 J/kg) and near the frontal triple point in southeastern Nebraska (TPW=0.30″, CAPE=0 Jkg) — and out ahead of the warm front, the air was moist but stable behind a line of thunderstorms in northeastern Arkansas (TPW=1.09″, CAPE=0 J/kg) but both moist and unstable in western Mississippi (TPW=1.36″, CAPE=3506 J/kg).

Suomi NPP VIIRS Visible (0.64 µm) image, with overlays of the surface analysis and available NUCAPS soundings [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) image, with overlays of the surface analysis and available NUCAPS soundings [click to enlarge]

During the early stages of cyclone development, this system spawned severe thunderstorms that produced tornadoes, large hail and damaging winds across New Mexico and Texas (SPC storm reports) late in the day on 12 March. A GOES-17 (GOES-West) Mesoscale Domain Sector had been positioned over that region — which was helpful during a brief GOES-16 data outage — providing images at 1-minute intervals (below).

GOES-17

GOES-17 “Clean” Infrared Window (10.3 µm) images, with plots of SPC storm reports [click to play animation | MP4]

===== 14 March Update =====

GOES-16 Mid-level Water Vapor (6.9 µm) images, with hourly plots of surface winds and gusts in knots [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images, with hourly plots of surface winds and gusts in knots [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images (above) showed the storm moving slowly northeastward across Kansas, Nebraska and Iowa on 14 March — with strong winds continuing north and west of the surface low, blizzard conditions persisted across much of the Midwest.

Farther to the east, severe thunderstorms produced large hail, damaging winds and tornadoes as far north as northern Illinois/Indiana/Ohio and southern Lower Michigan (SPC storm reports | NWS Detroit) — as shown with 1-minute Mesoscale Domain Sector GOES-16 Visible images (below). The corresponding GOES-16 Infrared image animation is available here; the coldest cloud-top infrared brightness temperatures were only in the -30 to -40ºC range

GOES-16 "Red" Visible (0.64 µm) Visible images, with SPC storm reports plotted in red [click to play MP4 animation]

GOES-16 “Red” Visible (0.64 µm) Visible images, with SPC storm reports plotted in red [click to play MP4 animation]