Record 24-hour rainfall in Nome, Alaska

August 3rd, 2019 |

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

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

The MIMIC Total Precipitable Water (TPW) product (above) showed a northward-moving atmospheric river that was responsible for producing a record 24-hour rainfall amount of 2.47 inches (62.7 mm) ending at 10 pm AKDT on 02 August (06 UTC on 03 August 2019). Some of the poleward transport of moisture was aided by the approach of a Gale Force low (surface analyses).

Blended TPW values reached 2.7 inches near Nome at 1537 UTC on 02 August — and broad areas of TPW greater than 200% of normal (yellow) were seen across the Bering Sea as the atmospheric river approached the Seward Peninsula (below).

Blended Total Precipitable Water and Percent of Normal [click to play animation | MP4]

Blended Total Precipitable Water and Percent of Normal TPW [click to play animation | MP4]

In a plot of surface data from Nome, Alaska over the 02-03 August period (below), heavy rain was reported at 1222 UTC on 02 August.

Time series of surface data from Nome, Alaska [click to enlarge]

Time series of surface data from Nome, Alaska [click to enlarge]

A plot of rawinsonde data from Nome at 12 UTC on 02 August (below) revealed a TPW value of 37.7 mm (1.48 inches), which is among the top 10 TPW amounts on record for that site.

Plot of rawinsonde data from Nome at 12 UTC on 02 August [click to enlarge]

Plot of rawinsonde data from Nome at 12 UTC on 02 August [click to enlarge]

Monsoon moisture and thunderstorms across the Southwest US

July 25th, 2019 |

GOES-16 Total Precipitable Water product [click to play animation | MP4]

GOES-16 Total Precipitable Water product [click to play animation | MP4]

The GOES-16 Total Precipitable Water product (above) highlighted the northward surge of monsoon moisture across portions of the Southwest US on 25 July 2019. TPW values as high as 2.0-2.1 inches were seen over the California/Arizona border early in the day, and also over far southeastern California and southwestern Arizona later in the day. The TPW value of 1.56 inches as derived from 12 UTC Las Vegas rawinsonde data was a record maximum for 25 July (below)and the TPW value of 1.76 inches at Phoenix was above the 90th percentile of the climatological average for the date.

Plot of Total Precipitable Water climatology for Las Vegas, Nevada [click to enlarge]

Plot of Total Precipitable Water climatology for Las Vegas, Nevada [click to enlarge]

Overlapping GOES-17 (GOES-West) Mesoscale Domain Sectors provided imagery at 30-second intervals from 1445-2100 UTC — and “Red” Visible (0.64 µm) images (below) showed the development of thunderstorms across the region during that period. Many of these storms produced heavy rainfall, prompting the issuance of numerous Flash Flood Warnings in California, Nevada and Arizona (with a Dust Storm Advisory being issued due to thunderstorm outflow in Arizona).

GOES-17

GOES-17 “Red” Visible (0.64 µm) images [click to play MP4 animation]

Flooding along portions of the Mississippi River

June 1st, 2019 |

Landsat-8 False Color RGB images + GOES-16 River Flood Areal Extent product near the confluence of the Mississippi and Ohio Rivers [click to enlarge]

Landsat-8 False Color RGB image + GOES-16 River Flood Areal Extent product near the confluence of the Mississippi and Ohio Rivers [click to enlarge]

A comparison of a Landsat-8 False Color Red-Green-Blue (RGB) image and the GOES-16 River Flood Areal Extent product near the confluence of the Mississippi and Ohio Rivers as viewed using RealEarth (above) showed areas of river flooding in the Cape Girardeau, Missouri and Cairo, Illinois areas on 01 June 2019.

The River Flood Areal Extent product — derived using GOES-16 data — as depicted in AWIPS is shown below.

GOES-16 River Flood Areal Extent product [click to enlarge]

GOES-16 River Flood Areal Extent product [click to enlarge]

Farther to the northwest, a similar comparison of a Landsat-8 False Color RGB image and the GOES-16 River Flood Areal Extent product near the confluence of the Mississippi and Missouri Rivers (below) revealed river flooding near St. Louis, Missouri.

Landsat-8 False Color RGB images + GOES-16 River Flood Areal Extent product near the confluence of the Mississippi and Missouri Rivers [click to enlarge]

Landsat-8 False Color RGB image + GOES-16 River Flood Areal Extent product near the confluence of the Mississippi and Missouri Rivers [click to enlarge]

The GOES-16 River Flood Areal Extent product over this area as depicted in AWIPS is shown below.

GOES-16 River Flood Areal Extent product [click to enlarge]

GOES-16 River Flood Areal Extent product [click to enlarge]



Maps of 7, 14 and 30-day precipitation (below) depicted heavy rainfall focused across southern Iowa, northern Missouri and northwestern Illinois — it was this heavy rain that exacerbated the ongoing river flooding problems in parts of the central US.

7-day, 14-day and 30-day precipitation ending at 12 UTC on 01 June 2019 [click to enlarge]

7-day, 14-day and 30-day precipitation ending at 12 UTC on 01 June 2019 [click to enlarge]

Much of the 30-day precipitation north (upstream) of the flooding areas shown above was 4-8 inches above normal, or 200-300% of normal (below).

30-day precipitation, departure and percent of normal ending at 12 UTC on 01 June 2019 [click to enlarge]

30-day precipitation, departure and percent of normal ending at 12 UTC on 01 June 2019 [click to enlarge]

Severe thunderstorms in Texas and Oklahoma

May 20th, 2019 |

GOES-16

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

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed the development of widespread thunderstorms that produced tornadoes, large hail (up to 5.5 inches in diameter in Texas) and damaging winds (as high as 94 mph in Oklahoma) (SPC storm reports) across parts of Texas and Oklahoma on 20 May 2019.

The corresponding GOES-16 “Clean” Infrared Window (10.35 µm) images (below) indicated that cloud-top infrared brightness temperatures were frequently as cold as -70 to -80ºC (black to white to violet enhancement) with the more vigorous thunderstorms.

GOES-16 "Clean" Infrared Window (10.35 µm) images, with SPC Storm Reports plotted in cyan [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.35 µm) images, with SPC Storm Reports plotted in cyan [click to play MP4 animation]

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

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

Zoomed-in versions of the Visible images (above) and Infrared images (below) are centered at Childress, Texas — which provide a better view of the storms which produced the 5.5-inch hail (Visible | Infrared) at Wellington, Texas and the large tornado near Magnum, Oklahoma (Visible | Infrared | YouTube video).

GOES-16 "Clean" Infrared Window (10.35 µm) images, with SPC Storm Reports plotted in cyan [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.35 µm) images, with SPC Storm Reports plotted in cyan [click to play MP4 animation]

One interesting aspect of this line of deep convection: it was effectively acting as an obstacle to the upstream southwesterly flow, resulting in the formation of a quasi-stationary band of gravity waves along its western edge — these waves were very evident in GOES-16 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (below).

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

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

GOES-16 Split Window Difference (10.3-12.3 µm) images (below) displayed the yellow signature of blowing dust in the vicinity of a cold front that was moving eastward across southeastern New Mexico and southwestern Texas. Blowing dust restricted surface visibility to 3 miles or less at El Paso in Texas and at Alamagordo and Artesia in New Mexico.

GOES-16 Split Window Difference (10.3-12.3 µm) images [click to play animation | MP4]

GOES-16 Split Window Difference (10.3-12.3 µm) images [click to play animation | MP4]

During the subsequent overnight hours, these thunderstorms produced heavy rainfall from northern Oklahoma into southern Kansas, causing flash flooding — and flooding from rising rivers across that region on the following day were captured by the Suomi NPP VIIRS Flood Detection Product (below).

Suomi NPP VIIRS True Color and False Color RGB images, along with the Flood Detection Product [click to enlarge]

Suomi NPP VIIRS True Color and False Color RGB images, along with the Flood Detection Product [click to enlarge]

The river flooding in northern/northwestern Oklahoma was also evident in a before/after comparison of Terra MODIS False Color RGB images from 15 May and 21 May (below). Water appears as darker shades of blue in the False Color images.

Terra MODIS False Color RGB images over northern Oklahoma on 15 May and 21 May [click to enlarge]

Terra MODIS False Color RGB images over northern Oklahoma on 15 May and 21 May [click to enlarge]