Severe thunderstorms in Pennsylvania

October 2nd, 2018 |

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 severe thunderstorms that moved across Pennsylvania on 02 October 2018, producing large hail, damaging winds and a few tornadoes (SPC storm reports). A parallax-corrected version of the animation — which shifts the location of SPC storm reports northwestward, to be more closely aligned with the storm-top features (assumed to be at a mean altitude of 12 km, based on 00 UTC Pittsburgh rawinsonde data) seen on satellite imagery — is available here.

The corresponding GOES-16 “Clean” Infrared Window (10.3 µm) images (below) indicated that the coldest cloud-top infrared brightness temperatures were in the -60 to -70ºC range (red to black enhancement).

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with SPC storm reports plotted in purple [click to play MP4 animation]



Heavy rainfall in Arizona from the remnants of Rosa

October 2nd, 2018 |

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, 25 September – 02 October [click to play MP4 animation]

Rosa became a Tropical Storm on 25 September 2018, and reached peak intensity as a Category 4 Hurricane on 28 September. As it gradually weakened and made landfall over Baja California on 02 October, its moisture moved across the US Desert Southwest causing heavy rainfall and flash flooding — parts of Arizona received record-setting rainfall (NWS Phoenix | NWS Flagstaff), with precipitation rates as high as 1 inch in 30 minutes in the Phoenix area. GOES-16 (GOES-East) “Clean” Infrared Window (10.3 µm) images during the 8 days from 25 September to 02 October (above) showed the life cycle of Rosa.

A closer look at Rosa during that same time period is shown below. The image interval is 15 minutes, except for 5-minute imagery during a test of Mode 4 scanning strategy on 01 October (from 0000-1550 UTC).

GOES-16 "Clean" Infrared Window (10.3 µm) images, 25 September - 02 October [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images, 25 September – 02 October [click to play MP4 animation]

The transport of tropical moisture associated with Rosa could be followed using the MIMIC Total Precipitable Water product (below). The moisture over southwestern Arizona on 02 October was >4 standard deviations above normal for that region and time of year.

MIMIC Total Precipitable Water product, 25 September - 02 October [click to play MP4 animation | MP4]

MIMIC Total Precipitable Water product, 25 September – 02 October [click to play MP4 animation | MP4]

The increase in deep tropical moisture was very evident in plots of rawinsonde data from Tucson, Arizona (below) — Total Precipitable Water peaked at 43.9 mm or 1.73 inches at 12 UTC on 01 October.

Plots of rawinsonde data from Tucson, Arizona 30 September - 02 October [click to enlarge]

Plots of rawinsonde data from Tucson, Arizona 30 September – 02 October [click to enlarge]