Record Total Precipitable Water in Alaska

August 14th, 2019 |

Plot of rawinsonde data from Anchorage, Alaska [click to enlarge]

Plot of rawinsonde data from Anchorage, Alaska [click to enlarge]

Plot of rawinsonde data from Fairbanks, Alaska [click to enlarge]

Plot of rawinsonde data from Fairbanks, Alaska [click to enlarge]

Total Precipitable Water (TPW) calculated from rawinsonde data at both Anchorage and Fairbanks, Alaska were all-time record maximum values at 00 UTC on 14 August 2019.

The microwave-based MIMIC TPW product (below) showed an atmospheric river of moisture moving northeastward toward Alaska during the 2 days leading up to the record-setting TPW values on the Anchorage and Fairbanks soundings. The global view suggested that some of this moisture may have originated from the northern periphery of the TPW reservoir associated with slow-moving Typhoon Krosa in the West Pacific Ocean, being transported eastward then northeastward by a series of frontal waves (surface analyses).

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

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

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

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

 

Largest hailstone on record for the state of Colorado

August 13th, 2019 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, left) and “Clean” Infrared Window (10.35 µm, right) images, with plots of SPC Storm Reports [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.35 µm) images (above) displayed the increasing coverage of thunderstorms along the Colorado/Kansas border on 13 August 2019, These thunderstorms produced a few tornadoes and large hail — including hail of 5.00 inches in diameter at 2135 UTC near Bethune in extreme eastern Colorado (SPC storm reports).

A toggle between NOAA-20 VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images (below) showed the storms at 2022 UTC — just over an hour before the 5.00-inch hail report at 2135 UTC. Note that the NOAA-20 images are incorrectly labelled as Suomi NPP.hunderstorms

NOAA-20 Visible (0.64 µm) and Infrared Window (11.45 µm) images, with NUCAPS sounding locations and surface reports [click to enlarge]

NOAA-20 VIIRS Visible (0.64 µm) and Infrared Window (11.45 µm) images, with NUCAPS sounding locations and surface reports [click to enlarge]

The NOAA-20 NUCAPS profile for the green dot in far western Kansas (below) showed that the airmass in advance of the approaching thunderstorms was very unstable, with a Most Unstable parcel Convective Available Potential Energy (MU CAPE) value of 2737 J/kg and a Lifted Index (LI) value of -10ºC (with no Convective Inhibition CINH).

NOAA-20 NUCAPS profile in far western Kansas [click to enlarge

NOAA-20 NUCAPS profile in far western Kansas [click to enlarge]

In contrast, the NUCAPS profile for the green dot in eastern Colorado (below) revealed an airmass that was less unstable in the wake of the departing thunderstorms.

NOAA-20 NUCAPS profile in eastern Colorado [click to enlarge]

NOAA-20 NUCAPS profile in eastern Colorado [click to enlarge]

===== 14 August Update =====

NWS Goodland Public Information Statement.

Thunderstorm over the Arctic Ocean

August 11th, 2019 |

NOAK49 PAFG 110400 CCA
PNSAFG
AKZ222-111600-

Public Information Statement…CORRECTED
National Weather Service Fairbanks AK
800 PM AKDT Sat Aug 10 2019

…Lightning Detected within 300 Miles of North Pole Today…

A number of lightning strikes were recorded between 4pm and 6pm
today within 300 miles of the North Pole. The lightning strikes
occurred near 85 degrees north, 120 degrees east, which is about
700 miles north of the Lena River Delta of Siberia. This lightning
was detected by the GLD lightning detection network which is used
by the National Weather Service. This is one of the furthest
north lightning strikes in Alaska Forecaster memory.

$$

JB

As noted by the NWS Fairbanks forecast office, lightning was detected with a thunderstorm located over the Arctic Ocean north of Siberia between 6-8 pm AKDT on 10 August (or 00-02 UTC on 11 August 2019). A sequence of AVHRR Visible (0.63 µm) and Infrared Window (10.8 µm) images from NOAA-15 (at 2315 UTC), NOAA-19 (at 0100 UTC) and NOAA-15 (at 0232 UTC) (below) showed the eastward motion of this thunderstorm, which had developed in advance of a 500 hPa lobe of vorticity — the coldest cloud-top infrared brightness temperature associated with this feature was -49.9ºC (yellow enhancement) at 0100 UTC.

NOAA-19 AVHRR Visible (0.63 µm) and Infrared Window (10.8 µm) images [click to enlarge]

AVHRR Visible (0.63 µm) and Infrared Window (10.8 µm) images from NOAA-15 (at 2315 UTC), NOAA-19 (at 0100 UTC) and NOAA-15 (at 0232 UTC) [click to enlarge]



GOES-17 ABI Temperature Data Quality Flags (TDQF) thresholds update

August 8th, 2019 |

Top: Thumbnails of GOES-17 and GOES-16 ABI Band 12 (9.6 µm) on August 1, 2019. Bottom: Time series of GOES-17 minus GOES-16 brightness temperature for a region located between the two satellites. Also plotted is the GOES-17 Focal Plane Temperature. The reduced duration of the GOES-17 data to be flagged is highlighted. [click to enlarge]

As of 19:45 UTC on August 8, 2019, the new Look-Up-Table (LUT) went into operations for use in the GOES-17 ABI Temperature Data Quality Flags (TDQF). These hotter thresholds are possible due to the recent implementation of the Predictive Calibration algorithm.  Note that the image also includes the percent good (and conditionally usable) values (flagged 0 or 1) for both GOES-16 and GOES-17 ABI. Recall there are 5 Data Quality Flags for ABI data:

  • DQF:percent_good_pixel_qf = 1.f ;
  • DQF:percent_conditionally_usable_pixel_qf = 0.f ;
  • DQF:percent_out_of_range_pixel_qf = 0.f ;
  • DQF:percent_no_value_pixel_qf = 0.f ;
  • DQF:percent_focal_plane_temperature_threshold_exceeded_qf = 0.f

The last one, DQF:percent_focal_plane_temperature_threshold_exceeded_qf, reports what percentage of the images pixels are warmer than the threshold value. Note that the thresholds on both the increasing and decreasing temperatures are also reported in the meta-data.

Near realtime brightness temperature comparisons between GOES-16 and GOES-17, as well as historical comparisons for a region centered on the equator and half way between the two satellites.

From the NOAA Notification:

Product(s) or Data Impacted: GOES-17 ABI auxiliary field change

Date/Time of Initial Impact: August 8, 2019 1945 UTC

Details/Specifics of Change:

The GOES-17 ABI Temperature Data Quality Flags (TDQF) thresholds for the thermal bands have been updated to the values in the table below.  This update will make utilizing the TDQF more effective for flagging saturated data caused by the GOES-17 ABI cooling system anomaly. There will be no impacts to distribution caused by this update.

Table of updated Temperature Quality Data Flag thresholds [click to enlarge]

Table of updated Temperature Quality Data Flag thresholds [click to enlarge]