Strong Northeast US coastal storm

November 8th, 2010
GOES-13 6.5 µm water vapor images + surface frontal and pressure analyses

GOES-13 6.5 µm water vapor images + surface frontal and pressure analyses

A strong Northeast US coastal storm developed on 08 November 2010, which produced as much as 3.56 inches of rainfall in Maine, 2.5 inches of snow in Massachusetts and New York, and wind gusts to 63 mph in Maine (and 75 mph on top of Mt. Washington, New Hampshire). AWIPS images of 4-km resolution GOES-13 6.5 µm “water vapor channel” data (above) showed a classic example of a signature of an occluding cyclone, with a spiral of dry air (yellow to orange color enhancement) wrapping inward around the storm center.

A sequence of 1-km resolution MODIS 6.7 µm water vapor images (below) shows a bit more detail at various stages of the storm’s life cycle.

MODIS 6.7 µm water vapor images + surface frontal and pressure analyses

MODIS 6.7 µm water vapor images + surface frontal and pressure analyses

A sequence of 1-km resolution POES AVHRR 10.8 µm “IR window” images (below) showed an arc of cold clouds that wrapped inland ahead of the occluded frontal boundary.

POES AVHRR 10.8 µm IR images + surface frontal and pressure analyses

POES AVHRR 10.8 µm IR images + surface frontal and pressure analyses

Additional 1-km resolution POES AVHRR derived products can be used to further characterize the clouds over a particular region. For example, the 22:32 UTC Cloud Top Temperature (CTT), Cloud Height, and Cloud Type products are shown below. The coldest CTT values associated with the well-defined inland cloud arc were -55º C, with a maximum cloud height value of 11 km. The Cloud Type product can be used to discriminate between water droplet clouds, supercooled water droplet clouds, opaque ice crystal clouds, cirrus clouds, or clouds that are likely overshooting the tropopause.

POES AVHRR Cloud Top Temperature product

POES AVHRR Cloud Top Temperature product

POES AVHRR Cloud Top Height product

POES AVHRR Cloud Top Height product

POES AVHRR Cloud Type product

POES AVHRR Cloud Type product

Note to NWS forecast offices: MODIS and POES AVHRR satellite images and products such as those seen above can be added to your local AWIPS workstations via Unidata LDM subscription.

Hurricane Tomas

November 5th, 2010
Storm track of Tomas (during the period 29 September - 05 November 2010)

Storm track of Tomas (during the period 29 September - 05 November 2010)

Tropical Storm Tomas became the 19th named storm of the 2010 Atlantic tropical cyclone season on 29 September 2010 (NHC advisory archive). The path of Tomas from the CIMSS Tropical Cyclones site can be seen above, along with a plot of the Advanced Dvorak Technique (ADT) intensity estimate (below) which showed that there were a number of fluctuations in the intensity of Tomas: it initially intensified into a Category 1 and then a Category 2 hurricane as it crossed the Windward Islands of the Lesser Antilles on 30-31 August, but then was degraded to a Tropical Storm due to unfavorable deep layer wind shear on 01 November. Atmospheric steering currents then helped Tomas turn to the north, and the storm re-intensified into a Category 1 hurricane as it passed between Cuba and Hispaniola on 05 November.

Automated Dvorak Technique (ADT) plot for Tomas

Automated Dvorak Technique (ADT) plot for Tomas

Animations of GOES-13 0.63 µm visible channel imagery and GOES-13 10.7 µm IR channel imagery (below) revealed a number of convective bursts as Tomas intensified into a Category 1 hurricane on 30 August.

GOES-13 0.63 µm visible channel images

GOES-13 0.63 µm visible channel images

GOES-13 10.7 µm IR images

GOES-13 10.7 µm IR images

A comparison of a GOES-13 10.7 µm IR image with the corresponding SSMI/S 85 GHz microwave image around 22:45 UTC on 30 August (below) showed that Hurricane Tomas had a large closed eye and a well-defined spiral band extending northward as the storm passed to the west of the Windward Islands of St. Lucia and St. Vincent.

Hurricane Tomas GOES-13 10.7 µm IR + SSMI/S 85 GHz microwave images

Hurricane Tomas GOES-13 10.7 µm IR + SSMI/S 85 GHz microwave images

On 05 November, AWIPS images of POES AVHRR 10.8 µm IR data (below) showed that Hurricane Tomas was exhibiting IR brightness temperatures as cold as -93º C (darker purple color enhancement) as the storm passed between Jamaica and Hispaniola.

POES AVHRR 10.8 µm IR images

POES AVHRR 10.8 µm IR images

Note the improvement in cloud top temperature structure that can be seen on the 1-km resolution POES AVHRR IR image, compared to the corresponding 4-km resolution GOES-13 IR image (below). On the POES AVHRR image, subtle storm top gravity waves can be seen emanating southward away from the region of coldest cloud tops, and the transverse banding structure along the western and southwestern edge of the storm are better resolved.

POES AVHRR 10.8 µm IR image + GOES-13 10.7 µm IR image

POES AVHRR 10.8 µm IR image + GOES-13 10.7 µm IR image

Note to NWS users: POES AVHRR images and products can be added to your local AWIPS workstations (via Unidata LDM subscription): for more details, see the AVHRR Imagery and Products in D-2D site.

Lake Mendota fog features

November 2nd, 2010
AO&SS building rooftop camera (facing northwest)

AO&SS building rooftop camera (facing northwest)

Nocturnal radiation fog formed over Lake Mendota (the largest of the 4 lakes in the immediate vicinity of Madison, Wisconsin) on 02 November 2010 — the evolution and motion of this fog was captured by a northwest-facing camera (above; smaller 640×480 version) mounted on the top of the Atmospheric, Oceanic, and Space Sciences building on the University of Wisconsin – Madison campus (Google map). The camera video begins at 09:54 UTC (4:54 am local time) and ends at 15:39 UTC (10:39 am local time). During the daylight hours, there even appeared to be evidence of a local-scale cyclonic circulation within the fog feature along the southern shore of Lake Mendota. Thanks to Pete Pokrandt, AOS, for supplying the QuickTime animation.

AWIPS images of the 4-km resolution GOES-13 fog/stratus product at night (followed by 1-km resolution GOES-13 0.63 µm visible channel images after sunrise) are shown below. In spite of the high amount of noise and “false fog/stratus pixels” (yellow enhancement), the GOES-13 fog/stratus product did show a relatively persistent fog signal over Lake Mendota through much of the night-time hours — and then the fog features could then be seen dissipating on the GOES-13 visible images after sunrise. On both the rooftop camera video and the GOES-13 visible images, the fog features appeared to be drifting to the southwest — in fact, the surface visibility at the Middleton Municipal Airport (KC29, located just to the west of Lake Mendota) dropped to 0.15 mile, while the surface visibility at Madison’s Dane County Regional Airport airport (KMSN, located just to the east of Lake Mendota) only fell to 3.0 miles.

GOES-13 fog/stratus product + GOES-13 0.63 µm visible channel images

GOES-13 fog/stratus product + GOES-13 0.63 µm visible channel images

An AWIPS image of the POES AVHRR 1-km resolution Sea Surface Temperature product (below) indicated that SST values over the central portion of Lake Mendota were as warm as 54.5º F at 23:55 UTC (6:55 PM local time) before sunset. With light winds and strong radiational cooling during the night, the surface air temperate at nearby Madison Dane County Regional Airport (KMSN) cooled to 27º F — and with such a large difference in water vs air temperature, thick fog eventually began to form over Lake Mendota.

POES AVHRR Sea Surface Temperature product

POES AVHRR Sea Surface Temperature product

Looking ahead to the future GOES-R era, Geostationary Cloud Algorithm Test-bed (GEOCAT) images of a GOES-R Fog Probability product (below) did indeed suggest that fog probabilities were increasing across south-central Wisconsin during the night-time hours as radiational cooling continued.

GEOCAT experimental GOES-R Fog Probability product

GEOCAT experimental GOES-R Fog Probability product

Powerful Great Lakes Cyclone

October 26th, 2010
GOES-13 6.5 µm water vapor imagery + surface analyses + storm reports

GOES-13 6.5 µm water vapor imagery + surface analyses + storm reports

An unusually large and strong mid-latitude cyclone rapidly intensified over the western Great Lakes region on 26 October 2010 (see HPC 18 UTC surface analysis and 22 UTC SPC Watches, Warnings, and Advisories). AWIPS images of GOES-13 6.5 µm water vapor channel data with overlays of surface analyses and SPC storm reports (above) showed a well-defined dry slot (yellow color enhancement) wrapping into the southern and eastern quadrants of the storm. Very strong surface wind gusts (NWS Milwaukee | NWS Green Bay | HPC) associated with this cyclone were reported in Wisconsin (79 mph at Sherwood), the Upper Peninsula of Michigan (70 mph at Point Aux Barques), South Dakota (70 mph at Union Center), and Minnesota (65 mph at Mehurin).

AWIPS Northern Hemisphere composite water vapor images covering the period 23-27 October 2010 (below; also available as a QuickTime movie) revealed the large amount of jet stream energy that was approaching the Lower 48 states from the central and eastern Pacific Ocean during the days leading up to the development of the strong Great Lakes cyclone.

Northern Hemisphere composite water vapor images (23-27 October 2010)

Northern Hemisphere composite water vapor images (23-27 October 2010)

One notable aspect of this storm is that it set new all-time lowest barometric pressure readings for the states of Wisconsin and Minnesota (which were the equivalent to those that would be seen in a Category 3 hurricane):

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE DULUTH MN
1227 PM CDT WED OCT 27 2010

…LOW PRESSURE RECORDS BROKEN ON OCTOBER 26 2010…

THIS IS A PRELIMINARY STATEMENT ON THESE PRESSURE RECORDS. HERE IS WHAT WE KNOW SO FAR ABOUT THE LOW PRESSURE RECORDS SET ON OCTOBER 26TH:

A FEW OF THE RECORDS HAVE BEEN RECALCULATED TO ADJUST FOR TRUE MEAN SEA LEVEL PRESSURE. SOME OF THE PREVIOUS VALUES WERE CALCULATED USING A STANDARD ATMOSPHERE ASSUMPTION /THE ALTIMETER SETTING AT THE STATION/. THE VALUES IN MILLIBARS ARE THE ONES THAT WILL BE MORE EXACT.

AN UNUSUALLY INTENSE LOW AFFECTED THE STATE OF MINNESOTA. AT 513 PM CDT…THE AUTOMATED WEATHER OBSERVING SYSTEM AT BIGFORK MINNESOTA RECORDED A 955.2 MILLIBAR /28.21 INCHES/ PRESSURE. THIS BREAKS THE ALL TIME MINNESOTA STATE RECORD FOR THE LOWEST OBSERVED PRESSURE.

THE PREVIOUS RECORD WAS 962.7 MB SET ON NOVEMBER 10 1998 AT ALBERT LEA AND AUSTIN IN SOUTHERN MINNESOTA. THE RECORD WAS INITIALLY BROKEN SHORTLY AFTER 10 AM AS THE LOW PASSED BY AITKIN MINNESOTA. HOWEVER…THE LOW CONTINUED TO INTENSIFY INTO THE AFTERNOON OVER NORTH CENTRAL MINNESOTA WHERE THE RECORD PRESSURE READING WAS ULTIMATELY ESTABLISHED AT BIGFORK.

.DULUTH…THE LOW PRESSURE RECORD AT DULUTH WAS SET AT 1115 AM WITH A PRESSURE OF 960.2 MILLIBARS /28.35 INCHES/. THE PREVIOUS RECORD WAS 964.3 MILLIBARS WHICH OCCURRED ON NOVEMBER 10 1998.

.INTERNATIONAL FALLS…THE LOW PRESSURE RECORD AT INTERNATIONAL FALLS WAS SET AT 345 PM WITH A PRESSURE OF 956.0 MILLIBARS /28.23 INCHES/. THE PREVIOUS RECORD WAS 971.9 MILLIBARS ON OCTOBER 10 1949.

.WISCONSIN…THE LOW PRESSURE RECORD FOR THE STATE OF WISCONSIN WAS SET IN SUPERIOR AT 1115 AM WITH A PRESSURE OF 961.3 MILLIBARS /28.39 INCHES/. THE PREVIOUS RECORD WAS 963.43 MILLIBARS /28.45 INCHES/ WHICH OCCURRED AT GREEN BAY ON APRIL 3 1982.

$$

LAMERS

A comparison of 1-km resolution MODIS 6.7 µm and 4-km resolution GOES-13 6.5 µm water vapor images (below) demonstrated the advantage of higher spatial resolution for detecting subtle wave features that could be indicators of possible turbulence. In this case, the MODIS water vapor image did indicate the presence of a subtle packet of waves aloft over central Lake Michigan — and there were pilot reports of moderate turbulence very near these wave features at 20,000 and 23,000 feet. Satellite-derived atmospheric motion vectors also showed that the axis of highest jet stream winds (134 knots at 300 hPa) was located along the far eastern edge of the dry slot on the water vapor image.

MODIS vs GOES-13 water vapor images + turbulence reports + satellite winds

MODIS vs GOES-13 water vapor images + turbulence reports + satellite winds

AWIPS images of 1-km resolution POES AVHRR 10.8 µm IR data with overlays of surface analyses (below) showed the evolution of the deepening storm, which exhibited very detailed cloud top structure on many of the IR images.

POES AVHRR 10.8 µm IR images + surface analyses

POES AVHRR 10.8 µm IR images + surface analyses

To get a feel for the overall size of the cyclone, a GOES-13 false color full disk image is shown below (courtesy of Rick Kohrs, SSEC).

GOES-13 false color full disk image (14:15 UTC, 27 November)

GOES-13 false color full disk image (14:15 UTC , 27 November)