QuikSCAT wind vectors + GOES IR and water vapor images

From an email received on the morning of 23 November 2009: “Several hours ago, shortly past 7:00Z today, telemetry received from QuikSCAT indicates that the antenna rotation rate has dropped to zero and remains at zero. The motor remains powered. The system can be operated safely in this state for an indefinite period. The QuikSCAT operations team will be meeting later this morning, but in all likelihood this is probably the end of the nominal mission.”

The image above shows the last QuikSCAT data processed on the AWIPS system at the Cooperative Institute for Meteorological Satellite Studies (CIMSS). The scatterometer wind data show the flow around a developing cyclone located southeast of the southern tip of Greenland. The underlying GOES-12 IR and water vapor images also reveal a classic baroclinic leaf pattern southeast of the developing cyclone, which is a satellite signature of impending cyclogenesis.

With the loss of QuikSCAT, the only scatterometer winds available in AWIPS are those from ASCAT. For additional information, see the VISIT training modules QuikSCAT Winds and ASCAT Winds.

A strong storm is bringing high winds and rain to the east coast of the United States from North Carolina northward to New Jersey. This dangerous weather will persist through tomorrow. The weather results from the combination of the extratropically transitioned remnants of Ida — over southern North Carolina — and a strong high pressure system over New England. (See a surface analysis here). Various satellite-derived products can be used to explore this system.

Consider the water vapor loop above. Towards the end of the loop, features in the vapor are developing and moving westward over Virginia and North Carolina. That observation combined with the continued eastward motion in the water vapor signal over the southeast part of the US suggests the formation of a closed circulation. Such a development will slow the eastward progression of the system, prolonging the period of stormy weather on the coast.

Satellite observations of total precipitable water (a blended product from AMSU and SSM/I on the NOAA series of Polar Orbiters) show large values — greater than 200% of normal — over the eastern United States. Superimposed near-surface winds from the QuikScat scatterometer show a broad region of gale-force winds over the Ocean. The long fetch of the wind over open ocean will allow large waves to develop. (A zoomed-in version of the QuikScat winds, here, includes a 57-knot wind with a rain flag of only 1% — meaning it’s a “good” wind. Peak surface wind gusts from reporting stations on land at this time included 44 knots at Norfolk, Virginia, 43 knots at Wallops Island, Virginia, and 42 knots at Elizabeth City, NC). The long duration of the storm event and the winds will exacerbate matters. A loop of precipitable water derived from SSMI and AMSRE (here) shows the tropical origins of the moisture over the eastern part of the United States, and also the movement of more moisture in from the east.

Abundant moisture is leading to large rainfalls. Rainfall rates are estimated using data from the AMSU instrument on the NOAA series of POES spacecraft. There are numerous pixels in the short loop above, including suggesting rains exceeding 20 mm per hour. There is also a westward drift suggested in the loop.

Visible image loops (rocking loops) from GOES-12 and GOES-14 show the westward drift of clouds into western Virginia and the Carolinas as the system starts to close off. A near-surface circulation center can also be inferred over southern North Carolina.