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Understanding Planetary Boundary Layer: Impact of Strong Winds

Discover how strong winds in the free atmosphere affect the planetary boundary layer, redistributing moisture, heat, and momentum. Learn about weather balloon observations and forecast model discrepancies.

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Understanding Planetary Boundary Layer: Impact of Strong Winds

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  1. Strong winds free atmosphere Mixing in the PBL vertically redistributes moisture, heat, and momentum. planetary boundary layer (PBL) ground

  2. Strong winds free atmosphere In the presence of strong winds in the free atmosphere, a deep PBL can mix high momentum air down to the surface, causing dangerously strong wind conditions at the ground. planetary boundary layer ground

  3. Strong winds free atmosphere The 4:00 and 7:00 am EST 13 Dec 2010 weather balloons launched by UNCA ATMS Dept personnel indicated that the PBL measured in Swannanoa, NC was deeper than what had been predicted by the computer weather forecast models… planetary boundary layer ground

  4. Strong winds free atmosphere … causing forecasters at the National Weather Service in Greenville, SC to re-think some of their advisories. The result was the issuance of a high wind warning for some NC mountain counties planetary boundary layer ground

  5. AS FAR AS THE WIND CONCERNS...GUSTS HAVE BEEN PICKING UP ACROSS THE MTNS WITH INCREASED INSOLATION. MORNING SOUNDINGS LAUNCHED NEAR SWANNANOA BY UNCA ATMOS SCIENCES DEPT INDICATE A VERY DEEP MIXED LAYER (UP TO 750 MB) ABOVE A WEAK SURFACE-BASED INVERSION. THIS IS QUITE A BIT HIGHER THAN FORECAST BY THE 06Z MODELS. AM THEREFORE BEGINNING TO THINK WIND MAY BE MORE OF AN ISSUE THAN PREVIOUSLY EXPECTED. DURING COMBINED WIND/SNOW EVENTS...POLICY DICTATES THAT WE CHOOSE THE GREATER THREAT AND ISSUE A SINGLE PRODUCT (NPW OR WSW) BASED UPON THE LARGER THREAT. WHILE I STILL BELIEVE SNOW WILL BE THE LARGER CONCERN ACROSS THE TENN BORDER COUNTIES...IT BECOMES LESS CLEAR WHETHER WIND OR SNOW IS THE GREATER THREAT IN THE INTERIOR NC MTN COUNTIES. SINCE A WSW IS ALREADY IN EFFECT FOR THESE AREAS...WE ARE OPTING TO AVOID NPW ISSUANCE AND INSTEAD ENHANCE THE WIND WORDING IN THE WSW. FOR NC MOUNTAIN AREAS OUTSIDE OF A WSW...A HIGH WIND WARNING WILL BE ISSUED. A NEW WIND ADVISORY WILL ALSO BE ISSUED FOR LOCATIONS IN THE IMMEDIATE LEE OF THE MTNS. AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 933 AM EST MON DEC 13 2010

  6. Strong winds free atmosphere planetary boundary layer ground UNCA ATMS Dept weather balloon observations can be viewed at http://blizzard.atms.unca.edu/sempe/rt_sempe1213.html slide show prepared by Douglas Miller

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