"I--ce COULD be home for Christmas..."
- The third little known variation of Bing Crosby's timeless song
- The third little known variation of Bing Crosby's timeless song
UPDATE # 3 - 8:30 PM THURSDAY 12-24
Warm Holiday Wishes to all our readers! The potential ice situation may be trending toward mostly rain for the immediate Baltimore area, but not elsewhere. Details on why the forecast has changed:
SYNOPSIS: A large and powerful winter storm moving into the Midwest today will produce MOSTLY RAIN with SOME LIGHT FREEZING RAIN across much of the Mid-Atlantic on Christmas Day into the evening.
* Areas at risk for ice accretion to .20" from 4 am - 6 pm Christmas night remain central and western Pennsylvania and western Maryland.
* Areas at risk of ice accretion to .10" from 6 am - 12 pm Christmas before changing to rain are along and west of a line from Charlottsville, VA to Washington, DC to Bel Air, MD.
The Sterling, VA NWS has posted a Winter Weather Advisory for much of this region.
WHY DID OUR FORECAST CHANGE? We elected to follow that simple rule taught in the Penn State Meteorology Department: "Predict the high and you predict the storm." The Stormcast Team, upon analyzing most recent computer model projections, realized the game-changer was a weak surface high which appeared over central Maryland yesterday.
Although this "Jack Frost" high, at 1028 mb or less, caused the frigid temperatures this morning, once it drifts east, return flow on backside of the high will interact with southerly flow ahead of the midwestern storm. It came down to simple physics: Development of a weak "double-barrel" southerly flow between the distant low and local high. This will permit surface temperatures east of the Blue Ridge to range from upper 20's to near 30 once precip arrives Friday morning, limiting ice build-up before changing to rain.
SO WHAT ABOUT THE ICING POTENTIAL? There will definitely pockets of ice across many in cold valleys of central and western Maryland. The good news is that any significant icing (> .25") may now be confined just to the roof of Grandmother's gingerbread house.
REVISED STORM TIMELINE (as of 4:00 PM 12-24)
THIS EVENING Residents of the Mid-Atlantic attending Christmas Eve services or holiday gatherings should not encounter any travel problems. Even lighting the lumineres tonight will be problem-free, if a bit chilly. At least the candles will stay lit!
Overnight, one particular traveler making his rounds may encounter some light freezing rain and freezing drizzle. This should not delay delivery of important packages. Parents are no longer advised to make arrangements - and can prepare children to reach the appointed bedtime accordingly. All residents not involved in package delivery are encouraged to clear chimneys, sidewalks, bus stops, rooftops and parking lots in an effort to provide children with the opportunity for this visitor to make deliveries unimpeded. Parents of the Howard County Public Schools appreciate your help.
CHRISTMAS DAY Residents across the Mid-Atlantic west of I-95 will awaken to a calm and foggy landscape, with a thin glaze of ice bespeckling the windshields and trees. Surface cold air will erode throughout the day, permitting any precip falling by afternoon to be mostly rain with some sleet mixed.
THE CHANGEOVER Occuring east to west, starting along I-95 by late morning 12-25, progressing across Maryland and Pennsylvania to a line from Centre County, PA to Carroll County, MD. West of this line, freezing rain may continue to accrete past .10 inch into Christmas night. In some areas, there is risk of falling tree branches weakened by heavy snow. Residents west of Carroll County, MD would be wise not to permit children to venture outside. Let's not have sad breaking news on Christmas Day that a branch fell on a child taking the new family dog for it's first walk.
Juuustt in case things change back (and we've all seen that before) text of our earlier ideas is left below for comparison. Many thanks to the team for taking a step back and looking at the big picture! But...given widespread cold surface, it seems prudent to remain cautious when traveling to evening services...one slip on the church sidewalk can make for a less than pleasant Christmas Eve. Earlier forecast revised at 7:30 AM 12-24 :
AREAS OF OUR FORECAST FOCUS
--> Eastern boundary: I-95 corridor ~ Washington to Philadelphia,
including Philly suburbs of Chester County northwest to Centre County
--> Northern boundary: State College area/Centre County, PA
--> Western boundary: Northern VA across the MD/VA Blue Ridge
to the WV Panhandle and north to Bedford and Centre County, PA
EARLIER IDEAS ON ICE ACCRETION
(we may go back to this!)
Approx .10 inch = Along I-95 including Baltimore-Washington metro, and extending north into the western Philadephia suburbs of Chester County
Approx .20 inch = Western DC suburbs through northern Virginia to Carroll County and into south-central Pennsylvania including Harrisburg and Lancaster.
More than .25 inch = The Stormcast Team believes Frederick, MD will be the "dividing line" between significant icing above .25 an inch. Areas west of that line are at risk of a dangerous ice storm, including Western Virginia north through the WV panhandle into west central PA to all MD counties west of Frederick. The Sterling, VA NWS has issued Winter Storm Watches for these regions effective late Thursday through Friday afternoon.
DATA SOURCES & REFERENCES
NWS CURRENT: Hazardous Wx Outlook | HPC Winter Wx
DISCUSSIONS Sterling, VA | State College, PA | HPC Snow/Ice Warm Holiday Wishes to all our readers! The potential ice situation may be trending toward mostly rain for the immediate Baltimore area, but not elsewhere. Details on why the forecast has changed:
SYNOPSIS: A large and powerful winter storm moving into the Midwest today will produce MOSTLY RAIN with SOME LIGHT FREEZING RAIN across much of the Mid-Atlantic on Christmas Day into the evening.
* Areas at risk for ice accretion to .20" from 4 am - 6 pm Christmas night remain central and western Pennsylvania and western Maryland.
* Areas at risk of ice accretion to .10" from 6 am - 12 pm Christmas before changing to rain are along and west of a line from Charlottsville, VA to Washington, DC to Bel Air, MD.
The Sterling, VA NWS has posted a Winter Weather Advisory for much of this region.
WHY DID OUR FORECAST CHANGE? We elected to follow that simple rule taught in the Penn State Meteorology Department: "Predict the high and you predict the storm." The Stormcast Team, upon analyzing most recent computer model projections, realized the game-changer was a weak surface high which appeared over central Maryland yesterday.
Although this "Jack Frost" high, at 1028 mb or less, caused the frigid temperatures this morning, once it drifts east, return flow on backside of the high will interact with southerly flow ahead of the midwestern storm. It came down to simple physics: Development of a weak "double-barrel" southerly flow between the distant low and local high. This will permit surface temperatures east of the Blue Ridge to range from upper 20's to near 30 once precip arrives Friday morning, limiting ice build-up before changing to rain.
SO WHAT ABOUT THE ICING POTENTIAL? There will definitely pockets of ice across many in cold valleys of central and western Maryland. The good news is that any significant icing (> .25") may now be confined just to the roof of Grandmother's gingerbread house.
The Foot girls enjoying their first gingerbread house.
It has long since been consumed.
It has long since been consumed.
THIS EVENING Residents of the Mid-Atlantic attending Christmas Eve services or holiday gatherings should not encounter any travel problems. Even lighting the lumineres tonight will be problem-free, if a bit chilly. At least the candles will stay lit!
Overnight, one particular traveler making his rounds may encounter some light freezing rain and freezing drizzle. This should not delay delivery of important packages. Parents are no longer advised to make arrangements - and can prepare children to reach the appointed bedtime accordingly. All residents not involved in package delivery are encouraged to clear chimneys, sidewalks, bus stops, rooftops and parking lots in an effort to provide children with the opportunity for this visitor to make deliveries unimpeded. Parents of the Howard County Public Schools appreciate your help.
CHRISTMAS DAY Residents across the Mid-Atlantic west of I-95 will awaken to a calm and foggy landscape, with a thin glaze of ice bespeckling the windshields and trees. Surface cold air will erode throughout the day, permitting any precip falling by afternoon to be mostly rain with some sleet mixed.
THE CHANGEOVER Occuring east to west, starting along I-95 by late morning 12-25, progressing across Maryland and Pennsylvania to a line from Centre County, PA to Carroll County, MD. West of this line, freezing rain may continue to accrete past .10 inch into Christmas night. In some areas, there is risk of falling tree branches weakened by heavy snow. Residents west of Carroll County, MD would be wise not to permit children to venture outside. Let's not have sad breaking news on Christmas Day that a branch fell on a child taking the new family dog for it's first walk.
Juuustt in case things change back (and we've all seen that before) text of our earlier ideas is left below for comparison. Many thanks to the team for taking a step back and looking at the big picture! But...given widespread cold surface, it seems prudent to remain cautious when traveling to evening services...one slip on the church sidewalk can make for a less than pleasant Christmas Eve. Earlier forecast revised at 7:30 AM 12-24 :
AREAS OF OUR FORECAST FOCUS
--> Eastern boundary: I-95 corridor ~ Washington to Philadelphia,
including Philly suburbs of Chester County northwest to Centre County
--> Northern boundary: State College area/Centre County, PA
--> Western boundary: Northern VA across the MD/VA Blue Ridge
to the WV Panhandle and north to Bedford and Centre County, PA
EARLIER IDEAS ON ICE ACCRETION
(we may go back to this!)
Approx .10 inch = Along I-95 including Baltimore-Washington metro, and extending north into the western Philadephia suburbs of Chester County
Approx .20 inch = Western DC suburbs through northern Virginia to Carroll County and into south-central Pennsylvania including Harrisburg and Lancaster.
More than .25 inch = The Stormcast Team believes Frederick, MD will be the "dividing line" between significant icing above .25 an inch. Areas west of that line are at risk of a dangerous ice storm, including Western Virginia north through the WV panhandle into west central PA to all MD counties west of Frederick. The Sterling, VA NWS has issued Winter Storm Watches for these regions effective late Thursday through Friday afternoon.
DATA SOURCES & REFERENCES
NWS CURRENT: Hazardous Wx Outlook | HPC Winter Wx
EXAMPLES: Westminster, MD | West Chester, PA | Lancaster, PA
ANALYSIS: US Hazards | 12-36 Hour Short Range | 5-day Precip
And now, for a little holiday fun and video memorabilia...
WHO WINS THE 2009 CHRISTMAS BATTLE:
SNOW MISER OR HEAT MISER?
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