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September 29, 2010

2 to 4 inches of rain due from TS Nicole

Forecasters are warning that a new tropical storm near Cuba this morning will merge with low pressure forming off the southeastern U.S. overnight to bring Central Maryland 2 to 4 inches of rain tonight and Thursday, with up to 6 inches in some locations.

Although the storm is forecast to bring sustained winds of 20 mph, gusting to 45 or 50 along the Western Shore of the Chesapeake, this is expected to be mainly a heavy rain event.

The National Weather Service has issued a Flash Flood Watch for Maryland from drought-stricken Washington County east to the Lower Eastern Shore - also reeling from a very dry summer. Light rain is expected to begin near the Chesapeake by early evening, increasing in intensity and moving westward overnight.

NOAA/NHC/Nicole"Rainfall totals of two to four inches are expected, with isolated amounts up to five inches possible. This may cause streams and creeks to quickly rise out of their banks," the Watch says. "People living in areas that are prone to flash flooding should monitor later forecasts and be prepared to take action should Flash Flood Warnings be issued. Motorists tonight and Thursday should be aware of the possibility of flooded roads. These should never be crossed."

A Coastal Flood Watch is also in effect for Thursday on the Maryland portion of the Chesapeake Bay as the approaching low and onshore winds conspire to drive water into the Western Shore's rivers and creeks. Tides are forecast to rise two to three feet above normal at high tides Thursday.

Urban flooding is expected, so Baltimore's Department of Public Works Wednesday asked residents to clear trash from storm drains in advance of the rain, and to secure trash that might wash into the storm sewers and clog them. To report storm drains that can't be easily cleared, officials asked residents to dial 311.

Maryland's Emergency Management Agency urged residents to assemble an emergency supply kit with water, non-perishable food, a flashlight and batteries, and and a battery-operated radio for monitoring weather conditions.

"Those living in in areas subject to flooding should be prepared to evacuate if needed," the agency said. "Motorists are reminded to never drive through standing water because several inches of fast-moving water can carry a vehicle down stream."

BGE officials said its crews were preparing for the heavy rain and strong winds, which could cause power outages. "At this time, given the projected path of the storm, we fully anticipate several thousand service interruptions," said A. Christopher Burton,  senior vice president for gas and electric operations. "We strongly urge our customers to take the time now to prepare."

This latest round of extreme weather seems to have impressed even seasoned meteorologists. A forecaster at the NWS's Baltimore-Washington Forecast Office was moved to add this to his Wednesday morning forecast discussion:

"I'll say this - The weather of 2010 is something I won't soon forget. Blizzards, severe storms, record-breaking heat, drought, and now potential flooding."

There are several things playing into the very wet weather ahead for Central Maryland. The first is a trough of low pressure - a cold front - which is lurking just to our west. The second is the  Bermuda High still lingering off the coast. Together, they have formed a kind of one-way wind NOAA/NHCcorridor from the tropics to Maryland.

What's preparing to move up that corridor is a huge gusher of tropical moisture that has been percolating for a week in the northwestern Caribbean. That system is the newly-named Tropical Storm Nicole.

The National Hurricane Center says Nicole finally made tropical storm status this morning. It is a minimal storm, with top sustained winds of just 40 mph. But it's a very wet one that has been drenching Cuba, and is moving today to do the same to southern Florida. And then forecasters say it will head north, along that open corridor, to the mid-Atlantic states. Here's the latest advisory on Nicole.

The current storm track takes it straight toward Baltimore. And along the way it will be swept up by the final component in this sprawling weather event, the coastal storm that is expected to form off the Southeastern states Wednesday night.

As the tropical moisture is drawn north along the Atlantic corridor, it will run into the Appalachians and the cold front Turn Around, Don't Drownparked to our west, unloading all that tropical rainfall on us. Expect periods of torrential rains, strong and gusty winds, possible thunderstorms or tornadoes. The region is also likely to experience power outages as trees and limbs succomb to the weather and tear down wires as they fall.  

The good news is that much of the East Coast really needs a big dose of rain. But we don't need flooding and we don't need people skidding off wet roads or driving into overflowing streams. So the other bit of good news is that by the time it gets here, this system will be moving north pretty fast, minimizing the time it spends unloading its water on us.

Jeffrey Halverson, an associate professor of environmental science at UMBC, offers this analysis of what's ahead:

"My commentary, after studying charts and reading various discussions, this AM:

"1. The models are still having trouble with regard to placement of the heavy rain axis, and we are now [less than] 24 hours from the onset of a major event. There may be a tendency for some models to push Prof. Jeffrey Halversonheavy rain too far to the NW, away from the coast. Nor have the models successfully predicted the very early arrival of the moist air mass, now pushing up through Richmond toward Baltimore.

"2. Widespread 2" - 4" with higher amounts seems likely along  and east of the I-95 corridor.

"3.  There are two components to this system that are expected to phase: (a) the deep tropical mositure plume which includes remnants of [Nicole]; and (b) the closed upper low over the SE US with a lingering frontal boundary along the coast. This upper-level low - which is distinctly non-tropical in origin - is expected to form a new coastal low somewhere in the vicinity of NC-VA, which will then draw in and process the tropical plume.

"Heavy rains over our area will come from three elements: (1) the tropical plume gliding up over the coastal front; (2) uplift provided by the remnants of [Nicole]; and (3) the developing coastal low."

Here's more from the Maryland Emergency Management Agency:

The Maryland Emergency Management Agency urges Maryland residents to make preparations.

The storms could lead to power outages, and residents are urged to have an emergency supply kit with water, food, a flashlight and a battery operated radio or weather radio. Residents should monitor local news broadcasts for updates and those living in areas subject to flooding (low-lying areas, areas along streams and creeks) should be prepared to evacuate if needed.

When driving in such conditions, motorists are reminded to never drive through standing water because several inches of fast moving water can carry a vehicle down stream. TURN AROUND, DON’T DROWN.

If your area is under a tornado warning, move quickly to the basement or an interior room away from windows and doors. If you cannot get into a building, lie flat in a ditch or on low ground and cover your head with your hands.

For more information on preparedness, go to the following web sites:

"">and click on be prepared, which will take you to pages for general preparedness, flooding and other natural disasters (which includes a section on tornado preparedness.

"">which has detailed information on assembling emergency kits and creating a family emergency plan.


"">and click on the Preparedness and Getting Trained tab, then the Preparedness Fast Facts link.

For more information, contact Ed McDonough, MEMA public information officer, at 410-517-3632 (office) or 410-446-3333 (cell).


Posted by Frank Roylance at 10:29 AM | | Comments (4)
Categories: Forecasts


Weather Channel is now saying 5-8" for us...

FR: Doesn't look to me like the yellow region of the map quite reaches Baltimore. But it wouldn't take much of an error to bring us that kind of rain.


Last night at around 11:45 I looked up in the sky and saw the coolest looking alignment of stars I think I have ever seen.

It was one big star which I think may have been Jupiter and another little one right above it that appeared to be purple in color.
Any idea what these were. It was really cool looking for sure. I stared at it for quite some time. Wish I would have had a telescope.


FR: Hard to say without knowing which way you were looking. At that time of night, Jupiter is very high in the sky, and the brightest object in the sky except the moon. Jupiter is currently very close to Uranus, but you can't see Uranus without a telescope. Bright stars just above Jupiter are those that form the Great Square of Pegasus - Algenib, Markab, Sirrah and Scheat.

What time will it begin to rain in the Baltimore City area today?

FR: Any time now. It's been raining lightly at Reagan National in DC. since before noon. Here's the radar loop, which shows rain just to our south.

Hi Frank,

Just when you would think that this/these storm(s) have been figured out a new wrinkle develops. All models now hold back TS Nicole or a portion thereof from the developing frontal low that will develop tonight along the Carolinas and begin entraining tropical moisturee into the area. The GFS and WRF models keep Nicole of the coast and we get 2-4" of rain from the low developing along the stalled frontal boundry tonight, but rain would taper off tomorrow afternoon or evening as Nicole (or its remnant) cruises by to the east and misses us.

The Canadian, the Navy NOGAP and ECWMF models all take the remnant of Nicole either over us or close enough to reintroduce heavy rain Thursday night into Friday. If this scenario plays out there could be serious flooding problems, well beyond what is currently anticipated.

We better hope that the GFS and WRF are correct or Nicole will become an infamous name in these parts.

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About Frank Roylance
This site is the Maryland Weather archive. The current Maryland Weather blog can be found here.
Frank Roylance is a reporter for The Baltimore Sun. He came to Baltimore from New Bedford, Mass. in 1980 to join the old Evening Sun. He moved to the morning Sun when the papers merged in 1992, and has spent most of his time since covering science, including astronomy and the weather. One of The Baltimore Sun's first online Web logs, the Weather Blog debuted in October 2004. In June 2006 Frank also began writing comments on local weather and stargazing for The Baltimore Sun's print Weather Page. Frank also answers readers’ weather queries for the newspaper and the blog. Frank Roylance retired in October 2011. Maryland Weather is now being updated by members of The Baltimore Sun staff

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