Maryland Weather Forecast Blog

New Blog

2011-02-21T08:00:00.000-05:00

For those that are following this blog, I have moved to a new blogging service and integrated it fully into my website. If you go to http://www.marylandwx.com you will see that the homepage is now the blog.

I have been wanting to make the blog a bigger part of the site and update it much more frequently.

The one draw back is, the new service doesn't allow for instant emailing of a new blog post, so if you are signed up to receive an email when I post, you will no longer have that. I did set up a mailing list with the new site that will send an email between 5pm and 7pm of any new posts made in the previous 24 hours. I know this isn't ideal, but I am hoping with the new layout of the website, most people will be able to see the latest blog posts right on the homepage. If you want to sign up to receive this daily digest email, simply click on the black envelope icon under the "Stay Connected!" section of the left menu bar.

Thanks for the support and for following Maryland Weather! I hope you enjoy the new site layout!

2/4/11: Freezing Rain Advisory

2011-02-04T15:03:00.000-05:00

Freezing Rain Advisory in effect from 1AM to 6AM tomorrow for: S. Baltimore, Baltimore City, Howard, and Montgomery counties.

* ACCUMULATIONS...LESS THAN A TENTH OF AN INCH.

* TIMING...RAIN IS EXPECTED TO CHANGE OVER TO LIGHT FREEZING RAIN

AFTER MIDNIGHT AND LAST UNTIL EARLY MORNING SATURDAY. THE BEST

CHANCE FOR ICE ACCUMULATION WILL BE BETWEEN 2AM AND 5AM.

Freezing Rain Advisory in effect from 1AM to 10AM tomorrow for: Allegany, N. Baltimore, Carroll, Frederick, Harford, and Washington counties.

* ACCUMULATIONS...LESS THAN A TENTH OF AN INCH.

* TIMING...RAIN IS EXPECTED TO CHANGE OVER TO LIGHT FREEZING RAIN

AFTER MIDNIGHT AND LAST THROUGH MID MORNING SATURDAY. THE BEST

CHANCE ICE ACCUMULATION WILL BE BETWEEN 3AM AND 8AM.

2/2/11: Jim Cantore witnesses thundersnow

2011-02-02T20:24:00.001-05:00

This is a clip of Jim Cantore witnessing thundersnow in Chicago last night at the height of the blizzard:

1/31/11: Some Ice, Then Rain

2011-01-31T20:08:00.000-05:00

Expect light snow and sleet to continue to develop over the area tonight, transitioning to freezing drizzle. The freezing drizzle will continue, off and on into Tuesday morning, before possibly changing to plain rain and ending tomorrow afternoon.

A heavier batch of precipitation will move in late tomorrow night. This batch will likely be freezing rain for most areas Tuesday night. The freezing rain will continue into Wednesday morning for the northern and western counties, while it changes to rain in central and Southern MD.

Up to a half inch of ice accumulation is possible in the Northern and Western counties (those under the Winter Storm Watch), but significant icing should not be a concern for the rest of the area.

Rain/freezing rain will continue into Wednesday afternoon, before the cold front moves through.

Be sure to check the website for updates on the progress of the storm and surface temperatures, as well updates on Watches and Warnings.

1/30/11: Forecast - Another Midweek Threat

2011-01-30T13:07:00.000-05:00

Another week, another significant storm threat

We are in a very active pattern right now and it continues to produce major storms in the Eastern US. This week's storm will not be a coastal storm however, as all model guidance take it west of the Appalachians. This storm track will ultimately mean rain for the area, but there looks to be frozen precipitation for a period, before we change over.

Take a look at the following GFS model graphic for 1am Tuesday morning:

If you look along the east coast, you can see the isobars (black lines) and the isotherms (red and blue lines) bending south. This is a classic representation of cold air damming. As the storm moves in, it is bringing a surge of warm air. This warm air runs over top the cold air that is trapped near the surface. The high pressure to the north of us keeps the cold air locked in east of the mountains.

This map also shows some light precipitation over the area. This is a result of the rush of warm air ahead of the system. At this time (1AM) it should be cold enough for this precip to be all snow, but as we head into the morning afternoon hours on Tuesday, it will change to sleet and then freezing drizzle.

Here is the map for 7am Tuesday morning:

This map continues to show the cold air damming and the freezing line down to near the VA/NC border. Surface temperatures are still below freezing, but the warm air continues to surge northward aloft.

1PM on Tuesday:

Here we see the freezing line moving back north and basically right through the state. As the storm continues its northward trek, the warm air continues to surge and displaces the sub-freezing temperatures at the surface and changing the precip to just plain rain.

The good news is that most of the precipitation that falls from this storm will indeed be plain rain. The bad news is, most models do a fairly poor job at handling cold air damming situations and tend to erode the cold faster than it actually does. What this means is, we could see a fairly long period of light sleet and freezing rain into Tuesday evening.

By Tuesday night, the transition should be well underway and temperatures will continue to climb all the way to the mid-40s on Wednesday. The bulk of the precip will fall late Tuesday night and Wednesday so there is no concern of a major ice event for our area.

7AM Wednesday morning:

The freezing line has moved well to our north by 7AM Wednesday morning, while the heavier precip is falling as rain. Expect Wednesday to be a relatively mild day, with rain lasting into the late afternoon, early evening hours. When all is said and done the GFS shows us ending up with an inch of liquid precip, but again this will fall mostly as rain:

While it will be mostly rain for us east of the track, those west of it appear to be line for a heavy snowstorm. Illinois and Indiana appear to be in the jackpot zone, where Winter Storm and Blizzard Watches are already posted for snowfall totals in "feet" not inches.

Looking ahead

Several models are hinting at yet another coastal low possibly affecting the area by the end of the week. It will take a few days to sort through everything to see how it may affect us, if at all. For now, it is just something to keep an eye on.

1/27/11: Snow Totals and Next Possible Storm

2011-01-27T13:55:00.002-05:00

Here is a map of reported snow totals from the NWS:

Here is the forecast I made on Tuesday afternoon:

As you can see, my forecast was a bit low. The morning snow was unexpected. I didn't anticipate that accumulation as I thought we would have more of a rain/snow mix overnight Tuesday night. That gave the area a 1-4" head start and snarled the morning commute.

I also didn't anticipate the snow being able to stick as fast as it did. Most areas saw a period of very heavy sleet that provided a crusty ice base for the snow once it started so not much was lost to melting on wet surfaces. I also didn't anticipate the widespread thundersnow. Like storms in the summer, these quickly upped the snow rate (over 2+ inches an hour) and allowed for the localized amounts near a foot. I knew that thundersnow would be possible, I just didn't think it would be as prevalent as it was.

Overall, I believe I still had the right idea and without the morning snow, numbers would fall more in line with my thinking.

Next Snow Chances?

We could see some snow showers tomorrow and Saturday from a series of weak clippers, with minor (half inch) accumulations. Our next chance of significant snow appears towards the middle of next week.

The GFS model is advertising a Groundhog Day special with another coastal storm potentially affecting the area:

It is still a long way away and things will definitely change, but I wanted to give a heads up that this is the next snow possibility.

1/26/11: Storm Update

2011-01-26T15:24:00.001-05:00

Everything continues to unfold about as expected... the NWS has expanded the Winter Storm Warning back to the east to include the central Maryland counties that were previously under an Advisory. Southern MD and the lower Eastern Shore remain under the Advisory for 2-5 inches.

I am sticking with my original forecast from last night:

Here is the text of the Winter Storm Warning:

WWUS41 KLWX 262014

WSWLWX

URGENT - WINTER WEATHER MESSAGE
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC

314 PM EST WED JAN 26 2011

DCZ001-MDZ004>007-009>011-013-014-VAZ036>040-042-050>056-501-502-
270415-

/O.CON.KLWX.WS.W.0003.000000T0000Z-110127T0900Z/

DISTRICT OF COLUMBIA-FREDERICK MD-CARROLL-NORTHERN BALTIMORE-
HARFORD-MONTGOMERY-HOWARD-SOUTHERN BALTIMORE-PRINCE GEORGES-
ANNE ARUNDEL-NELSON-ALBEMARLE-GREENE-MADISON-RAPPAHANNOCK-LOUDOUN-
ORANGE-CULPEPER-PRINCE WILLIAM/MANASSAS/MANASSAS PARK-FAIRFAX-
ARLINGTON/FALLS CHURCH/ALEXANDRIA-STAFFORD-SPOTSYLVANIA-
NORTHERN FAUQUIER-SOUTHERN FAUQUIER-
INCLUDING THE CITIES OF...WASHINGTON...FREDERICK...WESTMINSTER...
GAITHERSBURG...COLUMBIA...BALTIMORE...ANNAPOLIS...
CHARLOTTESVILLE...LEESBURG...CULPEPER...MANASSAS...
MANASSAS PARK...FAIRFAX...ALEXANDRIA...FALLS CHURCH...
FREDERICKSBURG...WARRENTON
314 PM EST WED JAN 26 2011

..WINTER STORM WARNING REMAINS IN EFFECT UNTIL 4 AM EST
THURSDAY...

A WINTER STORM WARNING REMAINS IN EFFECT UNTIL 4 AM EST THURSDAY.

* PRECIPITATION TYPE...SNOW. SNOW MAY MIX WITH RAIN AND SLEET
THROUGH THE MID AFTERNOON.

* ACCUMULATIONS...4 TO 8 INCHES.

* TIMING...RAIN AND SLEET CHANGING TO SNOW DURING THE MID TO LATE

AFTERNOON. SNOW WILL END AFTER MIDNIGHT FROM SOUTHWEST TO
NORTHEAST. THE HEAVIEST SNOWFALL IS EXPECTED BETWEEN 4PM AND 10

PM...IMPACTING THE AFTERNOON AND EVENING RUSH HOUR.

* TEMPERATURES...LOWER TO MID 30S...DROPPING INTO THE LOWER TO MID
20S OVERNIGHT

* WINDS...NORTHEAST 10 TO 15 MPH...BECOMING NORTHWEST THIS

EVENING.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A WINTER STORM WARNING MEANS SIGNIFICANT AMOUNTS OF SNOW...
SLEET...AND ICE ARE EXPECTED OR OCCURRING. STRONG WINDS ARE ALSO
POSSIBLE. THIS WILL MAKE TRAVEL VERY HAZARDOUS OR IMPOSSIBLE.

&&

$$

1/25/11: Snowfall Forecast

2011-01-25T18:34:00.000-05:00

I disagree a bit with the National Weather Service forecast for this storm.  I do not think we will see Winter Storm Watch level snows (5+ inches) in the DC/Baltimore Metro areas.  I think the snow will have a difficult time sticking at first, and the shot of heavier snow they expect tomorrow evening will be of short duration, as the storm races northeast.

Nonetheless, I expect a few inches in Central Maryland with higher amounts north and west of the cities, where the changeover will happen sooner (mid-morning vs. early afternoon).

My Forecast:

NWS Forecast:

1/25/11: NWS Bumps Snow Totals

2011-01-25T10:59:00.001-05:00

There is a possibility of snow accumulation tomorrow evening as colder air begins to filter back into the area, changing the rain back to snow.

Snow totals will be cut down, due to the rain and wet surfaces but a few inches along the I-95 corridor isn't out of the question.

EDIT: The entire state, except for the lower Eastern Shore is now under a Winter Storm Watch for 5 inches or more of snow:

Winter Storm Watch

Predicted Snow Totals

1/24/11: Near Perfect Track... Imperfect Pattern

2011-01-24T15:35:00.002-05:00

For the first time this winter, the models are converging on almost a perfect storm track to bring a significant snowfall to our area. The only problem (for snow lovers) is that the cold airmass that is currently in place will move out to sea before it arrives.

The blue line is the freezing line. As you can see, central MD and points east are above freezing.

With no strong cold air source to the west or north, and the storm bringing plenty of warmer air with it, our perfect storm track looks to bring mostly rain to areas east of the mountains.

As it looks right now, this should be a mostly rain event, with snow mixing at times and ending as a bit of snow. Here is the NWS forecast for central MD:

Tuesday Night	A chance of rain and snow after midnight. Mostly cloudy, with a low around 30. East wind between 3 and 7 mph. Chance of precipitation is 40%. New precipitation amounts of less than a tenth of an inch possible.
Wednesday	Rain and snow likely, becoming all rain after noon. Cloudy, with a high near 37. North wind between 9 and 15 mph. Chance of precipitation is 70%. New precipitation amounts between a quarter and half of an inch possible.
Wednesday Night	Rain and snow likely before midnight, then a chance of snow. Mostly cloudy, with a low around 27. Chance of precipitation is 60%. New precipitation amounts between a tenth and quarter of an inch possible.

The one certainty is that as this system pulls away, it will drag in another reinforcing shot of cold air for next week.

1/22/11: Midweek Snow Threat

2011-01-22T13:32:00.000-05:00

Another coastal storm system will approach the area Tuesday and Wednesday of this coming week. As it has been all season, the models continue to have disagreements as to where the system will fully develop and where exactly it goes after doing so.

Currently, the GFS model is trending towards a storm that develops to our south, then moves Northeast, bringing very little precipitation to the area. The ECMWF (a European model) has the low much closer to the coast and more precipitation for the area.

Latest GFS for Wednesday Evening (00z Thursday):

Latest ECMWF for Wednesday Evening (00z Thursday):

As you can see, the GFS has the low about 500 miles further east than the ECMWF, which has the low just off the Delmarva coast on Wednesday evening. This gap is significant, as is the difference in the resulting weather for our area.

Given the seasonal trends, I am leaning towards the GFS solution and little to no snow. This is a low confidence forecast, and things will most certainly change. I will update as things (hopefully) come into better focus over the next few days.

12/25/10: Post Christmas Snow?

2010-12-25T13:21:00.000-05:00

I was out of town last week and have been busy with Christmas festivities since my return, so I have not been able to look at the models too closely.

I did check in with the NWS while I was away and it appears that this possible storm has been very hard to pin down. Even today, there is great uncertainty regarding the track of this system.

What is known:

A low pressure system will develop off the Carolina coast and move NE tomorrow into tomorrow night.

What is unknown:

The exact track of the system. One scenario has it moving up the coast, just off shore while the other scenario has the track further off the coast, resulting in little to no snow.

The models began showing this system a week ago, but have flip flopped and shown no consensus on the track. Generally, we see the models begin to converge on a track a few days out. What we saw this week instead, was each sticking to their different ideas, and not until Friday did we see a trend towards an off the coast solution.

...and then last night's models came in...

Beginning yesterday, a subtle shift back towards the west occurred and then last night a more substantial shift occurred, raising our chances for accumulating snow. Today's GFS model continues the trend:

It is still possible that the storm tracks off the coast, but the National Weather Service is confident enough to issue Winter Storm Watches for the area with accumulations greater than 5 inches possible.

This forecast is very tricky, and will definitely change before tomorrow. Stay tuned to the NWS and local news outlets for the latest information on this possible storm, affecting our area tomorrow afternoon into Monday morning.

9/29/10: Heavy Rain On The Way

2010-09-29T07:40:00.009-04:00

A stationary front will setup over the state today as a low pressure develops and moisture from Tropical Depression 16 gets pulled north and through the area.

Flash Flood Watch in effect until Thursday evening.

Rain will overspread the area this afternoon and become heavy overnight as a low pressure forms off the North Carolina coast. This low will also pull in moisture from TD 16 enhancing the rainfall. The stationary front should move back through the area as a cold front Thursday afternoon, bringing another chance of showers and storms before clearing out Thursday evening.

Rainfall totals of 2-4" are expected by Thursday evening.

9/10/10: NWS bumps rain chances to "likely" for Sunday

2010-09-10T08:38:00.004-04:00

After holding the chances to 40% for the past few days, the NWS has increased the chance of showers on Sunday up to 60% and "likely." Totals don't look to be a lot, but up to a quarter of an inch could fall and every little bit helps at this point.

The last measurable rain in Central MD fell on 8/23.

Hopefully everyone gets some much needed rain, as after this it appears another dry week is on the way.

9/2/10: Earl moving towards the OBX

2010-09-02T08:53:00.008-04:00

Earl continues to move towards the OBX with sustained winds of 145 mph. The storm should pass just east of Cape Hatteras and begin to turn to the NE, sparing Ocean City of hurricane force winds.

8/5/10: Severe Thunderstorm Watch in Effect until 10PM

2010-08-05T13:26:00.003-04:00

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 575
NWS STORM PREDICTION CENTER NORMAN OK
120 PM EDT THU AUG 5 2010

THE NWS STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

DISTRICT OF COLUMBIA
CENTRAL AND SOUTHERN DELAWARE
MARYLAND
NORTHWEST NORTH CAROLINA
VIRGINIA
SOUTHEAST WEST VIRGINIA
COASTAL WATERS

EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 120 PM UNTIL 1000 PM EDT.

HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 85
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 15 MILES WEST SOUTHWEST OF BLUEFIELD WEST VIRGINIA TO 50 MILES EAST OF PATUXENT RIVER MARYLAND. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES.

OTHER WATCH INFORMATION...CONTINUE...WW 574...

DISCUSSION...THUNDERSTORMS ARE EXPECTED TO INCREASE IN COVERAGE/INTENSITY EARLY THIS AFTERNOON IN ADVANCE OF A SURFACE COLD
FRONT AS STRONG SURFACE HEATING CONTINUES TO DESTABILIZE THE BOUNDARY LAYER. MLCAPE HAS NOW INCREASED TO NEAR 3000 J/KG OVER MUCH OF VA...IN AN ENVIRONMENT SUPPORTIVE OF ORGANIZED MULTICELL CLUSTERS/LINE SEGMENTS ON THE SRN FRINGE OF THE STRONGER MIDLEVEL WLY FLOW. GIVEN THE MODERATE-STRONG INSTABILITY AND STEEP LOW-LEVEL LAPSE RATES...DAMAGING WINDS WILL BE LIKELY WITH THE STRONGER STORMS THROUGH LATE EVENING.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM MOTION VECTOR 28030.

...THOMPSON

7/29 - World Record Hailstone

2010-07-29T11:49:00.000-04:00

World Record Hailstone Weighed In Vivian

By Shawn Neisteadt
Published: July 27, 2010, 5:52 PM

VIVIAN, SD - A small South Dakota town is being recognized for a big find after last Friday's storms.

It was Friday afternoon when a line of thunderstorms fired up in central South Dakota. High winds, heavy rains and even a possible tornado rolled through the town of Vivian. But now days later, a hailstone picked up just moments after the storm is getting worldwide attention.

The damage is proof that it wasn't a typical South Dakota thunderstorm. Holes were punched through the top of buildings, and Les Scott will never forget what it sounded like.

"A guy throwing bricks at the house and many of them and it was scary," Scott said.

Scott watched as massive hailstones pummeled the ground. Tuesday, the dents in the ground are still visible, some as large and deep as coffee cans. But when the hail stopped, a certain stone grabbed his attention.

"I just happened to see this one fall and the only reason I went out and got it is because it has all these fingers sticking out of it and I thought, 'Oh, that's weird.' So I thought I'd go get that one," Scott said.

Scott originally wanted to make a daiquiri out of the hail, but decided to contact the National Weather Service instead. Tuesday, they were in Vivian. They carefully took the stone from the freezer and placed it in a cooler with dry ice. The next stop was at the post office where the hail had a date with the federally certified scale. Moments later, the hailstone weighed in at 1.9375 pounds.

“Officially, where records have been kept, this will be the U.S. record and world record for weight. So very impressive," Mike Fowle of the National Weather Service said.

But the inspection of the new world record hail wasn't done there. To ensure that the hailstone didn't melt, it was then measured while inside a freezer at a local convenience store.

The hailstone is down to 17 inches around, but was measured just a few days ago at 18 and a half inches. That is another world record number.

"I didn't think it was near that, but I'm glad I got it I guess. I'm just sad about the town of Vivian. I hope the insurance people help them out as much as they can because they need it," Scott said.

As impressive as the size and weight are, it may have topped two pounds when it fell from the sky. While Scott placed it in the freezer, the power was out for six hours following the storm, and it likely melted a bit in that time.

7/13/10: Flash Flood Watch

2010-07-13T14:34:00.002-04:00

NORTHERN BALTIMORE-HARFORD-MONTGOMERY-HOWARD-SOUTHERN BALTIMORE-PRINCE GEORGES-ANNE ARUNDEL-PRINCE WILLIAM/MANASSAS/MANASSAS PARK-FAIRFAX-ARLINGTON/FALLS CHURCH/ALEXANDRIA-

INCLUDING THE CITIES OF...WASHINGTON...GAITHERSBURG...COLUMBIA...BALTIMORE...ANNAPOLIS...MANASSAS...MANASSAS PARK...FAIRFAX...ALEXANDRIA...FALLS CHURCH
221 PM EDT TUE JUL 13 2010

..FLASH FLOOD WATCH IN EFFECT FROM 6 PM EDT THIS EVENING THROUGH LATE TONIGHT...

THE NATIONAL WEATHER SERVICE IN STERLING VIRGINIA HAS ISSUED A

* FLASH FLOOD WATCH FOR PORTIONS OF THE BALTIMORE AND WASHINGTON METROPOLITAN AREAS FROM 6 PM THIS EVENING THROUGH LATE TONIGHT.

* AN UPPER-LEVEL DISTURBANCE WILL MOVE ACROSS THE MID ATLANTIC REGION LATE TONIGHT AND INTO THE OVERNIGHT HOURS. SHOWERS AND THUNDERSTORMS WILL PRODUCE LOCALLY HEAVY RAINFALL ACROSS THE AREA. RAINFALL RATES OVER ONE INCH PER HOUR ARE POSSIBLE IN HEAVIER SHOWERS AND THUNDERSTORMS. THE BEST CHANCE FOR THE HEAVIER PRECIPITATION WILL BE OVERNIGHT.

* ONE HOUR FLASH FLOOD GUIDANCE IS BELOW TWO INCHES AND SIX HOUR FLASH FLOOD GUIDANCE REMAINS BELOW THREE INCHES ACROSS PORTIONS OF THE AREA DUE TO RECENT RAINFALL. AVERAGE RAINFALL AMOUNTS BETWEEN ONE AND TWO INCHES ARE EXPECTED...BUT RAINFALL AMOUNTS OVER THREE INCHES ARE POSSIBLE IN HEAVIER SHOWERS AND THUNDERSTORMS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION.

YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION SHOULD FLASH FLOOD WARNINGS BE ISSUED.

7/5/10: Heat Advisory

2010-07-05T13:54:00.001-04:00

WWUS71 KLWX 051750
NPWLWX

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
150 PM EDT MON JUL 5 2010

DCZ001-MDZ011-VAZ054-060200-
/O.NEW.KLWX.HT.Y.0001.100706T1600Z-100708T0000Z/
DISTRICT OF COLUMBIA-SOUTHERN BALTIMORE-ARLINGTON/FALLS CHURCH/ALEXANDRIA-INCLUDING THE CITIES OF...WASHINGTON...BALTIMORE...ALEXANDRIA...FALLS CHURCH

150 PM EDT MON JUL 5 2010

..HEAT ADVISORY IN EFFECT FROM NOON TUESDAY TO 8 PM EDT WEDNESDAY...

THE NATIONAL WEATHER SERVICE IN STERLING VIRGINIA HAS ISSUED A HEAT ADVISORY...WHICH IS IN EFFECT FROM NOON TUESDAY TO 8 PM EDT WEDNESDAY.

TEMPERATURES ARE EXPECTED TO REACH 100 DEGREES IN THE CITIES TUESDAY AFTERNOON AND AGAIN WEDNESDAY AFTERNOON. WHEN COMBINED WITH HUMIDITY HEAT INDEX VALUES MAY REACH 105 EACH DAY. IN ADDITION - TEMPERATURES WILL REMAIN ABOVE 80 DEGREES THROUGH THE MAJORITY OF THE NIGHTTIME HOURS.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A HEAT ADVISORY MEANS THAT A PERIOD OF HOT TEMPERATURES IS EXPECTED. THE COMBINATION OF HIGH TEMPERATURES AND HUMIDITY WILL COMBINE TO CREATE A SITUATION IN WHICH HEAT ILLNESSES ARE POSSIBLE. THE VERY YOUNG AND ELDERLY ARE MOST AT RISK.

THE MOST IMPORTANT THING TO REMEMBER IS TO DRINK PLENTY OF FLUIDS. WATER AND SPORT DRINKS ARE THE BEST CHOICES. IF YOU MUST BE OUTSIDE...TAKE FREQUENT BREAKS IN THE SHADE DURING THE AFTERNOON SUN. SPEND TIME IN AN AIR CONDITIONED ROOM DURING THE HOTTEST PART OF THE DAY. NEVER LEAVE CHILDREN OR PETS IN AN CAR...TEMPERATURES INSIDE THE VEHICLE CAN EXCEED 130 DEGREES IN A MATTER OF MINUTES.

&&

$$

SEVERE THUNDERSTORM WATCH

2010-06-24T12:33:00.006-04:00

EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 1230 PM UNTIL 800 PM EDT.

HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY DO PRODUCE TORNADOES.

DISCUSSION...TSTMS EXPECTED TO CONTINUE INCREASING ALONG DIFFUSE COLD FRONT NOW BISECTING PA. OTHER STORMS MAY FORM AHEAD OF FRONT ALONG LEE TROUGH. STRENGTH OF DEEP UNIDIRECTIONAL WIND FIELD AND CONTINUED LOW LVL DESTABILIZATION LIKELY WILL LEAD TO INCREASED POTENTIAL FOR DMGG WIND GUSTS AS STORMS...INCLUDING A FEW SUPERCELLS...ORGANIZE INTO SHORT LINE/BANDS.

...CORFIDI

MESOSCALE DISCUSSION 1074

2010-06-22T11:48:00.003-04:00

MESOSCALE DISCUSSION 1074
NWS STORM PREDICTION CENTER NORMAN OK
1035 AM CDT TUE JUN 22 2010

AREAS AFFECTED...WRN/CENTRAL PA...MD...PARTS OF ERN WV...NRN/ERN VA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 221535Z - 221600Z

WW IS BEING CONSIDERED FOR PARTS OF WRN/CENTRAL PA SWD THROUGH MD...PARTS OF ERN WV AND NRN/ERN VA.

SHORTWAVE TROUGH...CURRENTLY TRACKING EWD INTO THE LOWER GREAT LAKES/UPPER OH VALLEY PER WATER VAPOR IMAGERY...WILL MOVE EWD INTO NY/PA AND NRN VA/MD THIS AFTERNOON. 12Z UPPER AIR DATA INDICATED 40 KT WLY MIDLEVEL FLOW WITHIN THE BASE OF THIS TROUGH OVER OH. OBJECTIVE ANALYSES SHOWED EFFECTIVE BULK SHEAR ALREADY INCREASING ACROSS CENTRAL PA TO NRN VA AS THE STRONGER FLOW ALOFT SPREADS EWD. IN THE LOW LEVELS...SURFACE FRONT ATTENDANT TO THE SHORTWAVE TROUGH EXTENDED SSWWD FROM SWRN ONTARIO THROUGH CENTRAL OH. THIS BOUNDARY WILL CONTINUE EWD TODAY AND MARK THE WRN EXTENT OF THE SEVERE WEATHER THREAT.

CLOUDINESS/FILTERED SUNSHINE ACROSS PA...ASSOCIATED WITH CIRRUS AND LEADING BAND OF ONGOING CONVECTION OVER CENTRAL PA TO THE ERN WV PANHANDLE IS LIMITING SURFACE HEATING SOME THIS MORNING. THIS COMBINED WITH WEAK MIDLEVEL LAPSE RATES APPEARS TO BE RESULTING IN A SLOWER DESTABILIZATION OF THE AIR MASS THUS FAR. HOWEVER... FURTHER DIABATIC HEATING WITHIN A MOIST AIR MASS IS EXPECTED TO SUPPORT AT LEAST MODERATE INSTABILITY BY THIS AFTERNOON WITH MLCAPE 1000-1500 J/KG EXTENDING FROM OH INTO CENTRAL PA AND SWD TO VA/MD.

12Z WRF-HRRR SUGGESTED THE ONGOING STORMS OVER CENTRAL PA TO ERN WV PANHANDLE WILL CONTINUE TO WEAKEN...WITH NEW TSTMS DEVELOPING OVER WRN PA TO WV AROUND 17Z AS THE FRONT MOVES EWD. MODERATE INSTABILITY AND EFFECTIVE BULK SHEAR UP TO 40 KT WILL SUPPORT ORGANIZED STORMS WITH A THREAT OF HAIL...STRONG WIND GUSTS AND A POTENTIAL TORNADO THREAT. THE TORNADO THREAT WILL BE GREATER IN ANY LOCATION WHERE LOW LEVEL WINDS ARE MORE SLY...HENCE INCREASING LOW LEVEL DIRECTIONAL SHEAR. GREATEST TORNADO THREAT SHOULD BE EAST OF THE MOUNTAINS. HOWEVER...FORECAST SOUNDINGS SUGGEST SURFACE WINDS
AHEAD OF THE FRONT IN WRN PA WILL REMAIN FAVORABLY BACKED TO SUPPORT A TORNADO THREAT WITH INITIAL ACTIVITY PRIOR TO WINDS VEERING WITH
FRONTAL PASSAGE.

..PETERS.. 06/22/2010

6/10/10: 4 Months Ago Today

2010-06-10T07:39:00.000-04:00

6/7/10: Video - Incredible Lightning Strike

2010-06-07T07:36:00.001-04:00

Video of a near-miss lightning strike in Norman, OK in July 2007.

6/6/10: Forecast - The Week Ahead

2010-06-06T07:20:00.000-04:00

Showers and storms are likely today, with highs in the upper 80s as a cold front moves through the area.

Monday and Tuesday should be pleasant, with highs in the low 80s.

Shower and thunderstorm chances increase again Tuesday night and Wednesday with an associated cold front.

The front should clear the area on Wednesday night, allowing high pressure to move in with a return to sunshine and temperatures in the mid-80s on Thursday, Friday and Saturday.

5/27/10: Video - Angry Weather Caller

2010-05-27T16:24:00.000-04:00