12:15 PM | It Ain't Over Till Its Over - winter that is

Discussion

A very interesting late winter weather pattern is forecast to evolve in the US over the next week or so. We often talk about “teleconnections” here at thesiweather.com and how atmospheric and oceanic patterns in one part of the world can have an effect on the weather pattern here in the Mid-Atlantic region. For example, the wintertime atmospheric pressure and sea surface temperature pattern in the North Atlantic can dictate whether cold air masses will penetrate into the central and eastern US from Canada and, if so, can they be sustained. One way to track the overall pattern in the North Atlantic is through an index called the North Atlantic Oscillation (NAO). If the NAO is negative, for example, a blocking pattern can set up in the northern latitudes (such as in the region between Hudson Bay, Canada and Greenland), and this typically results in cold air intrusions into the central and eastern US. In addition, the pressure pattern in the eastern Pacific can determine whether Canadian cold air masses can drop southward into the central and eastern US. One way to track the pressure pattern in the eastern Pacific is through an index called the Pacific-North American (PNA) pattern. If, for example, the PNA is positive then high pressure ridge is likely to set up along the US west coast and this typically pushes cold air masses into the US from Canada due to the circulation (clockwise) around high pressure.

Experienced snow lovers and “weather weenies” in the Mid-Atlantic region know that while there are no guarantees, the best pattern for cold and snow usually involves a couplet with a positive PNA and a negative NAO. We really haven’t had that couplet combination all winter, at least not more than for a couple of days at a time, but that may be about to change. All indications are that this type of “teleconnections” pattern will develop over the next week or so enhancing the chances for cold and snow in the Mid-Atlantic region by early March. While we have had a negative NAO reading at times this winter, the change to a positive PNA is quite a change in the eastern Pacific. It should result in a trough of low pressure to develop in the Gulf of Alaska and a corresponding downstream ridge of high pressure to form along the US west coast. This, in turn, should help to bring cold air southward into the US from Canada. One final note, experienced snow lovers and “weather weenies” also know that when the calendar flips to March, time is running short for snow as climatological temperatures begin to climb quite rapidly.

Stay tuned.

7:00 AM | *Snow event winds down as storm pulls into the central Plains*

6-Day Forecast

Today

Cloudy, more snow in the morning with another inch or two possible, windy, cold, highs only reaching the mid 20’s

Tonight

Mostly cloudy, cold, lows in the middle teens

Friday

Partly sunny, breezy, cold, upper 30’s

Friday Night

Partly cloudy, cold, upper teens

Saturday

Partly sunny, chilly, mid-to-upper 40’s

Sunday

Mostly cloudy, breezy, cold, chance for some snow, mid 30’s

Monday

Mostly sunny, cold, mid-to-upper 30’s

Tuesday

Partly sunny, cold, mid-to-upper 30’s

Discussion

The major storm that generated significant accumulating snow around here will pull to the north and east today from the southern Plains and, as our snow winds down, the central Plains will receive an all-out blizzard. NW flow will prevail here on Friday to close out the work week and that will keep us quite cold and dry with possible snow showers in the mountains. Another storm system will approach the region late this weekend, but there are still some uncertainties regarding the evolution of this low pressure. Stay tuned.

Video

httpv://youtu.be/JIqmYS-mc5E

12:30 PM | An update on global sea ice

Discussion

Sea ice occupies about 7% of the surface area of planet Earth and is especially important in polar regions. Even though sea ice is found predominately in polar regions, it does have an influence on global climate as its bright surface reflects much sunlight back into space. The North Pole region is considerably different than the South Pole in that up north there is an ocean (Arctic) that is surrounded by land whereas down south there is land (continent of Antarctica) surrounded by ocean. The Arctic responds much more directly to changes in air and sea-surface temperatures than does Antarctica. Currently, the northern hemisphere sea ice content is below normal while the southern hemisphere is above normal and the combination of the two has produced a global sea ice content that is very close to normal.

The below normal trend for northern hemispheric sea ice began in the mid-90’s at which time the Atlantic Ocean entered a warm (positive) phase. Atlantic Ocean sea surface temperatures can be tracked through an index called the Atlantic Multidecadal Oscillation (AMO). Specifically, sea-surface temperatures in the north Atlantic have been running at above normal levels in recent years and this is having an influence on the northern hemisphere sea ice content. Oceanic cycles can last two or three decades and it is quite possible that when the AMO returns to a cold (negative) phase the sea ice in the Arctic region will return to normal or even above levels on a consistent basis. Meanwhile, way down south the sea-surface temperatures have been running below normal in recent times in those areas surrounding the continent of Antarctica and this is contributing to the above normal levels of sea ice in that part of the world.

Video

httpv://youtu.be/RGMCFKflC_w

7:00 AM | Improvement begins today as major storm pulls away to the east of here

6-Day Forecast

Today

Mostly cloudy early with lingering shower possible then becoming partly sunny, windy and cool, highs in the mid-to-upper 50’s

Tonight

Partly cloudy, windy, cold, lows in the lower 40’s

Thursday

Partly sunny, windy, cool, upper 50’s

Thursday Night

Mostly cloudy, cold, lows near 45

Friday

Mostly sunny, breezy, cool, near 60

Saturday

Partly sunny, cool, near 60

Sunday

Mostly sunny, cool, low 60’s

Monday

Mostly sunny, cool, low 60’s

Discussion

The cold storm that originated in the Gulf of Alaska and brought some rain to the coastal regions and snow to the mountains will move east of here today and after possible lingering early morning showers there will be the return of some sunshine, but winds will remain quite gusty. Below normal temperatures are likely to persist through the week, but the late week and weekend is likely to feature copious amounts of sunshine.

Video

httpv://youtu.be/S8WNuybe7rU

7:00 AM | *"Western storm" to develop into a blizzard for the Central Plains and it will bring us significant accumulating snow as well*

6-Day Forecast

Today

Mostly cloudy, chance for some snow this afternoon, chilly, afternoon highs near 40 degrees

Tonight

Cloudy, cold, becoming windy with snow, heavy at times, lows near 20 degrees

Thursday

Cloudy, snow ending in the morning with total snow accumulations of 4-8 inches, windy, cold, upper 20's

Thursday Night

Mostly cloudy, cold, upper teens

Friday

Partly sunny, cold, upper 30’s

Saturday

Partly sunny, not quite as cold, low-to-mid 40’s

Sunday

Mostly cloudy, cold, chance for some snow, upper 30’s

Monday

Partly sunny, cold, upper 30’s

Discussion

Strong low pressure centered just east of California this morning will move east over the next 24 hours and it will become an all-out blizzard for the central Plains on Thursday and bring significant accumulating snow to the southern Rockies as well. Snow may develop this afternoon, but the full brunt will occur tonight and early tomorrow with total accumulations by late tomorrow morning on the order of 4-8 inches. Winds will also be a factor with gusts to 25 mph or so causing some blowing and drifting during the storm. Once this system does move to our east, our weather will dry out, but stay on the cold side to close out the work week.

Video

httpv://youtu.be/S8WNuybe7rU

7:00 AM | Cold storm that originated in the Gulf of Alaska affects the region today

6-Day Forecast

Today

Mostly cloudy, breezy, showers and thunderstorms possible, cool, mid-to-upper 50’s

Tonight

Mostly cloudy, breezy, cool, still the chance for showers and thunderstorms, upper 40’s

Wednesday

Mostly cloudy, breezy, showers possible in the morning, cool, mid 50’s

Wednesday Night

Becoming partly cloudy, cold, lows near 40

Thursday

Partly sunny, cool, cannot rule out a shower, mid 50’s

Friday

Partly sunny, not as cool, near 60

Saturday

Mostly sunny, cool, near 60

Sunday

Mostly sunny, cool, low 60’s

Discussion

A cold storm that originated in the Gulf of Alaska will bring us some shower and thunderstorm activity, low elevation snow, and gusty winds right from today into early Wednesday. Given the cold air expected aloft, some of the thunderstorms can produce hail as freezing levels are going to be quite low. There might be a break in the unsettled weather briefly Wednesday night, but another quick moving system could bring showers to the region on Thursday. Temperatures will remain below normal right through the upcoming weekend.

Video

httpv://youtu.be/RXfsK-n87sg

7:00 AM | A quiet day in the southern Rockies with sunshine and moderation in temperatures this afternoon

6-Day Forecast

Today

Partly sunny, not as cold this afternoon after a cold start, low-to-mid 40’s

Tonight

Mostly cloudy, cold, lows in the upper 20’s

Wednesday

Mostly cloudy, chance for a few rain or snow showers, chilly low 40’s

Wednesday Night

Mostly cloudy, cold, chance for some snow, low 20’s

Thursday

Mostly cloudy, cold, maybe a few snow showers, mid 30’s

Friday

Partly sunny, cold, upper 30’s

Saturday

Partly sunny, not as cold, mid 40’s

Sunday

Partly sunny, cold, upper 30’s

Discussion

Today will be a quiet day as high pressure moves over eastern Colorado. Another storm system will moves out of the Pacific Northwest and into the Great Basin region at mid-week and this will enhance the chances for some snow by late Wednesday. Drier air will return towards the latter part of the week and, at this vantage point, the weekend looks dry and chilly.

Video

httpv://youtu.be/RXfsK-n87sg

11:50 AM | The Year of the Comet??

Discussion

There are not one, but two comets coming this year that very well could end up making 2013 remembered as the “Year of the Comet”. The first comet will become visible in the next several weeks while the second comet comes late this year and it promises to be one of the best of all-time according to some experts.

The first comet is officially known as Comet C/2011 L4 and it was discovered by the Panoramic Survey Telescope and Rapid Response System known as Pan-STARRS. As a result, the comet may soon take on the name “Comet Pan-STARRS”. This will be the comet’s first visit as it has never been pulled in by the sun’s gravity so some surprises are possible. “Pan-STAARS” will become visible to the naked eye in the southern hemisphere in early March. By that time, the comet will pass about 100 million miles from Earth as it briefly dips inside the orbit of Mercury. It should become visible to observers in the northern hemisphere around mid-March. In fact, some experts have pinpointed March 12th and 13th as two of the best dates for viewing the new comet in the northern hemisphere as it emerges in the western sunset sky. “Pan-STAARS” will continue to be a bright object in the evening sky for the rest of March and during the first half of April.

The second comet coming in 2013 was discovered last September by Russian astronomers and it could blossom into one of the best comets ever according to some astronomers. This comet is known as “ISON” since it was discovered through a telescope in Russia as part of the “International Scientific Optical Network (ISON)”. “ISON” should become visible in August and September to obervers at dark locations using small telescopes or binoculars. It should then make its first appearance to the naked eye during the first week of November in both the northern and southern hemispheres. It will make its closest approach to the sun on November 28th, some 680,000 miles away, much closer even than the planet Mercury. If the comet survives this encounter and doesn’t break up, it is predicted to become brighter than the full moon, visible even in the daytime sky, and the bright object should be visible right through December and into early January 2014. Currently, the comet is located near Jupiter and is only visible with large telescopes.

So if all goes well, 2013 could turn out to be known as “The Year of the Comet”; however, as a word of caution, many comets have failed to live up to expectations (e.g. Comet Kohoutek, 1973) - stay tuned.

7:00 AM | Early morning snow showers give way to a dry and chilly start off to the new week

6-Day Forecast

Today

Becoming partly sunny after early morning snow shower activity, windy, cold, highs near 40 degrees

Tonight

Mostly clear, quite cold, lows in the middle teens

Tuesday

Mostly sunny, milder, mid 40’s

Tuesday Night

Mostly cloudy, cold, near 25

Wednesday

Mostly cloudy, mild, maybe a few rain or snow showers, mid 40’s

Thursday

Mostly cloudy, colder, chance for some snow, mid-to-upper 30’s

Friday

Partly sunny, not as cold, low 40’s

Saturday

Partly sunny, chilly, mid 40’s

Discussion

High pressure will control our weather to begin the new week and we’ll start off quite cold, but modify some for Tuesday. By mid-week, a trough of low pressure will approach the region and there may be some precipitation from Wednesday night into Thursday. Dry weather will return by Friday and Saturday with moderately cold conditions expected.

Video

httpv://youtu.be/spmb2pX7Is4

7:00 AM | Cold storm approaches from the Gulf of Alaska and brings shower and thunderstorm threat

6-Day Forecast

Today

Some patchy fog early then remaining mostly cloudy, breezy, cool, upper 50’s

Tonight

Mostly cloudy, chilly, some rain likely, lows in the upper 40’s

Tuesday

Mostly cloudy, breezy, showers and thunderstorms possible, cool, upper 50’s

Tuesday Night

Mostly cloudy, breezy, cool, still the chance for showers and a thunderstorm, upper 40’s

Wednesday

Partly sunny, cooler, cannot rule out a shower or thunderstorm, mid 50’s

Thursday

Partly sunny, breezy, cool, upper 50’s

Friday

Mostly cloudy, cool, chance for showers, near 60

Saturday

Mostly sunny, cool, low 60's

Discussion

All in all this looks like a cool week across the region with unsettled conditions at times. Beginning tonight, a cold storm from the Gulf of Alaska will enhance the chances around here for shower and thunderstorm activity, low elevation snow, and gusty winds right into mid-week. Given the cold air expected aloft, some of the thunderstorms can produce hail as freezing levels are going to be quite low. There might be a break in the unsettled weather briefly Wednesday night and Thursday, but another quick moving system could bring showers to the region on Friday.

Video

httpv://youtu.be/spmb2pX7Is4