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Sandy/EC Discussion Part IV


andyhb

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Um...wow....

PUBLIC INFORMATION STATEMENT

NATIONAL WEATHER SERVICE MOUNT HOLLY NJ

631 PM EDT FRI OCT 26 2012

...POTENTIAL HISTORIC STORM FOR THE AREA...

TROPICAL CYCLONE SANDY IS EXPECTED TO MOVE NORTHWARD AND THEN TAKE A

TURN BACK TO THE NORTHWEST, MAKING LANDFALL ALONG THE MID ATLANTIC

COAST. IT APPEARS THIS OCCURS SOMEWHERE BETWEEN THE DELMARVA

PENINSULA AND WESTERN LONG ISLAND.

SANDY IS EXPECTED TO INTENSIFY AS IT INTERACTS WITH AN UPPER LEVEL

SYSTEM MOVING OUT OF THE GREAT LAKES, AND INDICATIONS ARE THAT OUR

REGION MAY EXPERIENCE A WIDESPREAD DAMAGING STORM, POSSIBLY OF

HISTORIC PROPORTIONS.

WIDESPREAD DAMAGING WINDS ARE POSSIBLE. THE EXACT STORM TRACK IS

STILL UNCERTAIN AND THIS WILL DETERMINE THE ACTUAL IMPACTS. HOWEVER,

THE STORM IS FORECAST TO BE A LARGE STORM THEREFORE DO NOT FOCUS ON

THE EXACT CENTER OF THE STORM. IT APPEARS THAT THE STRONGEST WINDS

WILL OCCUR MONDAY AND TUESDAY.

IN ADDITION, WIDESPREAD HEAVY RAIN /POSSIBLY AS MUCH AS 6 TO 10

INCHES/ WOULD CAUSE SIGNIFICANT FLOODING ON RIVERS AND STREAMS

ACROSS THE REGION. THIS COULD BE MAJOR TO EVEN RECORD FLOODING.

RAIN CAN BE EXPECTED TO BEGIN DURING THE DAY SUNDAY OR SUNDAY

EVENING AND THEN CONTINUE MONDAY WHEN IT WILL BECOME HEAVY AT

TIMES. AS WATER IS PUSHED TOWARD THE COAST, COASTAL FLOODING WILL

INCREASE AND THIS COULD BE TO MAJOR TO PERHAPS EVEN RECORD LEVELS

ALONG THE COASTS OF NEW JERSEY AND DELAWARE. THE EXTENT OF THE

COASTAL FLOODING WILL BE DEPENDENT ON THE TRACK OF THE STORM.

THIS HAS THE POTENTIAL TO BE A LARGE AND RECORD SETTING STORM, WITH

WIDESPREAD WIND DAMAGE, INLAND AND COASTAL FLOODING, AND BEACH

EROSION. THE COMBINATION OF THE HEAVY RAIN AND WIND WILL CREATE THE

POTENTIAL FOR WIDESPREAD POWER OUTAGES AND SIGNIFICANT FLOODING. AT

THIS TIME, THE MOST LIKELY TIME FRAME FOR THE WORST OF THE RAIN AND

WIND LOOKS TO BE MONDAY AND TUESDAY. THIS MEANS THERE IS STILL TIME

TO PREPARE.

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I bet this was posted already (BOX discussion) but I almost can't believe I'm seeing this right... 100+ mph wind gusts. Of course this is a worst case scenario but the fact that the potential even exists is incredible by itself.

IN THE WORST-CASE...SUSTAINED GALE FORCE WINDS WITH FREQUENT HURRICANE FORCE WINDS /AT OR GREATER THAN 74 MPH/. WE COULD SEE GUSTS EXCEEDING 100 MPH.

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For archive purposes... this BOX discussion 2:13am is pretty astonishing. (Apologies if this was previously posted)

We've had plenty of hyperbole this past year, but you get the feeling this truly will be a storm that will be studied and remembered for a long time.

BOX discussion:

Area forecast discussion

National Weather Service Taunton Massachusetts

213 am EDT Sat Oct 27 2012

Synopsis...

high pressure over New England will bring dry and mild weather to New England into Saturday. Hurricane Sandy moving north through

the Bahamas will run nearly parallel to the East Coast during the weekend...and has the potential to bring a significant impact to southern New England next week.

Previous discussion...

Tricky forecast this evening with a fairly high inversion for this time of night. The main question is what will happen with the moisture trapped beneath this inversion. Stratus has already developed across much of CT and west of the Berkshires in Massachusetts and New York state. Latest 3.9 micron imagery showing this stratus starting to creep north into western and central Massachusetts. Also seeing many observations in the lower CT River Valley were fog and low clouds are becoming more prevalent as well.

&&

Short term /6 am this morning through 6 am Sunday/...

Saturday...

surface high pressure breaks down...but upper high pressure ridge remains intact. Remains of a cold front will stall to our west as it runs into that ridge. So we expect a dry weather day. The main concern will...as with today...be the persistence of any clouds that reform overnight and linger into Saturday morning. Meanwhile...increasing high clouds as high level moisture streams up the coast. Mixing depths are expected to reach 950 mb...with temperatures at that level supporting maximum temperatures in the 60s.

Saturday night...

increasing east flow and increasing moisture at all levels. This will bring increasing clouds. Not much confidence on precipitation...none of the models show any before 09z...although some signs of isentropic lift in CT/western mass during 06z-12z. We will work slight chance probability of precipitation into all areas during the night with chance probability of precipitation reaching CT and western mass after 06z...although not a lot of confidence in this part of the forecast.

&&

Long term /Sunday through Friday/...

headlines...

* Sandy is a dangerous hurricane/Post-tropical cyclone setting a historical precedent compared to climatology of other tropical/ Post-tropical systems during the autumn months...highly likely to have an impact upon southern New England

* Sandy has the potential to be a very destructive storm with strong to damaging winds /storm to hurricane force/...moderate coastal flooding and severe beach erosion...and finally heavy rain and interior flooding.

* Details are presented below with Cape May New Jersey serving as the benchmark between best- and worst-case scenarios

Overall...

While it is likely Sandy will left-hook into the northestern Continental U.S....the exact location where it makes landfall remains uncertain. We are looking at an area extending from the Delaware-Maryland-Virginia peninsula north to the S coastline of New England where Sandy will make landfall. At the very minimum...strong winds /gale force with storm force gusts/ and high seas are expected...in addition to significant southeast swell. Moderate coastal flooding and severe beach erosion is anticipated with the expectation of storm surge...with downed trees and widespread power outages at the least.

But with focus upon the 26/12z model solutions...this could be a very catastrophic and destructive storm for all of southern New England and neighboring localities. Hurricane force winds would be expected. Downed trees and widespread power outages /likely for days/ would be anticipated. With significant southeast swell and the near-passage of the center of the storm...we would see significant storm surge resulting in moderate to major coastal flooding. Substantially severe beach erosion along all beaches would be a likely outcome. A greater propensity for heavy rain should lead to more interior flooding.

There still remains a level of uncertainty this far out in the forecast...specifically to the strength of the system...landfall... and consequential impacts. Numerous possibilities remain on The Table...but the best advice is to be tuned to the latest forecasts and start getting prepared.

Synoptic setup...

A very strong negative nao will prevail with a large hemispheric blocking pattern through the Atlantic...promoting deep troughing and draw down of colder air from the Canadian Maritimes into the northeastern Continental U.S.. it is through this trough that most ensemble and deterministic guidance agree upon a series of shortwave impulses rotating through the base...cyclonically digging...drawing down colder air further south and amplifying the trough /becoming negatively tilted/. Consequentially the thermal gradient between the trough and Atlantic ridge enhances resulting in an increase in the middle-upper level jet axis /from the Ohio River Valley North into Canada/. Subsequently... diffluence increases in the right-rear quadrant of the jet axis promoting height falls across the middle-Atlantic into the eastern Great Lakes.

Blocked by low-middle level ridging building S out of the eastern Canadian Maritimes /the strength of which remains in dispute amongst model solutions and likely a factor in the numerous possibilities in where Sandy will make landfall/...Sandy Hooks west towards the region of greatest height falls impressively deepening /though am remaining hesitant as it has been noted that model solutions can be overzealous with a strong bias on cyclone deepening with phasing systems/. Post-tropical and the more dominant wave...Sandy usurps energy associated with the negatively-tilted baroclinic trough as it meanders west into the interior northestern Continental U.S.. thereafter the remnants of Sandy wobble slowly through eastern Great Lakes and St Lawrence River valley through the end of the week possibly into next weekend.

Storm surge and coastal flooding...

There is a fair amount of confidence of seas at or exceeding 30 feet along both the east and S coastlines. Dependent upon the track of Sandy with attendant wind and surge patterns there is the plausibility for moderate coastal flooding along the entire shoreline of New England. The potential situation is enhanced thanks to the timing of the full moon and building of tide cycles prior to the onset of Sandy. Severe beach erosion is anticipated.

In the best-case...the southern pass of Sandy will diminish the u-component of the wind. Seas around 25 to 30 feet with surges along the east shoreline of 4-6 feet would be expected...around 4 feet for the S coastline.

In the worst-case...a strong anomalous u-component of the wind will result in waves exceeding 40 feet with storm surges of 6 to 8 feet along the east shoreline /with the perfect storm of 1991 the buoy outside Boston Harbor was recording 35 feet waves and this may likely occur again or be higher with Sandy/. The S coast is not spared with surges of 4-6 feet with wave heights building to 30 to

35 feet.

Wind...

With the approach of Sandy from the S/E...southern New England finds itself transitioning from the northwest quadrant to the NE quadrant as it Hooks west into the interior northestern Continental U.S.. initial north/northeasterly flow would be expected to veer out of the E/se. The onset of winds begins Sunday night continuing into the midweek period. The strongest of winds based on forecast guidance center around the Monday night into Tuesday time frame.

In the best-case...gale force winds /40-54 miles per hour/ with frequent storm force gusts /55 miles per hour to 73 mph/.

In the worst-case...sustained gale force winds with frequent hurricane force winds /at or greater than 74 mph/. We could see gusts exceeding 100 miles per hour.

Heavy rain and interior flooding...

With regards to the storm center...the heaviest of rain will likely be along the short wave periphery collocated with the strongest deep layer

lift. But a warm-cored system with tropical characteristics conveyoring around the center of storm...the onshore moist east/NE flow rotating around the storm center is expected to orographically lift resulting in widespread rains of 4-8 inches /up to 10 inches possible/ in a 24 to 36 hour period. Should this occur in a shorter period of time would result in extensive interior flooding.

In the best-case...heaviest of rains remain well short wave of the southern New England...with pockets of heavy rain across southern New England along east facing higher terrain. Localized flooding would be expected for urban areas...small rivers...streams and creeks.

In the worst-case...while the heaviest of rains may be immediately short wave of the forecast area...a better warm conveyor belt of tropical air would usher across New England resulting widespread 1-2 inches of rain in very short periods of time /1-3 hours/ with locally higher amounts. Widespread flooding would be expected for all areas including mainstem rivers.

&&

Marine...

tonight...

winds and seas will remain below small craft levels.

Saturday...

winds and seas are expected to remain below small craft levels through midday Saturday. Seas may climb to 5 feet on the southern outer waters late in the day Saturday. We will issue a Small Craft Advisory for rough seas for the latter part of Saturday afternoon and Saturday night for this area.

Saturday night...

winds and seas will continue to build with 25-30 knot east wind gusts on the southern waters and 5-8 foot seas.

Outlook...Sunday through Wednesday...

Low to moderate confidence.

Sandy will make landfall somewhere between the Delaware-Maryland-Virginia peninsula to the S coast of New England. Strong southeast swell is anticipated generating waves at least of 30 feet along the S and east coastlines. Ely winds at minimum will be gale force with frequent storm force gusts...but there is increasing confidence of storm force winds with frequent hurricane force gusts. Storm surge of at least 4 feet will result in severe beach erosion along all beaches. Rain will be on the increase beginning Sunday night on through the event. Sandy is expected to make landfall during the Monday night into Tuesday time frame.

&&

Box watches/warnings/advisories...

CT...none.

Massachusetts...none.

New Hampshire...none.

Rhode Island...none.

Marine...Small Craft Advisory for hazardous seas from 3 PM this

afternoon to 6 am EDT Sunday for anz255-256.

$$

Synopsis...wtb/sipprell

near term...Belk

short term...wtb

long term...sipprell

aviation...Belk/sipprell

marine...wtb/sipprell

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Wow, thanks for posting. I know we're all excited, but if that verifies I can how it would make for a long night. Maybe Kevin will be high fiving the kids at 6z as limbs are smashing the windows but most us will be nervously awaiting daylight, reminding ourselves how much we actually love this stuff.

Me too. Changing planes in PHL then head to BDL late sunday night. Cutting it close. Good luck!

Monday nite might be the first time I ever pull an all nighter in my almost 40 years
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