6 replies to this topic

[metallicwx366]

http://www.hpc.ncep....php?disc=pmdepd
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
203 PM EDT SUN MAY 13 2012

VALID 12Z WED MAY 16 2012 - 12Z SUN MAY 20 2012

...COASTAL LOW/NOR'EASTER POSSIBLE NEAR THE CAROLINAS NEXT
WEEKEND...

OUTSIDE THE 00Z CANADIAN GUIDANCE BEYOND FRIDAY MORNING...THE
AVAILABLE DETERMINISTIC AND ENSEMBLE MEAN GUIDANCE IS IN VERY GOOD
AGREEMENT CONCERNING THE EXPECTED FLOW PATTERN.  TROUGHING BECOMES
ESTABLISHED ACROSS THE INTERMOUNTAIN WEST WHILE RIDGING EXISTS
ACROSS THE PLAINS/MIDWEST AND A DEEP CYCLONE MOVES OFFSHORE THE
SOUTHEAST COAST.  SINCE THERE WAS SUCH GOOD AGREEMENT...USED A
40/30/30 BLEND OF THE 00Z UKMET/00Z GFS/00Z ECMWF THROUGH FRIDAY
BEFORE SWITCHING TO A 50/50 BLEND/COMPROMISE OF THE 00Z GFS AND
00Z ECMWF SOLUTIONS.  THIS PREFERENCE LED TO GOOD CONTINUITY.

THE DEEP CYCLONE/NOR'EASTER FORECAST OFFSHORE THE SOUTHEAST COAST
THIS WEEKEND HAS A CHANCE TO BECOME A HYBRID SYSTEM AS IT HOVERS
NEAR THE WARM GULF STREAM WATERS FROM FRIDAY INTO EARLY THE
FOLLOWING WEEK.  EVEN IF IT REMAINS COLD CORE...THE SYSTEM SHOULD
LEAD TO LOWERED PRESSURES/DISTURBED WEATHER ACROSS THE WESTERN
CARIBBEAN LATE IN THE PERIOD NEAR THE BASE OF ITS UPPER
TROUGH/COLD FRONT...NORMALLY A PROBLEM WHEN A DEEP LAYERED CYCLONE
FORMS BETWEEN THE SOUTHEAST AND BERMUDA.  HEAVY COMMA HEAD
RAINS/WINDY CONDITIONS ARE POSSIBLE NEAR THE
CAROLINA/GEORGIA/NORTHEAST FLORIDA COAST IF THE SYSTEM TAKES A
MORE COASTAL ROUTE AS SEEN IN THE 00Z ECMWF.  IF IT DEVELOPS AND
STAYS FARTHER OFFSHORE...IT COULD EVOLVE INTO A WILDFIRE CONCERN
FOR SOUTH CAROLINA/GEORGIA/NORTHERN FLORIDA WHICH ARE WITHIN THEIR
ANNUAL SPRING DROUGHT...SIMILAR TO THE SITUATION SEEN DURING
SUBTROPICAL STORM ANDREAS DEVELOPMENT DURING EARLY MAY 2007. THE
POTENTIAL DEVELOPMENT AS SEEN BY ECMWF OVER THE PAST SEVERAL RUNS
IS DIFFERENT THAN THAT OF 2007 EVOLUTION OF ANDREAS...BUT THE
FINAL DEVELOPMENT OF ANDREAS INTO ITS SUBTROPICAL FORM IS SIMILAR
IN THE MID LEVEL H500 FLOW OF THIS EVENT.    

VELOCITY POTENTIAL ANOMALIES OF GFS/ECMWF/CMC CONTINUE TO INDICATE
A FAVORABLE ENVIRONMENT FOR TROPICAL DEVELOPMENT IN THE EASTERN
PACIFIC/WESTERN CARRIBEAN AND OFF THE U.S. SOUTHEASTERN SEABOARD.
THE EASTERN PACIFIC ALREADY HAS A SYSTEM READY TO GO AND WILL
LIKELY BE AT LEAST A TROPICAL DEPRESSION IN THE NEXT DAY OR SO.
SEE NHC DISCUSSIONS. THE ATLANTIC SIDE OFF THE SOUTHEASTERN
SEABOARD ALSO HAS FAVORABLE CONDITIONS AS MENTIONED ABOVE WITH A
LARGE NUMBER OF ECMWF ENSEMBLE MEMBERS SUPPORTING THE OPERATIONAL
RUN WITH THE SYSTEM LATE NEXT WEEK AND WEEKEND. BEYOND THIS TIME
FRAME LONGER TERM RUNS OF GFS HAVE BEEN PRODUCING TROPICAL SYSTEMS
IN THE WESTERN CARRIBEAN WITH AN EXIT NORTH AND NORTHEASTWARD.
THIS IS ANOTHER INDICATION THAT THE MODELS RECOGNIZE FUTURE
FAVORABLE DEVELOPMENT CONDITIONS OR CYCLOGENESIS.

UPDATED MORNING PRELIMS REMAIN SIMILAR TO THE OVERNIGHT PACKAGE
WITH AN ADJUSTMENT OF THE SOUTHEASTERN SEABOARD LOW SOUTHWARD OF
THE EARLY PRELIMS OFF THE SC COAST AS A BETTER FIT TO LAGGED
AVERAGE FORECASTS OF ECMWF AND GFS.

AFTN FINALS REMAIN THE SAME. ADDITIONAL SUPPORT FOR EARLIER PROGS
BY HIRES UKMET OVER CONUS AND ADJACENT WATERS. SOUTHEAST SEABOARD
LOW FORECAST SE OF CAPE FEAR IN GOOD AGREEMENT WITH 00Z ECMWF DAYS
6-7.
ROTH/ROSENSTEIN
This has my interest.

[Thunder91]

Are nor'easters common in Mid to Late May ?

[andyhb]

Nor'easters can happen at anytime of the year, it usually just changes with what type of precipitation they bring. Obviously your ones during the winter have better chances to be the historic snow storms in the eastern portion of the country.

[SD]

Thunder91, on 13 May 2012 - 02:15 PM, said:

Are nor'easters common in Mid to Late May ?

They aren't totally uncommon but by this point the jet has generally lifted enough so that we don't see noreasters this far south. The big question mark with this guys is will it have enough time to gain sub tropical characteristics. Most models today say no which I would agree with given the quick timing of the next incoming eastern trough, it's something to watch though through the next few weeks if the east coast trough can stay established and we can get another piece to linger

Edited by SD, 13 May 2012 - 04:52 PM.

[metallicwx366]

Seems like the threat has lessoned according to the early morning discussion.   This is this afternoons discussion.
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
119 PM EDT MON MAY 14 2012

VALID 12Z THU MAY 17 2012 - 12Z MON MAY 21 2012


PRELIMINARY UPDATE...

USED A NEAR EVEN BLEND OF THE 00Z/14 ECMWF AND ECENS MEAN TO
UPDATE THE PRELIMINARY FRONTS AND PRESSURES FOR DAYS 3 THROUGH 7.
THE RECENT GLOBAL MODELS ARE IN ABOVE AVERAGE AGREEMENT AT THE
MEDIUM RANGE FOR THE HANDLING OF THE FLOW ACROSS CENTRAL NORTH
AMERICA.  CHOSE THE EUROPEAN CENTRE GUIDANCE FOR THE MANUAL BLEND
TO CAPITALIZE ON ITS BETTER SURFACE PRESSURE VERIFICATION OVER THE
PAST SEVERAL MONTHS...PARTICULARLY AT THE DAY 6 AND 7 TIME FRAME.
THE PATTERN IS NOT PARTICULARLY STORMY NOR WET FOR THE
NATION...WITH MOST OF THE RAINFALL FOCUSING ALONG THE POLAR FRONT
SNAKING ACROSS THE CENTRAL STATES.


FINAL...

MADE ONLY COSMETIC CHANGES TO THE UPDATE PACKAGE FOR THE FINAL
ISSUANCE.  THE 12Z/14 GFS AND UKMET ERODE THE LOW LEVEL COOL AIR
OVER THE UPPER MIDWEST FASTER THAN THE MANUAL FORECAST...12Z/14
GEM GLOBAL...AND 12Z/14 GFS PARALLEL.  THE UKMET RETROGRADES THE
WAVE OVER THE ATLANTIC INTO THE SOUTHEAST COAST BY DAY 6...BUT IS
CURRENTLY ALONE IN THAT EXTREMITY.  WITH THE ROBUST SUPPORT FROM
THE LATEST GEM GLOBAL AND GFS PARALLEL...FEEL THAT THE CURRENT
FORECAST IS A STABLE ONE.


CISCO

Edited by metallicwx366, 14 May 2012 - 03:37 PM.

[SD]

Interesting little surface low off of the Carolina coast tonight. Totally cold core but a decent radar presentation, curious to see how much if any rain makes it this far west. Model runs have ranged from 0 to near 1 inch. Looks like the growing consensus is more toward zero to a quarter inch. The nc and northern sc beaches should get s big soaking

[apocalyptic_pleasures]

From J Bastardi- seems to think this wants to be Tropical. Its from twitter so in reverse order from his posts.

Quote

Joe Bastardi ‏@BigJoeBastardi
IR loop shows the twist that has developed http://www.meteo.psu...SE/anim8ir.html

51m Joe Bastardi ‏@BigJoeBastardi
Pt : System over gulf stream water warm enough for dev& nr coast is more worthy of mention in May than something near Azores over 20c water

57m Joe Bastardi ‏@BigJoeBastardi
Lets see how this looks in the morning, it has persisted since yesterday at this time.

58m Joe Bastardi ‏@BigJoeBastardi
Modeling not handling this part of forecast problem well at all, as they are focused more on true baroclinic development to northeast

1h Joe Bastardi ‏@BigJoeBastardi
Gusts to 35 kts now as wind is increasing from the north near the center of the cloud mass.. Frying Pan Shoals http://pic.twitter.com/dPYvTfqP