FXUS61 KOKX 142332
AFDOKX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
632 PM EST MON DEC 14 2009
.SYNOPSIS...
A WEAK AREA OF LOW PRESSURE OVER THE GREAT LAKES THIS EVENING WILL
BYPASS THE AREA TO THE NORTH ON TUESDAY...DRAGGING A COLD FRONT
THROUGH THE NORTHEAST IN THE MORNING. FOR THE MOST PART...THE
FRONTAL PASSAGE IS FORECAST TO BE DRY...BUT THERE MAY BE A BRIEF
PERIOD OF LIGHT PRECIPITATION. MUCH COLDER AIR WILL MOVE INTO THE
AREA TUESDAY NIGHT THROUGH THURSDAY ON A STRONG NORTHWEST FLOW.
POLAR HIGH PRESSURE OVER THE CENTRAL U.S. WILL BUILD EASTWARD
THROUGH THE END OF THE WEEK.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
LARGE SCALE WARM ADVECTION AHEAD OF AN AMPLIFYING SHORT WAVE OVER
THE UPPER MIDWEST THIS EVENING...WILL ALLOW FOR HIGH CLOUDS TO
STREAM ACROSS THE AREA FROM THE WEST THIS EVENING. THE ASSOC SFC
LOW OVER THE GREAT LAKES WILL TRACK INTO UPSTATE NY BY DAYBREAK...
WITH ITS TRAILING COLD FRONT APPROACHING THE AREA. A STRENGTHENING
SLY FLOW OVERNIGHT WILL LEAD TO STRATUS AND POSSIBLY SOME DRIZZLE...
GENERALLY THOUGH AFTER MIDNIGHT. TEMPS SHOULD DROP LITTLE FROM
THEIR CURRENT VALUES DUE TO AN INCREASE IN CLOUD COVER AND SLY
FLOW OF 5 TO 10 MPH.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
THE COLD FRONT PUSHES THROUGH DURING THE MORNING HOURS TUE...POSSIBLY
PRECEDED BY SOME LIGHT DRIZZLE THROUGH MID MORNING. A LACK OF UPPER
SUPPORT AND DEEP MOISTURE DOES NOT WARRANT MUCH MORE. TEMPS ARE
FORECAST TO BE ABOVE FREEZING..THUS NO WINTRY WEATHER IS ANTICIPATED
AT THIS TIME. COLD ADVECTION BEHIND THE FRONT AND SUBSIDENCE WILL
ALLOW FOR PARTIAL CLEARING BY AFT WITH A GRADUALLY STRENGTHENING
WEST WIND. THIS WILL BE THE WARMEST DAY OF THE UPCOMING WEEK WITH
HIGHS AROUND 50 IN MOST LOCATIONS.
A NEGATIVE NAO PATTERN WILL ALLOW FOR THE AMPLIFYING SHORT WAVE
TROF OVER EASTERN CANADA AND THE NE U.S. TO CLOSE OFF INTO UPPER
LOW...WHERE IT WILL BECOME NEARLY STATIONARY. THIS WILL ALLOW FOR
A STEADY STREAM OF POLAR AIR TO FILTER INTO THE AREA FROM TUE
NIGHT INTO THU WITH DAYTIME HIGHS NOT GETTING OUT OF THE 30S WED
AND THU. GUSTY NW WINDS WILL ALSO ACCOMPANY THE COLD AIR WITH WIND
GUST UP TO 30 MPH POSSIBLE LATE TUE NIGHT AND WED. OVERNIGHT LOWS
WILL BE IN THE TEENS WELL NORTH AND WEST OF NYC...TO THE 20S
ELSEWHERE.
POLAR HIGH PRESSURE OVER THE MID SECTION OF THE COUNTRY WILL BE
SLOW TO BUILD EAST THROUGH THE PERIOD. THUS...DRY...COLD WEATHER
IS FORECAST THROUGH THE END OF THE WEEK.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
THE LONG TERM PATTERN IS DEFINED BY CONTINUANCE OF THE NEGATIVE
NAO (NORTH ATLANTIC OSCILLATION). THUS...BELOW NORMAL TEMPS
THROUGH THE PERIOD. 500 HPA HEIGHTS FALL TO 1-2 SIGMA BELOW CLIMO
FROM SOUTHERN NEW ENGLAND ALL THE WAY SOUTH INTO CARIBBEAN BY LATE
MONDAY.
AT THE SURFACE...ENSEMBLE FORECAST SYSTEMS (GFS) SUGGESTING HIGH
PRESSURE LOCALLY AS GULF CYCLOGENESIS EJECTS ACROSS FLORIDA AND INTO
THE OPEN ATLANTIC ON FRIDAY. UNCERTAINTY RELIES AROUND EAST COAST
CYCLOGENESIS ON SUNDAY UPPER LEVEL CUT OFF RETROGRADES AND SHARPENS
EASTERN US TROUGH IN RESPONSE TO BACK BUILDING GREENLAND HIGH. GFS
ENSEMBLE SYSTEM INDICATES THAT THE LOW WILL PASS WELL EAST OF THE
REGION.
00Z ECMWF HAS A FAIRLY SIGNIFICANT NOR'EASTER PASSING CLOSE TO THE
40N/70W BENCHMARK SUNDAY EVENING WITH THE POTENTIAL OF SIGNIFICANT
SNOW. THIS SINGLE ECMWF RUN IS MUCH CLOSER TO THE COAST AND SLOWER
THAN THE GFS ENSEMBLE SYSTEM AND GFS OPERATIONAL PRODUCTS. IT'S ALSO
VERY DIFFERENT THAN PREVIOUS RUN.
12Z ECMWF NOW IN WITH NOT MUCH OF ANYTHING. SO THE UNCERTAINTY
REMAINS.
NOW FOR SOMETHING COMPLETELY DIFFERENT...THE 12Z CANADIAN GEM TAKES
THE SOUTHERN SYSTEM AND PULLS IT NORTH FOR SATURDAY WITH A 962 BOMB
IN THE GULF OF MAINE BY SUNDAY AM. DON'T THINK THIS IS LIKELY...BUT
IT MAKES FOR HIGHER UNCERTAINTY FOR THE WEEKEND.
BOTTOM LINE...WILL KEEP A LOW CHC -SN FOR LATE SATURDAY NIGHT INTO
SUNDAY NIGHT WITH HIGH UNCERTAINLY. TEMPS WILL BE BELOW MOST
GUIDANCE DUE TO THE ABNORMALLY COLD PATTERN.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
MID AND HIGH CLOUDS OVERNIGHT...BUT DEVELOPING STRATUS DECK
EXPECTED AS LIGHT SOUTH FLOW MOISTENS LOW LEVELS OF THE
ATMOSPHERE. SOUTHERLY WINDS WITH SPEEDS BELOW 10 KTS.
EXPECT WIDESPREAD MVFR CIGS BUT EXACT TIMING DIFFICULT. ALSO THE
BASE HEIGHT OF THE CIGS OVERNIGHT MAY BE A FEW HUNDRED FEET LOWER
THAN FORECAST...GOING INTO IFR FOR A BRIEF PERIOD OF TIME TOWARDS
DAYBREAK. SLOW IMPROVEMENT EXPECTED TUESDAY AS WINDS SHIFT TO THE
WEST AND INCREASE ABOVE 10 KNOTS. GUSTS EXPECTED MID TO LATE AFTERNOON.
OUTLOOK 00Z WED THROUGH SAT...
TUE NIGH THROUGH THU...VFR WITH GUSTY NW WINDS.
FRI...VFR.
SAT...VFR EXPECTED BUT NEED TO KEEP AN EYE ON POTENTIAL CSTL
STORM.
&&
.MARINE...
A SLY SWELL THIS EVENING MAY KEEP SEAS RIGHT AROUND 5 FT FOR A
SHORT TIME ON THE OCEAN ZONES...BUT THIS SHOULD NOT POSE A THREAT
TO SMALL CRAFT. THUS...HAVE DISCONTINUED THE SCA FOR SEAS ON THE
OCEAN. SEAS ARE FORECAST TO DROP 2 TO 4 FT LATER THIS EVENING.
A TIGHT PRESSURE GRADIENT IS EXPECTED TO DEVELOP TUE NIGHT INTO
WED FOLLOWING A COLD FRONTAL PASSAGE TUE MORNING. A DEEP MIXED
LAYER WITH THE COLD AIR OVER THE WARMER WATERS RAISES THE POTENTIAL
FOR A MARGINAL GALE TUE NIGHT INTO WED ACROSS THE EASTERN WATERS.
THUS...A GALE WATCH HAS BEEN HOISTED FOR THE EASTERN WATERS...WITH
A SCA FOR THE WESTERN WATERS. AT A MINIMUM...SCA CONDITIONS WILL
PERSIST INTO THU.
SCA WILL LIKELY BE NEEDED THU NIGHT INTO FRI AS A TIGHT PRES
GRADIENT REMAINS ACROSS THE AREA.
TRANQUIL FRIDAY INTO AT LEAST EARLY SATURDAY. DEPENDING ON TRACK AND
INTENSITY OF LOW PRESSURE ON SUNDAY TO THE EAST OF THE
REGION...GALES ARE POSSIBLE.
&&
.HYDROLOGY...
LITTLE TO NO PRECIP IS FORECAST THROUGH THE END OF THE WEEK.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 7 PM TUESDAY TO 6 PM EST WEDNESDAY
FOR ANZ335-338-345-355.
GALE WATCH FROM TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON
FOR ANZ330-340-350-353.
&&
$$
SYNOPSIS...DW
NEAR TERM...DW
SHORT TERM...DW
LONG TERM...JST
AVIATION...PW
MARINE...DW/JST
HYDROLOGY...DW
