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Area Forecast Discussion
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000
FXUS61 KOKX 170551
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
1251 AM EST WED DEC 17 2014

.SYNOPSIS...
LOW PRESSURE SKIRTS JUST SOUTHEAST OF THE REGION TONIGHT AND MOVES
TO THE EAST WEDNESDAY AND WEDNESDAY NIGHT. THE REGION REMAINS IN
BETWEEN CANADIAN HIGH PRESSURE TO OUR WEST AND A MEANDERING LOW
OVER THE CANADIAN MARITIMES THURSDAY AND THURSDAY NIGHT. THE HIGH
THEN BUILDS OVER THE AREA THROUGH SATURDAY...THEN SLOWLY RETREATS
TO THE NORTHEAST INTO EARLY NEXT WEEK. MEANWHILE...LOW PRESSURE
DEVELOPS ALONG THE GULF COAST LATE THIS WEEK...TRACKS TO OFF THE
CAROLINA COAST BY SUNDAY MORNING...AND TO SOUTH OF NOVA SCOTIA BY
MONDAY MORNING. HIGH PRESSURE THEN BUILDS DOWN FROM SOUTHEASTERN
CANADA INTO TUESDAY.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
A PRIMARY LOW PRESSURE CENTER MOVES THROUGH SOUTHERN ONTARIO
TONIGHT...WHILE SECONDARY LOW PRESSURE SKIRTS SE PORTIONS OF THE
REGION OVERNIGHT.

MAIN AXIS OF RAIN WILL CONTINUE TO PUSH EAST WITH SCATTERED
SHOWERS LINGERING IN IT/S WAKE AS TRAILING SHORTWAVE ENERGY PASSES
THROUGH.

TEMPERATURES WILL REMAIN FAIRLY STEADY BEFORE DROPPING TOWARDS
DAYBREAK IN WAKE OF LOW PRESSURE.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM THURSDAY/...
A LINGERING SHOWER POSSIBLE OVER THE FAR EASTERN PORTION OF THE CWA 
EARLY ON WEDNESDAY MORNING...OTHERWISE THE MORNING WILL BE DRY. A 
SHORTWAVE APPROACHES FROM THE WEST DURING THE AFTERNOON WITH ENOUGH 
MOISTURE FOR A SLIGHT CHANCE OF A SHOWER NORTH OF THE CITY. STRONGER 
COLD AIR ADVECTION WILL BE DELAYED ENOUGH...COMBINED WITH A MODERATE 
WEST DOWNSLOPING WIND...TO ALLOW TEMPERATURES TO RISE TO AROUND 50 
ON AVERAGE.

SLIGHT CHANCE POPS DURING THE EVENING HOURS ACROSS THE REGION AS THE 
SHORTWAVE PASSES THROUGH. PRECIPITATION TYPE EXPECTED TO BE
RAIN...EXCEPT MIXED RAIN AND SNOW WELL INLAND. AFTER
MIDNIGHT...ANOTHER SHORTWAVE APPROACHES FROM THE WEST...BUT
PROBABLY WITH LESS MOISTURE TO WORK WITH. HAVE GONE WITH A
SPRINKLE OR FLURRY POSSIBLE OVER EASTERN ZONES FOR THIS TIME
FRAME...RELATED TO THE POSITIVE VORTICITY ADVECTION AND AVAILABLE
MOISTURE ASSOCIATED WITH THE FIRST SHORTWAVE.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
SOUTHERN STREAM SHORTWAVE RIDGE TRIES TO UNDERCUT CUTOFF LOW NEAR 
NOVA SCOTIA ON THURSDAY. RESULT WILL BE NON-UNIDIRECTIONAL LOW
LEVEL FLOW - SO THAT...COUPLED WITH POSSIBLE SUBSIDENCE FROM THE
RIDGE...DEPENDING ON HOW FAR N IT GETS...SHOULD PRECLUDE ANY
WIDESPREAD FLURRIES ON THURSDAY. HAVE REMOVED FROM FORECAST AS A
RESULT...HOWEVER ISOLATED FLURRIES EARLY THURSDAY OVER FAR E ZONES
AND DURING THE DAY OVER HIGHER ELEVATIONS IN FAR N/W PORTIONS OF
THE LOWER HUDSON VALLEY CANNOT BE COMPLETELY RULED OUT. HOWEVER
CONFIDENCE IN OCCURRENCE IS TOO LOW TO REFLECT IN THE OFFICIAL
FORECAST. APPEARS SHOULD HAVE SOME LOW LEVEL MOISTURE TRAPPED
UNDER A DEVELOPING INVERSION WITH A BASE AROUND 925 HPA SO WOULD
EXPECT PARTLY SUNNY SKY CONDITIONS. FAIRLY TIGHT PRESSURE GRADIENT
OVER THE REGION...SO SHOULD BE BREEZY TO WINDY AS WELL.

FOR HIGHS THURSDAY A BLEND OF MAV/MET/ECS GUIDANCE WITH NAM 2-METER 
TEMPERATURES AND A MIX DOWN FROM 925 HPA PER BUFKIT SOUNDINGS WAS 
USED. THIS SHOULD YIELD NEAR NORMAL TEMPERATURES.

A WEAK 500-700 HPA SHORTWAVE CROSSES THE AREA THURSDAY NIGHT IN THE 
WAKE OF THE AFOREMENTIONED SHORTWAVE RIDGE. FOR NOW APPEARS FORCING 
WILL BE TOO WEAK TO PRODUCE ANY PRECIPITATION...SO KEPT THE FORECAST 
DRY. FOR LOWS THURSDAY NIGHT A BLEND OF MAV/MET/ECS GUIDANCE WITH 
NAM 2-METER TEMPERATURES WAS USED...WITH VALUES FORECAST TO BE NEAR 
TO SLIGHTLY ABOVE NORMAL.

A NORTHERN STREAM RIDGE BUILDS IN OVER SW QUEBEC FRIDAY...AND TRACKS 
EAST FRIDAY NIGHT...WITH ASSOCIATED SUBSIDENCE KEEPING THINGS DRY. 
FOR HIGHS FRIDAY USED A BLEND OF MEX/MEN/EKD/ECE/ECM GUIDANCE WITH 
NAM 2-METER TEMPERATURES AND A MIX DOWN FROM 925 HPA PER BUFKIT 
SOUNDINGS. VALUES SHOULD BE A FEW DEGREES BELOW NORMAL. FOR LOWS 
FRIDAY NIGHT A BLEND OF MEX/MEN/EKD/ECE/ECM/WPC GUIDANCE WAS 
USED...WITH READINGS FORECAST TO BE SLIGHTLY BELOW NORMAL.

DEVELOPING DEEP LAYERED RIDGE AXIS SLIDES TO THE EAST 
SATURDAY...POSSIBLY ALLOWING FOR SOME LIGHT RAIN TO REACH FAR SW 
ZONES BY LATE AFTERNOON IN RESPONSE TO LOW LEVEL WARM ADVECTION.

MODELS CONTINUE TO DISPLAY DIFFERENCES WITH RESPECT TO THE TIMING 
AND STRENGTH OF A COASTAL LOW FORECAST TO IMPACT THE AREA FROM LATE 
SATURDAY...POSSIBLY INTO MONDAY. 12Z CMC IS NOW MOST PROGRESSIVE 
WITH THE SYSTEM...WITH 12Z ECMWF NOT TOO FAR BEHIND. GFS AND GEFS
AS WELL AS ECMWF ENSEMBLE MEANS ARGUE FOR A SOMEWHAT SLOWER
SOLUTION...SO LEANED TOWARDS GEFS MEAN TIMING WITH THE SYSTEM.
MODELS GENERALLY AGREE ON A TRACK TO THE SE OF THE 40N/70W
BENCHMARK - SO USED A BLEND FOR TRACK. THE CMC IS THE FASTEST TO
DEEPEN THE LOW...WHILE MOST OTHER GUIDANCE SUGGESTS THE LOW DOES
NOT DEEPEN UNTIL IT IS SE TO E OF THE AREA. LEANED TOWARDS SLOWER
DEVELOPING ECMWF/GFS AND THEIR ENSEMBLE MEANS FOR SYSTEM STRENGTH.

BASED ON THE ABOVE...APPEARS MOST PRECIPITATION FROM THIS SYSTEM 
WILL BE DUE TO SUPPORTING 850-500 HPA TROUGH TRACKING FROM THE 
WESTERN GREAT LAKES SATURDAY EVENING...TO SOME PLACE AROUND NOVA 
SCOTIA BY LATE MONDAY...AND LOW LEVEL WARM ADVECTION AHEAD OF THE 
TROUGH. AS A RESULT EXPECT PRECIPITATION TO BE RELATIVELY LIGHT. 
GIVEN UNCERTAINTY HAVE CAPPED POPS AT 50 PERCENT FOR NOW. STILL 
CANNOT RULE OUT THE AREA ULTIMATELY BEING IN BETWEEN THE UPPER 
SYSTEM LIFTING TO THE NE AND THE COASTAL LOW TO THE SE...WITH LITTLE 
OR NO PRECIPITATION...OR BETTER PHASING BETWEEN THE N AND S 
STREAMS...WITH COASTAL REDEVELOPMENT TO THE S...RESULTING IN MORE 
PRECIPITATION...AND MORE LIKELY MORE SNOW.

TRACK OF THE LOW WOULD SUGGEST MAINLY SNOW...BUT TRACK OF THE 
850-700 HPA TROUGH WOULD SUGGEST SOME WARMING OF THE LOW-MID 
LEVELS...MAKING P-TYPE POTENTIALLY MORE PROBLEMATIC. FOR NOW...WENT 
WITH A BLEND OF ECMWF AND GFS THERMAL PROFILES...WEIGHED TOWARDS 
COLDER ECMWF...AS GFS SEEMS WARMER THAN MOST IN THE LOW LEVELS...AND 
LIMITED P-TYPE POSSIBILITIES TO SNOW...SNOW/RAIN...OR RAIN FOR 
SIMPLICITY THIS FAR OUT.

BASED ON THIS...EXPECT MAINLY SNOW ACROSS THE INTERIOR AND A 
SNOW-RAIN MIX ELSEWHERE SATURDAY NIGHT...TRANSITIONING TO MAINLY 
RAIN DURING THE DAY ON SUNDAY. PRECIPITATION SHOULD CHANGE BACK TO 
MAINLY SNOW ACROSS THE INTERIOR AND A RAIN-SNOW MIX ELSEWHERE SUNDAY 
NIGHT...BEFORE TAPERING OFF LATE SUNDAY NIGHT W/EARLY MONDAY MORNING 
E AS THE LOW EXITS TO THE NE.

ONCE AGAIN...AT THIS TIME IT APPEARS PRECIPITATION SHOULD BE 
LIGHT...SO NO SIGNIFICANT IMPACT IS CURRENTLY EXPECTED...BUT AS 
NOTED ABOVE CANNOT BE COMPLETELY RULED OUT.

FOR NOW KEPT THINGS DRY INTO TUESDAY AS DEEP LAYERED RIDGING BUILDS 
IN. HOWEVER THERE ARE SOME INDICATIONS THAT SOME OVER RUNNING 
PRECIPITATION COULD ENCROACH ON SW ZONES BY LATE TUESDAY...BUT 
CONFIDENCE IN THIS IS NOT HIGH ENOUGH TO PUT IN THE FORECAST QUITE 
YET.

FOR TEMPERATURES SATURDAY-TUESDAY USED A BLEND OF
MEX/MEN/EKD/ECE/ECM/WPC GUIDANCE...WITH ECMWF 2-METER TEMPERATURES
BLENDED IN SATURDAY NIGHT-SUNDAY NIGHT. BELOW NORMAL TEMPERATURES
ARE FORECAST SATURDAY...WITH NEAR TO SLIGHTLY ABOVE NORMAL
TEMPERATURES SATURDAY NIGHT-TUESDAY. THIS IS SUBJECT TO CHANGE
BASED ON EVENTUAL TRACK AND STRENGTH OF COASTAL LOW THIS
WEEKEND...WITH EXPECTATION THAT TEMPERATURES MOST LIKELY WOULD
TREND LOWER AND NOT WARMER IF CHANGES ARE MADE.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
A FRONTAL SYSTEM WILL MOVE ACROSS THE AREA TONIGHT.

MAINLY IFR FOR THE REST OF THE NIGHT WITH -RA AND BR. ISOLATED
AREAS COULD VARY BY A CATEGORY. SLOW IMPROVEMENT FOLLOWING THE
FRONTAL PASSAGE AFTER 09Z.

MAINLY VFR EXPECTED TODAY WITH CIGS AROUND 3500 FT.

WINDS VARIABLE AND LESS THAN 10 KT BUT GENERALLY NE-NW INTO THIS
MORNING. A GUSTY WEST FLOW DEVELOPS BY LATE THIS MORNING...WITH
G20-25KT BY AFTN LASTING THRU THE OVERNIGHT.

.OUTLOOK FOR 06Z THU THROUGH SAT...
.WED NIGHT...VFR. W 10-15KT. GUSTS 20-25KT.
.THU...VFR. NW 10-15KT. GUSTS 20-25KT.
.FRI-SAT...VFR.
.SUN...SUB-VFR IN RAIN AND/OR SNOW.

&&

.MARINE...
A RELATIVELY WEAK LOW PRESSURE CENTER PASSES THROUGH THE AREA
WATERS OVERNIGHT. VARIABLE WINDS SHIFT TO THE WEST LATE AND
BECOME GUSTY. SCA CONDITIONS ON THE OCEAN WATERS STARTING DURING
THE MORNING...AND ON THE OTHER WATERS BY MID-AFTERNOON. SCA
CONDITIONS THEN CONTINUE THROUGH THURSDAY WITH PERHAPS A GUST OR
TWO UP TO GALE FORCE OVER THE OCEAN WATERS FOR COUPLE OF HOURS
THURSDAY MORNING.

WINDS WILL GUST TO SCA LEVELS ON ALL WATERS THURSDAY AND ON
LIKELY ON THE COASTAL OCEAN AND EASTERN WATERS THURSDAY
NIGHT...AND POSSIBLY ON THE REMAINDER OF THE WATERS AS WELL.
OCCASIONAL GUSTS TO GALE FORCE ARE PROBABLE ON THE COASTAL OCEAN
WATERS THURSDAY AS WELL.

CONDITIONS SHOULD SUBSIDE BELOW SCA LEVELS ON ALL WATERS BY LATE 
FRIDAY...WITH SUB-SMALL CRAFT CONDITIONS EXPECTED FROM LATE FRIDAY 
INTO SUNDAY FOR NOW. HOWEVER...WILL HAVE TO MONITOR A COASTAL LOW 
FORECAST FOR NOW TO TRACK WELL TO THE SE THIS WEEKEND. STILL QUITE A 
BIT UNCERTAINTY ON EXACT TRACK...STRENGTH...AND TIMING...SO ABOVE 
NORMAL POTENTIAL FOR THE FORECAST TO CHANGE.

&&

.HYDROLOGY...
LITTLE ADDITIONAL QPF IS EXPECTED LATE TONIGHT. NO HYDROLOGIC
ISSUES ARE ANTICIPATED.

NO SIGNIFICANT PRECIPITATION - WIDESPREAD 1/2 INCH OR GREATER QPF
- IS EXPECTED FROM AROUND MIDDAY WEDNESDAY INTO EARLY NEXT WEEK AT
THIS TIME. IT SHOULD BE DRY FROM THURSDAY THROUGH AT LEAST
SATURDAY MORNING IN THIS TIME FRAME.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO 6 PM EST 
     THURSDAY FOR ANZ330-335-338-340-345.
     SMALL CRAFT ADVISORY FROM 6 AM THIS MORNING TO 6 PM EST 
     THURSDAY FOR ANZ350-353-355.

&&

$$
SYNOPSIS...JC/MALOIT
NEAR TERM...JC/NV/PW
SHORT TERM...JC
LONG TERM...MALOIT
AVIATION...JMC/JM
MARINE...JC/MALOIT/PW
HYDROLOGY...JC/MALOIT









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