Area Forecast Discussion
Issued by NWS Upton, NY

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000
FXUS61 KOKX 211525
AFDOKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
1025 AM EST SUN DEC 21 2014

.SYNOPSIS...
A WEAK UPPER LEVEL DISTURBANCE WILL CROSS THE AREA TODAY WITH A
SURFACE TROUGH REMAINING NEARBY. HIGH PRESSURE OTHERWISE REMAINS
OVER THE REGION INTO MONDAY. A WAVE OF LOW PRESSURE WEAKENS AS IT
APPROACHES MONDAY NIGHT INTO TUESDAY. A MORE SIGNIFICANT STORM
SYSTEM THEN AFFECTS THE AREA TUESDAY NIGHT THROUGH WEDNESDAY
NIGHT...WITH BREEZY CONDITIONS IN ITS WAKE ON CHRISTMAS. HIGH
PRESSURE BUILDS IN ON FRIDAY. ANOTHER LOW WILL THEN AFFECT THE
REGION NEXT WEEKEND.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
A SURFACE TROUGH OVER THE EASTERN ZONES CONTINUES TO ACT AS A
FOCUS FOR MOISTURE CONVERGENCE...AND LIFT IS PROVIDED ALOFT AS THE
SHORTWAVE PASSES THROUGH. PCPN TYPE MAINLY SNOW WITH SUFFICIENT
ICE NUCLEI LIKELY PRESENT...BUT BOUNDARY LAYER TEMPS ACROSS
EASTERN LONG ISLAND COMPLICATE THE FORECAST. PROBABLY A MIXTURE OF
LIGHT RAIN AND SNOW THERE...PROBABLY EVEN MOSTLY OR ALL RAIN OVER
THE PARTS OF THE FORKS REGION. IN SHORT...TRACE TO HALF INCH OF
SNOW CURRENTLY FORECAST OVER LONG ISLAND...WITH UP TO AROUND AN
INCH ACROSS PARTS OF SE CT. MOST OF THE REST OF THE CWA COULD GET
A FLURRY OR TWO THIS MORNING.

OTHERWISE...PLENTY OF CLOUDS HANGING TOUGH THIS MORNING ACROSS THE
REMAINDER OF THE AREA. TEMPS WILL STRUGGLE TO RISE THIS
AFTERNOON...AND MAINLY STAY IN THE 30S...EXCEPT FOR THOSE
AFOREMENTIONED EASTERN LOCALES OF THE TWIN FORKS OF LONG ISLAND.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/...
LIFT AND MID LEVEL MOISTURE EXIT EAST BY EARLY THIS EVENING...AND
THE SURFACE TROUGH IS PROGGED TO WEAKEN AS IT SHIFTS SLIGHTLY WEST.
WILL GO WITH SCT FLURRIES OVER LI AND CT...AND PCPN TYPE OF
SPRINKLES ALSO PROBABLY PRESENT EARLY IN THE EVENING FOR THE
COASTAL SECTIONS.

WEAK LOW PRESSURE FORMS ALONG A FRONTAL BOUNDARY OFF THE CAROLINA
COAST ON MONDAY AND BEGINS TO HEAD NORTH. MEANWHILE...HIGH PRESSURE
CENTERED TO THE NORTHEAST SHIFTS FARTHER EAST. THIS WILL ALLOW LOW
LEVEL WINDS HERE VEER TO THE EAST AND AID LOW LEVEL MOISTURE
ADVECTION. A SURFACE TROUGH EXTENDING NORTH FROM THE CENTER OF THE
LOW WILL SERVE AS A FOCUS FOR WEAK LIFT AND MOISTURE CONVERGENCE.
LOW CHANCES OF LIGHT RAIN RESULT...BUT RESERVED FOR THE AFTERNOON.

THE LOW CENTER WEAKENS AS IT HEADS NORTH MONDAY NIGHT.
HOWEVER...ISENTROPIC LIFT AHEAD OF THE LOW STILL STRENGTHENS...LOW
LEVEL MOISTURE STILL INCREASES ON AN ENE FLOW...AND THE SURFACE
TROUGH WILL STILL BE IN THE VICINITY. CHC POPS FOR THIS PERIOD.
THERMAL PROFILES SUPPORT RAIN FOR MOST OF THE CWA. HOWEVER...FOR
SOME NW SECTIONS...MODELS SHOWING A WARM NOSE ALOFT...ALLOWING FOR
A CHANCE OF SLEET DURING THE EVENING...THEN POSSIBLY FREEZING RAIN
AS THE WARMEST PART OF THE NOSE EXCEEDS 3C AND SURFACE TEMPS HOVER
AROUND FREEZING.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
WEAK LOW TO THE SOUTH CONTINUES TO WEAKEN ON TUESDAY...BUT THE
SURFACE TROUGH REMAINS IN THE VICINITY. ECMWF OVER THE PAST FEW RUNS
HAS BEEN CONSISTENTLY WETTER FOR TUESDAY...WITH THE GFS CONSISTENTLY
DRIER...AND THE NAM SOMEWHERE IN BETWEEN DEPENDING ON LOCATION. WILL
CAP POPS AT 50% AS PER PREVIOUS FORECAST GIVEN THE UNCERTAINTY.
FREEZING RAIN STILL POSSIBLE EARLY ON IN THE MORNING FOR THE FAR NW
PORTION OF THE CWA...OTHERWISE...LIGHT RAIN. RAIN THEN BECOMES MORE
LIKELY TUESDAY NIGHT.

A STRONGER STORM SYSTEM THEN AFFECTS US CHRISTMAS EVE AND DAY.
MODELS SHOW A STRONG PRIMARY LOW CENTER MOVING THROUGH THE GREAT
LAKES REGION ON WEDNESDAY BEFORE MOVING INTO ONTARIO ON THURSDAY. A
WEAKER SECONDARY LOW PRESSURE CENTER OR TRIPLE POINT LOW FORMS IN
THE MID ATLANTIC REGION BEFORE PASSING NORTH OF US WEDNESDAY NIGHT.
THIS WILL DRAG A COLD FRONT ACROSS THE AREA DURING THE NIGHT.
CATEGORICAL POPS FOR WEDS/WEDS EVENING BEFORE THE COLD FRONT MOVES
THROUGH. MODELS HAVE TRENDED SLOWER WITH THE PASSAGE OF THE
FRONT...SO BY CHRISTMAS MORNING...SHOWERS STILL LIKELY EARLY ON FOR
THE EASTERN FRINGE OF THE CWA...WITH MAINLY LOW CHANCES OF SHOWERS
ELSEWHERE. BY NOON...LIKELY DRY EVERYWHERE.

BREEZY CONDITIONS FOR WEDS THRU THURS. A STRONG LOW LEVEL JET PUSHES
THROUGH THE EASTERN ZONES WEDS AFTN/EVE...BUT STRONG GUSTS WILL
PROBABLY HAVE A TOUGH TIME MIXING DOWN THROUGH AN INVERSION.
STRONGER GUSTS MAY BE REALIZED DURING THURSDAY BEHIND THE COLD FRONT
COURTESY OF BETTER MIXING. LOOKS LIKE WE FALL SHORT OF WIND ADVISORY
CRITERIA HOWEVER. WILL NEED TO KEEP AND EYE ON THIS TO SEE IF THE
WEAKENING TREND CONTINUES. TEMPS DURING THIS PERIOD WILL BE ABOVE
AVERAGE. HIGHS ON WEDS IN WELL INTO THE 50S...AND WITH A MODERATE
WSW FLOW AND PARTIAL SUNSHINE ON THURSDAY...HIGH TEMPS IN THE UPPER
40S TO LOWER 50S EXPECTED.

HIGH PRESSURE BUILDS IN FOR FRIDAY WITH LIGHTER WINDS COOLER
TEMPS...BUT STILL ABOVE NORMALS. THEN FOR NEXT WEEKEND...ANOTHER
INLAND LOW PRESSURE SYSTEM COULD IMPACT THE AREA.

&&

.AVIATION /15Z SUNDAY THROUGH THURSDAY/...
BRIEF IFR VSBYS IN -SN ACROSS EASTERN TERMINALS THIS MORNING.
OTHERWISE...MVFR CIGS WILL LIFT TO VFR LATE THIS MORNING OR EARLY
THIS AFTERNOON. FOR EASTERN TERMINALS...MVFR CIGS MAY LINGER
THROUGH THE AFTERNOON.

THERE IS SOME UNCERTAINTY WITH CIGS BECOMING VFR WITH SOME
GUIDANCE SUPPORTING MVFR CONDITIONS REMAINING THROUGH THIS AFT.
WILL HAVE TO CLOSELY MONITOR OBS AND SATELLITE IMAGERY FOR TRENDS.

MVFR CIGS RETURN TO THE TERMINALS AFTER 00Z MONDAY.

NW-N AT 5-8 KT. WINDS WILL BECOME LGT/VRB AGAIN TONIGHT.

.OUTLOOK FOR 12Z MONDAY THROUGH THURSDAY...
.MONDAY-MONDAY NIGHT...MVFR OR LOWER POSSIBLE IN E FLOW. RAIN
DEVELOPING IN THE AFTERNOON AND AT NIGHT.
.TUESDAY-TUESDAY NIGHT...IFR CIGS/VSBYS LIKELY IN RAIN. E WINDS
10-20 KT...BECOMING SE.
.WEDNESDAY...HIGH IMPACT EVENT BECOMING LIKELY. IFR CONDS WITH
HEAVY RAIN AND SE WINDS 15-20 KT WITH 20-25 KT GUSTS. WINDS SHIFT
TO THE SW LATE WEDNESDAY NIGHT.
.THURSDAY...SUB-VFR CONDS IN THE MORNING IN RAIN SHOWERS. VFR
CONDS BY AFTERNOON. WEST WINDS 15-20 KT WITH 25-35 KT GUSTS.

&&

.MARINE...
HIGH PRES BUILDS NORTH OF THE WATERS. NORTH WINDS 10 KT OR LESS
ALONG WITH SEAS GENERALLY 1-2 FT ON THE OCEAN OR 1 FT OR LESS ON ALL
OTHER WATERS THIS AFTERNOON AND TONIGHT.

A LIGHT EAST TO SOUTHEAST FLOW MONDAY INTO TUESDAY AHEAD OF A WARM
FRONT WILL REMAIN BELOW SMALL CRAFT LEVELS...WITH SEAS ALSO
REMAINING BELOW 5 FT. DEEPENING LOW PRESSURE MOVING THROUGH THE
WESTERN GREAT LAKES WEDNESDAY WITH A COLD FRONT APPROACHING THE AREA
WATERS WILL RESULT IN AN INCREASING SOUTHERLY FLOW. SMALL CRAFT WIND
AND SEAS WILL BE POSSIBLE ON THE OCEAN LATE TUESDAY INTO TUESDAY
NIGHT...AND ACROSS ALL THE WATERS WEDNESDAY. THEN IN THE COLDER AIR
BEHIND THE COLD FRONT THURSDAY WIND GUSTS WILL BE GALE FORCE ACROSS
ALL THE WATERS AND REMAIN INTO THURSDAY NIGHT WITH GUSTS DIMINISHING
TOWARD FRIDAY MORNING...WITH GUSTS BELOW SMALL CRAFT LATER WEDNESDAY
MORNING. SEAS ON THE OCEAN WATERS WILL REMAIN AT SMALL CRAFT LEVELS
THROUGH FRIDAY.

&&

.HYDROLOGY...
RAINFALL FROM MONDAY AFTERNOON THROUGH WEDNESDAY NIGHT COULD TOTAL 1
TO 2 INCHES WITH LOCALLY HIGHER AMOUNTS. MUCH OF THE RAINFALL IS
EXPECTED TO OCCUR WEDNESDAY INTO WEDNESDAY NIGHT. MINOR URBAN AND
POOR DRAINAGE FLOODING IS POSSIBLE.

&&

.OKX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
NY...NONE.
NJ...NONE.
MARINE...NONE.

&&

$$

SYNOPSIS...JC
NEAR TERM...JC/PW
SHORT TERM...JC
LONG TERM...JC/DW
AVIATION...MPS/DW
MARINE...MPS/PW
HYDROLOGY...JC






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