HAMweather.com Area Forecast Discussion for County Warning Area OKX

Thu, 16 Feb 2012 08:37:14 GMT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NEW YORK NY
1233 AM EST THU FEB 16 2012

.SYNOPSIS...
HIGH PRESSURE REMAINS OVER THE REGION DURING THE OVERNIGHT BEFORE
MOVING OFFSHORE ON THURSDAY. A FRONTAL SYSTEM APPROACHES FROM THE
WEST WITH AN OCCLUDED FRONT MOVING THROUGH LATE THURSDAY NIGHT
INTO FRIDAY MORNING. HIGH PRESSURE BUILDS IN FROM THE WEST FRIDAY
AND SATURDAY. LOW PRESSURE PASSES TO OUR SOUTH SUNDAY...GIVING WAY
TO ANOTHER AREA OF HIGH PRESSURE EARLY NEXT WEEK. LOW PRESSURE
APPROACHES TOWARD MID WEEK.

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
HAVE UPDATED HOURLY TEMPERATURES...DEW POINTS...AND SKY GRIDS
OVERNIGHT. CLEAR SKIES OVER THE NEXT FEW HOURS...COMBINED WITH
LIGHT TO CALM WINDS WILL ALLOW FOR GOOD RADIATIONAL COOLING. HAVE
LOWERED LOW TEMPERATURE FORECAST IN MANY SPOTS TO ACCOUNT FOR
THIS. HIGH TO MID CLOUDS SHOULD FILTER IN LATE...SLOWING DOWN
RADIATIONAL COOLING FOR AT LEAST THE WESTERN ZONES.

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/...
ON THURSDAY...THE HIGH PRESSURE RIDGE SHIFTS OFFSHORE. INITIALLY 
LIGHT WINDS WILL TURN MORE SOUTHERLY BY AFTERNOON. CLOUDS CONTINUE 
TO INCREASE FROM WEST TO EAST WITH THE APPROACH OF A FRONTAL SYSTEM 
APPROACHING FROM THE WEST. UPPER LEVEL SUPPORT SEEMS TO BE LIMITED 
WITH THIS SYSTEM WITH A SLIGHT UNDULATION OF GEOPOTENTIAL HEIGHT AT 
500 MB...AND THEREBY A SMALLER AMPLITUDE SHORTWAVE. POSITIVE 
VORTICITY ADVECTION AHEAD OF THIS SHORTWAVE AND INCREASING 
ISENTROPIC LIFT WILL LEAD TO AN INCREASED CHANCE FOR RAIN FOR 
WESTERN AREAS LATE MORNING TO EARLY AFTERNOON. THE CHANCE INCREASES 
AND SPREADS TO THE REST OF THE FORECAST REGION FROM WEST TO EAST 
LATER INTO THE AFTERNOON AND EARLY EVENING. WITH HIGHS TOOK LOWER
OR JUST BELOW GUIDANCE WITH EXPECTED INCREASE IN CLOUDS AND
POPS...GENERALLY RANGING FROM LOWER TO UPPER 40S.

MUCH OF THE UPPER LEVEL SUPPORT IS SHOWN TO EXIT TO THE EAST OF THE 
FORECAST REGION DURING THE EVENING AND WITH MODEL PRECIP...THE QPF 
FIELDS BECOME SPATIALLY DISCONTINUOUS BETWEEN 00Z AND 
06Z...ESPECIALLY WITH THE GFS AND ECMWF 12Z RUNS. EXPECTING THE 
PRECIP MAY BE MORE PERIODIC DURING THIS TIMEFRAME. STILL HAVE HIGH 
CHANCE TO LIKELY POPS THOUGH AS ONE SUPPORTING UPPER LEVEL FACTOR IS 
THE AREA BEING UNDER THE LEFT EXIT REGION OF THE UPPER LEVEL JET. 
PRECIP TYPE IS MOSTLY RAIN OUTSIDE OF THE INTERIOR PORTIONS OF THE 
LOWER HUDSON VALLEY...NORTHEAST NEW JERSEY AND SOUTHWEST CONNECTICUT 
ESPECIALLY ON THE HIGHER ELEVATIONS WHERE SNOW OR A MIX OF RAIN AND 
SNOW IS FORECAST. THE SNOW WOULD BE SEEM A LITTLE MORE LIKELY WITH 
COLD AIR ADVECTION RIGHT BEHIND THE OCCLUDED FRONT. HOWEVER...BY 
THAT TIME...DRIER AIR IS WORKING ITS WAY INTO THE MID LEVELS. 
THEREFORE...THERE WOULD BE LESS ICE NUCLEATION OCCURRING AND ANY 
SNOW AMOUNTS ARE JUST A TENTH OF AN INCH OR LESS IN THE 
AFOREMENTIONED AREAS.

PRECIPITATION WILL BE ON A DOWNWARD TREND GOING INTO FRIDAY MORNING 
AS THE OCCLUDED FRONT MOVES TO THE EAST OF THE REGION AND 
ACCELERATES AS MORE OF A LONGWAVE TROUGH PUSHES SOUTHEASTWARD INTO 
THE GREAT LAKES.

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
FAMILIAR PATTERN THROUGH THIS TIME FRAME...WITH WESTERLY MID/UPPER 
LEVEL FLOW PREVAILING KEEPING COLD AIR TO THE NORTH. QUESTIONS
ARISE ON PHASING BETWEEN THE NORTHERN AND SRN BRANCHES THIS WEEKEND. 
THE DEGREE OF PHASING WILL OBVIOUSLY PLAY A MAJOR ROLE IN ACTUAL 
FORECAST FOR OUR AREA...PARTICULARLY THE SECOND HALF OF THIS WEEKEND.

ON FRIDAY...INITIAL SHORTWAVE PIVOTS TO THE NORTHEAST...WITH ANOTHER 
SHORTWAVE ROUNDING THE MAIN TROUGH EXTENDING SOUTHWARD FROM HUDSON 
BAY. AS THIS HAPPENS FRIDAY INTO THE EARLY PORTION OF THE 
WEEKEND...SOUTHWESTERN TROUGH/CLOSED LOW EJECTS TO THE EAST AND 
WEAKENS AS IT MOVES ACROSS THE GULF STATES. GFS DOES PHASE THE 
SOUTHERN AND NORTHERN BRANCHES...WITH THE RESULT A POTENT COASTAL 
STORM PASSING INSIDE THE BENCHMARK. THE OPERATIONAL RUN DOES HAVE 
SOME SUPPORT FROM OTHER ENSEMBLE MEMBERS.

PROJECTING NAM OUT BEYOND 84 HOURS...ONE WOULD NOT EXPECT PHASING TO 
OCCUR AS NORTHERN TROUGH MOVES ACROSS THE NORTHEAST QUICKLY BY 00Z 
SUNDAY...AND SRN TROUGH/SFC LOW LAGS WAY BACK TO THE SOUTH.

AS FOR ECMWF...LACK OF PHASING ALSO RESULTS IN A TRACK TOO FAR SOUTH 
TO HAVE A MAJOR IMPACT ON THE AREA...AT LEAST REGARDING 
PRECIPITATION.

WILL CONTINUE WITH CHC POPS BEGINNING SATURDAY NIGHT THROUGH 
SUNDAY...AND TRENDS WILL NEED TO BE WATCHED. IF OP GFS IS CLOSE TO 
BEING CORRECT...WINTRY MIX TO RAIN NEAR THE COAST...WITH LONGER 
PERIOD OF WINTRY WEATHER INTERIOR ZONES. LACK OF COLD AIR/HIGH 
PRESSURE PLACEMENT AHEAD OF THIS SYSTEM LEADS ME TO BELIEVE MORE 
LIQUID THAN FROZEN FOR THE CWA...BUT STAY TUNED.

ONCE THIS SYSTEM PASSES TO THE EAST BY MONDAY...BRIEF DRY PERIOD 
EXPECTED AS SFC HIGH PRESSURE BUILDS...THEN MOVES OFFSHORE. WARM AIR 
ADVECTION REGIME BEGINS IN THIS PROGRESSIVE PATTERN...WITH A RETURN 
TO CLOUDS AND POSSIBLE WAA PRECIP BEGINNING TUESDAY OR WEDNESDAY. 
REGARDING GFS...OBVIOUSLY THE STRENGTH OF THE SUNDAY SYSTEM BLOCKS 
THE PROGRESSION OF THE NEXT SYSTEM UPSTREAM...RESULTING IN A DELAY 
IN PRECIP CHANCES.

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
HIGH PRES WILL MOVE OHD OVERNIGHT THEN SLIDE OFFSHORE ON THU.
MEANWHILE...LOW PRES WILL MOVE ACROSS THE GREAT LAKES WITH A FRONTAL 
SYSTEM AND ASSOCIATED PRECIP APPROACHING FROM THE WEST.

VFR THROUGH AT LEAST 18Z FRI WITH MODERATE TO HIGH CONFIDENCE IN 
FORECAST. MID AND HIGH CLOUDS WILL MOVE IN FROM THE WEST THROUGH THE 
MORNING HOURS. LIGHT NLY WINDS WILL GRADUALLY VEER...EVENTUALLY 
BECOMING SLY BY LATE THU MORNING/EARLY AFTN. PRECIP EXPECTED TO MOVE 
IN WESTERN TERMINALS BETWEEN 17Z AND 20Z...EASTERN TERMINALS 19Z TO 
23Z.

BOUNDARY LAYER TEMPS ARE WARM ENOUGH FOR LIQUID PRECIP THROUGH
00Z. CONDS WILL DETERIORATE AND MVFR IS POSSIBLE BETWEEN 21Z AND 
00Z...HOWEVER MORE LIKELY AFTER 00Z FRI. IFR MAY ALSO DEVELOP AFT 
00Z...BUT HAVE LOW CONFIDENCE ATTM.

30-HOUR TAF SITES...MAY BE TOO OPTIMISTIC/EARLY IMPROVING CONDS BACK 
TO VFR AT 09Z.

OUTLOOK FOR 06Z THURSDAY THROUGH MONDAY...

THU NIGHT...MVFR TO POSSIBLY IFR CONDS LIKELY IN RAIN. A MIX OR 
CHANGEOVER TO -SN IS POSSIBLE AT KSWF BEFORE ENDING LATE.

FRI...BECOMING VFR. NW WINDS CLOSE TO 310 MAGNETIC AND G20-25 KT IN 
THE AFTERNOON.

SAT...HIGH CONFIDENCE VFR DURING THE DAY.

SUNDAY...MEDIUM CONFIDENCE VFR...WITH POSSIBLE SUB-VFR WITH ANY
PRECIP.

.MARINE...
FORECAST ON TRACK. LIGHT WINDS WITH SEAS REMAINING BELOW SCA WITH
HIGH PRESSURE MOVING ACROSS TONIGHT AND THEN OFFSHORE ON THURSDAY.
WEAK MAGNITUDE OF FRONTAL SYSTEM MOVING ACROSS THURSDAY NIGHT WITH
GUSTS ONLY EXPECTED TO 20 KT. THEREFORE...NO SCA CONDITIONS
EXPECTED TONIGHT THROUGH THURSDAY NIGHT.

AS THE COLD FRONT PASSES TO THE EAST FRIDAY MORNING...GUSTY 
NORTHWEST FLOW PREVAILS OVER THE WATERS...WITH SCA CONDITIONS 
POSSIBLE...ESPECIALLY BY AFTERNOON AND INTO FRIDAY NIGHT. HIGH 
PRESSURE BUILDS SATURDAY...THEN QUESTIONS ARISE WITH SPEED OF NEXT 
FRONT...THEN POSSIBLE COASTAL STORM LATER SATURDAY THROUGH SUNDAY. 
MARINERS WILL NEED TO MONITOR POSSIBLE COASTAL LOW PRESSURE IMPACTS 
TO THE AREA WATERS SUNDAY. GALES REMAIN A POSSIBILITY SUNDAY AND 
SUNDAY NIGHT...DEPENDING ON THE EXACT TRACK AND STRENGTH OF THE LOW.

GUSTY NW FLOW IN THE WAKE OF THE SYSTEM EXPECTED MONDAY.

AS FOR SEAS...WILL FOLLOW WAVE WATCH III OUTPUT THROUGH SATURDAY. 
THEREAFTER...WILL BLEND WAVE WATCH WITH OFFICIAL FORECASTS TO TREND 
LOWER WITH SEA FORECASTS GIVEN MODEL DISPARITIES WITH HANDLING OF COASTAL 
STORM.

.HYDROLOGY...
TOTAL PRECIPITATION AMOUNTS ARE EXPECTED TO BE GENERALLY UNDER A
QUARTER OF AN INCH THURSDAY NIGHT.

PRECIPITATION IS POSSIBLE SATURDAY NIGHT AND SUNDAY...HOWEVER...CONFIDENCE
OF SIGNIFICANT PRECIPITATION REMAINS LOW.

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