HAMweather.com Area Forecast Discussion for County Warning Area BOX

Thu, 16 Feb 2012 06:21:17 GMT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
1246 AM EST THU FEB 16 2012

.SYNOPSIS...
HIGH PRESSURE WILL BUILD OVER NEW ENGLAND TONIGHT AND MOVE
OFFSHORE THURSDAY. A PAIR OF LOW PRESSURE AREAS...ONE IN THE ST
LAWRENCE VALLEY AND ONE OFFSHORE...WILL PASS NEW ENGLAND THURSDAY
NIGHT AND FRIDAY. SLIGHT CHANCE OF PRECIPITATION WILL MOVE THROUGH
ON SUNDAY. TEMPERATURES AT OR SLIGHTLY ABOVE NORMAL APPEAR LIKELY
THIS WEEKEND...FOLLOWED BY A POTENTIAL MODERATING TREND NEXT WEEK.

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
1245 AM UPDATE...MADE MINOR CHANGES TO THE TEMPERATURES AND
DEWPOINTS. SHOWERS HAVE MOVED OUT OF THE AREA NOW AND THE DRIER
AIR IS STARTING TO MOVE IN...CLEARING SKIES.

PREV DISCUSSION... 
HIGH PRESSURE BUILDS OVER NEW ENGLAND WITH DRIER AIR WORKING IN.
MOISTURE CROSS SECTIONS SHOW DRYING ALOFT...MAINLY AFTER MIDNIGHT.
MEANWHILE HIGH LEVEL MOISTURE INCREASES TOWARD MORNING SUGGESTING
INCREASING CIRRUS. FOR MIN TEMPS WE USED A BLEND OF MAV AND MET
BIAS CORRECTED VALUES.

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM FRIDAY/...
LOW LEVEL MOISTURE DIMINISHES WHILE HIGH LEVEL MOISTURE INCREASES.
SO THE DAY MAY START WITH A MIX OF CLOUDS AND SUN...GIVING WAY TO
THICKENING CLOUDS. GOOD CONSENSUS AMONG THE OPERATIONAL MODELS
THAT MEASURABLE PCPN REACHES THE HUDSON VALLEY AROUND 18Z AND
EASTERN MASS TOWARD 00Z. WE USED THIS CONSENSUS FOR TIMING
THE POPS...AND BASED ON THE SREF WE MAINTAINED THE CATEGORICAL
POPS FOR THURSDAY NIGHT FROM THE PREVIOUS FORECAST.  

THE 950 MB AND 925 MB ZERO ISOTHERMS MOVE NORTH OF OUR AREA
THURSDAY EVENING. BUT 1000-850 MB THICKNESS VALUES ARE MARGINAL IN
THE BERKSHIRES AND MONADNOCKS...SO THESE AREAS COULD SEE EITHER
SNOW OR A RAIN/SNOW MIX. ANY SNOW ACCUMULATION SHOULD REMAIN BELOW
AN INCH.

THURSDAY TEMPERATURES AT 925 MB WILL BE 0C TO 2C...WHICH WOULD
SUPPORT MAX TEMPS IN THE 40S. CAN/T RULE OUT A 50...BUT WITH
INCREASING CLOUDS LIMITING THE MIXING OF THIS AIR WE PREFER TO
KEEP THE FORECAST IN THE 40S. THURSDAY MAX TEMPS AND THURSDAY
NIGHT MIN TEMPS ARE A BLEND OF BIAS CORRECTED MOS VALUES.

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
HIGHLIGHTS...
  * LINGERING PRECIP EARLY FRI  
  * MAINLY DRY AND SEASONABLE THIS WEEKEND...LOW PROB OF PRECIP ON SUN  
  * DRY WEATHER RETURNS FOR THE WORK WEEK

CONFIDENCE...
HIGH CONFIDENCE AT THE BEGINNING OF THE FORECAST PERIOD AS THE 
FRIDAYS SYSTEM QUICKLY MOVES EASTWARD AND HIGH PRESSURE SET IN. 
CONFIDENCE DROPS INCREDIBLE BEGINNING ON SUNDAY AS MODEL SPREAD IS 
QUITE HIGH AND NOT CONSISTENT RUN TO RUN. DEEPENING ON HOW THE 
WEEKEND PANS OUT...MODERATE CONFIDENCE ON THE DRY WEATHER BEGINNING 
DURING THE WORK WEEK. 

FRIDAY-SATURDAY....
UPPER LEVEL SHORTWAVE WILL CONTINUE TO PUSH THROUGH DURING THE DAY 
ON FRIDAY. EXPECT LINGERING SHOWERS TO MOVE EASTWARD ON FRIDAY 
MORNING AND CLEAR OUT BY FRIDAY AFTERNOON. TEMPERATURES WILL BE 
ABOVE AVERAGE WITH LOW 50S ALONG THE SOUTHERN COAST AND MID TO UPPER 
40S ACROSS THE INTERIOR AS WINDS REMAIN OUT OF THE WEST AND DRY AIR 
PUSHES THROUGH CLEARING OUT SKIES. 

HIGH PRESSURE WILL BEGIN TO BUILD IN FRIDAY NIGHT AND INTO 
SATURDAY. THE NAM IS TRYING TO SUPPORT SOME SORT OF QUICK MOVING 
SYSTEM DURING THE DAY OUT OF THE ZONAL FLOW ALOFT TRANSITIONING TO 
A RIDGE...BELIEVE THIS TO BE AN OUTLIER AND KEPT THE FORECAST DRY 
FOR NOW. 

TEMPERATURES WILL BE QUITE SEASONABLE ON FRIDAY NIGHT INTO SATURDAY 
AS HIGH PRESSURE DOMINATES THE REGION. CLEAR SKIES AND LIGHT WINDS 
WILL MAKE FOR A PLEASANT DAY...ALTHOUGH A TAD CHILLY AS TEMPS WILL BE 
CLOSER TO SEASONABLE. 

SATURDAY NIGHT-SUNDAY...
BIG DIFFERENCE AMOUNTS THE MODEL GUIDANCE HAS LEAD TO A VERY LOW 
CONFIDENCE IN THIS PORTION OF THE FORECAST. THE GFS/UKMET ARE THE 
MORE PROGRESSIVE AND GUN-HO ABOUT A DYNAMIC SYSTEM MOVING ACROSS THE 
SOUTHEAST AND UP TOWARDS NEW ENGLAND DURING THE DAY ON SUNDAY. THE 
ECMWF HAS THE SOUTHEAST SYSTEM STAYING WELL TO OUR SOUTH AND 
AFFECTING THE MID-ATLANTIC INSTEAD. FINALLY THE CANADIAN MODEL 
SEEMS TO DISSOLVE THE SYSTEM ENTIRELY. ONE CAUTION WITH THE 
GFS...IT HAS BEEN FLIP-FLOPPING THIS SYSTEM WITH EACH RUN SO HAVE 
ZERO CONFIDENCE IN THE MODEL AT ALL. THEREFORE DECIDED TO KEEP WHAT 
PREV FORECASTER HAD AND BLEND IN HPC. SO DID A 50/50 BLEND OF PREV 
FORECAST AND HPC AS MODEL SPREAD IS QUITE LARGE. BELIEVE THAT THERE 
IS A SLIGHT CHANCE OF PRECIP DURING BEGINNING LATE SATURDAY NIGHT 
AND LASTING THROUGH SUNDAY. PRECIP SHLD START IN THE FORM OF SNOW AS 
THERMAL PROFILES ARE BELOW ZERO...AND AS THE DAY GOES ON AND 
HEATING OCCURS...THE SNOW WILL TRANSITION OVER TO RAIN. AGAIN LOW 
CONFIDENCE ON THIS FORECAST AND WILL HAVE TO WAIT AND SEE WHAT THE 
LATEST GUIDANCE GIVES US...SO STAY TUNED TO UPDATED FORECASTS. 

EXTENDED: BEGINNING OF THE WORK WEEK...
MANY MODELS AGREE THAT HIGH PRESSURE WILL MOVE THROUGH NEW ENGLAND 
BEGINNING LATE MONDAY AND LASTING THROUGH EARLY WEDNESDAY. THEREFORE 
EXPECT SOME HIGH LEVEL CLOUDS TO MOVE THROUGH...AND TEMPERATURES TO 
BE CLOSE TO SEASONABLE DURING THIS TIME FRAME. LOOKS AS IF MONDAY 
NIGHT WILL BE THE COLDEST NIGHT OF THIS FORECAST PERIOD AS TEMPS 
WILL DROP TO THE MID TEENS ACROSS THE INTERIOR WHILE THE COASTAL 
REGIONS WILL SEE THE LOW 20S. BELIEVE THIS IS CAUSED BY CLEARING 
SKIES AND LIGHT WINDS...RADIATIONAL COOLING WILL OCCUR. LOOKING 
AHEAD...PERHAPS A FEW HIT OR MISS SHOWERS DURING THE LATE AFTERNOON 
ON WEDNESDAY. 

THANKS TO OKX/ALY/BTV AND GYX FOR THE COLLABORATION TODAY.

.AVIATION /05Z THURSDAY THROUGH MONDAY/...
FORECASTER CONFIDENCE LEVELS...
  LOW...LESS THAN 30 PERCENT 
  MODERATE...30 PERCENT TO 60 PERCENT
  HIGH...GREATER THAN 60 PERCENT 

THROUGH 12Z...MODERATE TO HIGH CONFIDENCE. MAINLY VFR. CLOUDS ARE
CLEARING OUT AND WILL CONTINUE TO DO SO THROUGH THE NIGHT. PATCHY
FOG HAS LED TO MVFR VSBYS IN VARIOUS LOCATIONS ACROSS SOUTHERN NEW
ENGLAND.

TODAY...HIGH CONFIDENCE. VFR. INCREASING CLOUDS THROUGH THE DAY
WITH CIGS AS LOW AS 5KFT REACHING THE CT VALLEY LATE THIS
AFTERNOON. -RA/-SN ACROSS THE WEST LATE THIS AFTERNOON.

TONIGHT...MODERATE TO HIGH CONFIDENCE. MVFR/IFR CONDITIONS LIKELY
IN -SHRA MOST AREAS...-SHSN ACROSS THE NW ZONES. 

FRIDAY...MODERATE TO HIGH CONFIDENCE. MVFR/IFR CONDITIONS LIKELY
IN -SHRA MOST AREAS...-SHSN ACROSS THE NW ZONES...IMPROVING
THROUGH THE AFTERNOON. 

KBOS TERMINAL...MODERATE TO HIGH CONFIDENCE IN TAF. CONDITIONS
WILL IMPROVE THROUGH THE MORNING AND EXPECT SOME HIGH LEVEL CLOUDS
TO STREAM THROUGH DURING THE DAY. CONDITIONS DETERIORATE TONIGHT
AS SHOWERS MOVE IN. MODERATE CONFIDENCE ON TIMING.

OUTLOOK...FRIDAY NIGHT THROUGH MONDAY...

SATURDAY...MODERATE CONFIDENCE. VFR.

SUNDAY...LOW CONFIDENCE.  VFR LIKELY.  LOW PROBABILITY OF MVFR/IFR 
CONDITIONS IN RAIN/SNOW.

MONDAY...LOW CONFIDENCE. MVFR/IFR CONDITIONS WILL IMPROVE
THROUGHOUT THE DAY INTO VFR.

.MARINE...
WINDS AND SEAS WILL BE LIGHT THROUGH THURSDAY. WINDS AND SEAS WILL
BUILD SOMEWHAT THURSDAY NIGHT...BUT SHOULD REMAIN BELOW SMALL
CRAFT ADVISORY LEVELS.

OUTLOOK...FRIDAY THROUGH MONDAY...

WINDS AND SEAS INCREASE AS COLD FRONT MOVES ACROSS THE WATERS
EARLY FRIDAY. SCA LIKELY NEEDED FOR AT LEAST A PORTION OF THIS
TIME. BORDERLINE SCA WINDS AND SEAS LINGER INTO FRIDAY NIGHT
THROUGH SATURDAY NIGHT. CHANCE OF UNCERTAINTY AS SYSTEM
APPROACHES THE WATERS...COULD SEE INCREASING WAVES AND WINDS
DURING THE DAY ON SUNDAY LASTING INTO MONDAY.

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...NONE.
MA...NONE.
NH...NONE.
RI...NONE.
MARINE...NONE.