March 9, 2013 Forecast Discussion

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
113 PM EST SAT MAR 9 2013

.SYNOPSIS…
HIGH PRESSURE WILL DOMINATE OUR WEATHER OVER THE WEEKEND
WITH FAIR WEATHER…SUNSHINE AND ABOVE NORMAL TEMPERATURES. THE HIGH
WILL SHIFT OFFSHORE SUNDAY NIGHT. A LOW PRESSURE SYSTEM WILL MOVE
THROUGH THE GREAT LAKES REGION AND EVEN MILDER AIR WILL STREAM INTO
THE REGION TO START THE WEEK. BY MONDAY NIGHT…A COLD FRONT WILL
MOVE INTO THE REGION AS AN AREA OF LOW PRESSURE ORGANIZES ALONG
IT…BRINGING A WIDESPREAD MAINLY RAIN EVENT.

&&

.NEAR TERM /THROUGH TONIGHT/…
AS OF 1245 PM…FORECAST CONTINUES ON TRACK…ONLY SOME MINOR
ADJUSTMENTS WERE MADE BASED ON OBSERVATIONAL DATA WHICH GENERALLY
INCREASED TEMPS A DEGREE OR TWO.

.PREVIOUS DISCUSSION…
AS OF 627 AM EST…A LARGE COASTAL STORM OVER THE WESTERN ATLANTIC
OCEAN WILL GRADUALLY SHIFT EASTWARD THROUGH THE DAY TODAY. CLEAR
SKIES ARE IN PLACE ACROSS THE REGION AS HIGH PRESSURE OVER THE
EASTERN GREAT LAKES BEGINS TO MOVE EASTWARD TOWARDS THE AREA. WITH A
RIDGE AT 500 HPA BUILDING INTO THE AREA AND WARM AIR ADVECTION IN
PLACE…MAX TEMPS TODAY WILL BE WARMER THAN RECENT DAYS. WE WILL
PROBABLY ONLY MIX TO ABOUT 925 HPA…BUT 925 HPA TEMPS OF +1 TO +4
DEGREES C SHOULD STILL ALLOW TEMPS TO BE NEAR TO SLIGHTLY ABOVE
NORMAL. ALTHOUGH THE FRESH SNOW COVER WILL ALLOW FOR A SEASONABLY
CHILLY START…TEMPS SHOULD RISE INTO THE LOWER TO MIDDLE 40S FOR
MOST AREAS BY AFTN…AS THE STRENGTHENING MARCH SUN SHOULD MAKE UP
FOR ANY COOLING THAT THE SNOW PACK WILL PROVIDE.

ON SATURDAY NIGHT…THE HIGH PRESSURE AREA WILL MOVE OVER THE REGION
AND BEGIN TO MOVE TOWARDS NEW ENGLAND BY SUNDAY MORNING. IT LOOKS TO
STAY MAINLY CLEAR…WITH JUST PERHAPS SOME THIN HIGH CIRRUS MOVING
INTO THE AREA BY LATE IN THE NIGHT. WITH THE SNOWPACK IN
PLACE…CONTINUED NEARLY CLEAR SKIES…AND LIGHT WINDS…GOOD
RADIATIONAL COOLING WILL ALLOW FOR A COOL NIGHT. MIN TEMPS WILL BE
IN THE TEENS AND 20S ACROSS THE AREA.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/…
FOR THE SHORT TERM THE MODEL SUITE HAS MOVED TO AN UNCOMMON DEGREE
OF AGREEMENT WITH THE GFS/NAM/GEM AND 12UTC ECMWF ALL SUGGESTING
THE SAME SCENARIO…AND ONLY DIFFERENCES IN DURATION AND QPF OF
PCPN TUES.

SUN MORNING 500HPA RIDGE AND SFC HIGH ARE IN CONTROL ALONG THE
SEABOARD. THIS SYSTEM SLIDES OFFSHORE SUN NT…AS 500HPA CUT OFF
OPENS IN WESTERN GRTLKS AND LIFTS NE…WHILE A SFC LOW NR CHICAGO
ALSO MOVES NE.

UNDER HIGH PRESSURE TEMPS WILL BE ABV NORMALS BUT WILL BCM EVEN
MILDER AS SW RETURN FLOW AROUND DEPARTING SFC HI INCR SUN NT INTO
MON. WITH FCA WEST OF RIDGE AXIS IN WAA CLOUDS WILL BEGIN INCRG
SUN AFTN INTO MON. OTHERWISE MDLS HAVE BEEN SLOWING CHC OF PCPN
FOR PAST 2 DAYS…AND IT SHOULD REMAIN DRY INTO MONDAY IN MOST
AREAS…WITH INCR CHC POPS LATE MONDAY.

FINALLY BY LATE MONDAY 500HPA CUT OFF LOW HAS OPENED INTO PROGRESSIVE
SHORT WV LIFTING NE…THIS IS TYPICALLY A WEAKENING SET OF DYNAMICS.
AT SAME TIME THE SFC LOW IS DRAGGING A DECELERATING CDFNT INTO E
GRTLKS WHICH IS BCMG INCR PARALLEL TO 500HPA FLOW. -SHRA SHOULD INCR
MON NT…AHEAD OF AND ALONG THE CDFNT. HWVR BY TUE MRNG IT HAS BCM
AN ANNA TYPE FRONT WITH MOST PCPN POST FRONTAL…AS S SFC LOW
ORGANIZES ALONG IT…MOVING NE AND PRODUCING A WIDESPREAD AREAS OF
RN MUCH OF TUES.

THE GFS PRODUCES QPF OF 1-3 INCHES LIQ…THE ECMWF ON THE ORDER
OF A 0.75 TO 1.25 IN…WHILE THE GEM HAS 1-2 IN LIQ AND WHILE
THERE ARE SLIGHT DIFFERENCES IN PLACEMENT OF MAX QPF AXIS…THE
GENERAL CONCEPT IS A WIDESPREAD AND ALL DAY RAIN. GIVEN THE GFS
TENDENCY TO OVER DO QPF WILL CONSIDER IT AN OUTLIER…HWVR ITS
AMOUNTS RAISE CONCERN FOR POTENTIAL FLOODING IMPACTS. THE GEM QPF
LOOKS MORE REASONABLE ATTM…BUT IT WOULD STILL RESULT IN SOME
SIGNIFICANT RISES AND WITH SNOW MELT COULD PUSH STREAMS UP AND
OVER.

IN ANY CASE MILD TEMPS WILL CONTINUE INTO TUES…WITH -SHRA LATE
MONDAY EVOLVING INTO A MORE WIDESPREAD RAIN MUCH OF TUES. GRID
TEMPS USED 3HRLY TEMPS SUN AND MON NTS AS MAX/MINS WERE 24 HR
VALUES.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/…
SFC LOW AND CDFNT MOVE E OF RGN TUE NT…PCPN ENDS AND CAA BEGINS
IN ITS WAKE. FOR A TIME TUE NT FCA IS DRY SLOTTED. AT 500HPA CUT
OFF HAS REFORMED OVER GRTLKS RGN. MAIN SFC LOW RACES NNE TWRD
JAMES BAY…BUT HAS TRAILING 2NDRY CDFNT INTO GRTLKS WHICH FINDS
ITS WAY ACROSS FCA THUR MORNING.

ALL THIS SETS THE STAGE FOR A RETURN TO WINTER FOR THE REST OF THE
WEEK. 500HPA TROF SHIFTS INTO NE…WITH STRONGER CAA THU. WITH
MOIST NW FLOW IN CAA AND FLOW ACROSS GRTLKS RESULT WILL BE SVRL
DAYS OF VRBL CLOUDS…SCT -SHSN PARTICULARLY W PTNS OF FCA. TEMPS
FALL TO BLO NORMALS DURING THIS PERIOD. WILL POPULATE EFP WITH
MIDNIGHT HPC WHICH IS IN AGREEMENT WITH GFS/ECMWF.

&&

.AVIATION /18Z SATURDAY THROUGH WEDNESDAY/…
VFR CONDITIONS WILL CONTINUE THROUGH THE TAF PERIOD 18Z/SUNDAY AS
HIGH PRESSURE AT THE SURFACE AND ALOFT DOMINATES. THE HIGH WILL
CREST OVER THE REGION TONIGHT. WILL HAVE CLEAR SKIES UNTIL SOME
CIRRUS SPILLS OVER THE RIDGE LATE TONIGHT AND ON SUNDAY.

LIGHT WINDS WILL BECOME CALM THIS EVENING WITH A LIGHT SOUTHEASTERLY
FLOW DEVELOPING ON SUNDAY. THE EXCEPTION IS AT KPOU WHERE
NORTHEASTERLY WINDS OF AROUND 10 KNOTS HAVE BEEN GUSTING TO ABOUT 20
KNOTS…WINDS HERE WILL WEAKEN LATER THIS AFTERNOON AND BECOME CALM
TONIGHT.

OUTLOOK…
MON…VFR/MVFR. CHC RAIN SHOWERS.
MON NIGHT-TUE…MVFR/IFR IN RAIN AND FOG.
TUE NIGHT…VFR.MVFR. CHC -SHRA/-SHSN.
WED…VFR. NO SIG WX.

&&

.HYDROLOGY…
NO WIDESPREAD HYDRO PROBLEMS ARE EXPECTED THOUGHT MONDAY NIGHT.

HOWEVER AFTERNOON HIGHS THE NEXT FEW DAYS IN MID 40S TO MID 50S
INTO TUESDAY WILL RESULT IN INCRG SNOW MELT…PARTICULARLY MONDAY
AND TUESDAY WHEN OVERNIGHT LOWS WILL NOT FALL TO BLO FREEZING. IN
ADDITION 1-2 INCHES OF RAIN IS POSSIBLE TUESDAY…AND COMBINED WITH
MELT COULD RESULT IN RISES TO AREA STREAMS AND RIVERS…AND THE
POTENTIAL FOR FLOODING.

FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES…INCLUDING
OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS…PLEASE
VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON
OUR WEBSITE.

&&

.ALY WATCHES/WARNINGS/ADVISORIES…
CT…NONE.
NY…NONE.
MA…NONE.
VT…NONE.

&&

$$
SYNOPSIS…IAA/SNYDER
NEAR TERM…GJM/IAA/FRUGIS
SHORT TERM…SNYDER
LONG TERM…SNYDER
AVIATION…IAA
HYDROLOGY…SNYDER

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