February 10, 2013 Forecast Discussion

000
FXUS61 KALY 101108
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
608 AM EST SUN FEB 10 2013

.SYNOPSIS…
HIGH PRESSURE ALONG THE EASTERN SEABOARD TODAY WILL SLIDE OFFSHORE
TONIGHT. A STORM WILL CROSS THE UPPER GREAT LAKES MONDAY…AND
MOVE TO THE MARITIMES BY TUESDAY. IT WILL DRAG A WARM FRONT ACROSS
THE REGION MONDAY…WITH A WINTRY MIX FOR A FEW HOURS BEFORE
CHANGING TO RAIN. TWO COLD FRONTS WILL FOLLOW LATE MONDAY. TUESDAY
WEAK HIGH PRESSURE WILL CREST OVER THE REGION.

&&

.NEAR TERM /THROUGH MONDAY/…
AT 610AM EST…TEMPS ARE OR NEAR BOTTOMING OUT. ONLY MINOR CHANGES
TO GRIDS FOR TEMPS. OTRW NO OTHER CHANGES ATTM.

AS OF 345 AM EST…CLEAR SKIES…FRESH SNOW COVER…AND ALMOST
CALM WINDS TEMPS HAVE PLUNGED. CURRENT TEMPS ARE -10 TO -25 ACROSS
NORTH COUNTRY…-10 TO +10 ELSEWHERE WITH 3 MORE HOURS TO DROP.

AFTER THE FRIGID MORNING WAA WILL BEING LITERALLY AT DAWN. AT ALL
LEVELS OF ATMOSPHERE RIDGING BUILDS ALONG THE E SEABOARD.
1000-500DM THICKNESS INCREASES 15DM TODAY. BY EVENING SFC HIGH
HAS SHIFTED OFFSHORE AND RETURN FLOW HAS SET UP. 500HPA RIDGE
PASSES ACROSS RGN OVERNIGHT…AND MID AND HI CLOUDS FOLLOW
TONIGHT. DURING THE FIRST PART OF THE NIGHT TEMPS WILL PLUNGE
UNDER CLR SKIES…BUT WITH INCRG SFC WINDS…CLOUDS MINS WILL
OCCUR BFE MIDNIGHT…BFE HOLDING STEADY AND RISING TWRD DAYBREAK.
TEMP FREE FALL EARLY WILL BE DECENT…BUT LIKE THIS MORNING.

AS WMFNT PUSHES TWRD RGN TNGT…WARM NOSE WILL PRECEDE PCPN…WHILE
BOUNDARY LAYER REMAINS BLO FREEZING FOR SVRL HOURS WHILE OVERRUNNING
PCPN BREAKS OUT. ALL NAM/GFS MODEL SOUNDINGS BRING IN SVRL HOURS
OF ZR MAYBE SOME SLEET. WINTER WX ADVISORIES MAY BE NEEDED…BUT
TOO EARLY YET TO ISSUE. BULK OF OVERRUNNING PCPN WILL END MID
DAY…WITH SOME -SHRA WITH CFP. BY LATE IN THE DAY 500HPA TROF
CROSSING RGN AND CAA WILL RESULT IN MODEST LK EFFECT RESPONSE OF
-SHRA/-SHSN INTO NW PTNS OF FCA GIVEN EXPECTED H850 AND SFC FLOW.
MAX TEMPS WILL OCCUR LATE MON AFTN AFTER MIXING ASSOC WITH CFP.

MODEL SUITE HAS BEEN IN AGREEMENT FOR SVRL DAYS ON THIS EVENT.
FAIRLY HIGH CONFIDENCE IN EXPECTED SEQUENCE.

&&

.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY/…
LAKE EFFECT/UPSLOPE SNOW SHOWERS WILL OCCUR MONDAY NIGHT AND TUESDAY
AS A SURFACE LOW MOVES EAST ACROSS SOUTHERN CANADA MONDAY NIGHT AND
TO THE CANADIAN MARITIMES TUESDAY. RELATIVELY MOIST WESTERLY FLOW
BEHIND THIS SYSTEM WILL PRODUCE UPSLOPE AND LAKE EFFECT SNOW SHOWERS
ACROSS THE REGION. DURING PEAK DIURNAL HEATING TIMES RAIN SHOWERS
WILL OCCUR OVER LOWER TERRAIN AREAS. HAVE FORECAST LIKELY TO
CATEGORICAL POPS FOR THE ADIRONDACK ZONES DURING THIS PERIOD WITH
ABOUT 1 TO 4 INCHES OF SNOW FORECAST THERE. ELSEWHERE…MAINLY
CHANCE POPS MONDAY NIGHT IN ALL AREAS WITH THE HIGHEST POPS ACROSS
HIGHER TERRAIN AREAS. ON TUESDAY POPS DECREASE TO 30 TO 40 PERCENT
ACROSS HIGHER TERRAIN AREAS…AND SLIGHT CHANCE TO DRY CONDITIONS
FORECAST FOR THE HUDSON VALLEY AND SOUTHEAST AREAS. LOWS MONDAY
NIGHT WILL BE IN THE MID 20S TO LOWER 30S. HIGHS TUESDAY IN THE 30S
TO LOWER 40S.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/…
RELATIVELY QUIET WEATHER PATTERN EXPECTED FOR THE LONG TERM PERIOD.

POPS WILL DECREASE QUICKLY TUESDAY NIGHT AS THE MOIST WESTERLY FLOW
SUBSIDES…WITH MAINLY FAIR WEATHER WEDNESDAY INTO THURSDAY NIGHT AS
WEAK HIGH PRESSURE WILL AFFECT THE REGION. THE ONLY POSSIBLE PROBLEM
DURING THIS PERIOD WILL BE A DEVELOPING SURFACE LOW MOVING RAPIDLY
OUT TO SEA FROM THE CAROLINAS WEDNESDAY NIGHT AND EARLY THURSDAY.
MOST MODEL RUNS INDICATE THIS SYSTEM WILL STAY TO THE SOUTH OF THE
ALBANY FORECAST AREA. HAVE INCLUDED SLIGHT CHANCE POPS FOR MOST OF
THE REGION WEDNESDAY NIGHT WITH 30 PERCENT POPS ACROSS ULSTER…
DUTCHESS AND LITCHFIELD COUNTIES. A CLIPPER TYPE SYSTEM MOVING
ACROSS THE NORTHERN GREAT LAKES WILL BEGIN TO AFFECT THE FAR
NORTHWEST PART OF THE FORECAST AREA LATE THURSDAY NIGHT AND HAVE
FORECAST SLIGHT CHANCE POPS THERE. LOWS TUESDAY THROUGH THURSDAY
NIGHT NIGHTS WILL BE IN THE MID TEENS TO LOWER 20S. HIGHS WEDNESDAY
WILL BE UPPER 20S AND 30S…AND 30 TO 40 ON THURSDAY.

THE CLIPPER SYSTEM WILL BECOME NEARLY STATIONARY OVER SOUTHERN
CANADA JUST NORTH OF NY…AND REMAIN THERE FRIDAY THROUGH SATURDAY.
NO SIGNIFICANT WEATHER ANTICIPATED DURING THAT TIME…BUT THERE WILL
BE A CHANCE OF MAINLY SNOW SHOWERS DURING THIS PERIOD IN ALL AREAS.
HIGHS FRIDAY WILL BE IN THE 30S AND LOWER 40S. LOWS FRIDAY NIGHT IN
THE UPPER TEENS TO MID 20S. HIGHS SATURDAY IN THE 30S.

&&

.AVIATION /11Z SUNDAY THROUGH THURSDAY/…
VFR CONDITIONS ARE EXPECTED THROUGH THE NEXT 18 HOURS…WITH SCT
MID AND HIGH CLOUDS. CONDITIONS WILL RAPIDLY DETERIORATE FROM
WEST OT EAST BTWN 07-10UTC WITH CIGS AND VSBY BCMG IFR IN
-SN/ZR/IP. WINDS WILL BE LIGHT AND VARIABLE TODAY. BECOMING
SOUTHEAST UNDER 10MPH LATE NIGHT.

OUTLOOK…
MON-MON NIGHT…MVFR/IFR. -SN/-PL/-FZRA LIKELY CHANGING TO -RA.
TUE-TUE NT…VFR/MVFR. SLIGHT CHC -SHRA/-SHSN PARTICULARLY
ADRNKS
WED-THU…VFR.

&&

.HYDROLOGY…
TODAY WILL BRING FAIR DRY CONDITIONS WITH TEMPERATURES RECOVERING
FROM FRIGID MORNING LEVELS TO NEAR NORMALS. MONDAY…DAYTIME
TEMPERATURES WILL BEGIN THE DAY BLO FREEZING…IN A WINTRY
MIX…BUT RISE TO THE MID 30S TO MID 40S DURING THE AFTERNOON. ICE
GROWTH SHOULD SLOW AFTER TODAY. QPF OF AROUND 0.35 INCHES IS
LIKELY MONDAY…PART OF WHICH WILL FALL AS FREEZING RAIN AND
SLEET. IT SHOULD HAVE NO IMMEDIATE SHORT TERM HYDROLOGIC IMPACTS
AND NO HYDRO ISSUES ARE ANTICIPATED THROUGH THE NEXT FEW DAYS.

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…SNYDER
NEAR TERM…SNYDER
SHORT TERM…GJM
LONG TERM…GJM
AVIATION…GJM
HYDROLOGY…SNYDER

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