February 17, 2012 Forecast Discussion

000
FXUS61 KALY 171530
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
1030 AM EST FRI FEB 17 2012

.SYNOPSIS…
LOW PRESSURE WILL LIFT NORTHEASTWARD THROUGH QUEBEC TODAY…WHILE
HIGH PRESSURE BUILDS EASTWARD FROM THE OHIO VALLEY REGION. THIS HIGH
WILL DRIFT SOUTH AND EAST TONIGHT…WHILE A CLIPPER TYPE SYSTEM
APPROACHES FROM THE UPPER GREAT LAKES. THIS SYSTEM WILL CROSS OUR
AREA SATURDAY AFTERNOON INTO SATURDAY EVENING. HIGH PRESSURE WILL
BUILD INTO SOUTHEAST CANADA ON SUNDAY…AS A POWERFUL STORM SYSTEM
OVER THE GULF COAST STATES HEADS TOWARDS THE COASTAL CAROLINAS.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/…
— Changed Discussion —
SCATTERED TO BROKEN CLOUDS OVER THE REGION THIS MORNING DUE TO SOME
CONVERGENCE ALONG THE LOW LEVEL WINDSHIFT/DEWPOINT BOUNDARY AND
SOME COOLING ALOFT. THEN THERE IS A BREAK OF CLEARING AHEAD OF THE
NEXT BAND OF CLOUDINESS THAT IS IN WESTERN NY/PA ASSOCIATED WITH
ANOTHER WINDSHIFT BOUNDARY AND MORE LOW LEVEL COOLING. WITH THE
WEST OT NORTHWEST LOW LEVEL FLOW THROUGH THE BOUNDARY LAYER…AND
DECENT MIXING…ALL AREAS SHOULD BE PARTLY TO MOSTLY SUNNY THROUGH
THIS AFTERNOON. MOSTLY CLOUDY INTO THE SOUTHERN ADIRONDACKS DUE TO
SOME UPLSOPE AND SOME MOISTURE OFF THE LAKE. SOME ISOLATED
RAIN/SNOW SHOWERS ALSO IN THE SOUTHERN ADIRONDACKS.

CURRENT TEMPERATURES NEARING FORECASTED HIGHS…BUT BASED ON 12Z
SOUNDINGS AND MIXING POTENTIAL…HIGH TEMPERATURES SHOULD BE
CAPPED NEAR CURRENT FORECASTED HIGHS. SO ONLY MINOR ADJUSTMENTS
TO TEMPERATURES IF ANY. MINOR ADJUSTMENTS TO PROBABILITIES OF
PRECIPITATION AND SKY COVER AS WELL BASED ON CURRENT OBSERVATIONS
AND TRENDS.
— End Changed Discussion —

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/…
AS OF 345 AM…LAKE EFFECT SNOW SHOWERS WILL CONTINUE THIS EVENING
INTO THE OVERNIGHT WITH CYCLONIC FLOW REGIME PERSISTING THROUGH AT
LEAST THE FIRST HALF OF THE NIGHT. DUE TO EXPECTED RATHER
DISORGANIZED NATURE OF THE SNOW SHOWERS…WILL MENTION ACCUMULATIONS
BELOW ADVISORY CRITERIA…AROUND 2-4 INCHES ACROSS CENTRAL/SOUTHERN
HERKIMER COUNTIES…WITH 1-2 POSSIBLE IN MAINLY WESTERN PORTIONS OF
FULTON/MONTGOMERY COUNTIES.

FLOW TRAJECTORIES SHIFT TO MORE OF A 290 DIRECTION…SO MAIN FOCUS
OF ACTIVITY WOULD SHIFT FROM THE SOUTHWEST ADIRONDACKS TO THE
WESTERN MOHAWK VALLEY. HOWEVER…INVERSION HEIGHTS WILL START TO
LOWER OVERNIGHT WITH DIRECTIONAL SHEAR INCREASING AFTER MIDNIGHT AS
WELL…SO SNOW SHOWERS SHOULD DIMINISH TO FLURRIES LATE. SHORT WAVE
RIDGING WILL OCCUR SATURDAY MORNING AHEAD OF A CLIPPER LOW
APPROACHING FROM THE UPPER GREAT LAKES.

VARIOUS SOURCES OF MODEL GUIDANCE IN AGREEMENT WITH THE CENTER OF
THE WEAK SURFACE LOW FORECAST TO PASS RIGHT OVER OR SLIGHTLY SOUTH
OF THE CAPITAL REGION LATE SATURDAY INTO SATURDAY EVENING. SO…AS
IS TYPICALLY THE CASE WITH THESE SYSTEMS…MOST OF THE MEASURABLE
PRECIP WILL OCCUR ALONG AND NORTH OF THE LOW CENTER TRACK. THIS
SYSTEM WILL NOT HAVE MUCH MOISTURE TO WORK WITH…ALTHOUGH A PRETTY
VIGOROUS MID/UPPER LEVEL VORT MAX WILL BE MOVING ACROSS THE
AREA…SO THERE COULD BE A FAIRLY WIDESPREAD SWATH OF SNOW SHOWERS
WITH ACCUMULATIONS TOTALING AROUND AN INCH OR TWO FROM THE CAPITAL
REGION NORTHWARD. TEMPS EXPECTED TO RISE INTO THE UPPER 30S TO LOWER
40S THROUGH MUCH OF THE HUDSON RIVER VALLEY…HOWEVER EVAPORATIVE
COOLING WILL TAKE PLACE WITH INITIALLY HIGH DEWPOINT
DEPRESSIONS…SO PRECIP EXPECTED TO FALL MAINLY AS SNOW. THERE COULD
BE SOME RAIN MIXED IN FROM ALBANY SOUTHWARD AT THE ONSET.

THE CLIPPER LOW WILL QUICKLY PULL AWAY INTO EASTERN NEW ENGLAND BY
LATE SATURDAY EVENING…AS HIGH PRESSURE STARTS TO BUILD SOUTH AND
EAST FROM CANADA. DRYING CONDITIONS WILL OCCUR WITH WINDS SHIFTING
TO A N-NW DIRECTION.

FOR SUNDAY…PRETTY MUCH ALL SOURCES OF GUIDANCE NOW IN AGREEMENT
WITH SUPPRESSING A MAJOR STORM SYSTEM DEVELOPING OVER THE SOUTHEAST
CONUS TO EMERGE NEAR THE COASTAL CAROLINAS AND OUT TO SEA FROM
THERE. THE NORTHERN EDGE OF THE PRECIP SHIELD SHOULD HAVE A SHARP
GRADIENT…BUT SHOULD NOT REALLY GET CLOSE TO OUR AREA AND CONFINED
TO THE MID ATLANTIC STATES. SO A DRY DAY WITH SEASONABLE TEMPS IN
STORE FOR OUR AREA WITH A NORTHERLY FLOW.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/…
DURING THE EARLY PART OF THE LONG TERM PERIOD…ALL MODELS REMAIN
CONSISTENT THAT THE LOW MOVING OFF THE NORTH CAROLINA COAST WILL
REMAIN WELL SOUTH OF THE FORECAST AREA…SO THE BEGINNING OF THE
LONG TERM PERIOD WILL FEATURE HIGH PRESSURE BUILDING INTO THE REGION
FROM THE MIDDLE OF THE COUNTRY WITH MAINLY CLEAR SKIES AND DRY
WEATHER. THERE WILL BE A DECENT PRESSURE GRADIENT BETWEEN THIS HIGH
AND THE OFFSHORE LOW WHICH WILL PRODUCE GUSTY WINDS SUNDAY NIGHT AND
MONDAY. LOWS SUNDAY NIGHT WILL RANGE FROM 5 TO 10 ABOVE ZERO OVER
THE ADIRONDACKS…TO THE LOWER 20S OVER THE FAR SOUTH. HIGHS MONDAY
WILL BE IN THE MID 20S TO THE 30S.

THE SURFACE HIGH WILL MOVE OFF THE NORTH CAROLINA COST BY TUESDAY
WITH A SOUTHERLY FLOW BRINGING MILDER AIR TO THE REGION. IT WILL
REMAIN DRY MONDAY NIGHT AND TUESDAY. LOWS MONDAY NIGHT WILL
GENERALLY BE BETWEEN 10 AND 20…WITH HIGHS TUESDAY IN THE MID 30S
TO MID 40S.

ALTHOUGH THE GFS/ECMWF DISAGREE ON THE DETAILS…THE PERIOD FROM
TUESDAY NIGHT THROUGH THURSDAY WILL BE A PERIOD OF UNSETTLED WEATHER
WITH A SERIES OF FRONTAL/UPPER LEVEL TROF PASSAGES PRODUCING PERIODS
OF PCPN DURING THAT PERIOD. WITH THE TIMING OF THESE SYSTEMS
DIFFICULT TO PREDICT THIS FAR OUT DUE TO MODEL INCONSISTENCY…DID
NOT FEEL IT WOULD BE USEFUL TO FORECAST ANY HIGHER THAN CHANCE POPS
DURING THIS PERIOD. TEMPS WILL CONTINUE TO BE MILD DURING THIS
PERIOD…SO WOULD EXPECT MOST VALLEY LOCATIONS AND SOUTHERN AREAS TO
SEE MAINLY RAIN WHEN PCPN DOES OCCUR…WITH THE TYPE OF PCPN THAT
DOES OCCUR HIGHLY DEPENDENT ON THE TIME OF DAY. LOWS TUESDAY AND
WEDNESDAY NIGHTS WILL BE IN THE MID 20S TO LOWER 30S. WITH THE HIGHS
WEDNESDAY AND THURSDAY IN THE UPPER 30S AND 40S.

&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/…
AS OF 630 AM…WITH THE PASSAGE OF A SURFACE TROF…THE IFR STRATUS
DECK THAT WAS OVER KALB/KGFL DURING THE NIGHT HAS BROKEN UP…AND IS
IN THE PROCESS OF BREAKING UP AT KPOU. THUS…EXPECT VFR CONDITIONS
AT THE TAF SITES FOR MOST OF THE TAF PERIOD. MVFR CIGS/VSBYS IN FOG
ARE POSSIBLE AT KALB/KGFL UNTIL AROUND 13Z-14Z…AND IFR CIGS ARE
POSSIBLE AT KPOU UNTIL AROUND 13Z. OTHERWISE VFR CONDITIOSN WILL
PREVAIL THROUGH 12Z SATURDAY.

AT ALL THREE TAF SITES…WESTERLY WINDS WILL PICK UP TO AROUND 10
KTS WITH GUSTS TO AROUND 15 KTS THIS MORNING…THEN CONTINUE TO
INCREASE TO 10 TO 12 KTS…AND GUSTS OF 15 TO 20 KTS DURING THE
AFTERNOON. THE WESTERLY WINDS WILL SUBSIDE TO 7 TO 10 KTS AROUND
00Z…BUT GUSTS UP TO 15 KTS STILL POSSIBLE AT KALB THROUGH MOST OF
TONIGHT.

OUTLOOK…
SAT…VFR…NO SIG WX.
SAT NGT…VFR. CHC MVFR WITH -SW POSS MIX WITH -RA.
SUN…VFR…NO SIG WX.
MON-TUE…VFR…NO SIG WX.

&&

.HYDROLOGY…
NO HYDRO PROBLEMS ARE EXPECTED THROUGH THE NEXT SEVERAL DAYS. SOME
GAGES WILL CONTINUE TO HAVE ICE EFFECTS NORTH OF THE MOHAWK RIVER
VALLEY IN THE ALBANY HYDRO SERVICE AREA.

RAIN/SNOW SHOWERS WILL END THIS MORNING…WITH MAINLY DRY CONDITIONS
DEVELOPING FOR THE REST OF TODAY EXCEPT FOR LAKE EFFECT SNOW SHOWERS
NORTH AND WEST OF THE CAPITAL REGION. OTHERWISE SOME LIGHT SNOW IS
POSSIBLE ON SATURDAY WITH DRY CONDITIONS EXPECTED SUNDAY THROUGH
TUESDAY OF NEXT WEEK.

THE WINTER SPRING FLOOD POTENTIAL OUTLOOK HAS BEEN ISSUED FOR
EASTERN NEW YORK AND WESTERN NEW ENGLAND. PLEASE REFER TO
ALBESFALY /FGUS71 KALY/ FOR FURTHER DETAILS.

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…NAS
NEAR TERM…NAS
SHORT TERM…JPV
LONG TERM…GJM
AVIATION…GJM
HYDROLOGY…JPV

Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-ShareAlike 3.0 License