February 5, 2013 Forecast Discussion

000
FXUS61 KALY 051147
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
647 AM EST TUE FEB 5 2013

.SYNOPSIS…
A WEAK DISTURBANCE WILL PASS TO OUR SOUTH TODAY…OTHERWISE WEAK
HIGH PRESSURE WILL INFLUENCE OUR WEATHER. ANOTHER CLIPPER SYSTEM
WILL APPROACH AND MOVE ACROSS THE REGION TONIGHT…BRINGING SOME
VERY LIGHT SNOW TO THE AREA. FAIR WEATHER IS EXPECTED MID WEEK AS
HIGH PRESSURE BUILDS IN. A WIDESPREAD SNOWFALL IS ANTICIPATED LATE
IN THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/…
THE SOUTHERN MOST PORTION OF THE FORECAST AREA IS BEING BRUSHED BY
SOME LIGHT SNOW ASSOCIATED WITH A WEAK DISTURBANCE PASSES TO OUR
SOUTH. HAVE ADJUSTED POPS TO ACCOUNT FOR THIS. ALSO MADE MINOR
ADJUSTMENTS TO TEMPERATURES…DEW POINTS AND SKY COVER BASED ON
OBSERVATIONAL DATA. OTHERWISE…SOME WEAK RIDGING INFLUENCES THE
AREA TODAY.

ANOTHER SHORT WAVE TROUGH/WEAK CLIPPER SYSTEM WILL APPROACH THIS
AFTERNOON/EVENING AND CROSS THE REGION TONIGHT. THE MODEL GUIDANCE
IS NOT AS CONSISTENT WITH THE LIGHT QPF ASSOCIATED WITH THIS
FEATURE AS IT WAS EARLIER. THE EXPECTED QPF IS EVEN LIGHTER AND
MORE BLOTCHY. GUIDANCE FROM HPC INDICATES LESS THAN AN INCH OF
SNOW IS EXPECTED. WILL LIMIT LIKELY POPS TO A VERY BRIEF PERIOD
DURING THE OVERNIGHT HOURS. HESITATE TO DROP BACK TO CHANCE POPS
COMPLETELY AS THE MODELS HAVE BEEN HAVING A TOUGH TIME WITH THE
LIGHT QPF AMOUNTS WITH THE WEAK SYSTEMS/SHORT WAVES MOVING
THROUGH.

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/…
HIGH PRESSURE FROM CANADA BUILDS IN AT THE SURFACE WEDNESDAY AND
WEDNESDAY NIGHT. WILL GET SOME WEAK RIDGING ALOFT BETWEEN THE
DEPARTING SHORT WAVE TROUGH AND THE NEXT APPROACHING ONE. WILL BE
FAIR AND SEASONABLE.

THE ECMWF HAS BEEN CONSISTENTLY STRONGER WITH THE NEXT SYSTEM THAN
THE GFS EVEN AS IT MOVES ACROSS THE GREAT LAKES REGION THURSDAY AND
APPROACHES OUR REGION THURSDAY NIGHT. THE ECMWF AND GFS ARE MORE
SIMILAR THAN THEY HAVE BEEN…BOTH DEVELOP A COASTAL LOW ALONG THE
NORTH CAROLINA COAST BY 12Z/FRIDAY. INITIALLY PRECIPITATION/SNOW
WILL BE ASSOCIATED WITH THE APPROACHING SHORT WAVE TROUGH AND ITS
ASSOCIATED WEAK SURFACE LOW. BEST CHANCES WILL BE ACROSS THE
NORTHERN PORTION OF THE FORECAST AREA. INCREASE POPS THURSDAY
NIGHT BUT KEEP THEM LIMITED TO CHANCE SINCE THE GUIDANCE VARIES
WITH THE ONSET OF PRECIPITATION.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/…
SIGNIFICANT SHIFTS IN THE MEDIUM RANGE GUIDANCE FOR A POTENTIAL
MODERATE TO POSSIBLY SIGNIFICANT SNOW EVENT FOR A LARGE PORTION OF
THE ALY FCST AREA TO CLOSE THE WORK WEEK.

THE LATEST CAN GGEM…NAM…GFS…AND THE GEFS ARE SHIFTING CLOSER
TO THE ECMWF FOR A NOTABLE STORM THU NIGHT THROUGH FRI NIGHT. THE
ECMWF IS A LITTLE SLOWER ON THE PHASING OF THE SRN AND NRN STREAM
SHORT-WAVES FOR RAPID SFC CYCLOGENESIS TO BEGIN SOUTH OF LONG ISLAND
ON FRIDAY. THE COASTAL LOW IS ALSO SLIGHTLY FURTHER SOUTH…BUT THE
H500 LOW CLOSES OFF OVER NY AND PA TO CAPTURE THE STORM AND KEEP THE
POTENTIAL DEFORMATION ZONE SNOWFALL GOING FOR THE BETTER PART OF FRI
NIGHT.

BACKING UP A BIT…THE NAM/GFS/CAN GGEM DON/T COMPLETELY PHASE THE
NRN STREAM CLIPPER OR HYBRID CYCLONE…TO THE WAVE PASSING ALONG THE
CAROLINAS THU NIGHT. THEY ALL SHOW THE NRN STREAM WAVE TAPPING SOME
GULF MOISTURE STREAMING IN FROM THE SOUTH AND WEST. SOME STRONG QG
LIFT OCCURS ASSOCIATED WITH THE CONVERGENCE AHEAD OF THE WAVE…ALSO
AND INVERTED TROUGH EXTENDS N/NW FROM THE SRN STREAM WAVE NEAR THE
NC/VA BORDER FRI MORNING. ALL INDICATIONS ARE FOR SOME RAPID
INTENSIFICATION OR CYCLOGENESIS TO OCCUR…ESPECIALLY IF THE NRN
STREAM CYCLONE WEAKENS QUICKLY FRI MORNING.

ANOTHER CONCERN IS THE QPF IS INCREASING ON MUCH OF THE GUIDANCE.
THE CAN GGEM…NAM…AND GFS ARE INDICATING A QUARTER TO THREE
QUARTERS OF AN INCH. THE NAM AND CAN GGEM WOULD HAVE SOME OF THE
OVER RUNNING PCPN MOVING IN MUCH EARLIER THAN THE GFS AND ECMWF.
THERMAL PROFILES AND CRITICAL PARTIAL THICKNESSES INDICATE MAINLY
ZONE AWAY FROM THE MID HUDSON VALLEY…AND SRN LITCHFIELD COUNTY
CT. SOME RAIN MAY IN BRIEFLY ON FRI IN THE SRN TIER. THE LATEST
00Z GEFS PLUME FOR ALBANY INDICATES A DECENT CLUSTER OF MEMBERS
BETWEEN 0.2-0.40 INCHES OF LIQUID EQUIVALENT WITH A TRIO BETWEEN
0.5-0.6 INCHES…AND TWO OUTLIERS AROUND AN INCH. THERE CONTINUES
TO BE A LOT OF SPREAD…BUT THE GENERAL TRENDS WARRANT A MENTION IN
THE HAZARDOUS WX OUTLOOK FOR AT LEAST A MODERATE SNOWFALL FOR
POTENTIALLY ADVISORY OR LOW END WARNING CRITERIA. THIS SYSTEM WILL
HAVE TO BE WATCHED CAREFULLY…IF THE LAST 6 RUNS OF THE ECMWF
VERIFY…AND THEY HAVE BEEN VERY CONSISTENT…WE COULD BE LOOKING AT
SIZABLE SIGNIFICANT STORM FOR PARTS OF ERN NY AND WRN NEW ENGLAND.

FRIDAY NIGHT…THE SNOWFALL WILL TAPER TO SCATTERED SNOW SHOWERS
OVER THE ERN HALF OF THE FCST AREA…AS THE COASTAL WAVE MOVES WELL
EAST OF CAPE COD INTO THE NRN ATLANTIC. ANOTHER SURGE OF POLAR AIR
MOVES INTO THE REGION…AS HIGH PRESSURE BUILDS IN FROM QUEBEC.
TEMPS MAY NOSE DIVE WITH CLEARING SKIES…AND LIGHT WINDS COUPLED
WITH A FRESH BLANKET OF SNOWFALL. LOWS WILL RANGE FROM 5 ABOVE TO 5
BELOW ZERO NORTH OF THE CAPITAL REGION…AND SINGLE DIGITS TO TEENS
FROM ALBANY SOUTH AND EAST.

SATURDAY INTO SUNDAY…HIGH PRESSURE OVER QUEBEC WILL REMAIN IN
CONTROL. FAIR AND COLD WEATHER IS EXPECTED WITH PARTLY TO MOSTLY
SUNNY CONDITIONS. AS THE SFC HIGH SHIFTS DOWNSTREAM ON SUNDAY…LOW
AND MID LEVEL WARM ADVECTION WILL OCCUR…AND TEMPS MAY RISE A TAD
ABOVE NORMAL.

SUNDAY NIGHT INTO MONDAY…THE MEDIUM RANGE GUIDANCE DIVERGES AGAIN
WITH THE ECMWF SHOWING THE UPSTREAM CYCLONE OVER THE UPPER
MIDWEST/GREAT LAKES REGION AND ITS ASSOCIATED WARM OR OCCLUDED FRONT
WELL SOUTH AND WEST OF THE FCST AREA BY DAYBREAK ON MONDAY. THE GFS
ACTUALLY HAS A COLD FRONT DROP SOUTH SUNDAY NIGHT INTO MONDAY…AND
THEN RETURN NORTH OF AS A WARM FRONT. FOR NOW…WE CONTINUED A
SLIGHT OR LOW CHANCE OF SNOW SHOWERS SUNDAY NIGHT…AND THEN IF
TEMPS WARM UP AS HPC ADVERTISES…THERE COULD BE A CHC OF RAIN
SHOWERS FOR MOST OF THE FCST AREA WITH TEMPS ABOUT 10-15 DEGREES
ABOVE NORMAL.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/…
A WEAK DISTURBANCE WILL PASS SOUTH OF THE REGION THIS MORNING…AS
HIGH PRESSURE WILL BRIEFLY BUILD IN FROM THE NORTH. ANOTHER CLIPPER
LOW WILL APPROACH THE REGION TONIGHT WITH SOME LIGHT SNOW.

VFR CONDITIONS WILL PREVAIL PRIOR TO THIS EVENING. A DISTURBANCE
PASSING SOUTH OF THE REGION THIS MORNING MAY PRODUCE A BRIEF PERIOD
OF MVFR CIGS AT KPOU. A TEMPO GROUP WAS USED THERE.

THE SKIES WILL BECOME PARTLY CLOUDY IN THE LATE MORNING…BEFORE THE
MID AND HIGH CLOUDS INCREASE AHEAD OF THE CLIPPER. SOME LIGHT SNOW
WILL MOVE IN BTWN 00Z AND 06Z FROM SOUTH TO NORTH. MVFR CONDITIONS
HAVE BEEN FORECAST FOR MOST OF THE TAF SITES. THERE MIGHT BE
LOCALIZED REDUCTIONS TO IFR VSBYS WHICH MAY BE ADDRESSED WITH LATER
TAF ISSUANCES.

THE WINDS WILL BE CALM TO LIGHT AT 5 KTS OR LESS THE NEXT 24 HOURS.

OUTLOOK…
WED…VFR. CHC -SHSN.
WED NIGHT-THU…VFR. NO SIG WX.
THU NGT-FRI NIGHT. MVFR/IFR WITH SNOW LIKELY.
SAT…VFR…NO SIG WX.

&&

.HYDROLOGY…
NO HYDRO PROBLEMS ARE NOT ANTICIPATED OVER THE NEXT FEW DAYS AS OUR
COLD WEATHER CONTINUES WITH ANY PRECIPITATION IN THE FORM OF SNOW.

SOME RIVER AND STREAM GAGES ARE EXPERIENCING ICE EFFECTS. ICE
WILL CONTINUE TO FORM AND THICKEN ON ALL BODIES OF WATER.

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
NEAR TERM…IAA
SHORT TERM…IAA
LONG TERM…WASULA
AVIATION…WASULA
HYDROLOGY…IAA

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