January 21, 2012 Forecast Discussion

000
FXUS61 KALY 211500
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
1000 AM EST SAT JAN 21 2012

.SYNOPSIS…
WEAK LOW PRESSURE WILL TRACK OFF THE NEW JERSEY COAST TODAY AND
BRING SNOW TO THE AREA. A HIGH PRESSURE SYSTEM WILL BUILD INTO THE
NORTHEAST TONIGHT AND SUNDAY BRINGING FAIR WEATHER. ON MONDAY…A
POWERFUL STORM MOVES FROM THE UPPER GREAT LAKES INTO WESTERN
QUEBEC…LIKELY BRINGING MIXED PRECIPITATION CHANGING TO RAIN.

&&

.NEAR TERM /THROUGH TONIGHT/…
WEAK MIDLEVEL SYSTEM MOVING FROM WEST TO EAST. SNOW HAS ENDED OR
GREATLY DIMINISHED OVER NORTHWEST PART OF AREA. LATEST RUC ANALYSIS
SHOWS H850 WARM ADVECTION CONTINUING ACROSS THE AREA AND VAD WIND
PROFILE CONFIRMS THIS. SNOW SEEMS TO BE ENDING ONCE MID/HIGH LEVEL
CLOUDS MOVE AWAY AND SEEDER FEEDER MECHANISM DIMINISHES. CLOUD TOPS
COOLING OVER SOUTHEAST PART OF FORECAST AREA INDICATING ONE MORE
BAND OF MODERATE SNOW POSSIBLE THERE LATE THIS MORNING BEFORE HIGHER
CLOUDS MOVE OFF AND SNOW DIMINISHES.

RECENT UPDATE TO ADJUST POPS WHERE SNOW HAS DIMINISHED OR ENDED.
ALSO ADJUSTED MAX TEMPS DOWNWARD 2 DEGREES VALLEYS AND 3-5 DEGREES
MOUNTAINS AS OBS SHOW TEMPS NOT MOVING THIS MORNING.

PREVIOUS…
CURRENTLY -SN HAS OVER SPREAD MOST OF NY FCA EXCPT N ADIRONDACKS
AND W NEW ENG…WHERE SNOW WILL BEGIN SHORTLY. OTHER THAN SOME
MINOR ADJUSTMENTS TO POPS/WX FCST REMAINS ON TRACK.

SURFACE WAVE MOVES FROM TN VLY TO NJ COAST TODAY. ISENTROPIC LIFT
IS MAIN MECHANISM PRODUCING UVM FOR SNOW TODAY. ALTHOUGH 500HPA
TROF AND ITS VORT MAX PASSING ACROSS US/CAN BORDER RGN SUPPORT
SOME UVM IN N PTNS OF FCA. OVERALL SNOW WILL BE GENERALLY LIGHT
ON ORDER OF 1-3 INCHES…EXCEPT IN SOUTHERN MOST AREAS WHERE
MODERATE AMOUNTS ARE EXPECTED (3-6IN) CLOSEST TO THE BEST
ISENTROPIC LIFT AND UVM.

MODELS (GEM/NAM/GFS/ECMWF) IN GOOD AGREEMENT FOR THIS PERIOD. QPF
A BLEND OF CURRENT FCST…HPC AND ALL 00UTC MODELS. GIVEN CONTRAST
ACROSS THERMAL RIBBON USED SNOW/LIQ RATIO OF 13. AS OF 230AM -SN
HAS REACHED A RME-BGM LINE. THIS WILL CONTINUE TO ADVANCE REACHING
HUD VLY BY 5-6AM.

SNOW WILL PERSIST INTO THE EARLY AFTN THEN END RAPIDLY FM NW TO SE
AS 500HPA TROF AND SFC LOW MOVES OFFSHORE CUTTING OFF ISENTROPIC
LIFT. OVERNIGHT 500HPA RIDGE BUILDS INTO NE USA..AND SFC HIGH
BUILDS OVER NEW ENG AND NY IN RESPONSE TO DIF ACVA. SKIES WILL
CLEAR DURING THE LATE AFTN AND ERLY EVENING…WITH CLR CONDS AND
FRESH SNOW IN MOST AREAS. SHOULD ALLOW FOR GOOD RAD COOLING AND
TEMPS TO PLUNGE TO NR NORMAL.

WINDS SHOULD BE LIGHT NE DURING THIS PERIOD EXCEPT ARND 10KTS IN S
PTNS OF FCA.

&&

.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/…
WE BEGIN THIS SHORT TERM PORTION OF THE FORECAST ON A TRANQUIL
NOTE WITH A 1035MB SURFACE HIGH SLIDING ACROSS THE EASTERN GREAT
LAKES REGIONS AND NEW ENGLAND THROUGH THE DAY. FAIRLY DRY BELOW
500MB TO KEEP POPS AT ZERO AND SKIES PT-MOSUNNY. TEMPERATURES WILL
BE SEASONABLE FOR THIS TIME OF THE YEAR WITH MAINLY 20S FOR THE
TERRAIN AND LOWER 30S FOR THE VALLEY FLOOR.

MEANWHILE…A POWERFUL SHORT WAVE COINCIDING WITH 150KT UPPER
LEVEL JET WAS COMING ASHORE ACROSS CALIFORNIA. THIS SYSTEM IS
FORECAST BY THE NCEP MODEL SUITE TO IMPACT THE 4-CORNERS REGION
AND EJECT OUT ONTO THE CENTRAL-SOUTHERN PLAINS SUNDAY INTO MONDAY.
A POWERFUL SURFACE CYCLONE WILL DEVELOP OVER THE MID-LOWER
MISSISSIPPI RIVER VALLEY AND TRACK INTO THE CENTRAL GREAT LAKES
REGION THROUGH MONDAY. THE MAIN IMPACT FOR OUR REGION WILL BE AN
INCREASE IN CLOUD COVER AND A STRENGTHEN SOUTHERLY WIND.
HOWEVER…ISSUES ARISE OVERNIGHT SUNDAY INTO MONDAY MORNING FOR
THE REGION.

A CLOSER EXAMINATION OF BUFKIT AND HOURLY BUFR PROFILES FROM THE
MODEL SUITES THIS MORNING ALL SUGGEST A RAPID INCREASE IN LOWER
LEVEL MOISTURE FROM SOUTH TO NORTH. COMBINE THAT WITH THE WIND
MAGNITUDE INCREASE AND LOW LEVEL SHEAR FOR DRIZZLE FORMATION SINCE
ICE NUCLEI IS NOT EXPECTED IN THE COLUMN WITH THE HEIGHT OF THE
MOISTURE PROFILES STAYING BELOW THE -10C THROUGH AT LEAST 15Z
MONDAY. DUE TO SEASONABLE TEMPERATURES EXPECTED ON SUNDAY…AND
SOME PARTIAL CLEAR SKIES SUNDAY EVENING…OVERNIGHT SURFACE
TEMPERATURES ARE EXPECTED TO DROP BACK INTO THE TEENS ACROSS THE
DACKS AND LOW-MID 20S ELSEWHERE. THIS SEEMS TO SUGGEST THAT ANY
DRIZZLE FORMATION WILL FREEZE ON CONTACT. TEMPERATURES ARE
EXPECTED TO CLIMB ABOVE FREEZING ALONG THE HEELS OF THE STRENGTHEN
SOUTHERLY FLOW BY NOON MONDAY WHERE WE WILL REMOVE THE MENTION OF
FROZEN DRIZZLE/RAIN.

MONDAY AFTERNOON…AN INCREASE IN LOW LEVEL WARM ADVECTION ALONG
WITH THE APPROACH OF THE FRONTAL BOUNDARY WILL KEEP POPS QUITE
HIGH FOR PERIODS OF RAIN/SHOWERS. THERE ARE SOME SUBTLE HINTS THAT
THUNDER COULD BE A POSSIBILITY SOUTH OF THE CAPITAL REGION WITH
SHOWALTER INDICES DROPPING BACK TO NEAR 1C AND SLIGHTLY FAVORABLE
MID LEVEL LAPSE RATES. WE WILL CONTINUE TO MONITOR AND NOT MENTION
IN THE FORECAST/GRIDS. HIGH TEMPERATURES COULD EXCEED 40F FOR THE
MAJORITY OF THE REGION.

THE FRONT AND ASSOCIATED MOISTURE TRACK QUICKLY TO OUR NORTHEAST
WITH A DECREASE IN POPS. HOWEVER…WITH A NEAR VERTICALLY STACKED
LOW OVER THE GREAT LAKES REGION AND COLD ADVECTION…LAKE ONTARIO
CONTRIBUTION IS EXPECTED TO INCREASE. DELTA T/S ARE ONLY EXPECTED
TO REMAIN MARGINAL SO WE WILL KEEP POPS FOR PORTIONS OF THE DACKS
IN THE 30% THRESHOLDS FOR SNOW SHOWERS.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/…
THE AFOREMENTIONED LAKE EFFECT ACTIVITY COULD STILL BE IMPACTING
PORTIONS OF THE DACKS WITH A WEST-SOUTHWEST BOUNDARY LAYER WINDS
AROUND THE PERIPHERY OF THE SLOWLY DEPARTING UPPER LOW.
OTHERWISE…BUILDING SURFACE PRESSURES ARE EXPECTED TUESDAY
THROUGH WEDNESDAY. A WEAK MID LEVEL IMPULSE APPROACHES LATE
WEDNESDAY AS THE MAIN IMPACT SHOULD BE FROM AN INCREASE IN HIGH-
MID LEVEL MOISTURE.

THURSDAY THRU FRIDAY…CONSIDERABLE UNCERTAINTY REMAINS AS THE GFS
REMAINS THE MOST PROGRESSIVE AND THE ECMWF A BIT MORE PRONOUNCED
WITH RESPECT TO APPALACHIANS STORM SYSTEM THAT COULD IMPACT THE
REGION THURSDAY NIGHT INTO FRIDAY. ENSEMBLES FROM THE GFS OFFER A
WIDE VARIETY OF SOLUTIONS WITH A FEW CLUSTERS EVEN STRONGER THAN
THE ECMWF AND FURTHER WEST. FOR NOW…A LOW CONFIDENCE FORECAST
FOR THE END OF THIS WEEK.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/…
MVFR CIGS/VSBY IN -SN EXIST OVER MOST OF FCA. OVER NEXT FEW HRS MOST
AREAS FM ADIRONDACKS SOUTH WILL LOWER TO MVFR/IFR CIGS AND VSBY IN
-SN. IFR CONDS WILL BE MORE WIDESPREAD SOUTH. CONDS WILL IMPV DURING
THE AFTN BCMG MVFR FM NW TO SE…AND VFR BY EVENING. WINDS WILL BE
NORTH-NORTHEAST AROUND 5-10 KT TODAY.

OUTLOOK…
SAT NIGHT-SUN…VFR. NO SIG WX.
SUN NIGHT-MON MRNG…BCMG MVFR/IFR LATE. CHC -RA/-SN/-PL/-FZRA.
MON AFTN…MVFR/IFR. RA LIKELY.
MON NIGHT-TUE…VFR. SLIGHT CHC -SHRASN AND MVFR.
TUE NIGHT-WED…VFR. NO SIG WX.

&&

.HYDROLOGY…
NO MAJOR PROBLEMS ARE EXPECTED ON THE MAIN STEM RIVERS THROUGH
NEXT FRIDAY. ANY PRECIPITATION WHICH FALLS THROUGH THIS WEEKEND
WILL BE SNOW. MONDAY MAY BRING SOME LIGHT MIXED PRECIPITATION
EARLY AND 0.25" TO 0.50" OF RAIN DURING THE AFTERNOON.

ICE FORMATION ON BODIES OF WATER IS EXPECTED TO INCREASE AGAIN
THROUGH THE WEEKEND AS COLD AIR WILL BE IN PLACE ACROSS THE
REGION. TEMPS WILL BEGIN RISING LATE SUNDAY AND MONDAY…ONLY
COOLING TO NEAR OR SLIGHTLY ABOVE NORMAL NEXT WEEK.

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…WINTER WEATHER ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR
CTZ001-013.
NY…WINTER WEATHER ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR
NYZ063>066.
MA…NONE.
VT…NONE.

&&

$$
SYNOPSIS…SNYDER/SND
NEAR TERM…SNYDER/SND
SHORT TERM…BGM
LONG TERM…BGM
AVIATION…SNYDER
HYDROLOGY…BGM

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