Forecast Discussion

000
FXUS61 KALY 030825
AFDALY

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
325 AM EST MON MAR 3 2014

.SYNOPSIS…
A BITTERLY COLD AIR MASS WILL SETTLE ACROSS THE REGION THROUGH
THIS FIRST HALF OF THE WEEK. A SLIGHT MODERATION IN THE
TEMPERATURES ARE EXPECTED TOWARD THE LATER HALF OF THE WEEK THAT
WILL BE ACCOMPANIED WITH SOME PERIODS OF LIGHT SNOW.

&&

.NEAR TERM /THROUGH TODAY/…
SURFACE ANALYSIS SHOWS THE ARCTIC BOUNDARY HAS PROGRESSED SOUTH OF
THE MASON-DIXON LINE WITH THE WAVE OF LOW PRESSURE OVER THE VA/NC
BORDER. REGIONAL RADAR MOSAIC REVEALS AN INCREASE IN REFLECTIVITY
OVER THE LOWER HUDSON VALLEY AND SOUTHERN CT…HOWEVER…SURFACE
OBSERVATIONS SUGGEST THIS IS MAINLY VIRGA DUE TO HIGH DEWPOINT
DEPRESSIONS. IF THE COLUMN WERE TO SATURATE ENOUGH…SEEMS THIS
WOULD OCCUR JUST SOUTH OF OUR CWFA SO NO MENTION OF SNOW IN THE
FORECAST THROUGH TODAY. AS THE ARCTIC DRY ENTRAINMENT ADVECTS
SOUTHWARD ACROSS OUR REGION WITH PWATS LESS THAN ONE TENTH OF
INCH…H850 TEMPS AVERAGING AROUND -15C…ALONG WITH INCREASING
SUNSHINE FROM NORTH TO SOUTH…HIGH TEMPERATURES WILL CONTINUE TO
STRUGGLE TO REACH /OR MAINTAIN STEADY VALUES OF ACROSS THE MID
HUDSON VALLEY AND SOUTHERN LITCHFIELD COUNTY/ 20F ACROSS MOST OF THE
REGION. A NORTHERLY WIND WILL CONTINUE AS MIXING LAYER HEIGHTS AOA
H925 SUGGEST A FEW GUSTS INTO THE MID TEENS /KNOTS/.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/…
TONIGHT…
A VERY COLD NIGHT IS EXPECTED ACROSS THE ENTIRE REGION TONIGHT AS
SKIES SHOULD REMAIN RELATIVELY CLEAR ALONG WITH LIGHT WINDS. THIS
SHOULD SET THE STAGE FOR NEAR IDEAL RADIATIONAL COOLING WITH MOST
AREAS EXPECTED TO FALL BELOW ZERO TONIGHT. THERE WILL BE SOME
INCREASE IN HIGH LEVEL MOISTURE AS THE SYSTEM TRACKING ACROSS THE
NORTHWEST CONUS QUICKLY MOVES OUT ONTO THE NORTHERN PLAINS AND
GREAT LAKES REGION OVERNIGHT. BY THE TIME THAT OCCURS…THE LOW
TEMPS WILL LIKELY ALREADY HAVE OCCURRED. OVERNIGHT LOWS WILL RANGE
FROM NEAR -20F ACROSS THE DACKS TO JUST BELOW ZERO ACROSS THE
SOUTHERN PORTIONS OF CWFA.

TUESDAY…
THE AFOREMENTIONED HIGHER LEVEL MOISTURE IS DUE TO THE SYSTEM
MOVING ASHORE ACROSS THE NORTHWEST CONUS. THE AGEOSTROPHIC
RESPONSE ACROSS THE NORTHERN PLAINS INCREASES THE SOUTHERLY LOW
LEVEL JET WHICH RESULTS IN BROAD ISENTROPIC LIFT SETTING UP OVER
THE NORTHERN MISSISSIPPI RIVER VALLEY AND GREAT LAKES REGION. NCEP
MODEL SUITE AGREES WITH THE INTERNATIONAL GLOBAL CONSENSUS OF
INCREASING CLOUD COVER /MAINLY NORTHERN 2/3RDS OF THE CWFA/ AND
PERHAPS A PERIOD OF LIGHT SNOW. EITHER WAY…QPF REMAINS VERY
LIGHT WITH MOST AMOUNTS LESS THAN ONE TENTH OF AN INCH. THE
COMBINATION OF CLOUD COVER AND A RATHER COLD START…WE WILL
UNDERCUT MOS NUMBERS BY A COUPLE OF DEGREES.

TUESDAY NIGHT…
THE BROAD ISENTROPIC LIFT LOSES ITS DEFINITION AS THE WEAKENING
WAVE PASSES OFFSHORE. HOWEVER…AMPLE LOWER LEVEL TROPOSPHERIC
MOISTURE REMAINS IN PLACE. IT DOES SEEM ANOTHER ARCTIC BOUNDARY
EVOLVES ACROSS THE REGION AS 1035MB SURFACE FROM HUDSON BAY
STRENGTHENS AND SLIDES SOUTHWARD. THIS SHOULD ENHANCE LOW LEVEL
CONVERGENCE ALONG WITH FAIRLY TIGHT BAROCLINICITY TO KEEP SLIGHT
CHC TO CHC POPS ACROSS THE ENTIRE REGION. WE WILL MAINTAIN THE
HIGHER POPS IN THE TERRAIN AS OVERNIGHT LOWS ARE EXPECTED TO BE
MILDER DUE TO THE MOISTURE AND CLOUDS IN PLACE WITH MAINLY SINGLE
DIGITS AND TEENS.

WEDNESDAY…
THE UPPER LEVEL FLOW REMAINS RATHER PROGRESSIVE AND CONFLUENT.
THERMAL GRADIENT/BAROCLINIC ZONE REMAINS ACROSS UPSTATE NY AND
SOUTHERN NEW ENGLAND. MODELS ATTEMPT TO BRING ANOTHER WAVE ACROSS
THE REGION WITH LIGHT QPF. HENCE…WE WILL RETAIN THE LOW CHC POPS
ACROSS THE REGION. THE THERMAL PROFILES POINT TOWARD SLIGHT
MODERATION AND THE CONSENSUS MOS CONFIRMS THIS NOTION WITH
TEMPERATURES APPROACHING MIDDLE 20S WITH SOME LOWER 30S ACROSS THE
MID HUDSON VALLEY AND SOUTHERN LITCHFIELD COUNTY.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/…
A FAST MOVING…BUT MOISTURE STARVED…NORTHERN STREAM SHORTWAVE
WILL BE APPROACHING THE REGION FOR WEDNESDAY NIGHT INTO THURSDAY.
WARM ADVECTION AHEAD OF THIS FEATURE WILL ALLOW FOR SOME LIGHT
SNOW/SNOW SHOWERS ACROSS THE REGION WEDNESDAY NIGHT…WITH SOME
ADDITIONAL SNOW SHOWERS DURING THE DAY THURSDAY. THE BEST CHANCE TO
SEE SNOW SHOWERS WILL BE ACROSS HIGH TERRAIN AND NORTHERN PARTS OF
THE REGION. QPF LOOKS RATHER LOW DUE TO LIMITED MOISTURE…AND DRY
AIR AT LOW LEVELS WILL LIKELY CAUSE SOME OF THIS TO BE LOST AS
VIRGA. HAVE GONE WITH SLIGHT CHC TO CHC POPS DURING WED NIGHT INTO
THURSDAY DUE TO THIS FEATURE…WITH CONTINUED BELOW NORMAL TEMPS
/SINGLE DIGITS AND TEENS FOR WED NIGHT AND 20S TO LOW 30S FOR
THURSDAY/.

BEHIND THIS FEATURE…THE FLOW AT 500 HPA LOOKS TO BECOME MORE ZONAL
ACROSS MUCH OF THE CONUS. THIS WILL ALLOW TEMPS TO MODERATE
SOMEWHAT…ALTHOUGH TEMPS WILL LIKELY STILL REMAIN SLIGHTLY BELOW
NORMAL…WITH 30S TO PERHAPS NEAR 40 FOR HIGHS…AND 20S AT
NIGHT…AS SOME COLD AIR WILL CONTINUE TO FILTER IN WITHIN THE
NORTHWEST FLOW BEHIND FAST MOVING CLIPPER SYSTEMS.

THE MODELS CONTINUE TO SHOW A SOUTHERN STREAM LOW PRESSURE AREA
REMAINING WELL SOUTH AND EAST OF THE AREA FRIDAY…SO HAVE ONLY GONE
WITH SLIGHT CHC POPS FOR SNOW SHOWERS FOR FRIDAY THROUGH THE WEEKEND
DUE TO THE EXPECTED CLIPPER SYSTEMS…AS ANY PRECIP LOOKS RATHER
SPOTTY.

&&

.AVIATION /08Z MONDAY THROUGH FRIDAY/…
VFR CONDITIONS WILL CONTINUE THROUGH THE ENTIRE TAF PERIOD FOR ALL
TERMINALS.

IN THE WAKE OF AN ARCTIC FRONTAL BOUNDARY…LINGERING MID/HIGH
LEVELS CLOUDS WITH BKN-OVC CIGS WILL CONTINUE THROUGH THE REMAINDER
OF THE OVERNIGHT HOURS FOR KALB/KPSF/KPOU. SKIES ARE NEARLY CLEAR
ALREADY AT KGFL WITH JUST SOME HIGH CIRRUS REMAINING. SOME STRATOCU
AROUND 6 KFT WILL ALSO OCCUR AT KPOU…ESP OVER THE NEXT FEW HOURS.
ALL THESE CLOUDS WILL START TO SCT OUT AFTER SUNRISE…WITH ALL
SITES SEEING JUST SOME PASSING HIGH CIRRUS BY THE AFTN HOURS. ALL
TERMINALS LOOK TO HAVE CLEAR SKIES BY THE EVENING HOURS.

NW WINDS WILL CONTINUE AROUND 5-10 KTS OVERNIGHT FOR
KALB/KPSF/KPOU…WITH A FEW HIGHER GUSTS ACROSS THE HIGH TERRAIN OF
THE BERKSHIRES. WINDS WILL START TO LOWER TOWARDS DAYBREAK.
MEANWHILE…THE DECOUPLING BOUNDARY LAYER HAS ALLOWED FOR CALM WINDS
AT KGFL…AND WINDS SHOULD REMAIN CALM THERE THROUGH THE OVERNIGHT
HOURS. DURING DAYTIME MIXING…NW WINDS OF 5-10 KTS WILL OCCUR
THROUGH THE DAY ON MONDAY…WITH A FEW HIGHER GUSTS AT KALB/KPSF.
ALL SITES LOOK TO FINALLY HAVE WINDS DIMINISHING…WITH LIGHT TO
CALM WINDS BY MONDAY EVENING.

OUTLOOK…
MONDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
TUESDAY-WEDNESDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SN.
WEDNESDAY NIGHT-FRIDAY: NO OPERATIONAL IMPACT. NO SIG WX.

&&

.HYDROLOGY…
NO WIDESPREAD HYDRO IMPACTS ARE EXPECTED ON THE MAIN STEM RIVERS
THE NEXT 5 DAYS. AN ARCTIC AIR MASS WILL REMAIN ACROSS THE HYDRO
SERVICE AREA INTO THE MIDDLE OF THE WEEK. THIS WILL ALLOW ICE TO
REFORM…THICKEN…AND STRENGTHEN ON AREA RIVERS AND LAKES THROUGH
MOST OF THE UPCOMING 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…NONE.
NY…WIND CHILL ADVISORY UNTIL 10 AM EST THIS MORNING FOR NYZ032-
033-042-082.
MA…NONE.
VT…NONE.

&&

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

FOR THE LATEST UPDATES…PLEASE VISIT OUR WEBPAGE AT
WWW.WEATHER.GOV/ALBANY

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