875
FXUS61 KALY 151744
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
1244 PM EST SAT DEC 15 2018
SYNOPSIS
HIGH PRESSURE WILL RIDGE IN FROM SOUTHEAST ONTARIO THIS
AFTERNOON WITH FAIR AND DRY WEATHER, AS TEMPERATURES WILL BE MILD
FOR MID DECEMBER WITH A NORTH TO NORTHWEST WIND. THOSE WINDS WILL
SLOWLY USHER IN COLDER AND DRIER AIRMASS TONIGHT. THEN A COMPLEX
STORM WILL EVOLVE ACROSS THE MIDDLE ATLANTIC COASTLINE ON SUNDAY AND
SPREAD A WINTRY MIXTURE ACROSS MOST OF THE REGION SUNDAY INTO SUNDAY
NIGHT. A STRONG COLD FRONT WILL MOVE THROUGH MONDAY ACCOMPANIED BY
SNOW SHOWERS AND POSSIBLE SQUALLS.
NEAR TERM /THROUGH TONIGHT/
AS OF 1230 PM EST...HIGH CLOUDS ARE STREAMING IN ACROSS THE
NORTHERN HALF OF THE FORECAST AREA WHERE SOME FILTERED PARTLY
SUNNY CONDITIONS ARE LIKELY THIS AFTERNOON. FURTHER SOUTH OF THE
I-90 CORRIDOR LOW CLOUDS ARE LINGERING WITH THE HIGH CLOUDS
ABOVE THEM, SO IT WILL LIKELY BE MOSTLY CLOUDY/CLOUDY BUT STILL
MILD AS THE COLDER AIR WILL GRADUALLY FILTER SOUTH LATE THIS
AFTERNOON INTO TONIGHT. WE REMOVED THE POPS OVER THE SOUTHERN
EXTREME OF THE FORECAST AREA BASED ON THE LATEST RADAR TRENDS,
BUT DID INCLUDE SOME PATCHY FOG FOR A FEW MORE HOURS NEAR KPOU
SOUTH AND EAST INCLUDING SOUTHERN LITCHFIELD COUNTY, CT.
WE INCREASED TEMPERATURES BASED ON THE OBSERVATIONAL TRENDS WITH
THE NORTH TO NORTHWEST WINDS, MAX TEMPS HAVE REACHED THE UPPER
40S IN PORTIONS OF THE CAPITAL REGION/MID AND UPPER HUDSON
VALLEY, SO WE COULD HAVE SOME READINGS AROUND 50F WHICH IS 10+
DEGREES ABOVE NORMAL. HIGHS WILL BE IN THE UPPER 30S TO LOWER
40S NORTH AND WEST OF THE CAPITAL REGION/GLENS FALLS AREA WITH
MID 40S TO AROUND 50F SOUTH AND EAST, EXCEPT SOME UPPER
30S/LOWER 40S OVER THE SOUTHERN GREENS. LOW LEVEL DEWPOINTS WILL
BECOME INCREASING DRIER THROUGH THE AFTERNOON HOURS WHICH WILL
LEAD INTO OUR FORECAST CHALLENGES IN THE SHORT TERM.
TONIGHT, MAINLY DRY AND CALM FOR THE REGION AS WE WATCH UPSTREAM
STORM OVER THE TENNESSEE VALLEY SLOWLY APPROACH WITH SURFACE
CYCLOGENESIS OVER THE MID-ATLANTIC UNFOLD. NEAR/SHORT TERM
GUIDANCE SUGGESTS THE CHANCES FOR PRECIPITATION MAY APPROACH
THE I84 CORRIDOR LATE TONIGHT YET DPROG/DT IS A BIT SLOWER WITH
THE ONSET DUE TO THE AFOREMENTIONED NORTHERLY FLOW WHICH
CONTINUES TO FILTER IN DRIER LOW LEVEL AIR. SO WE WILL CUT BACK
POPS FROM THE PREVIOUS FORECAST WITH THIS UPDATE. AS FOR
PRECIPITATION TYPES, VERY COMPLEX DUE TO THAT NORTHERLY LOW
LEVEL FLOW AND MILDER TEMPERATURES ALOFT. FORECAST SOUNDINGS AND
THICKNESSES SUGGEST THE POTENTIAL OF SLEET AND FREEZING RAIN AS
WET-BULB PROCESSES GET UNDERWAY. OVERNIGHT LOWS RANGE FROM THE
TEENS ACROSS THE MOUNTAINS TO NEAR THE FREEZING MARK NEAR THE
I84 CORRIDOR. THE LATEST 12Z NAM/GFS/HREF TRENDS INDICATE SOME
MIXED PCPN MAY GET IN THE LOCATIONS SOUTH AND WEST OF THE
CAPITAL REGION BEFORE DAYBREAK. SOME LIGHT FREEZING RAIN MAY BE
POSSIBLE, AND ADVISORIES MAY BE NEEDED LATER.
SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/
THE WORD 'COMPLEX' FOR PRECIPITATION TYPES AND THERMAL PROFILES
CONTINUES TO BE USED AS THE 00Z GUIDANCE DOES NOT SOLIDIFY
THINGS TOO MUCH. TRENDS IN THE OVERALL GUIDANCE HAS BEEN A
LITTLE STRONGER WITH THE SURFACE LOW ALONG THE COAST AND A BIT
CLOSER TO THE COAST AS WELL. HOWEVER, TEMPERATURES AND WET BULB
PROFILES VARY GREATLY ACROSS THE REGION ALONG WITH PERIODS OF
LIFT/OMEGA THAT WILL COMPLICATE PRECIPITATION TYPES EVEN
FURTHER. WITH THAT SAID, THE ONSET OF WINTRY MIXTURE ADVANCES
NORTHWARD THROUGH THE DAYLIGHT HOURS SUNDAY WITH THE BEST
POTENTIAL FOR RAIN CLOSER TO THE I84 CORRIDOR. THE PRECIP
INTENSITY SHOULD BE RATHER LIGHT THROUGH THE DAYLIGHT HOURS AS
BROAD ISENTROPIC LIFT WILL COMMENCE THROUGH THE DAY. THIS WILL
EVENTUALLY LEAD TOWARD WET-BULB PROCESSES TO OCCUR FOR MIXTURE
TO SOME SNOW WEST OF THE HUDSON RIVER THROUGH THE AFTERNOON
HOURS.
BY NIGHTFALL, THE SURFACE LOW INTENSIFIES AND PASSES CLOSE TO
THE BENCHMARK FOR PRECIPITATION TO SPREAD NORTHWEST ACROSS MOST
OF THE REGION. AGAIN, COMPLEX THERMAL PROFILES FROM NORTHWEST TO
SOUTHEAST AS SEEN IN CROSS SECTIONS WET BULB PROFILES ALONG WITH
SURFACE TEMPERATURE IN THE LOW AND MID 30S. AFTER CLOSE
COORDINATION AND UTILIZING PARTIAL THICKNESS AND TOP-DOWN
TECHNIQUES, THE BEST POTENTIAL FOR ICE ACCUMULATION SEEMS TO BE
AT OR ABOVE 1000 FEET, ESPECIALLY FOR PORTIONS OF THE CATSKILLS,
BERKS AND SOUTHERN GREENS. WHERE LIFT BECOMES MAXIMIZED, THIS
COULD BISECT THE DENDRITIC ZONE FOR A PERIOD OF TIME WHERE A
PERIOD OF MODERATE SLEET AND SNOW MAY OCCUR ACROSS THE CENTER OF
THE CWA. FURTHER NORTH AND WEST, THESE AREAS WILL LIKELY BE
LIGHTER WITH PRECIPITATION AMOUNTS AND REDUCED IMPACTS. DUE TO
RATHER LOWER CONFIDENCE IN PRECIP TYPES, WE WILL NOT ISSUE ANY
HEADLINES WITH THIS UPDATE BUT WILL LIKELY BE NEEDED WITH FUTURE
FORECAST UPDATES.
LONG TERM /MONDAY THROUGH FRIDAY/
ARCTIC FRONTAL BOUNDARY AND ASSOCIATED UPPER LEVEL DISTURBANCE WILL
BE MOVING THROUGH THE REGION FOR MONDAY. ALTHOUGH MOISTURE WILL BE
SOMEWHAT LIMITED, STRONG FORCING AND STEEP LAPSE RATES ALOFT WILL
PROMOTE THE DEVELOPMENT OF SCATTERED SNOW SHOWERS AND SQUALLS. IT'S
POSSIBLE THAT SOME VALLEY AREAS COULD ALSO SEE RAIN SHOWERS, BUT
WITH DRY LOW-LEVELS AND COLD TEMPS ALOFT, ANY PRECIP WILL ANY DECENT
INTENSITY SHOULD FALL AS SNOW SHOWERS. SQUALLS MAY BRIEFLY LOWER
VISIBILITY AND ALLOW FOR SLICK CONDITIONS (ESPECIALLY NORTH AND WEST
OF THE CAPITAL REGION AND ACROSS THE HIGH TERRAIN). HIGHS WILL BE
REACHED EARLY IN THE DAY, REACHING INTO THE MID TO UPPER 30S FOR
VALLEY AREAS, BEFORE FALLING IN THE AFTERNOON BEHIND THE COLD FRONT.
A FEW UPSLOPE AND LAKE-ENHANCED SNOW SHOWERS WILL CONTINUE INTO
MONDAY NIGHT ACROSS THE HIGH TERRAIN, BUT THIS SHOULD END BY TUESDAY
MORNING AS HIGH PRESSURE QUICKLY BUILDS INTO THE AREA FROM THE
MIDWEST. LOWS ON MONDAY NIGHT WILL BE IN THE TEENS AND 20S WITH
GUSTY NORTHWEST WINDS. HIGHS ON TUESDAY WILL BE NOTICEABLY COLDER
THAN RECENT DAYS, WITH TEMPS ONLY IN THE 20S. IT WILL STILL BE A
LITTLE BREEZY, ALTHOUGH THE WIND SHOULD BE DECREASING BY LATER IN
THE DAY AS THE HIGH GETS CLOSER TO THE AREA.
GOOD RADIATIONAL COOLING WILL SET UP FOR TUESDAY NIGHT WITH LIGHT
WINDS AND MAINLY CLEAR SKIES. TEMPS LOOK TO FALL INTO THE TEENS,
WITH SOME SINGLE DIGITS OVER THE ADIRONDACKS. DRY AND QUIET WEATHER
WILL CONTINUE FOR WEDNESDAY, ALTHOUGH IT WILL BE A LITTLE MILDER,
WITH HIGHS GENERALLY IN THE 30S.
THE NEXT STORM SYSTEM WILL BE ARRIVING FOR LATE IN THE WEEK. A
LARGE DIGGING TROUGH OVER THE MISSISSIPPI VALLEY LOOKS TO TAKE ON A
NEGATIVE TILT AND EVENTUALLY CLOSE OFF. MEANWHILE, A SURFACE STORM
DEVELOPING OVER THE DEEP SOUTH WILL LIFT NORTHWARD ACROSS THE
APPALACHIANS FOR THURSDAY INTO FRIDAY. WITH THIS STORM TAKING ON
MORE A WESTERLY TRACK (AS SHOWN IN THE 00Z ECMWF, GFS AND GGEM), OUR
AREA WOULD BE ON THE WARMER EASTERN SIDE OF THIS STORM. ASIDE FROM
A LITTLE WINTRY MIX OVER THE ADIRONDACKS AT THE INITIAL ONSET LATE
THURSDAY, MOST OF THE PRECIP FOR THURSDAY NIGHT THROUGH FRIDAY WILL
BE IN THE FORM OF RAIN, AS TEMPS ALOFT WARM UP CONSIDERABLY AND
SURFACE TEMPS RISE INTO UPPER 30S TO UPPER 40S. THIS SYSTEM LOOKS TO
TAP INTO PLENTY OF GULF AND ATLANTIC MOISTURE, SO SOME APPRECIABLE
RAINFALL AMOUNTS COULD POTENTIAL OCCUR BASED ON THE CURRENT FORECAST
TRACK, WHICH COULD BE SUBJECT TO CHANGE. BEHIND THE STORM, RAIN
SHOWERS COULD BRIEFLY CHANGEOVER TO SNOW SHOWERS BEFORE ENDING
ACROSS WESTERN AND HIGH TERRAIN AREAS FOR FRIDAY NIGHT INTO
SATURDAY.
AVIATION /18Z SATURDAY THROUGH THURSDAY/
A STORM SYSTEM PASSING BY TO THE SOUTH WILL ALLOW FOR PLENTY OF
CLOUDS ACROSS OUR AREA TODAY BUT ANY PRECIP SHOULD STAY WELL
SOUTH AND EAST OF THE REGION.
SKIES WILL BRIEFLY CLEAR OUT THIS EVENING WITH MAINLY CLEAR
SKIES, BUT SOME HIGH AND MID LEVEL CLOUDS WILL RETURN TO THE
REGION AFTER MIDNIGHT. FLYING CONDITIONS LOOK TO VFR THROUGH THE
OVERNIGHT.
SOME LIGHT PRECIP MAY START TO MOVE TOWARDS KPOU BY
DAYBREAK SUNDAY AND THEN EXPAND NORTHWARD THROUGHOUT THE MORNING
HOURS. FLYING CONDITIONS WILL DETERIORATE FROM SOUTH TO NORTH
FROM MID-MORNING INTO THE AFTERNOON, BUT ESPECIALLY BY THE END
OF THE TAF FORECAST PERIOD AS A WINTRY MIX ENVELOPES THE REGION.
PRECIPITATION TYPE IS STILL IN QUESTION SO HAVE ACCOUNTED FOR
MULTIPLE P-TYPES IN THE CURRENT TAFS. HIGHEST IMPACT OF THE
WINTRY MIX LOOKS LIKE IT WILL OCCUR LATE IN THE FORECAST PERIOD
AND BEYOND.
WINDS FROM THE WEST WILL CONTINUE DURING THE DAY AND EVENTUALLY
SWITCH TO THE NORTH BY LATE IN THE DAY AROUND 5 KTS. WINDS WILL
BECOME NORTH TO NORTHEAST OVERNIGHT AT 5 KTS OR LESS.
OUTLOOK...
SUNDAY NIGHT: HIGH OPERATIONAL IMPACT. LIKELY SN...FZRA...SLEET.
MONDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...SHSN.
MONDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
TUESDAY: NO OPERATIONAL IMPACT. NO SIG WX.
TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
WEDNESDAY: NO OPERATIONAL IMPACT. NO SIG WX.
WEDNESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.
THURSDAY: NO OPERATIONAL IMPACT. NO SIG WX.
HYDROLOGY
TEMPERATURES WILL REMAIN MILD FOR THE FIRST HALF OF THE
WEEKEND.
DRY WEATHER IS EXPECTED TODAY BEFORE SOME LIGHT MIXED PCPN
MOVES INTO THE SOUTHERN EXTREME OF THE HYDRO SERVICE AREA
SUNDAY MORNING. THE MIXED PCPN WILL EXPAND ACROSS THE REGION ON
SUNDAY BEFORE TRANSITIONING BACK TO SNOW SUNDAY NIGHT WITH LIGHT
ACCUMULATIONS OF ICE AND SNOW EXPECTED. TOTAL QPF FOR THIS
EVENT WILL RANGE FROM A TENTH OF AN INCH OF LESS OVER THE
NORTHERN PORTION OF THE HSA WITH A HALF TO THREE QUARTERS OF AN
INCH OVER THE MID HUDSON VALLEY, SOUTHEAST CATSKILLS AND
LITCHFIELD HILLS. SOME WITHIN BANK RISES ARE POSSIBLE ON THE
MAIN STEM RIVERS DUE TO SOME RAIN, MIXED PCPN AND SNOW MELT, BUT
FLOODING IS NOT EXPECTED AT THIS TIME (CAUTION STAGE FOR
STEVENSON DAM WHICH IS REGULATED).
A STRONG COLD FRONT MOVES THROUGH ON MONDAY WITH MUCH COLDER
AIR MOVING INTO THE REGION FOR TUESDAY, AS FLOWS WILL CONTINUE
TO LOWER DURING THE EARLY TO MIDDLE PORTION OF NEXT WEEK WITH
SOME ICE BUILD UP POSSIBLE.
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...BGM/WASULA
NEAR TERM...BGM/JLV/WASULA
SHORT TERM...BGM
LONG TERM...FRUGIS
AVIATION...FRUGIS/JLV
HYDROLOGY...BGM
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