102  
FXUS61 KALY 231821  
AFDALY  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE ALBANY NY  
121 PM EST FRI FEB 23 2018  
   
SYNOPSIS
 
 
ANOTHER SYSTEM WILL BRING A WINTRY MIXED PRECIPITATION  
TODAY, MAINLY INTO THE HIGHER TERRAIN. MILDER AND MAINLY DRY ON  
SATURDAY, BUT ANOTHER ROUND OF MIXED PRECIPITATION IS LIKELY LATE  
SATURDAY NIGHT INTO SUNDAY.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
AS OF 100 PM, POCKETS OF SHOWERS EXPANDING IN COVERAGE ACROSS  
THE FORECAST AREA, AND WILL CONTINUE TO DO SO THROUGH MID-  
AFTERNOON AS ISENTROPIC LIFT CONTINUES TO INCREASE. P-TYPE HAS  
BEEN MAINLY LIQUID WITH SOME FREEZING RAIN WHERE TEMPS ARE STILL  
BELOW FREEZING. COULD BE SOME LIGHT SLEET/SNOW STILL OVER  
WESTERN NEW ENGLAND AND THE LAKE GEORGE/GLENS FALLS AREA AS SPC  
MESOANALYSIS STILL INDICATED H850 TEMPS BELOW FREEZING. AS  
EXPECTED, SURFACE TEMPS HAVE BEEN SLOW TO BUDGE TODAY WITH EVEN  
SOME VALLEY AREAS REMAINING NEAR TO BELOW FREEZING EARLY THIS  
AFTERNOON. AN SPS WAS ISSUED FOR THOSE AREAS NOT IN THE ADVISORY  
FOR THE POSSIBILITY OF PATCHY ICY SPOTS. ELSEWHERE, HAVE  
EXTENDED THE ADVISORY WHICH WAS SET TO EXPIRE AT 1 PM INTO THE  
EVENING FOR THE MOHAWK VALLEY AND NORTHERN HERKIMER COUNTY WHERE  
TEMPS REMAIN IN THE UPPER 20S TO LOW 30S. WILL REEVALUATE IF WE  
CAN CANCEL SOME ZONES EARLY WITH THE NEXT UPDATE AROUND 4 PM.  
STILL EXPECTING ANY ICING TO BE AROUND A TENTH OR LESS, BUT A  
FEW HIGHER AMOUNTS ARE POSSIBLE OVER THE WESTERN MOHAWK VALLEY  
AND SOUTHERN ADIRONDACKS.  
 
PREVIOUS DISCUSSION...LIFT AND MOISTURE TRANSPORT WILL EXIT TO  
THE EAST OF THE REGION THROUGH THE EVENING HOURS. A WEAK THERMAL  
TROUGH LINGERS AS SLIGHT CHANCE POPS WILL BE KEPT THROUGH MOST  
OF THE NIGHT. QUESTION IS PRECIPITATION TYPE. PER SOUNDINGS,  
SEEMS WE LOSE THE ICE NUCLEI FOR EITHER A LIGHT SHOWER OR  
DRIZZLE AS THERMAL ADVECTION PROPERTIES WILL BE LITTLE HENCE NOT  
MUCH CHANGE TO THE TEMPERATURES FROM THE DAYTIME HIGHS TO THE  
FORECAST LOWS TONIGHT.  
 

 
   
SHORT TERM /SATURDAY THROUGH SUNDAY/
 
 
SATURDAY, LOW-LEVEL WINDS WILL BECOME WEST-NORTHWESTERLY AND  
USHER IN SLIGHTLY DRIER AIR AS WEAK HIGH PRESSURE EXPANDS INTO  
THE AREA AT ALL LEVELS. WE'LL START THE DAY FAIRLY MILD, AND  
DEPENDING ON THE AMOUNT OF CLEARING THAT OCCURS, WE COULD BE  
LOOKING AT A FAIRLY MILD DAY AS WE WILL FAVOR THE WARMER SIDE OF  
THE GUIDANCE ENVELOPE. CLOUDS INCREASE LATE IN THE DAY AHEAD OF  
THE NEXT SYSTEM, AND WE COULD EVEN SEE LIGHT PRECIPITATION  
BEGINNING IN THE EVENING OVER SOUTHERN ZONES AS YET ANOTHER  
ROUND OF ISENTROPIC LIFT BEGINS. SIMILAR TO OUR CURRENT SYSTEM,  
WET BULB PROCESSES MAY RESULT IN A PERIOD OF WINTRY MIXTURE,  
MAINLY NORTH AND EAST OF THE CAPITAL REGION AS LOW LEVEL  
AGEOSTROPHIC FLOW WILL REMAIN FROM THE NORTH FOR A PERIOD OF  
TIME. OTHERWISE, A PERIOD OF WET WEATHER EXPECTED SUNDAY.  
 

 
   
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
 
 
THROUGHOUT THE LONG TERM PERIOD, WE WILL SEE THE UPPER RIDGE OVER  
FLORIDA AND THE GULF FINALLY BREAK DOWN LEADING TO AN UNSETTLED  
WEATHER PATTERN OVER THE NORTHEAST CONUS.  
 
THE PERIOD STARTS OUT WITH A LOW PRESSURE SYSTEM PUSHING OFFSHORE  
WITH SOME LINGERING WINTRY PRECIP OVER THE EASTERN THIRD OF THE  
FORECAST AREA. THIS PRECIP SHOULD QUICKLY COME TO AND END SUNDAY  
NIGHT AS DRIER AIR AND HIGH PRESSURE BUILDS IN AT THE SURFACE.  
 
HIGH PRESSURE WILL STRENGTHEN OVER THE REGION THROUGH THE FIRST HALF  
OF THE WORK WEEK AS THE 850MB RIDGE BUILDS, ALLOWING FOR A PERIOD OF  
DRY WEATHER AND SLIGHTLY ABOVE NORMAL TEMPERATURES. THROUGH THIS  
PERIOD, HIGH TEMPERATURES WILL AVERAGE IN THE 40S TO LOW 50S, WITH  
OVERNIGHT LOWS IN THE 20S TO LOW 30S EACH DAY.  
 
THE NEXT POTENTIAL STORM SYSTEM DEVELOPS IN THE CENTRAL PLAINS AND  
MOVES TOWARDS THE GREAT LAKES BY THURSDAY. THIS SYSTEM IS QUITE  
COMPLEX AND DYNAMIC AS IT INVOLVES AN UPPER LEVEL SHORTWAVE MOVING  
INTO THE GREAT LAKES, A SURFACE LOW PRESSURE AND A POTENTIAL  
SECONDARY LOW THAT FORMS OUT OF THE SOUTHERN STREAM. GLOBAL MODELS  
ARE IN GOOD AGREEMENT WITH THE LOCATION OF THE SHORTWAVE BUT  
STRUGGLE WITH THE LOW FEATURES AND OVERALL STRENGTH OF THIS SYSTEM.  
DUE TO THE DISCONTINUITIES, HAVE BUMPED POPS DOWN FROM SUPERBLEND TO  
MAINTAIN CHANCE POPS FROM THURSDAY ONWARD INTO THE WEEKEND. A MIX OF  
RAIN/SNOW IS LIKELY DUE TO THE POTENTIAL PROLONGED PERIOD OF  
PRECIPITATION AND DIURNAL TEMPERATURE SWINGS EACH NIGHT.  
 

 
   
AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
 
 
SHOWERS WILL CONTINUE TO INCREASE ACROSS THE TERMINAL CORRIDOR  
INTO MID-AFTERNOON, WITH CIGS AND VSBY DROPPING TO MVFR/IFR.  
P-TYPE EXPECTED TO BE MAINLY LIQUID, ALTHOUGH SOME BRIEF  
SLEET/SNOW CANNOT BE RULED OUT EARLY THIS AFTERNOON. WITH  
TEMPERATURES NEAR FREEZING, SOME LIGHT FREEZING RAIN IS  
EXPECTED AT KGFL/KPSF THIS AFTERNOON. SHOWERS WILL DIMINISH  
AFTER 00Z, BUT SOME LINGERING SPOTTY SHOWERS OR DRIZZLE COULD  
CONTINUE. WITH A STEEP INVERSION DEVELOPING, LOW CLOUDS AND MIST  
ARE A GOOD POSSIBILITY OVERNIGHT, AT LEAST THROUGH 06Z, BEFORE  
LOW-LEVEL WINDS TURN WESTERLY AND USHER IN A BIT DRIER AIR. KPOU  
MAY REMAIN SOCKED IN ALL NIGHT.  
 
IMPROVING CONDITIONS SATURDAY WITH CIGS BECOMING VFR SHORTLY  
AFTER SUNRISE AS HIGH PRESSURE BRIEFLY BUILDS IN.  
 
WINDS WILL BE SOUTH TO SOUTHEAST FOR THE REST OF THE DAY AT  
AROUND 10 KT. THESE WINDS WILL GRADUALLY SHIFT WESTERLY  
OVERNIGHT WHILE DIMINISHING TO AROUND 5 KT, BUT MAINLY LIGHT  
AND VARIABLE AT KPOU. SURFACE WINDS SHOULD BE LIGHT ENOUGH TO  
SUPPORT LOW-LEVEL WIND SHEAR CONDITIONS OVERNIGHT AT AT LEAST  
KPOU/KPSF. WEST TO NORTHWEST WINDS SATURDAY MORNING INTO EARLY  
AFTERNOON WILL INCREASE TO AROUND 10 KT WITH SOME GUSTS AROUND  
20 KT AT KALB/KPSF.  
 
OUTLOOK...  
 
SATURDAY NIGHT: HIGH OPERATIONAL IMPACT. BREEZY LIKELY RA.  
SUNDAY: HIGH OPERATIONAL IMPACT. BREEZY DEFINITE RA.  
SUNDAY NIGHT: SLIGHT CHANCE OF RA.  
MONDAY: NO OPERATIONAL IMPACT. NO SIG WX.  
MONDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.  
TUESDAY: NO OPERATIONAL IMPACT. NO SIG WX.  
TUESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.  
WEDNESDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF RA...SN.  
 

 
   
HYDROLOGY
 
 
MAIN HYDROLOGIC CONCERN CONTINUES TO BE FLOODING DUE TO ICE JAMS  
ALONG THE MOHAWK RIVER IN CENTRAL SCHENECTADY, SOUTHERN SARATOGA AND  
NORTHEAST ALBANY COUNTIES, AS WELL AS THE HUDSON RIVER IN A SMALL  
AREA OF CENTRAL WARREN COUNTY. FLOOD WARNINGS OR FLOOD ADVISORIES  
ARE IN PLACE FOR THESE AREAS. REFER TO THE FLOOD STATEMENTS FOR  
ADDITIONAL DETAILS. THE MAIN LARGER ICE JAM HAS BROKEN INTO  
SMALL PIECES ON THE MOHAWK RIVER, BUT ARE SCATTERED BETWEEN LOCK  
9 AND COHOES FALLS. ICE JAMS APPEAR TO BE SETTLING IN PLACE,  
BUT SUDDEN MOVEMENT WILL STILL BE POSSIBLE TONIGHT INTO FRIDAY  
WHICH COULD CAUSE FLUCTUATIONS IN WATER LEVELS.  
 
OUTSIDE OF ICE JAM AREAS, ADDITIONAL WINTRY PRECIPITATION IS  
EXPECTED TODAY INTO THE WEEKEND, WITH RAIN AS WELL. WINTRY  
PRECIP INCLUDING FREEZING RAIN, IS EXPECTED FOR MAINLY HIGH  
ELEVATIONS AREAS. CURRENT FORECASTS CALL FOR AROUND A THREE  
QUARTERS OF AN INCH TO OVER AN INCH OF LIQUID EQUIVALENT  
PRECIPITATION DURING THIS TIME, WITH THE GREATEST AMOUNTS WEST  
OF THE HUDSON VALLEY. RUNOFF FROM THIS PRECIPITATION MAY RESULT  
IN ADDITIONAL RIVER RISES. TEMPERATURES ARE EXPECTED TO REMAIN  
ABOVE NORMAL DURING THIS TIME, BUT NOT AS WARM AS EARLIER THIS  
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...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR  
NYZ032-033-038>042-047-048-051-058-063-082-083.  
MA...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR  
MAZ001-025.  
VT...WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR  
VTZ013-014.  
 

 
 

 
SYNOPSIS...BGM/THOMPSON  
NEAR TERM...BGM/THOMPSON  
SHORT TERM...BGM/THOMPSON  
LONG TERM...JVM  
AVIATION...THOMPSON  
HYDROLOGY...BGM/JPV  
 
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