536  
FXUS61 KALY 190000  
AFDALY  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE ALBANY NY  
800 PM EDT SAT AUG 18 2018  
   
SYNOPSIS
 
 
A COLD FRONT WILL MOVE SOUTHWARD THROUGH THE SOUTHERN NEW YORK  
AND SOUTHERN NEW ENGLAND THIS EVENING. A DRIER AIRMASS WILL MOVE  
IN BEHIND THE FRONT THIS EVENING. SUNDAY AND MONDAY ARE  
EXPECTED TO BE MAINLY DRY AND MUCH LESS HUMID, ALTHOUGH A FEW  
SHOWERS ARE POSSIBLE FROM TIME TO TIME OVER FAR SOUTHERN AREAS.  
 

 
   
NEAR TERM /THROUGH SUNDAY/
 
 
AS OF 745 PM EDT, COOLER AND DRIER AIR CONTINUES TO FILTER INTO  
THE REGION FROM THE NORTH, RESULTING IN LOWER DEW POINTS AND  
BREEZY CONDITIONS. CLOUDS CONTINUE TO LINGER, HOWEVER, WITH  
SOME LOW TO MID LEVEL MOISTURE EVIDENT IN THE GOES-16 LAYERED WV  
IMAGERY. TEMPERATURES ARE CURRENTLY IN THE 60S BUT ARE EXPECTED  
TO DIP INTO THE UPPER 50S TO MID 60S OVERNIGHT. THIS IS ON TRACK  
WITH THE CURRENT FORECAST SO HAVE FRESHENED UP THE HOURLY TEMPS  
AND SENT THE UPDATE TO NDFD AND WEB SERVERS. FURTHER DETAILS  
REGARDING THE FORECAST FOLLOW...  
 
AS OF 145 PM EDT, SHOWERS AND THUNDERSTORMS ARE ONGOING AHEAD  
OF A COLD FRONT FROM THE BERKSHIRES SOUTHWESTWARD TO NORTHEAST  
PENNSYLVANIA. THE COLD FRONT WILL CONTINUE TO PUSH SOUTHEAST  
THROUGH THE REMAINDER OF THE FORECAST AREA LATER THIS AFTERNOON  
AND THIS EVENING. THE FRONT WILL BE INTERSECTING A STILL-MOIST  
AIRMASS CHARACTERIZED BY PWATS OF 1.75 TO 2.00 INCHES, SO IT  
WILL BE ACCOMPANIED BY SCATTERED SHOWERS AND THUNDERSTORMS. SOME  
OF THE STORMS STILL HAVE THE POTENTIAL TO PRODUCE LOCALLY HEAVY  
RAINFALL, ESPECIALLY ALONG AND SOUTH OF A LINE FROM THE SOUTHERN  
BERKSHIRES TO WESTERN ULSTER COUNTY WHERE MORE FAVORABLE  
FRONTAL TIMING MAY ALLOW FOR SOME RESPECTABLE SURFACE-BASED  
INSTABILITY OF 1000-2500 J/KG TO DEVELOP GIVEN DEWPOINTS IN THE  
LOW 70S AND TEMPERATURES HEATING UP INTO THE UPPER 70S/LOW 80S.  
THE FRONT SHOULD BE FAIRLY PROGRESSIVE WHICH WILL LIMIT A MORE  
SUBSTANTIAL FLASH FLOODING THREAT, BUT WILL HAVE TO ESPECIALLY  
WATCH AREAS THAT SAW HEAVY RAIN ON FRIDAY FOR LOCALIZED FLOODING  
CONCERNS. DEEP-LAYER SHEAR VALUES FORECAST TO BE 25 TO 30 KTS  
PRESENTS A MARGINAL OPPORTUNITY FOR STORMS TO BE ORGANIZED, WITH  
SEVERAL CAMS SHOWING A BROKEN LINE OF CONVECTION OCCURRING  
ALONG THE FRONT. ISOLATED GUSTY WINDS CANNOT BE RULED OUT. MAIN  
THREAT PERIOD FOR GUSTY WINDS AND HEAVY RAIN APPEARS TO BE  
ROUGHLY THROUGH 22Z.  
 
FOR THE AREAS NORTH OF THE FRONTAL BOUNDARY, A DRYING TREND IS  
EXPECTED WITH BREAKS OF SUNSHINE TOWARDS EVENING IN THE WAKE OF  
THE FRONT. HIGH TEMPS ARE A LITTLE TRICKY, BUT HAVE SIDED AWAY  
FROM THE MET MOS GUIDANCE WHICH APPEARS TO BE A COOL OUTLIER.  
HIGHS ARE EXPECTED TO RANGE FROM THE UPPER 60S TO LOWER 80S.  
 
TONIGHT, WE'LL BE IN A LOW-LEVEL NORTHEASTERLY FLOW REGIME IN  
THE WAKE OF THE FRONT AS THE DEEPER MOISTURE SHIFTS SOUTH OF THE  
REGION. A COUPLE OF LINGERING SHOWERS ARE POSSIBLE ACROSS THE  
EXTREME SOUTHEAST PORTION OF THE FORECAST AREA. TO THE NORTH, IT  
IS A TRICKY CALL WITH RESPECT TO SKY COVER AS SOME GUIDANCE  
INDICATES A MIDLEVEL CLOUD DECK DEVELOPING IN THE COLD  
ADVECTION. OUTSIDE OF THIS AREA, SOME PATCHES OF FOG ARE  
POSSIBLE ACROSS NORTHERN ZONES AS HIGH PRESSURE BUILDS FROM THE  
NORTH. IT WILL BE NOTICEABLY LESS HUMID WITH DEWPOINTS IN THE  
MID 50S TO MID 60S WITH LOWS IN THE MID 50S TO MID 60S.  
 
THE FRONTAL BOUNDARY IS EXPECTED TO STALL SOMEWHERE IN THE  
VICINITY OF THE DELMARVA SUNDAY, WHILE A WEAK MID-LEVEL TROUGH  
EXISTS OVER THE MID-ATLANTIC INTO THE NORTHEAST. WILL RETAIN  
LOW CHANCE POPS OVER SOUTHERN PORTIONS OF ULSTER/DUTCHESS/LITCHFIELD  
SUNDAY TO ACCOUNT FOR POSSIBLE FURTHER SHIFTS NORTHWARD OF A  
WAVE OF LOW PRESSURE ALONG THE FRONTAL BOUNDARY. FOR THE  
REMAINDER OF THE FORECAST AREA, DRY EAST TO NORTHEAST FLOW AT  
LOW/MID LEVELS SHOULD KEEP THINGS DRY, ALTHOUGH WE MAY SEE SOME  
HIGH CLOUDS. HIGHS SUNDAY MAINLY IN THE UPPER 60S TO UPPER 70S.  
 

 
   
SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/
 
 
SUNDAY NIGHT, DEPARTING UPPER LOW NEAR THE I84 CORRIDOR WILL  
EXIT OFF THE NEW ENGLAND COAST AS RIDGE OF HIGH PRESSURE AT THE  
SURFACE WILL LIKELY BUILD IN FROM THE NORTH-NORTHEAST. THIS MAY  
BRING SOME ADDITIONAL MOISTURE OFF THE ATLANTIC INTO OUR NEW  
ENGLAND COUNTIES, OTHER THE REMAINDER OF THE REGION THIS HIGH  
SHOULD ALLOW FOR GOOD RADIATIONAL COOLING CONDITIONS UNDER  
PARTLY CLOUDY TO MOSTLY CLEAR SKIES. HAVE BLENDED WITH GUIDANCE  
AND PREVIOUS FORECAST WITH NEAR SEASONAL NORMALS. DEWPOINTS  
SETTLE BACK INTO THE 50S.  
 
HIGHER CONFIDENCE IN A DRY FORECAST AND MORE CLEARING SKIES FOR  
THE ENTIRE FORECAST AREA MONDAY INTO MONDAY NIGHT. BOTH THE  
RIDGE AT THE SURFACE AND ALOFT INCREASE SO TRANQUIL AND NEAR  
SEASONABLE TEMPERATURES FOR THE LATER HALF OF AUGUST.  
 
TUESDAY, GLOBAL MODELS ARE A LITTLE SLOWER WITH THE APPROACH OF  
THE NEXT UPSTREAM STORM SYSTEM SET TO IMPACT THE CENTRAL AND  
NORTHERN MISSISSIPPI RIVER VALLEY. SO WE WILL REDUCE THE ONSET  
OF POPS/WX IN THE MORNING HOURS AND CONTINUE WITH POPS INTO THE  
AFTERNOON HOURS WITH THE HIGHER VALUES TO THE WEST OF THE HUDSON  
RIVER. CLOUDS WILL INCREASE THROUGH THE DAY AS TEMPERATURES  
SHOULD CLIMB TOWARD 80F FOR VALLEY LOCATIONS AND LOW-MID 70S  
ELSEWHERE.  
 

 
   
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
 
 
AN IMPRESSIVE LOW PRESSURE FOR LATE AUGUST MOVES UP THE SAINT  
LAWRENCE RIVER VALLEY TUESDAY NIGHT INTO WEDNESDAY. INITIALLY,  
PRECIPITATION ASSOCIATED WITH THE SYSTEM'S WARM FRONT MAY STRUGGLE  
TO REACH INTO EASTERN NY/WESTERN NEW ENGLAND AS HIGH PRESSURE  
MAINTAINS CONTROL OVER EASTERN NEW ENGLAND. HOWEVER, BY 06Z  
WEDNESDAY, ENOUGH WARM AIR ADVECTION ASSOCIATED WITH THE SYSTEM'S 35-  
45KTS 850MB JET SHOULD PUSH NORTHEASTWARD INTO OUR REGION LEADING TO  
WIDESPREAD PRECIPITATION. WE SHOULD BE WITHIN IN THE WARM SECTOR  
DURING THE OVERNIGHT HOURS AND WITH DEWPOINTS VERY MILD IN THE MID  
- UPPER 60S, IT SHOULD BE A HUMID NIGHT. PWATS LOOK TO BE OVER 1.5 -  
2 INCHES WITH THE HUDSON VALLEY POTENTIALLY OVER 2".  
 
IT'S WORTH NOTING THAT THE GFS AND CANADIAN SUGGEST A STRONGER 500MB  
HEIGHT AND WIND FIELD ASSOCIATED WITH THIS LOW TUESDAY NIGHT INTO  
WEDNESDAY OVER THE EURO. THESE MODELS SUGGEST THAT THE INITIAL  
NEUTRALLY TITLED 500MB TROUGH STRENGTHS, FORMS A CLOSED LOW OVER  
SOUTHERN CANADA AND TURNS NEGATIVELY TITLED HEADING INTO 12Z  
WEDNESDAY AS THE TROUGH AXIS MOVES THROUGH EASTERN NY/WESTERN NEW  
ENGLAND. SHOULD THIS OCCUR, WE MAY HAVE SOME STRONG TO EVEN SEVERE  
WEATHER TO CONTEND WITH WEDNESDAY MORNING. WHILE INSTABILITY IS  
LACKING WITH UNDER 1000J/KG OF MLCAPE SHOWING ON MOST PIECES OF  
GUIDANCE, THIS COULD BE A HIGH SHEAR LOW CAPE ENVIRONMENT AS 0-6KM  
SHEAR LOOKS TO BE 40-45KTS THANKS TO THE IMPRESSIVE 500MB WIND FIELD  
OF 50-55KTS. MID-LEVEL LAPSE RATES ARE DECENT AS WELL RANGING 5.5-  
6C/KM. THEREFORE, THE PERIOD FROM 12Z-18Z WEDNESDAY WILL NEED TO BE  
MONITORED FOR A POTENTIAL LINE OF STRONG TO SEVERE STORMS AS THE  
TROUGH AXIS/SURFACE COLD FRONT PROGRESSES THROUGH EASTERN NY/WESTERN  
NEW ENGLAND. GIVEN THE HIGH HUMIDITY, ANY STORM WILL BE CAPABLE OF  
HEAVY DOWNPOURS.  
 
BY WEDNESDAY AFTERNOON AND NIGHT, IT LOOKS TO TURN BREEZY AS THE  
IMPRESSIVE SURFACE LOW (WHICH ITS 990-995MB MSLP 3-4 STANDARD  
DEVIATIONS BELOW NORMAL FOR THIS TIME OF YEAR ACCORDING TO THE GFES)  
MOVES THROUGH NORTHERN NEW ENGLAND/SOUTHERN CANADA LEADING TO A  
DECENT PRESSURE RISE/FALL COUPLET AND ISALLOBARIC WIND FIELD.  
INCREASED WIND GUSTS TO 20-30MPH FOR WEDNESDAY AFTERNOON TO REFLECT  
THIS THREAT, ESPECIALLY IN THE DACKS AND SOUTHERN VT WHERE THE  
ISALLOBARIC WINDS LOOKS TO BE STRONGEST. COLD ADVECTION WILL LEAD TO  
GRADUALLY FALLING TEMPERATURES WEDNESDAY AFTERNOON AS WELL AND WE  
SHOULD SEE A DRASTIC DROP IN HUMIDITY HEADING INTO WEDNESDAY NIGHT.  
OVERNIGHT LOWS SHOULD BE COMFORTABLE FALLING INTO THE 50S.  
 
PLEASANT CONDITIONS REMAIN IN PLACE THURSDAY AND FRIDAY AS LARGE  
SCALE HIGH PRESSURE AND WEAK RIDGING MOVES IN FROM THE MIDWEST.  
TEMPERATURES SHOULD BE CLOSER TO NORMAL FOR LATE AUGUST ONLY  
REACHING INTO THE UPPER 70S BOTH DAYS. HUMIDITY LEVEL REMAIN LOW AS  
WELL THANKS TO THE NORTHERLY FLOW.  
 
THE WEAK RIDGE AXIS SHOULD MOVE INTO EASTERN NEW ENGLAND HEADING  
INTO SATURDAY WHICH SHOULD LEAD TO TO WEST-SOUTHWESTERLY FLOW ALOFT.  
THIS IN TURN SHOULD ALLOW TEMPERATURES TO WARM UP A FEW DEGREES  
SATURDAY REACHING INTO THE LOW 80S. FOR NOW LEFT A DRY FORECAST BUT  
A FEW SHORTWAVE EMBEDDED IN THE OVERALL FLOW ALOFT WILL NEED TO BE  
WATCHED.  
 

 
   
AVIATION /00Z SUNDAY THROUGH THURSDAY/
 
 
DRIER AND COOLER AIR, ALONG WITH BREEZY CONDITIONS, WILL  
CONTINUE TO FILTER INTO THE REGION FROM THE NORTH OVERNIGHT IN  
THE WAKE OF A COLD FRONT. THESE BREEZY CONDITIONS, ALONG WITH  
LINGERING LOW TO MID LEVEL CLOUDS/MOISTURE SHOULD INHIBIT FOG  
FORMATION. OUTSIDE OF MVFR/IFR CIGS AT KPSF/KPOU OVERNIGHT,  
CONDITIONS WILL BE VFR THROUGH THE FORECAST PERIOD. ALL SITES  
SHOULD IMPROVE TO VFR AFTER 12Z/SUN.  
 
OUTLOOK...  
 
SUNDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA.  
SUNDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.  
MONDAY: NO OPERATIONAL IMPACT. NO SIG WX.  
MONDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.  
TUESDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.  
TUESDAY NIGHT: HIGH OPERATIONAL IMPACT. DEFINITE SHRA...TSRA.  
WEDNESDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA.  
WEDNESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX.  
THURSDAY: NO OPERATIONAL IMPACT. NO SIG WX.  
 

 
   
FIRE WEATHER
 
 
AFTER A WET DAY FRIDAY AND SOUTHERN PORTIONS ON SATURDAY,  
A DRYING TREND WILL OCCUR FROM NORTH TO SOUTH IN THE EVENING,  
SETTING THE STAGE FOR A COOLER AND MAINLY DRY PERIOD SUNDAY AND  
SHOULD LAST INTO TUESDAY MORNING. HIGH TEMPERATURES WILL BE  
NEAR TO SLIGHTLY BELOW NORMAL SUNDAY AND MONDAY WITH A LIGHT  
EAST TO NORTHEAST WIND. RH VALUES WILL BOTTOM OUT MAINLY IN THE  
50 PERCENTILE.  
 

 
   
HYDROLOGY
 
 
MUCH OF THE REGION SAW RAINFALL ON FRIDAY AND SOUTHERN AREAS  
DURING SATURDAY, WITH SEVERAL SPOTS RECEIVING IN EXCESS OF AN  
INCH AND SOME AREAS ACROSS COLUMBIA AND BERKSHIRE COUNTIES  
SEEING TWO TO FIVE INCHES OF RAINFALL. SHOWERS AND THUNDERSTORMS  
WILL EXIT AND WEAKEN OUR SOUTHERN ZONES BY EARLY EVENING.  
 
WATERS WILL CONTINUE TO RECEDE INTO THE REMAINDER OF THE WEEKEND  
AND INTO TUESDAY MORNING.  
 
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...11/THOMPSON  
NEAR TERM...11/THOMPSON/JVM  
SHORT TERM...BGM  
LONG TERM...SPECIALE  
AVIATION...JVM  
FIRE WEATHER...BGM/THOMPSON  
HYDROLOGY...BGM/THOMPSON  
 
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