084
FXUS61 KALY 050049
AFDALY
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ALBANY NY
844 PM EDT SAT JUL 4 2009
SYNOPSIS
A WEAK RIDGE OF HIGHER PRESSURE WILL REMAIN IN PLACE
THROUGH THE REMAINDER OF THIS HOLIDAY WEEKEND. AS WE START THE NEW
WORK WEEK...ANOTHER UPPER LEVEL LOW PRESSURE SYSTEM APPROACHES.
THIS WILL INCREASE THE CLOUD COVER AND THE CHANCE FOR ADDITIONAL
SHOWERS AND THUNDERSTORMS THROUGH THE FIRST HALF OF THE WEEK.
NEAR TERM /THROUGH SUNDAY/
AS OF 845 PM EDT...HAVE AMENDED FORECAST TO INCLUDE MENTION OF
ISOLATED TO SCATTERED SHOWERS FROM THE CAPITAL REGION N AND W
THROUGH ABOUT MIDNIGHT. THE TAIL END OF COMPACT
SHORTWAVE...CURRENTLY TRAVERSING E ACROSS NORTHERN NEW
ENGLAND...WILL CONTINUE TO MOVE SE ACROSS THE REGION OVER THE NEXT
1-3 HOURS. SOME MID LEVEL DYNAMICS...IN COMBINATION WITH SOME
LINGERING LOW LEVEL MOISTURE FROM THE NEARBY GREAT LAKES HAS BEEN
CONTRIBUTING TO THESE LIGHT SHOWERS. THIS BAND OF SHOWERS SHOULD
CONTINUE TO SLOWLY WEAKEN UPON MOVING SE...BUT STILL SHOULD PRODUCE
SOME LIGHT SHOWERS/SPRINKLES TO AT LEAST NORTHERN PORTIONS OF THE
CAPITAL REGION...AND THE WESTERN MOHAWK VALLEY OVER THE NEXT COUPLE
OF HOURS. THEY SHOULD BE RELATIVELY BRIEF IN DURATION...ALTHOUGH
COULD LINGER A BIT LONGER ACROSS PORTIONS OF THE WESTERN MOHAWK
VALLEY.
PREVIOUS DISCUSSION FOLLOWS...
A STRONG UPPER LEVEL JET EXIT REGION DYNAMICS COMBINING WITH A
MID LEVEL SHORT WAVE HAS RESULTED IN A RATHER ORGANIZED AREA OF
CONVECTION JUST NORTHEAST OF OUR CWA TODAY. SOME LAKE ENHANCED
/YES IT IS COLD ENOUGH ALOFT/ SHOWERS CONTINUE TO PLAQUE THE TUG
HILL PLATEAU AND PORTIONS OF THE DACKS WHERE TEMPS HAVE STRUGGLED
TO REACH 60F. AS WE MOVE THROUGH THE EVENING...THE POSITION OF THE
UPPER JET IS EXPECTED TO SOUTHEAST OF THE REGION WHICH PLACES THE
REGION UNDER AN INCREASE INFLUENCE OF SUBSIDENCE. THIS SHOULD TAKE
ITS TOLL ON THE CONVECTION AND WE WILL DECREASE POPS ACROSS THE
DACKS OVERNIGHT. OTHERWISE...WINDS AND CLOUDS WILL DECREASE
THROUGH THE EVENING AS OVERNIGHT LOWS SETTLE TO BETWEEN 45F AND
55F.
A RATHER WEAK AND DIFFUSE REGION OF HIGH PRESSURE SETTLES INTO THE
REGION FOR THE REMAINDER OF THE HOLIDAY WEEKEND. NCEP MODEL SUITE
ALL SUGGEST DRY WEATHER AND SOME DIURNALLY DRIVEN CU AS WE SHOULD
EXCEED OUR CONVECTIVE TEMPERATURE AROUND NOON WHICH IS FORECAST TO
BE INTO THE LOWER 70S. BASED ON MIXING LAYER HEIGHT FORECASTS
BETWEEN 800-750MB...WE SHOULD TAP OUT NEAR 80F IN THE VALLEYS WITH
UPPER 60S TO MID 70S ELSEWHERE DEPENDING ON ELEVATION.
SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/
TIGHTENING BAROCLINIC ZONE ACROSS THE OHIO RIVER VALLEY AND THE
APPROACH OF THE MID-UPPER LEVEL JET MAX WILL KEEP THE MOISTURE
SOUTH OF THE CWA /GLOBAL MODELS SEEM TO BE SUFFERING FROM SOME
CONVECTIVE FEEDBACK ISSUES TODAY/. THEN THE APPROACH OF THE NEXT
UPPER LEVEL LOW FROM CENTRAL CANADA ARRIVES FOR EARLY NEXT WEEK.
LOW LEVEL MOISTURE DOES NOT LOOK AS HIGH COMPARED TO LAST TIME
WHICH RESULTS IN SBCAPES MONDAY AFTERNOON BELOW 1000 J/KG.
HOWEVER...WITH COOLING TEMPS ALOFT /APPROACHING -16C AT 500MB/
WOULD NOT BE SURPRISED TO HEAR/OBSERVE SMALL HAIL WITHIN THE
DEEPER CONVECTION.
WITH THE LOSS OF DAYTIME HEATING...CONVECTION WILL DECREASE IN
COVERAGE AND INTENSITY MONDAY NIGHT. HOWEVER...WE STILL EXPECT
SOME LINGERING SHOWER ACTIVITY OVERNIGHT. THE HIGHER CONCENTRATION
OF SHOWERS ARE EXPECTED ACROSS THE DACKS AND SOUTHERN GREENS IN
THE CWA WHERE THESE LOCATIONS ARE IN CLOSER PROXIMITY OF THE UPPER
LOW AND OROGRAPHIC ENHANCEMENTS.
LONG TERM /TUESDAY THROUGH SATURDAY/
UPPER LEVEL CUTOFF LOW WILL MOVE THROUGH THE FA TUESDAY...RESULTING
IN RAIN SHOWERS AND THUNDERSTORMS TUESDAY INTO TUESDAY NIGHT. HIGH
PRESSURE WILL BUILD IN ON WEDNESDAY THROUGH THURSDAY...ALLOWING FOR
DRY CONDITIONS AND MOSTLY SUNNY SKIES BEFORE THE NEXT DISTURBANCE
APPROACHES THURSDAY NIGHT.
HIGH PRESSURE WILL MOVE OFFSHORE RESULTING IN A SOUTHWEST FLOW OVER
THE FA. THIS WILL CAUSE SOME DOWNSLOPING OFF THE CATSKILLS WHICH
WILL AID IN THE MAX TEMPERATURE REACHING INTO THE MID TO UPPER 80S
IN THE VALLEYS ON FRIDAY. FRIDAY WILL ALSO HAVE A CHC OF SHOWERS AND
THUNDERSTORMS AS ANOTHER DISTURBANCE APPROACHES FROM JAMES BAY. THIS
WILL BE FOLLOWED BY YET ANOTHER DISTURBANCE FOR SATURDAY.
TEMPERATURES WILL START OFF 5-10 DEGREES BELOW NORMAL...INCREASING
TO AROUND NORMAL ON THURSDAY...WITH SLIGHTLY ABOVE NORMAL
TEMPERATURES FRIDAY.
AVIATION /01Z SUNDAY THROUGH THURSDAY/
AS OF 720 PM EDT...VFR CONDITIONS DOMINATE THE TAF SITES...WITH JUST
SCT-BKN CLOUDS WITH 5000-7000 FT AGL BASES. THESE CLOUDS SHOULD
DISSIPATE WITHIN AN HOUR OR TWO AFTER SUNSET...LEAVING MAINLY CLEAR
SKIES OVERNIGHT...ALONG WITH VFR CONDITIONS. THERE IS A SLIGHT CHC
FOR SOME LOCALIZED SHALLOW GROUND FOG TO DEVELOP LATER TONIGHT AT
KGFL...AND POSSIBLY KPOU. AT THIS TIME...HAVE INTRODUCED MVFR VSBYS
LATER THIS EVENING AT KGFL...WHERE PROBABILITY FOR SOME MIFG IS A
BIT HIGHER...AND LEFT OUT MENTION ELSEWHERE.
FOR SUNDAY...CONDITIONS WILL REMAIN VFR...WITH JUST SOME PATCHY
CLOUDS EXPECTED WITH BASES OF 5000-7000 FT AGL...ALONG WITH PERHAPS
SOME HIGHER CLOUDS AT KPOU IN THE AFTERNOON.
W TO NW WINDS WILL QUICKLY DIMINISH OVER THE NEXT 1-3 HOURS...WITH
SPEEDS MAINLY LESS THAN 8 KT OVERNIGHT. WEST TO NORTHWEST WINDS WILL
RESUME SUNDAY...WITH SPEEDS OF 10-15 KT...ALTHOUGH SOME GUSTS UP TO
20-25 KT IS POSSIBLE AT KALB WHERE FUNNELING ENHANCEMENT DOWN THE
MOHAWK RIVER VALLEY MAY OCCUR.
OUTLOOK...
SUN PM...VFR...NO WX.
MON/TUE...VFR/MVFR WITH CHC OF MVFR/IFR -SHRA/-TSRA...ESPECIALLY PM.
WED/THU...VFR...PSBL EARLY AM MVFR/IFR FOG.
FIRE WEATHER
A WEAK RIDGE OF HIGH PRESSURE WILL REMAIN ACROSS THE REGION THE
REMAINDER OF THIS HOLIDAY WEEKEND. ANOTHER UPPER LEVEL LOW
PRESSURE SYSTEM APPROACHES FOR EARLY NEXT WEEK.
RELATIVE HUMIDITY VALUES WILL RECOVER TO BETWEEN 90 TO 100
PERCENT TONIGHT...AND DROP TO 35 TO 55 PERCENT ON SUNDAY.
WINDS TONIGHT WILL BE WEST TO NORTHWEST AT 5 TO 15 MPH...SUBSIDING
TO LESS THAN 10 MPH OVERNIGHT. ON SUNDAY...WEST WINDS AT 5 TO 15
MPH WITH GUSTS UP TO 25 MPH ACROSS THE HIGHER TERRAIN.
HYDROLOGY
RESIDUAL SHOWERS WILL GRADUALLY DIMINISH THROUGH THIS EVENING AS
THE UPPER LOW GRADUALLY SHIFTS EAST AND SOMEWHAT COOLER AND DRIER
AIR MOVES IN FROM THE WEST. SUNDAY SHOULD BE DRY WITH AMPLE
SUNSHINE...WHICH WILL LET THE GROUND DRY OUT SOME. ANOTHER LOW
AND FRONTAL SYSTEM WILL KICK OFF SOME SHOWERS AND THUNDERSTORMS
MONDAY AFTERNOON. BY THEN...THE GROUND SHOULD HAVE BEEN ABLE TO
DRY ENOUGH THAT FLOODING SHOULD NOT BE A CONCERN AS IT DOES NOT LOOK
LIKE THIS SYSTEM WILL HAVE A LOT OF MOISTURE TO WORK WITH.
HOWEVER...LOCAL RESEARCH DOES POINT TOWARD SOME ELEVATED CONCERN
AND WE WILL CONTINUE TO MONITOR TRENDS. THIS SYSTEM WILL BE
FOLLOWED BY HIGH PRESSURE BUILDING IN ON WEDNESDAY WITH SEVERAL
DAYS OF WARM AND SUMMER LIKE WEATHER WITH A CHANCE OF AFTERNOON
AND EVENING THUNDERSTORMS TOWARD THE END OF THE 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...NONE.
MA...NONE.
VT...NONE.
SYNOPSIS...BGM
NEAR TERM...KL/BGM
SHORT TERM...BGM
LONG TERM...KGS
AVIATION...KL
FIRE WEATHER...BGM
HYDROLOGY...BGM
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