Area Forecast Discussion
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210 FXUS61 KPBZ 292148 AFDPBZ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 548 PM EDT FRI APR 29 2016 .SYNOPSIS...
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MAINLY DRY AND COOL OVERNIGHT INTO SATURDAY MORNING. LOW PRESSURE WILL BRING RAIN SATURDAY AFTERNOON INTO SUNDAY.
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&& .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
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SHORTWAVE TROUGH MOVING ACROSS NEW YORK STATE IS TAKING BULK OF THE SHOWERS NORTH OF I-80 WITH IT. HAVE TRIMMED BACK POPS MORE QUICKLY THIS EVENING. ADJUSTED HOURLY TEMPERATURES AND DEW POINTS TO REFLECT CURRENT OBSERVATIONS. COOL ADVECTION BEHIND SYSTEM WILL DROP TEMPERATURES TO NEAR THE SEASONAL AVERAGES BY DAYBREAK.
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&& .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... SOME CLEARING WILL BE LIKELY EARLY SATURDAY AS LOW LEVEL MOISTURE FINALLY MIXES OUT BEHIND THE SYSTEM FROM FRIDAY AND IN ADVANCE OF ANOTHER SYSTEM FOR THE LATTER HALF OF SATURDAY. IN THE INTERIM...DIURNAL MIXING COMBINED WITH A DECREASE IN LAYER MOISTURE SHOULD ALLOW FOR A PERIOD OF CLEARING IN THE INTERCESSION. HOWEVER...THIS DECREASE WILL BE FLEETING AS ISENTROPIC ASCENT AHEAD OF A NORTHEASTWARD TRANSLATING WARM FRONT WILL MEAN CLOUDS WILL AGAIN OVERSPREAD THE AREA BY LATER IN THE AFTERNOON. AFOREMENTIONED ISENTROPIC ASCENT WILL SPREAD DEEP MOISTURE AND LIFT OVER THE AREA BY SATURDAY EVENING WITH A COUPLED JET STRUCTURE LIKELY TO TRANSLATE DOWN I-70. THE COMBINATION OF THESE TWO ASSURES RAIN WILL OVERSPREAD THE AREA...AND POPS WERE THUS RAISED TO 100 PERCENT. THE WARM FRONT IS SET TO MOVE NORTHWARD AND THROUGH THE AREA BY SUNDAY MORNING...PLACING THE MAJORITY OF THE CWA INTO THE WARM SECTOR BY THAT JUNCTURE. POPS WERE WOUND DOWN A BIT IN THE WARM SECTOR...HOWEVER KEPT AT LEAST CHANCE AS THE MODE WILL EVOLVE FROM STRATIFORM TO CONVECTIVE. IN THE WARM SECTOR...THE 12Z GUIDANCE HAS TRENDED DECIDEDLY TOWARD SOME AMOUNT OF CLEARING BY THE LATE MORNING ON SUNDAY. THIS WOULD WORK TO STRONGLY DESTABILIZE THE COLUMN...AND MEAN A SECONDARY INCREASE IN SHOWER AND THUNDERSTORM ACTIVITY ON SUNDAY AFTERNOON...PARTICULARLY SOUTH OF I-80. NAM PROFILES SUGGEST UP TO 2000 J/KG OF CAPE WITH THE VAST MAJORITY OF IT ABOVE A FAIRLY LOW FREEZING LEVEL. EVEN IN THE ABSENCE OF STRONG VERTICAL SHEAR...THIS CLOUD LEAD TO SOME HAILERS. THIS WILL NEED TO BE MONITORED GOING FORWARD TO SEE HOW THE MODELS HANDLE THE WARM SECTOR IN SUBSEQUENT RUNS. EVEN AFTER A WEAK WAVE ON SUNDAY MOVES DOWN THE FRONT AND FORCES THE SHOWERS AND THUNDERSTORMS...THE UPPER JET AXIS LOOKS TO REMAIN RELATIVELY PARKED OVER THE OHIO VALLEY. THIS MEANS MOISTURE WILL BE SLOW TO DECREASE INTO EARLY NEXT WEEK WITH SHOWER CHANCES CURTAILING PAINFULLY SLOWLY. HOWEVER...AS A DEEPER UPPER LOW DIVES TOWARD THE TENNESSEE VALLEY BY TUESDAY...THE UPPER JET AXIS SHOULD FINALLY EVOLVE SOUTHWARD ENOUGH TO DRY OUT OUR AREA. FRIES && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... THE EXTENDED PERIOD LOOKS TO FEATURE A VERY STRONGLY ANCHORED PATTERN OVER THE WESTERN CONUS AS A RIDGE LOOKS TO EVOLVE OVER THE INTERMOUNTAIN WEST. DOWNSTREAM TROUGHING WILL THUS EVENTUALLY BECOME ESTABLISHED OVER THE GREAT LAKES AND NORTHEAST BY THE END OF THE WEEK AFTER A DRY MID-WEEK. THIS WILL MEAN SHOWER CHANCES WILL RETURN AND TEMPERATURES WILL GENERALLY TREND NEAR OR BELOW NORMAL. FRIES && .AVIATION /22Z FRIDAY THROUGH WEDNESDAY/...
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MVFR WITH PATCHY IFR CEILINGS SHOULD CONTINUE THROUGH THIS EVE WITH LOW LEVEL MOISTURE IN PLACE AND A CROSSING SHORTWAVE. BRIEF SFC RIDGING BUILDING IN SHOULD RESULT IN SOME DECREASE IN LOW LVL CLOUDS OVERNIGHT AS MID LVL CLOUDS INCREASE AHD OF APPROACHING LOW PRESSURE. THE LOW IS EXPECTED TO RESULT IN MVFR RESTRICTIONS AND RAIN LATE SAT FOR PORTS S OF I 80. .OUTLOOK /SATURDAY NIGHT THROUGH WEDNESDAY/... RESTRICTIONS ARE EXPECTED THRU MON AS LOW PRESSURE SLOWLY CROSSES THE REGION.
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&& .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$

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