Area Forecast Discussion
Issued by NWS State College, PA

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000 FXUS61 KCTP 232112 AFDCTP AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 412 PM EST SUN NOV 23 2014 .SYNOPSIS... STRONG LOW PRESSURE WILL PUSH NORTHWARD THROUGH THE GREAT LAKES TONIGHT AND MONDAY. IT WILL BRING A SLUG OF RAIN THROUGH THE STATE TONIGHT. VERY WARM AND EVEN NEAR-RECORD WARM TEMPERATURES ARE EXPECTED OVER MUCH OF THE AREA MONDAY...BEFORE THE COLD AIR FOLLOWING THE GREAT LAKES LOW MOVES ACROSS LATE MONDAY AND MONDAY NIGHT. A DEEPENING AREA OF LOW PRESSURE WILL MOVE NORTHWARD ALONG THE MID ATLANTIC COAST WEDNESDAY. THERE IS A LOW CONFIDENCE AS TO WHAT THE EXACT PATH OF THIS STORM WILL BE. HOWEVER...THE EASTERN THIRD TO HALF OF THE STATE COULD HAVE A SIGNIFICANT SNOWFALL. COLD AIR WILL FOLLOW FOR NEXT WEEKEND. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... LOW PRESSURE WILL DEEPEN SIGNIFICANTLY TO LESS THAN 980MB AS IT MOVES ACROSS THE UPPER GREAT LAKES ON MONDAY. THE WARM AIR AND MOISTURE ADVECTION THANKS TO A STRONG LOW LEVEL JET TO THE EAST OF THIS STORM WILL PEAK LATE TONIGHT. PWATS ARE 1.25 TO 1.5 INCHES AROUND 06Z. THE SPEED OF MOVEMENT OF THE RAIN SHOULD PRECLUDE ANY CONCERNS FOR HEAVY RAIN. GENERAL 0.50 INCHES QPF IS IN THE FCST. HOWEVER...SOME INSTABILITY COULD DEVELOP TONIGHT IN THE FAR SE. HAVE ADDED A CHC MENTION OF TSRA IN THE SE TO GO ALONG WITH THE 100POP OF RAIN/SHOWERS. WINDS ALOFT GET UP TO 50 KTS OVER THE CENTRAL MTNS...BUT THE GENERAL STABILITY OVER THE BULK OF THE AREA SHOULD KEEP GUSTS DOWN DURING THE NIGHT. THE EXCEPTION COULD BE THE HIGHER PEAKS IN THE WEST WHICH COULD BE GUSTY THROUGH THE NIGHT. TEMPS WILL LIKELY FALL A FEW DEGS THIS EVENING BEFORE LEVELING OFF OR EVEN RISING LATER TONIGHT. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... SUBSIDENCE/DRYING IMMEDIATELY BEHIND THE OVERNIGHT WAVE WILL START THE BREAK-UP OF THE CLOUDS FROM S-N. HOWEVER...THE AMBIENT MOISTURE WILL BE HIGH IN THE LLVLS AND FLOW OUT OF THE SOUTH THROUGH THE COLUMN WILL MAKE IT DIFFICULT TO CLEAR THE NORTHERN HALF OF THE AREA TOO RAPIDLY. THE SOUTH WILL LIKELY GET SOME DECENT CLEARING AND THE WARM AIR AHEAD OF THE COLD FRONT WILL PUSH TEMPS TO NEAR-RECORD LEVELS ON MONDAY AFTERNOON. WILL KEEP THE NUMBERS SLIGHTLY LOWER THAN RECORDS...THOUGH. THIS IS DUE TO THE UNCERTAINTY OF HOW MUCH SUN TIME WE WILL HAVE. THE BIGGEST TEMP BUST POTENTIAL AREA /STAY TOO COOL VS FCST/ WILL BE THE NORTHEASTERN MTNS. THEY COULD STAY TOO CLOUDY. THE INSTABILITY COULD ALSO TOUCH OFF A FEW SHOWERS -MAINLY IN THE CENTRAL AND NORTH. THE COLD FRONT SHOULD MOVE THROUGH LATER IN THE DAY AND EARLY EVENING. THE WINDS WILL BE THE OTHER STORY - ALONG WITH THE TEMPS. THE WESTERN MOUNTAINS/ALLEGHENIES WILL BE THE GUSTIEST PLACE. MIXED- WINDS WITH LITTLE DIRECTIONAL SHEAR OFF BUFKIT SOUNDS MAKE FOR WIND GUSTS EASILY INTO THE 30S. WILL KEEP THE GUSTS BELOW 40KTS FOR NOW. && .LONG TERM /TUESDAY THROUGH SUNDAY/...
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POTENTIAL FOR SIG WINTER IMPACTS FROM LOW PRESSURE MOVING UP THE EAST COAST ON WED/WED NIGHT. HIGHLY AMPLIFIED AND ACTIVE UPPER AIR PATTERN WILL BRING A PERIOD OF ACTIVE WEATHER THROUGH THE COMING WEEK. THE 500MB CONFIGURATION WILL FEATURE ANOMALOUS RIDGING ALONG THE WEST COAST AND IN THE WESTERN ATLANTIC WITH A FULL-LATITUDE PERSISTANT TROUGH EBBING AND FLOWING OVER THE CENTRAL AND EASTERN U.S. AFTER THE EXIT OF MONDAY/S LOW PRESSURE AREA...COLDER TEMPS RETURN ON BRISK W/SW FLOW FOR TUE DROPPING HIGHS SOME 20-25F FROM PREV DAYS READINGS. WE/LL ALSO SEE THE RETURN OF LIGHT SNOW SHOWERS IN THE WESTERN HIGHER TERRAIN. THEN FOCUS WILL TURN TO A WAVE CURRENTLY DROPPING SE FROM BRITISH COLUMBIA...WHICH WILL SPAWN A COASTAL MID ATLANTIC LOW THAT WILL MOVE NORTHWARD JUST OFF THE EAST COAST WEDNESDAY INTO THURSDAY. 00Z/12Z MODEL RUNS CONTINUING ONGOING TREND OF ECMWF TRACKING FURTHER WESTWARD THAN THE GFS/GEFS...WITH A SLIGHT OVERALL DRIFT WESTWARD BY NEARLY ALL GUIDANCE OVER PAST 24HRS. KEEP IN MIND THAT THOUGH FORECAST CONFIDENCE IN THE DEVELOPMENT OF THIS COASTAL LOW IS HIGH...THE TRACK CONTINUES TO HAVE A LARGE DEGREE OF UNCERTAINTY. THE LATEST MODEL GUIDANCE INDICATES THAT THE POTENTIAL HAS INCREASED FOR POTENTIAL SIG SNOWFALL OVER EASTERN THIRD OF PA WED/WED EVE. COLD AIR WILL BE IN PLACE WED MORNING AS A WEAK HIGH PRESSURE RIDGE RETREATS TO THE NORTH AHEAD OF THE APPROACHING LOW. NORTHERLY FLOW OVER CENTRAL PA NOT PARTICULARLY STRONG IN ANY MODEL...BUT A SHORTWAVE LOOKS POISED TO SLIDE IN FROM THE GREAT LAKES ON WED TO ADD SOME SYNOPTIC LIFT TO A RAPIDLY DEEPENING AND FAST MOVING SURFACE LOW. PRECIP MAY START OFF EARLY WED AS A MIX OF RAIN AND SNOW IN THE SE...BUT COOLING TEMPS ALOFT WILL CONVERT ALL PRECIP OVER TO SNOW BY MIDDAY. AS IS A GENERAL RULE WITH THESE TYPES OF EVENTS... THERE WILL LIKELY BE A SHARP DROPOFF IN ACCUMULATIONS ON THE NW EDGE OF THE HEAVIER SNOWS. BIGGEST POTENTIAL IMPACTS IN OUR CWA WILL BE THE SUSQ VALLEY...WHERE POTENTIAL FOR A SEVERAL HOUR PERIOD OF HEAVY ACCUMULATING SNOW WILL EXIST. BUT AGAIN...SMALL CHANGES IN THE ULTIMATE TRACK COULD LEAD TO MODIFICATIONS OF SNOWFALL FORECASTS. THE TAKE AWAY...THOUGH THE DETAILS REMAIN UNCERTAIN...THERE WILL BE SIG IMPACTS TO TRAVEL ALONG THE U.S. EAST COAST ON ONE OF THE BUSIEST DAYS OF THE YEAR /WED/. PLAN ACCORDINGLY. COLDER AIR REMAINS IN PLACE LATE WEEK AS SCT SNOW SHOWERS RETURN TO THE WESTERN HIGHER TERRAIN. TEMPS LOOK TO GRADUALLY MODIFY LATE WEEKEND HEADING INTO NEXT WEEK...WITH NO BIG STORM SYSTEMS EXPECTED AFTER THANKSGIVING.
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&& .AVIATION /21Z SUNDAY THROUGH FRIDAY/... STRONG LOW MOVING NORTH THROUGH THE UPPER GREAT LAKES WILL PULL A GOOD DEAL OF MOISTURE UP FROM THE GULF. RAIN WILL PUSH QUICKLY S-N THROUGH THE REGION TONIGHT. SHOWERS WILL BE LEFT OVER DURING THE DAY TOMORROW ALONG WITH SOME LOW CIGS EARLY IN THE DAY - ESP IN THE NORTH. THE WINDS JUST OFF THE DECK TONIGHT WILL BE VERY STRONG. LLWS IS A CERTAINTY OVERNIGHT AND ALL OF MONDAY. GUSTS WILL REACH 35 TO 40KTS DURING THE DAY ON MONDAY AS MIXING BRINGS THE STRONG WINDS DOWN TO THE SFC. THE RAIN MOVING THROUGH TONIGHT WILL LEAD TO REDUCED VISBYS - ALONG WITH THE EXPECTED DROP IN CIGS TO IFR OR EVEN LIFR WHICH MOST TERMINALS WILL SEE AT SOME POINT TONIGHT AND VERY EARLY MON MORNING. THE COLD AIR TAKES ANOTHER 12 HOURS AFTER THE HEAVIEST RAIN GOES THROUGH...WITH THE WINDS SWITCHING TO THE WSW IN THE LATE AFTN IN THE W AND EVENING ELSEWHERE. THE NEXT-BEST CHC OF SHOWERS WILL BE AS THE FRONT MOVES THROUGH LATE MONDAY. BUT THESE WILL BE VERY BRIEF. HIGH PRESSURE WILL VISIT MON NIGHT AND TUES...BUT THE COLD AIR CROSSING THE LAKES WILL GENERATE LK EFF SHSN...AND KBFD/KJST WILL LIKELY HAVE RESTRICTIONS MON NIGHT AND TUES. A STRONG STORM WILL MOVE UP THE COAST ON WEDNESDAY. SIGNIFICANT IMPACTS TO TRAVEL ARE POSSIBLE OVER THE EAST COAST AND PERHAPS INTO CENTRAL PA. OUTLOOK... TUE...MVFR WITH SHSN WEST. VFR ELSEWHERE. WED...IFR IN SN EAST. MVFR/IFR IN SN CENTRAL. MVFR/VFR WEST. THU-FRI...MVFR/IFR NW IN LK EFF SHSN. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DANGELO NEAR TERM...DANGELO SHORT TERM...DANGELO LONG TERM...RXR AVIATION...DANGELO

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