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Area Forecast Discussion
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000
FXUS61 KCTP 240029
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
729 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/...
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.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
A LOW PRES SYSTEM TRACKING NORTHWARD INTO THE GRT LKS WILL SPREAD
LOWERING CIGS AND RAIN ACROSS CENTRAL PA TONIGHT. REGIONAL RADAR
AT 00Z SHOWS THE RAIN ABOUT TO ENTER SOUTHERN PA AND LINEAR
EXTRAPOLATION SUGGESTS THE RAIN WILL OVERSPREAD ALL CENTRAL PA
AIRFIELDS BTWN 02Z-04Z. A BLEND OF LATEST LAMP GUIDANCE...SREF AND
HRRR MDL OUTPUT IMPLY CIGS WILL DROP TO IFR BTWN 04Z-06Z...JUST A
COUPLE HOURS AFTER THE RAIN BEGINS. 

SOUTHERLY WINDS IN THE 1-2 KFT LAYER WILL BECOME VERY STRONG
OVERNIGHT...MAKING LLWS A NEAR CERTAINTY. SFC GUSTS OVERNIGHT WILL
BE HIGHEST AT KJST DUE TO IT/S RIDGETOP LOCATION. HRRR OUTPUT
SUGGESTS GUSTS BTWN 25-35KTS ARE POSS THERE BTWN 03Z-07Z. MUCH
LIGHTER SFC WINDS EXPECTED ELSEWHERE...WHICH WILL LEAD TO THE
LLWS.

EARLY LOW CIGS AND LINGERING DRIZZLE WILL GIVE WAY TO IMPROVING
CONDS BY LATE MONDAY AM...AS WARM FRONT LIFTS NORTH OF THE
REGION. GENERALLY VFR CONDS ARE ANTICIPATED MON AFTN. HOWEVER...A
COLD FRONT MOVING FROM THE WEST WILL BE ACCOMPANIED BY SCT LATE
DAY SHRA ACROSS THE W MTNS...POSSIBLY PRODUCING A BRIEF VSBY
REDUCTION AT KBFD OR KJST.

OUTLOOK...

TUE...NO SIG WX EXPECTED. 

WED...SNOW/LOW VSBYS POSS EASTERN PA.

THU...-SHSN/REDUCED VSBYS POSS NW MTNS. 

FRI...NO SIG WX EXPECTED. 

&&

.CTP WATCHES/WARNINGS/ADVISORIES...
NONE.

&&

$$
SYNOPSIS...DANGELO
NEAR TERM...DANGELO
SHORT TERM...DANGELO
LONG TERM...RXR
AVIATION...FITZGERALD



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