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Area Forecast Discussion
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000
FXUS61 KCTP 130528
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
128 AM EDT FRI MAR 13 2015

.SYNOPSIS...
HIGH PRESSURE WILL CONTINUE FAIR AND DRY WEATHER ACROSS CENTRAL
PENNSYLVANIA THROUGH EARLY FRIDAY. RAIN WILL OVERSPREAD THE AREA
FRIDAY NIGHT AND CONTINUE INTO SATURDAY. THE RAIN COMBINED WITH
MELTING SNOW AND ICE JAM EFFECTS MAY POSE A MINOR FLOOD RISK.
SUNDAY WILL FEATURE COLDER TEMPERATURES AND GUSTY WINDS WITH RAIN
AND SNOW SHOWERS OVER THE WESTERN ALLEGHENIES.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
ASIDE FROM SOME WARM ADVECTION HIGH CLOUDS STREAMING ACROSS THE
SOUTHERN PORTIONS OF THE STATE LATE THIS EVENING FROM
CENTRAL OHIO...SKIES WILL BE MOSTLY CLEAR OVERNIGHT. VERY LOW SFC
DEWPOINTS PRECLUDE MENTIONS OF FOG.

WAA ALOFT AHEAD OF DEVELOPING STORM OVR THE MISS VALLEY WILL
CONTINUE TO SPREAD INCREASING CIRRUS INTO PA THROUGH EARLY FRIDAY. 
NOT EXPECTING MUCH IMPACT TO MINS OVERALL HOWEVER...WITH LIGHT
WIND AND SNOW COVER KEEPING MINS AROUND 20 NORTH AND UPPER 20S
SOUTH.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/...
HIGH PRESSURE MOVING EAST OF THE AREA WILL PROVIDE ANOTHER DRY
AND MOSTLY SUNNY DAY ACROSS THE REGION. LATEST GUIDANCE TRENDS
SUGGEST A SLOWER ARRIVAL OF PCPN TIL LATE FRIDAY AFTN/EVE.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
NO MAJOR CHANGES TO ONGOING WEEKEND FORECAST...AS RAIN EVENT STILL
EXPECTED TO UNFOLD WITH A DEEPENING LOW PRESSURE SYSTEM SLIDING
ACROSS PA FRI NIGHT INTO SAT NIGHT. PRECIP SPREADS OVER THE REGION
LATE FRI AFT/EVE...WITH HEAVIEST RAINS EXPECTED TO FALL LATER FRI
NIGHT/EARLY SAT WITH MAIN WAVE. QPF TOTALS RANGE FROM 0.75-1.00
INCHES ACROSS THE SOUTHERN MTNS...FADING TO AROUND HALF AN INCH
ALONG THE NORTHERN BORDER.

STRONG WAA WILL BATTLE DRY AIR IN THE LOW LEVELS EARLY ON IN
TERMS OF PCPN ONSET WHICH SHOULD BE AFTER 00Z SAT IN MOST
AREAS...KEEPING WITH THE CONTINUED TREND OF A SLIGHTLY LATER ONSET
THAT HAS BEEN EVIDENT IN PREVIOUS SEVERAL MODEL CYCLES. THERE IS
STILL A VERY LOW RISK /LESS THAN 20 PCT/ FOR A PERIOD OF -ZR OVER
THE ENDLESS MTNS NORTH OF IPT. BOTH THE SREF AND GEFS INDICATE
HIGHEST CONFIDENCE IN MODERATE RAINS BASICALLY OVER THE SRN 1/3 OF
THE CWA WITH SOME UPPER END PLUME MEMBERS SHOWING 1+ INCHES. THE
SEEMINGLY NON TRIVIAL RAIN AMOUNTS BECOME PROBLEMATIC WHEN
FACTORING IN COLD SEASON HYDROLOGIC IMPACTS SUCH AS MUCH ABOVE
NORMAL STREAMFLOWS AND RESIDUAL SNOWMELT/ICE JAM POTENTIAL. STILL
FEEL THAT A FLOOD WATCH MAY BE WARRANTED ESPECIALLY FOR THE LAUREL
HIGHLANDS WHICH EXPERIENCED THE MOST FLOODING DURING THE LAST
RAIN/SNOWMELT EVENT...BUT FOR NOW WILL MENTION POSSIBLE MINOR
FLOODING IN THE HWO. /SEE HYDRO SECTION FOR MORE DETAILS/. THE
FRONTAL SYSTEM WILL TRACK ACROSS CENTRAL PA ON SATURDAY WITH PCPN
TRENDS DECREASING BY SATURDAY AFTN FROM WEST TO EAST AS DRIER/LOW
PW AIR ARRIVES BEHIND THE FRONT.

1005MB SURFACE LOW OVER PA SAT DEEPENS TO 1000MB SAT NIGHT AS IT
SLIDES OFF NORTHERN NEW ENGLAND COAST. COLD AIR WRAPPING AROUND
THE BACKSIDE OF THE LOW WILL FAVOR LOWER DAYTIME TEMPERATURES WITH
UPSLOPE NW FLOW RAIN/SNOW SHOWERS PERSISTING OVER THE NRN AND WRN
ALLEGHENIES. WINDS WILL ALSO BECOME GUSTY WITH STRONG LLVL CAA
AND DECENT MIXING CONTRIBUTING TO TIGHT GRADIENT FLOW.

THE COOL DOWN BEHIND THIS SYSTEM FOR LATE WEEKEND SHOULD BE
BRIEF WITH 850MB TEMPS QUICKLY MODERATING BY EARLY MONDAY.
REINFORCING SHOT OF COLD AIR LIKELY FOR TUE. A SEASONABLY COOLER
PATTERN /WITH TEMPERATURES NEAR TO BELOW AVG/ SHOULD PREVAIL FROM
ST. PATRICK'S DAY INTO THE LAST FULL WEEK OF MARCH...WITH NAEFS
AND ECENS MEANS IN MUCH BETTER AGREEMENT DURING THE LAST COUPLE
MODEL CYCLES IN DEPICTING A WRN NOAM RIDGE/ERN TROUGH
CONFIGURATION OR +PNA TELECONNECTION.

&&

.AVIATION /05Z FRIDAY THROUGH TUESDAY/...
HIGH PRESSURE OVER THE REGION WILL RESULT IN A NEAR CERTAINTY OF
VFR CONDS AND LGT WIND THROUGH EARLY THIS EVENING. LOW PRES
LIFTING OUT OF THE MISS VALLEY WILL SPREAD RAIN AND LOWERING CIGS
ACROSS THE REGION AFTER DARK TONIGHT. WIDESPREAD IFR/LIFR CONDS
APPEAR LIKELY LATE TONIGHT IN RAIN/LOW CIGS. 

OUTLOOK...

SAT...RAIN/LOW CIGS LIKELY...MAINLY AM.

SUN-TUE...NO SIG WX EXPECTED.

&&

.HYDROLOGY...
36HR QPF AMTS ENDING 00Z SUN RANGE FROM 0.75 TO 1 INCH OVER THE
SOUTH-CENTRAL 1/3 OF THE FCST AREA. THESE AMOUNTS SHOULD POSE AT
LEAST A MINOR FLOOD RISK ESPECIALLY IN THE LOWER ALLEGHENY AND
MONONGAHELA BASINS. STREAMFLOWS ACROSS SOUTH-CENTRAL PA ARE
RUNNING WELL ABOVE NORMAL FOR THIS TIME OF YEAR. SNOWMELT AND ICE
JAM EFFECTS WILL ALSO CONTRIBUTE TO MINOR FLOODING CONCERNS
ESPECIALLY FOR SMALLER STREAMS/CREEKS. LATER SHIFTS MAY NEED TO
CONSIDER A FLOOD WATCH FOR PORTIONS OF THE AREA...BUT FOR NOW WILL
MENTION MINOR FLOOD RISK IN THE HWO.

&&

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

&&

$$
SYNOPSIS...STEINBUGL
NEAR TERM...DEVOIR/GARTNER
SHORT TERM...GARTNER/STEINBUGL
LONG TERM...RXR
AVIATION...FITZGERALD
HYDROLOGY...



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