349  
FXUS61 KCTP 242002  
AFDCTP  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE STATE COLLEGE PA  
402 PM EDT MON APR 24 2017  
   
SYNOPSIS
 
 
A STORM SYSTEM OVER THE SOUTHEASTERN STATES WILL BEGIN TO MAKE  
SLOW PROGRESS NORTHWARD ALONG THE COAST OVER THE NEXT SEVERAL  
DAYS.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
RAIN CONTINUES TO ADVANCE FROM THE SOUTH. SHOWERS REMAIN  
SCATTERED AS LOWER ATMOSPHERE IS FAIRLY DRY. HAVE TRIED TO  
REFINE THE TIMING AND NORTHWARD EXTENT OF THE RAIN AND OPAQUE  
CLOUD COVER FOR THE NEAR TERM. OVERALL, THE TIMING IS SIMILAR  
BETWEEN ALL THE GUIDANCE. QPF WILL BE LIGHT TODAY, ON THE ORDER  
OF A TENTH OF AN INCH OR LESS SOUTH OF I-80 AND A TENTH TO  
QUARTER OF AN INCH SOUTH OF THE TURNPIKE. MAXES SHOULD BE ABOVE  
NORMALS IN THE NORTH BUT BELOW NORMAL IN THE SOUTH. TEMPS  
THROUGH SOUTHERN AND CENTRAL PA ARE IN LOW 60S WHERE THE MAINLY  
SUNNY NORTHERN PORTION OF PA HAS REACHED THE 70S.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/
 
 
THE GUIDANCE IS VERY CONSISTENT WITH TIMING AND PLACEMENT OF THE  
MAJOR FEATURES. DEEP EASTERLY FLOW WILL SLIDE UP THE COAST INTO  
PA THROUGH THE SHORT TERM PERIOD. MOISTURE WILL SLOWLY  
INFILTRATE THE LOWER LEVELS AND RAINFALL WILL BECOME MORE  
WIDESPREAD OVERNIGHT INTO TUESDAY MORNING. THE CONFIDENCE IN  
OCCURRENCE OF THE DECENT RAIN IS HIGHEST TOMORROW AFTERNOON,  
ESPECIALLY THROUGH THE EASTERN HALF OF THE REGION. HOWEVER, THE  
TILT OF THE TROUGH WHICH THE UPPER LOW IS ASSOCIATED WITH IS A  
LITTLE FUZZY. WITH A MORE- NEGATIVE TILT IT MAY MOVE A LITTLE  
FASTER, AND BANDS OF RAIN MAY MOVE MORE QUICKLY. THIS WOULD  
PROBABLY KEEP THE RAIN LIGHTER AT ANY ONE LOCATION. LOOKING AT  
LATEST PLUMES KEEP PRECIP TOTAL/ACCUMULATION AROUND 0.5 THROUGH  
THE PERIOD. MOST OF THIS RAIN SHOULD BE OUT OF STABLE PROFILES,  
SO THUNDER AND BIG TOTALS ARE NOT LIKELY. TEMPS WILL BE  
SEASONABLY MILD OVERNIGHT TONIGHT. MAXES ON TUES WILL BE  
HOMOGENEOUS IN THE U50S TO LOW 60S IN THE FAR NORTHWEST WHERE  
SKIES WILL SEE SOME SUN.  
 

 
   
LONG TERM /TUESDAY NIGHT THROUGH MONDAY/
 
 
MOIST AND ANOMALOUSLY STRONG (APPROX -3 SIGMA) SOUTHEASTERLY  
FLOW OFF THE ATLANTIC WILL BRING OCCASIONAL RAIN/SHOWERS TO THE  
EASTERN 1/2 TO 2/3RDS OF THE CWA TUESDAY NIGHT WITH QPF LIKELY  
AVERAGING JUST ANOTHER 1-2 TENTHS IN MOST PLACES ACROSS THE SUSQ  
VALLEY AND WESTERN POCONOS (LESS ACROSS THE CENTRAL AND WESTERN  
MTNS). MIN TEMPS WILL BE ON THE MILD SIDE - IN THE UPPER 40S  
ACROSS THE WESTERN MTNS AND LOWER 50S ELSEWHERE.  
 
THE SLOWLY WEAKENING (1004-1006MB) SFC LOW, AND FILLING UPPER  
LOW WILL BE MOVING NE TWD CAPE COD LATE WED/WED NIGHT.  
 
BKN-OVC CLOUD COVER ON THE WESTERN FRINGE OF THE DEPARTING LOW  
WILL BRING A SLIGHT CHC FOR SHOWERS ACROSS THE EASTERN PART OF  
OUR CWA (MAINLY WEDNESDAY MORNING), WHILE INCREASING SUNSHINE  
GREETS RESIDENTS OVER THE WESTERN HALF OF THE STATE.  
 
A FAIRLY SHARP AND SLIGHTLY ANOMALOUS UPPER RIDGE WILL SLIDE  
ACROSS THE APPALACHIAN CHAIN AND MID ATLANTIC PIEDMONT WEDNESDAY  
NIGHT AND THURSDAY BRINGING DRY CONDITIONS AND WELL ABOVE  
NORMAL TEMPS MIN AND MAX TEMPS WED NIGHT AND THU WILL BE AT  
LEAST 12-15F ABOVE NORMAL WITH EVEN GREATER DEPARTURES OVER  
NEARLY 20 DEG F ABOVE NORMAL ACROSS THE NORTHERN AND WESTERN  
MTNS.  
 
LATE THIS WEEK AND OVER THE UPCOMING WEEKEND PERSISTENT  
AND QUITE STRONG SOUTHWESTERLY FLOW ALOFT WILL BE ACCOMPANIED BY  
A FEW EMBEDDED SHORTWAVES AND ASSOCIATED SFC WARM/WEAK COLD  
FRONTAL BOUNDARIES. THIS WILL BRING PERIODS OF UNSETTLED WEATHER  
WITH UNCERTAIN TIMING WITH RESPECT TO EXACT ONSET/ENDING TIMING  
OF THE SHOWERS. THE BEST CHCS FOR RAIN APPEAR TO BE THURSDAY  
NIGHT AND AGAIN LATER SUNDAY INTO MONDAY AS THE BROAD LIFT FROM  
THE RE REGION OF AN UPPER LEVEL JET (140-150 KT) AND QUITE  
POTENT SFC COLD FRONT SLIDES EAST FROM THE OHIO VALLEY.  
 
WELL ABOVE NORMAL MAX/MIN TEMPS (THOUGH PROBABLY NOT  
RECORD LEVEL TEMPS) WILL PERSIST FRIDAY THROUGH SUNDAY, BEFORE  
A GRADUAL COOL OFF BEGINS MONDAY. MAIN FORECAST CONCERN FOR THE  
FRI-SAT PERIOD, WHEN MEDIUM RANGE MODELS INDICATE A PEAK IN  
TEMPS (WITH MAXES IN THE 70S TO AROUND 80) WILL BE THE LOCATION  
OF A WARM/STATIONARY FRONTAL BOUNDARY ACROSS NORTHERN AND  
WESTERN PA. CLOUDS AND SOME SHOWERS COULD LEAD TO A TEMP BUST BY  
SEVERAL DEG OR MORE ON THE HIGH SIDE (WITH OBSERVED TEMPS  
POSSIBLY HOLDING IN THE 60S ACROSS THE NORTHERN MTNS).  
 

 
   
AVIATION /19Z MONDAY THROUGH SATURDAY/
 
 
HIGH PRESSURE AND ASSOCIATED DRY AIR MASS OVER PENNSYLVANIA WILL  
KEEP WIDESPREAD VFR CONDITIONS AND LIGHT WINDS THROUGH THE  
AFTERNOON OVER MUCH OF PA. LOW PRESSURE LIFTING UP THE EAST  
COAST WILL SPREAD LOWERING CLOUDS AND SPOTTY LIGHT RAIN INTO  
SOUTHERN PA THROUGH LATE THIS AFTERNOON. THE DRY AIR IN THE LOW  
LEVELS SHOULD KEEP CONDITIONS VFR. HOWEVER, MODEL SOUNDINGS AND  
SREF PROB CHARTS SUGGEST MVFR CONDITIONS WILL BECOME LIKELY BY  
THIS EVENING ACROSS SOUTHERN PA, WITH IFR EVEN POSSIBLE AT  
AOO/JST. OVERNIGHT TONIGHT INTO TOMORROW IFR AND LOWER CIGS ARE  
POSSIBLE ENCROACHING FROM THE SOUTH TO THE NORTH BEGINNING  
AROUND 06Z. EXPECT IFR POSSIBLE AT MOST TAF SITES AND POSSIBLY  
CONTINUING INTO TOMORROW AFTERNOON.  
 
OUTLOOK...  
 
TUE...RAIN/LOW CIGS LIKELY.  
 
WED...AM RAIN/LOW CIGS POSSIBLE.  
 
THU...AM FOG POSSIBLE. PM TSRA IMPACTS POSSIBLE.  
 
FRI...PM TSRA IMPACTS POSSIBLE.  
 

 
   
CTP WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  
 

 
 

 
SYNOPSIS...DANGELO  
NEAR TERM...DANGELO/CERU  
SHORT TERM...DANGELO/CERU  
LONG TERM...LAMBERT  
AVIATION...CERU/GARTNER  
 
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