Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 210545
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
145 AM EDT TUE APR 21 2015

.SYNOPSIS...
A COLD FRONT WILL PUSH EAST OF THE AREA EARLY THIS MORNING. A
LARGE UPPER LEVEL LOW OVER THE GREAT LAKES WILL SLOWLY EDGE
EASTWARD TO NORTHERN NEW ENGLAND BY LATE IN THE WEEK.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
HEAVY SHOWERS AND A FEW LINGERING LIGHTNING STRIKES OBSERVED
ACROSS FROM THE SUSQ RIVER EASTWARD AT 05Z ALONG AXIS OF LL JET
AND ASSOC BAND OF ANOMALOUS PWATS. COLD FRONT...WHICH IS
BISECTING THE STATE AT 05Z FROM ARND KUNV TO KAOO...SHOULD EXIT
THE EASTERN COUNTIES BY ARND 09Z. MUCH DRIER AIR HAS ALREADY
ARRIVED OVER THE ALLEGHENY PLATEAU WITH DWPTS FALLING INTO THE
L40S. PASSAGE OF UPPER LVL SHORTWAVE WILL SUSTAIN A FEW LINGERING
POST-FRONTAL -SHRA INTO THE PREDAWN HOURS. HOWEVER...LATEST
RAP/HRRR INDICATE THE LAST OF THE -SRHA SHOULD BE EXITING THE
EASTERN COUNTIES BY ARND 11Z.

EXPECT PARTIAL CLEARING TO DEVELOP EAST OF THE MTNS TOWARD
DAWN...AS DRIER WESTERLY FLOW ARRIVES. FURTHER WEST...SHALLOW LYR
OF MOISTURE ASCENDING THE MTNS WILL LIKELY RESULT IN BKN STRATOCU
PERSISTING OVR THE ALLEGHENIES.

TWEAKED MIN TEMPS A BIT BASED ON LATEST LAMP/RAP GUIDANCE.
READINGS BY DAWN SHOULD RANGE FROM ARND 40F OVR THE HIGH TERRAIN
OF THE ALLEGHENIES...TO THE M50S SE OF HARRISBURG.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
MDL DATA INDICATES CENTRAL PA WILL BE IN A REGION OF LG SCALE
SUBSIDENCE/SFC RIDGING LATE THIS MORNING WITH DRY WX ANTICIPATED.
HAVE REDUCED POPS SIGNIFICANTLY BTWN 12Z-18Z. MDL SOUNDINGS AND
UPSTREAM SATL IMAGERY IMPLY THERE WILL BE A FAIR AMT OF SUNSHINE
LATER THIS MORNING...ESP EAST OF THE MTNS...WITH PSUNNY SKIES
ACROSS THE NW MTNS. DIURNAL HEATING/DEEPENING BLYR DEPTH WILL
RESULT GUSTY WSW WINDS DEVELOPING DURING THE LATE AM AND AFTN
HOURS. BUFKIT SOUNDINGS SUPPORT WIDESPREAD GUSTS TO ARND 25KTS BY
AFTN.

ANOMALOUSLY COLD MID LVL TEMPS WILL PROMOTE DIURNAL CONVECTION
DURING THE AFTN...PRIMARILY OVR THE NW MTNS. LACK OF DEEP MOISTURE
WILL RESULT IN LIGHT RAINFALL AMTS. HOWEVER...HAVE BUMPED UP POPS
TO BTWN 60-70PCT ACROSS THE NW MTNS BASED ON ENSEMBLE QPF OUTPUT.
PER SPC OUTLOOK...HAVE INCLUDED THE CHC OF A PM TSRA OVR THE NW
COUNTIES...WHERE MDL SOUNDINGS BECOME MARGINALLY UNSTABLE BTWN
18Z-00Z.

ENS MEAN 8H TEMPS SUPPORT MAX TEMPS TODAY FROM AROUND 50F OVR THE
NW MTNS TO THE L60S ACROSS THE LOWER SUSQ.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
THE LONG TERM PATTERN WILL BE DOMINATED BY A LARGE UPPER LEVEL
LOW MOVING THROUGH THE NORTHERN GREAT LAKES...AND THROUGH SOUTHERN
CANADA MIDWEEK TO THE WEEKEND. THERE IS GOOD MODEL CONSENSUS
THROUGH THE MID RANGE PERIOD. AFTER THE FRONT LIFTS OUT BY TUESDAY
MORNING THE UPPER LOW HANGS AROUND S CANADA/NEW ENGLAND FOR
SEVERAL DAYS KEEPING FAIRLY BRISK W/NW FLOW ACROSS PA. THIS WILL
BRING A STEADY STREAM OF COLDER AIR AS TEMPS SLOWLY SLIP A BIT
LOWER EACH DAY WITH BELOW NORMAL READINGS FOR A SEVERAL DAY PERIOD
LINGERING INTO NEXT WEEKEND. PROXIMITY OF UPPER LOW WILL ALSO KEEP
MENTION OF SCT SHOWERS IN THE FORECAST. A SHORTWAVE SHOULD DROP
THROUGH THE REGION WEDNESDAY AFTERNOON INTO THURSDAY MORNING. THIS
COULD DROP EVEN COLDER AIR INTO THE REGION BRINGING THE
POSSIBILITY OF SNOW TO THE NW TO THE CENTRAL REGIONS OF PA. THE
MODELS ARE BECOMING CLOSER TO A CONSENSUS SOLUTION...HOWEVER
SOLUTION IS TRENDING TOWARD THE UPPER LEVEL LOW TO BECOME
QUASI-STATIONARY AND SLOWLY SPINNING OVER QUEBEC.WITH ONLY A
SLIGHT CHANCE FOR PRECIPITATION NEXT WEEKEND. THE MOVEMENT OF THE
LOW WILL DOMINATE THE PATTERN NEXT WEEK WITH IT POSSIBLY
RETROGRADING AND SWINGING ANOTHER TROUGH THROUGH THE REGION NEXT
WEEK.

&&

.AVIATION /05Z TUESDAY THROUGH SATURDAY/...
ASIDE FROM BRIEF IFR VIS IN +TSRA INVOF MDT/LNS THRU 06Z...EXPECT
MVFR/VFR CONDITIONS TO PREVAIL OVERNIGHT AND INTO TUESDAY. SFC
WNDS FROM 250 TO 300 DEGREES WILL BECOME GUSTY AT 25-30KTS BY
TUESDAY MORNING WITH PREDOMINATELY SCT TO BKN MVFR TO VFR CIGS.

OUTLOOK...

WED-SAT...PERSISTENT NW FLOW PATTERN WILL FAVOR MVFR CIGS OVER
THE NW AIRSPACE IN ZOB SECTOR...WITH MAINLY VFR CONDITIONS
PREVAILING IN ZNY DOMAIN. ISOLD TO SCT SHOWERS WILL BE POSSIBLE
ACROSS ALL OF THE AIRSPACE THROUGH THE REMAINDER OF THE WEEK.

&&

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

&&

$$
SYNOPSIS...FITZGERALD/LA CORTE
NEAR TERM...FITZGERALD
SHORT TERM...FITZGERALD/CERU
LONG TERM...CERU/RXR
AVIATION...STEINBUGL



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