Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 280939
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
539 AM EDT SAT MAR 28 2015

.SYNOPSIS...
A DEEP UPPER LEVEL TROUGH WILL SWING EAST ACROSS PENNSYLVANIA
TODAY. THE UPPER LEVEL FLOW WILL BECOME MORE ZONAL NEXT WEEK
LEADING TO A SLOW MODERATION IN TEMPERATURES.

&&

.NEAR TERM /THROUGH TONIGHT/...
ANOMALOUSLY DEEP AND COLD UPPER TROUGH IS DROPPING OUT OF THE
EASTERN GR LAKES TO PASS PRETTY MUCH OVERHEAD EARLY TODAY. STRONG
HEIGHT FALLS ALOFT HELPING SUPPORT AN AREA OF LARGE SCALE WEAK
ASCENT. LOW LEVEL FLOW HAS BECOME WEAKLY CYCLONIC AND THE RAP
SHOWS A SMALL AREA OF LOW LEVEL CONVERGENCE/FRONTOGENETIC FORCING
THAT COINCIDES FAIRLY CLOSELY WITH THE LOCALIZED SNOW SHOWERS WE
HAVE GOING ON FROM JUST EAST OF THE OFFICE OUT TO ABOUT
WILLIAMSPORT. THE RAP WEAKENS THIS SLOWLY OVER THE NEXT SEVERAL
HOURS AND STRETCHES IT OUT FROM NNW TO SSE AS THE UPPER LOW/HEIGHT
FALLS SETTLE SOUTHEAST.

GUIDANCE IN GOOD AGREEMENT WITH THE UPPER LOW/TROUGH MOVING
OVERHEAD THIS MORNING HEADING OFF TO SE TO BE MOVING OUT OF PA BY
LATE DAY. MODELS USE THE COLD AIR ALOFT TO CREATE AN AREA OF STEEP
LAPSE RATES IN EXCESS OF 8C/KM FROM 850-700MB. I WOULD NORMALLY
GET A LITTLE MORE EXCITED AT THIS TIME OF YEAR ABOUT LOW TOPPED
THUNDER AND PERHAPS SMALL HAIL...BUT MODEL SOUNDINGS SHOW A GREAT
DEAL OF DRY AIR ABOVE 700MB WHICH LIMITS DEEPER INSTABILITY. STILL
WITH UPPER TEMPS SO COLD...IF WE CAN BREAK OUT WITH SOME SUNSHINE
THIS MORNING INTO EARLY AFTERNOON...I WOULDN`T BE SURPRISED IF
THERE ARE A FEW SQUAT STORMS. CONFIDENCE IS LOW HOWEVER.

AT THIS POINT I USED A MODEL BLEND OF POPS SINCE THE SREF LOOKED
TOO WET AND DISPLACED FROM THE BEST LAPSE RATES...AND THE MOS POPS
LOOKED TOO LOW. BASICALLY ENDED UP WITH CHC POPS THIS MORNING INTO
THE FIRST PART OF THE AFTERNOON WITH THE END OF THE DAY BECOMING
DRY.

I`LL STICK WITH MY ASSESSMENT FROM YESTERDAY ABOUT TODAY BEING THE
COLDEST DAY WE WILL EXPERIENCE UNTIL LATER NEXT FALL OR EARLY
WINTER. HIGHS FROM THE LOWER 20S TO MID 30S WILL BE SOME 20-30 DEG
BELOW NORMAL. A GUSTY WIND WILL MAKE IT FEEL EVEN COLDER...MORE
LIKE JANUARY THAN THE LAST DAYS OF MARCH.

SKIES WILL CLEAR EARLY THIS EVENING ALLOWING TEMPS TO PLUNGE INTO
THE SINGE NUMBERS OVER THE NORTH TO AROUND 20 OVER THE SOUTH. IF
WINDS DROP OFF TO CALM...SOME READINGS NEAR ZERO COULD HAPPEN OVER
THE FAR NORTH.

&&

.SHORT TERM /SUNDAY/...
SUNDAY WILL BE BRIGHT AND SUNNY WHICH WILL HELP TEMPERATURES
REBOUND AFTER THE VERY COLD START TO THE DAY. HOWEVER HIGHS FROM
THE MID 30S TO MID 40S...WHILE MILDER THAN TODAY...WILL STILL BE
SEVERAL DEG BELOW NORMAL.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
NAEFS CONTINUES TO ADVERTISE A BREAKDOWN OF THE WESTERN NOAM
RIDGE WHICH EVENTUALLY TRANSLATES INTO A MORE ZONAL FLOW OVER THE
EASTERN CONUS. BUT BEFORE THAT HAPPENS WE WILL HAVE AT LEAST A
COUPLE OF SHORTWAVES THAT WILL KEEP CONDITIONS SOMEWHAT UNSETTLED
AND ON THE COOL SIDE.

THE FIRST SYSTEM IS A COLD FRONT THAT WILL BRING SOME LIGHT RAIN
OR SNOW SHOWERS SUNDAY NIGHT INTO MONDAY...FOLLOWED BY A BOUT OF
THE ALL TOO FAMILIAR CHILLY POST FRONTAL STRATOCU AND MOUNTAIN
RAIN OR SNOW SHOWERS DURING THE DAY MONDAY.

THIS IS FOLLOWED IN QUICK SUCCESSION BY ANOTHER SHORTWAVE FOR
TUESDAY. THE OPERATIONAL GFS/ECMWF BOTH HAVE AN INTERESTING
LOOKING SURFACE LOW THAT THEY TAKE SE THROUGH CENTRAL OR SOUTHERN
PA ALONG A TIGHT THERMAL RIBBON. AT THIS TIME ALL I HAVE MENTIONED
FOR PRECIP IS RAIN. FCST 850 TEMPS WOULD NORMALLY BE COLD ENOUGH
TO CONSIDER SNOW AT LEAST NORTH OF THE LOW...BUT THE FACT IT IS
COMING THROUGH DURING THE DAY AT THIS TIME OF YEAR...I AM
RELUCTANT TO FORECAST SNOW WITH HIGHS EXPECTED IN THE 40S AND 50S.

BY MIDWEEK WE SHOULD SEE UPPER HEIGHTS REBOUND AS THE MAIN TROUGH
AT LEAST TEMPORARILY SHIFTS INTO THE CANADIAN MARITIMES. HOWEVER
THE PARENT UPPER LOW REMAINS OVER HUDSON`S BAY AND EVEN DROPS
SOUTH IN TIME...REINFORCING THE TROUGHING OVER THE NRN US BY
WEEK`S END. BUT THE GOOD NEWS IS THE FLOW INTO THE LOCAL AREA
WILL BE ORIGINATING OVER THE PACIFIC NW MORE THAN THE DEEP
ARCTIC...SO TEMPS WHILE STILL EXPECTED TO BE BELOW NORMAL...SHOULD
MOVE AWAY FROM THE EXTREME COLD WE HAVE ENDURED FOR SO MUCH OF THE
TIME SINCE FEBRUARY.

&&

.AVIATION /10Z SATURDAY THROUGH WEDNESDAY/...
SNOW AT LNS AT TIMES.

09Z TAFS ADJUSTED FOR SNOW ETC.

EARLIER DISCUSSION BELOW.

DEEP UPPER LEVEL LOW RESULTING IN DEFORMATION SNOW DEVELOPING
BETWEEN UNV AND IPT AS OF 1 AM.

MADE SOME CHANGES TO THE TAFS BASED ON THIS...HARD TO SEE MUCH
CHANGE IN CONDITIONS UNTIL LATE AFTERNOON TODAY.

AS THE COASTAL LOW PULLS AWAY SATURDAY NIGHT...BREEZY
CONDITIONS WILL PREVAIL.

MORE LESS THAN GREAT WEATHER WILL WORK BACK INTO THE AREA
BY EARLY MONDAY MORNING.

OUTLOOK...

SUN...NO SIG WX/VFR.

MON...CHANCE OF LIGHT RAIN /LIGHT SNOW EARLY/ ACROSS THE
WESTERN HALF WITH MVFR REDUCTIONS. VFR SE.

TUE...CHANCE OF LIGHT RAIN ACROSS NW HALF WITH MVFR REDUCTIONS.
VFR SE.

WED...MAINLY VFR...AS HIGH PRESSURE BUILDS INTO THE AREA.

&&

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

&&

$$
SYNOPSIS...LA CORTE
NEAR TERM...LA CORTE
SHORT TERM...LA CORTE
LONG TERM...LA CORTE
AVIATION...MARTIN


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