Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 300949
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
549 AM EDT MON MAR 30 2015

.SYNOPSIS...

A COLD FRONT WILL MOVE THROUGH THE AREA EARLY TODAY. THIS WILL BE
FOLLOWED BY ANOTHER FAST MOVING DISTURBANCE THAT WILL BRING THE
CHANCE FOR MORE UNSETTLED WEATHER LATER TONIGHT AND TUESDAY. A
SLOW MODERATION IN TEMPERATURES IS EXPECTED FOR THE LATTER HALF OF
THE WEEK AHEAD BEFORE A NEW COLD FRONT APPROACHES FOR FRIDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...

AS OF 4 AM THE COLD FRONT IS JUST ENTERING WESTERN PA. THE MAIN
PRECIPITATION SHIELD IS FAIRLY DISORGANIZED AND HAS SURGED WELL
OUT AHEAD OF THE FRONT. SCATTERED LIGHT SHOWERS EXTEND ALL THE WAY
BACK TO WESTERN PA. HRRR TIMING HAS THE FRONT MOVING THROUGH MY
WESTERN COUNTIES BY 12Z...WITH ASSOCIATED SHOWERS STREAKING EAST
AND WEAKENING QUICKLY BY MID DAY WHEN THE FRONT WILL BE MOVING OUT
OF MY SERN COUNTIES.

IT WILL BECOME GUSTY AFTER THE FRONTAL PASSAGE AND BY AFTERNOON
ANY LEFTOVER PRECIPITATION WILL FAVOR MY WESTERN AND NORTHERN
MOUNTAINS WHERE IT COULD FALL AS RAIN OR SNOW. WITH SKIN TEMPS
EXPECTED TO BE IN THE MID TO UPPER 30S...SNOW ACCUMS SHOULD NOT
BE A PROBLEM.

MODELS ARE IN BETTER AGREEMENT TONIGHT IN THE TRACK AND INTENSITY
OF THE QUICK MOVING WAVE EXPECTED TO APPROACH FOR LATER TONIGHT
AND TUESDAY. I LEANED CLOSER TO THE SREF POPS TO HAVE PRECIP MOVING
INTO MY NWRN ZONES AFTER MIDNIGHT. THE PRECIP WILL INITIALLY BE
SNOW AS IT BREAKS OUT OVER THE NW AND A LIGHT COATING IS POSSIBLE
BY SUNRISE.

&&

.SHORT TERM /TUESDAY/...

THE BULK OF THE FAST MOVING STORM SYSTEM WILL AFFECT THE REGION
TUESDAY WITH A WET SNOW EXPECTED ACROSS THE NORTHERN HIGHER
ELEVATIONS...A RAIN SNOW MIX IN THE TRANSITION ZONE BETWEEN THE
RAIN OVER SOUTHERN PARTS OF THE STATE.

THE SHORTWAVE ALOFT IS FCST TO BE RATHER FLAT...BUT EMBEDDED IN
FAST FLOW ALLOWING FOR IMPRESSIVE JET DYNAMICS UNDER THE
APPROACHING LEFT EXIT REGION. STRONG WARM ADVECTION ON THE LOWER
BRANCH OF THIS JET STREAK SURGES INTO THE REGION AS LOW LEVEL
AGEOSTROPHIC WINDS INCREASE OUT OF THE NORTH HELPING TO TIGHTEN
THE ISOTHERMS. WHAT WE SEE IS THE DEVELOPMENT OF SOME DEEP LAYER
INSTABILITY WITH MID LEVEL LAPSE RATES EXCEEDING 6C/KM BY EARLY
AFTERNOON OVER MUCH OF THE STATE...WHILE AN AREA OF STRONG
FRONTOGENESIS TRACKS THROUGH CENTRAL AND NORTHERN AREAS.

THE SYSTEM WILL BE A QUICK HITTER AND NOT BLESSED WITH A
TREMENDOUS AMOUNT OF MOISTURE INFLOW...SO QPF WILL NOT BE
EXCESSIVE...GENERALLY ON THE ORDER OF .25-.50"...WITH HIGHEST
AMOUNTS OVER THE NRN HALF OF THE STATE. I FAVORED THE ENSEMBLE
SNOW ACCUM GUIDANCE WHICH SUGGESTED MOST OF MY AREA WILL SEE
LITTLE OR NONE...WITH THE BEST CHANCE OF A FEW SLUSHY INCHES BEING
ALONG THE NY BORDER. TEMPS EVEN THERE WILL BE IN THE MID 30S FOR
MUCH OF THE DAY SO UNLESS IT SNOWS FAIRLY HARD...MOST ACCUMS WILL
LIKELY BE ON GRASSY SURFACES. OVER CENTRAL AREAS WHERE A RAIN-SNOW
MIX IS LIKELY FOR A TIME...IT SHOULD BE TOO WARM TO STICK.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...

HIGH PRESSURE SHOULD BRING DRY WEATHER FOR MIDWEEK BEFORE THE
PATTERN TURNS INCREASINGLY UNSETTLED DURING THE LAST PART OF THE
WEEK.

THE LATEST NAEFSBC HAS NOT CHANGED THE OVERALL THINKING THAT A
WARMING TREND WILL DEVELOP AHEAD OF THE LATE WEEK COLD FRONT.

THE DETAILS OF THE FRONT AT THIS RANGE REMAIN FUZZY AS THE
OPERATIONAL ECMWF AND GFS HAVE TIMING AND INTENSITY ISSUES. THE
GFS DROPS THE FRONT INTO PA THURS NIGHT WHILE THE ECMWF STILL HAS
IT THROUGH THE LOWER GR LAKES. THE DIFFERENCES BETWEEN THE TWO
OPERATIONAL MODELS MEAN FRIDAY COULD EITHER BE MAINLY DRY WITH THE
FRONT SETTLING SOUTH...GFS...OR WET AS THE FRONT ENTERS THE
REGION...ECMWF.

FROM THERE IT GETS A LITTLE MORE COMPLICATED AGAIN WITH A
TRAILING WAVE OR WAVES MADE TO SURGE OUT OF THE TN VALLEY INTO THE
REGION FRIDAY NIGHT INTO SATURDAY. THE EC ENSEMBLE HINTS AT A WAVY
FRONT WITH PERHAPS A COUPLE OF LOWS RIPPLING ALONG IT EVENTUALLY
MOVING THROUGH CENTRAL PA...WHILE THE GFS/GEFS ARE MORE IN LINE
WITH A SINGLE MORE COHERENT LOW TAKING A MORE SOUTHERN TRACK.
BECAUSE OF THE UNCERTAINTY WITH THESE SCENARIOS...I KEPT POPS IN
THE CHANCE RANGE FOR THURS INTO FRIDAY NIGHT BEFORE BEGINNING TO
DRY THINGS OUT FOR SATURDAY.

IT SEEMS LIKELY THERE WILL BE SOMEWHAT OF A COOL DOWN OVER THE
WEEKEND AFTER THE FRONT PASSES AND WE SEE THE UPPER LOW OVER
HUDSON`S BAY SINK SOUTH ONCE AGAIN. WHILE WE WILL COOL DOWN...THE
LARGER SCALE FLOW OVER WESTERN NOAM IS EXPECTED TO HAVE MORE OF A
PACIFIC ORIGIN SO TEMPS SHOULD NOT CONTINUE THE TREND OF BEING
WELL BELOW NORMAL AS WE HAVE SEEN FOR MUCH OF THE LAST 2 MONTHS.

&&

.AVIATION /09Z MONDAY THROUGH FRIDAY/...
06Z TAFS SENT.

GUSTY WINDS AS SNOW SHOWERS MOVE ACROSS THE AREA FROM WEST TO
EAST...GIVEN VERY DRY AIR AT LOW LEVELS FOR EVAPORATIONAL
COOLING.

MUCH OF THE SNOW NOT REACHING THE GROUND.

EARLIER DISCUSSION BELOW.

VFR CONDITIONS CONTINUE ACROSS THE REGION. EVEN GIVEN THE SOMEWHAT
IMPRESSIVE RADAR RETURNS MOVING FROM EASTERN OHIO INTO WESTERN
PENNSYLVANIA...HARD PRESSED TO SEE ANY RESTRICTIONS BELOW
VFR...AND REALLY ANY REPORTS OF ANY SENSIBLE WEATHER AT THE
SURFACE. SIGNIFICANT T/TD DEPRESSIONS NEED TO BE OVERCOME.

APPARENTLY ANY SNOW ACTIVITY WILL NOT BE ASSOCIATED WITH THE WARM
FRONTAL ACTIVITY...BUT WITH AND SLIGHTLY AHEAD OF THE FROPA LATER
TONIGHT.

HAVE ALREADY SLOWED THE ONSET OF LOWER CLOUDS AND SNOW SHOWERS IN
THE TAFS...BUT WILL LIKELY NEED TO SLOW THEM AGAIN IN THE NEXT
UPDATED.

THE FAST MOVING COLD FRONT APPEARS ONLY ROBUST ENOUGH TO CAUSE
RESTRICTIONS AT KJST AND KBFD IN CENTRAL PENNSYLVANIA. WHILE THERE
MAY BE A FEW SNOW SHOWERS FURTHER EAST...EXPECT VFR CONDITIONS FOR
THE MOST PART TO PREVAIL THROUGH MONDAY.

SOME RAIN AND SNOW SHOWERS FOR TUESDAY INTO EARLY WEDNESDAY...AS
A FAST MOVING LOW DROPS SOUTHEAST FROM THE CENTRAL PLAINS OF
CANADA.

OUTLOOK...

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

TUE...CHANCE OF LIGHT SNOW/RAIN...MAINLY ACROSS THE NW HALF
WITH MVFR REDUCTIONS. VFR SE.

WED-THU MORNING...MAINLY VFR...AS HIGH PRESSURE BUILDS ACROSS
THE AREA.

THU PM-FRI...LOWERING CONDITIONS TO MVFR WITH SCATTERED RAIN
SHOWERS...AS A COLD FRONT MOVES EASTWARD.

&&

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

&&

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


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