Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 291933
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
333 PM EDT TUE JUL 29 2014

.SYNOPSIS...
BELOW NORMAL TEMPERATURES WILL CONTINUE TO GRIP THE REGION INTO
EARLY AUGUST BENEATH A BROAD AND ANOMALOUS UPPER LEVEL TROUGH
CARVED OUT OVER THE EASTERN U.S. THE OPPORTUNITY FOR APPRECIABLE
RAINFALL SHOULD PEAK DURING THE WEEKEND BEFORE DRYING OUT INTO
EARLY NEXT WEEK.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
DAYTIME HEATING COMBINED WITH UNSEASONABLY COLD CYCLONIC FLOW
PATTERN ALOFT /MORE REMINISCENT OF THE TRANSITION
SEASONS/..COMPLETE WITH SIGNIFICANT ANOMALIES IN BOTH H85/H7
TEMPERATURES AND 500MB HEIGHTS..CONTINUES TO PROMOTE INCR CVRG OF
INSTABILITY CU/SC PER LATEST VISIBLE STLT LOOP. 16Z REGIONAL RADAR
MOSAIC IS VOID OF SHOWER ACTIVITY...WITH LITTLE TO NO CHANGE
EXPECTED THIS AFTN/EVE BASED ON CONSENSUS OF NEAR TERM HIRES MODEL
GUIDANCE. HOWEVER WILL KEEP SCHC POPS ACRS THE N/W ZONES NEAR THE
LEADING EDGE OF COLDEST AIR ALOFT /-15C AT 500MB/ AND THUS STEEPER
MID-LVL LAPSE RATES OF 6C/KM. AFTERNOON HIGHS PROGGED IN THE MID
60S TO MID 70S WILL AVG 10-15F BELOW LATE JULY NORMALS...A FAR CRY
FROM THE USUAL DOG DAYS OF SUMMER.

EXPECT SOME DECREASE IN CLOUD COVER INTO TONIGHT ESPECIALLY OVER
ERN SXNS. DESPITE P-M CLOUDY SKIES...IT SHOULD BE ANOTHER RELATIVELY
COOL NIGHT WITH LOWS LKLY APPROACHING /WITHIN ~3 DEGREES/ DAILY
CLIMATE RECORDS IN SOME LOCATIONS WITH READINGS GENERALLY IN THE
LOW-MID 50S...SIMILAR TO 7/29 MINS. DIURNAL COOLING/STABILIZATION
SHOULD RESULT IN A MAINLY DRY AND TRANQUIL OVERNIGHT BUT SUPPOSE
ANY WK EMBEDDED SHORTWAVE IN THE CYC FLOW COULD TOUCH OFF A STRAY
SHOWER...WITH THE BEST CHC OVER THE FAR N/W ZONES.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
POTENT SHORTWAVE ROTATING S OF NEARLY STNRY UPPER LOW OVER JAMES
BAY INTO THE ERN GRT LKS REGION WILL TEAM WITH DAYTIME HEATING TO
LEAD TO WEAK INSTABILITY WITH ABNORMALLY COOL CYC FLOW ALOFT.
STEEP MID-LVL LAPSE RATES WILL SPREAD INTO CENTRAL PA DURING THE
LATE MORNING AND AFTN BENEATH POOL OF -15 TO -16C AIR AT 500MB.
EXPECT SCT CONVECTION TO DEVELOP WITH SOME STORMS CONTAINING SMALL
HAIL AND HAVE CONTINUED MENTION IN NDFD FCST AND ZONE TEXT.
SUPPOSE A FEW STRONGER CORES COULD HAVE HAIL APPROACHING SVR
LIMITS /1 INCH DIAMETER/ BEFORE GRADUALLY DIMINISHING INTO WED
NGT WITH THE LOSS OF HEATING. SPC D2 STILL HIGHLIGHTS THE NW MTNS
WITH A SEE TEXT. D2 MAX/MINS SHOULD WARM A FEW DEGREES BUT REMAIN
BELOW LATE JULY CLIMATE NORMALS.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
A DEEP UPPER LEVEL TROUGH WILL BE PRESENT ACROSS SOUTHEASTERN
CANADA EARLY IN THE LONG TERM PERIOD...BUT WILL RELOAD WITH A
SIGNIFICANT CHUNK ENERGY DIGGING INTO IT/S SW FLANK ACROSS THE MID
MISS AND OHIO RIVER VALLEYS LATE THIS WEEK AND OVER THE UPCOMING
WEEKEND /AS THE CANADIAN PORTION SHEARS OUT TO THE NE/.

THIS POTENT SHORTWAVE TROUGH /AND AN ASSOCIATED WELL-DEFINED RIGHT
ENTRANCE REGION OF A 90-95 KT 300 HPA JET/ WILL LIFT NORTHEAST
ACROSS THE MID ATLANTIC REGION FRIDAY THROUGH SUNDAY BEFORE
SHIFTING TO THE SOUTHERN NEW ENGLAND COAST BY THE START OF NEXT
WEEK. A SLOW MOVING /AND LIKELY STRENGTHENING/ BAROCLINIC ZONE...
AND ONE OR MORE WAVES OF WEAK LOW PRESSURE MVG NE ALONG IT WILL BE
LOCATED ACROSS CENTRAL OR ERN PENN DURING THIS 2-3 DAY PERIOD.

WHAT THIS MEANS FOR OUR SENSIBLE WEATHER IS FOR A MAINLY
DRY THURSDAY INTO FRIDAY WITH SLIGHTLY BELOW NORMAL TEMPS. A FEW
WEAK IMPULSES ALOFT WILL RIDE EAST IN THE TEMPORARY ZONAL FLOW AND
BRING THE LOW PROBABILITY OF AN AFTERNOON SHOWER OR BRIEF...
LOW-TOPPED TSRA BOTH DAYS.

PERIODS OF UNSETTLED WEATHER /SHOWERS AND TSTMS/ WILL OCCUR LATER
FRIDAY...SATURDAY AND SUNDAY. THE STRENGTH OF THE LARGE SCALE
FORCING AND INCREASINGLY ANOMALOUSLY HIGH PWAT AIR BENEATH THE
NORTHWARD MIGRATING JET AND ITS THERMALLY DIRECT BRANCH WILL BRING
THE POTENTIAL FOR SOME LOCALLY HEAVY/TRAINING SHOWERS AND TSRA...
ESP ACROSS THE EASTERN HALF OF THE STATE/.

MODEL DETAILS DIFFER SLIGHTLY WITH RESPECT TO THE TIMING AND
LOCATION OF THE STRONGEST MESO/LARGER SCALE FORCING...BUT ALL
GUIDANCE AGREES ON THE BASIC EVOLUTION AND NE MOVEMENT OF THIS
TROUGH /AND AXIS OF HIGH...40-50MM PWAT AIR/ RIDING NWD UP ALONG
THE MID ATLANTIC PIEDMONT...AND SPREADING ACROSS THE EASTERN HALF
OF OUR CWA.

AS A RESULT OF THESE TIMING/LOCATION DIFFERENCES...POPS WERE
CAPPED OFF IN THE HIGH CHC CATEGORY...BUT AS THE FINER DETAILS
UNFOLD WITH HIGHER RES MODEL GUIDANCE OVER THE NEXT FEW
DAYS...POPS WILL UNDOUBTEDLY TREND HIGHER FOR SEVERAL PERIODS
BETWEEN LATE FRIDAY AND SUNDAY.

GRADUAL IMPROVEMENT /WITH NEAR NORMAL TEMPS/ IS EXPECTED FOR
EARLY NEXT WEEK.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
LOW VFR CIGS WILL PERSIST INTO THE EVE WITH SOME DEC IN CLOUDS
AFTER DARK. AN ISOLD -SHRA IS PSBL MAINLY OVR THE NW 1/3 OF THE
AIRSPACE ALTHOUGH CVRG IS SPARSE ENOUGH NOT TO MENTION IN TAFS.
MUCH LIKE THIS MORNING...SUPPOSE CIGS MAY TRY TO LOWER INTO MVFR
RANGE DURING THE PREDAWN AND EARLY MORNING HOURS WED...BUT FOR NOW
WILL MAINTAIN VFR. APPROACH OF UPPER LEVEL DISTURBANCE FROM THE
ERN GRT LKS ALONG WITH WEAK INSTABILITY SHOULD PROMOTE SCT SHRA
AND LOW-TOPPED TSTM DEVELOPMENT FROM LATE WED MORNING INTO THE
AFTN..WITH SOME OF THE STRONGEST STORMS CONTAINING SMALL TO
MARGINALLY SVR HAIL.

OUTLOOK...
WED...SCT PM TSRA IMPACTS POSSIBLE.
THU...AM FOG POSSIBLE NW MTNS.
FRI-SAT...SCT PM TSRA IMPACTS POSSIBLE.

&&

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

&&

$$
SYNOPSIS...STEINBUGL
NEAR TERM...STEINBUGL
SHORT TERM...STEINBUGL
LONG TERM...LAMBERT
AVIATION...STEINBUGL


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