Area Forecast Discussion
Issued by NWS State College, PA

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FXUS61 KCTP 100925
AFDCTP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE STATE COLLEGE PA
525 AM EDT THU JUL 10 2014

.SYNOPSIS...
A PERSISTENT UPPER LEVEL TROUGH OVER THE GREAT LAKES WILL DAMPEN
AS IT CROSSES THE NEW ENGLAND STATES INTO THE WEEKEND...WITH A
WEAKENING QUASI-STATIONARY FRONT TRAILING SOUTHWARD ALONG THE MID
ATLANTIC COAST. DESPITE THE INFLUENCE OF HIGH PRESSURE AT THE
SURFACE...THE AREA WILL REMAIN VULNERABLE TO ISOLATED SHOWERS AND
THUNDERSTORMS INTO THE FIRST PART OF THE WEEKEND. A SERIES OF
REINFORCING COLD FRONTS WILL PROVIDE SEVERAL OPPORTUNITIES FOR
RAINFALL THROUGH EARLY NEXT WEEK...WHILE HELPING TO CARVE OUT A
HIGHLY ANOMALOUS UPPER TROUGH AND BONAFIDE POLAR VORTEX ACROSS
SOUTHEASTERN CANADA AND THE UPPER GREAT LAKES.

&&

.NEAR TERM /THROUGH TONIGHT/...
DWINDLING SHRA CONTINUE TO RIDE ALONG DYING SECONDARY COLD FRONT
ACROSS THE N MTNS EARLY THIS MORNING. LATEST RAP SUGGESTS THESE
SHOWERS DISAPPEAR TOWARD DAWN...AS BLYR CONTINUES TO COOL/STABILIZE.
ELSEWHERE...MCLEAR SKIES AND A LIGHT WIND HAVE RESULTED IN PATCHY
FOG. 11-3.9U IMAGERY INDICATES THE MOST EXTENSIVE FOG/LOW CLOUDS
ARE ACROSS THE NW MTNS.

ANY FOG AND LOW CLOUDS WILL BURN OFF SHORTLY AFTER DAWN...GIVING
WAY TO M/SUNNY START TO THE DAY OVER MOST OF CENTRAL PA.
HOWEVER...AN UPPER LEVEL TROUGH MOVG EWD ACRS THE LOWER GRT
LKS...COMBINED WITH WEAK INSTABILITY...SHOULD BE ENOUGH TO
GENERATE SCT SHRA/TSRA DURING THE AFTN...MAINLY ACRS THE SCNTRL
MTNS. 8H TEMPS BTWN 12-14C SHOULD TRANSLATE TO HIGHS FROM THE M70S
OVR THE HIGHEST TERRAIN OF THE ALLEGHENIES...TO THE M80S ACROSS
THE LOWER SUSQ VALLEY.

A SHOWER OR TWO MAY LINGER OVER THE SERN ZONES LATE THIS
EVE...BUT HIGH PRES WILL DOMINATE FOR THE MOST PART WITH CLEARING
AND PATCHY VALLEY FOG DEVELOPING OVERNIGHT AND INTO EARLY FRIDAY
MORNING. GFS MOS APPEARS TOO COOL TONIGHT BASED ON BLEND OF ALL
MDL SFC DWPTS. BCCONSALL APPEARS MUCH MORE REASONABLE...WITH LOWS
RANGING FROM THE L50S OVR THE NW MTNS TO THE M60S OVR THE LOWER
SUSQ VALLEY.

&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
VERY LITTLE CHANGE IN THE OVERALL PATTERN EXPECTED INTO DAY 2
WITH EVEN WEAKER FORCING ALOFT DUE TO DAMPENING OF UPPER TROUGH.
EXPECT BULK OF PCPN TO REMAIN CONFINED TO ERN NC/VA TO THE
DELMARVA NEAR Q-STNRY FRONT AND HI MSTR PWS AXIS. STILL CANT RULE
OUT AN ISOLD SHRA/TSTM DURING THE AFTN OVER ERN PRTNS OF THE CWA
BUT POPS WILL BE BARELY MENTIONABLE/AOB 20 PCT. TEMPS SHOULD EDGE
A LITTLE WARMER THAN THURSDAY. STG WAA UPSTREAM OVER THE GRT
LKS/OH VLY WILL LKLY BRING SOME MID-HIGH CLOUDS INTO WRN SXNS BY
12Z SAT.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
THE AREA SHOULD BE IN MORE OF A RETURN FLOW REGIME BY SAT AS THE
SFC HIGH SLIPS OFF THE EAST COAST. SIMILAR TO DAYS 1 AND 2..STILL
CANT RULE OUT AN ISOLD SHRA/TSTM IN SPOTS WHILE MOST AREAS STAY
DRY. STALLED FRONT ALONG THE SOUTHEAST COAST SHOULD PIVOT BACK
NWD AS WARM FRONT SAT NGT INTO EARLY SUNDAY WITH S-SWLY LLJ INC
LLVL MSTR FLUX THRU THE UPPER OH VLY INTO WRN PA IN ADVANCE OF
LEAD SHORTWAVE ENERGY AND ASSOCD SFC COLD FRONT MOVG SEWD ACRS THE
GRT LKS-MIDWEST.

AMPLIFICATION OF THE UPPER PATTERN BEGINS EARLY NEXT WEEK WITH A
MODEL CONSENSUS GENERALLY INDICATING A FRONTAL PCPN AXIS SHIFTING
SEWD THRU THE GRT LKS/OH VLY REGIONS INTO CENTRAL PA SUN-MON.
ALTHOUGH PREDICTABILITY IS TOO LOW ATTM...A SEVERE WX THREAT
SHOULD SPREAD SEWD IN TIME FROM THE UPPER MIDWEST/GRT LKS/OH VLY
INTO THE MID ATLC AND NORTHEAST STATES...ALONG SRN PERIPHERY OF
STRONGER WINDS/CYC FLOW ALOFT AND SEVERAL REINFORCING COLD
FRONTAL SURGES ASSOCIATED WITH THE AMPLIFYING SYNOPTIC UPPER
TROUGH. EACH COLD FRONTAL SURGE WILL PROVIDE AN OPPORTUNITY FOR
SHOWERS/TSTMS THROUGH AT LEAST TUESDAY.

THE HIGHLY ANOMALOUS AMPLIFICATION OF THE LARGE SCALE PATTERN IS
A VIRTUAL LOCK BY THE END OF THE PERIOD AS INDICATED BY ALL MEDIUM
RANGE GLOBAL NUMERICAL MODELS AND ENSEMBLE SYSTEMS. THIS WELL-
ADVERTISED HIGH MERIDIONAL EVENT WILL FEATURE A FULL-LATITUDE
RIDGE AND SEARING HEAT OUT WEST...NOT BE BE OUTDONE BY THE RETURN
OF THE POLAR VORTEX IN THE EAST OVER QUE/ONT AND THE UPPER GREAT
LAKES. CONSIDERING THE MAGNITUDE OF THE UPPER LEVEL TROUGH WITH
500MB STANDARDIZED ANOMALIES ON THE ORDER OF -3 TO -4SD IN BOTH
THE DETERMINISTIC GLOBAL MODELS AND THEIR RESPECTIVE ENSEMBLE
MEANS...CONFIDENCE IN A PERIOD OF BELOW AVG TEMPS /DURING WHAT IS
CLIMATOLOGICALLY THE HOTTEST TIME OF THE YEAR/ IS VERY HIGH FROM
TUE-THU OF NEXT WEEK.

&&

.AVIATION /09Z THURSDAY THROUGH MONDAY/...
11-3.9UM SATL IMAGERY SHOWING EXTENSIVE VALLEY FOG ACROSS THE
NORTHERN MTNS EARLY THIS MORNING. A COMBINATION OF 09Z SFC
OBS...CONDITIONAL CLIMATOLOGY AND LATEST RAP OUTPUT SUGGEST
KBFD...KIPT AND KUNV WILL EXPERIENCE SOME IFR CONDS IN THE 09Z-11Z
TIME FRAME.

ANY LOW CIGS/FOG SHOULD RAPIDLY MIX OUT BY 12Z...WITH
PREDOMINATELY VFR CONDS EXPECTED FOR THE REST OF THE DAY.
HOWEVER...A TROUGH OF LOW PRES APPROACHING FROM THE WEST WILL
LIKELY TRIGGER SCT SHRA/TSRA DURING THE AFTN AND EVENING HRS. THE
BEST CHANCE OF A BRIEF VIS REDUCTION WILL BE ACROSS THE SC
MTNS...INCLUDING KJST AND KAOO.

OUTLOOK...

FRI-SAT...PATCHY AM FOG POSSIBLE.

SUN-MON...BRIEF...MAINLY PM...THUNDERSTORM IMPACTS POSSIBLE.

&&

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

&&

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


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