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Extended Forecast Discussion
 
(Caution: Version displayed is not the latest version. - Issued 1601Z Oct 28, 2014)
 
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Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1201 PM EDT TUE OCT 28 2014

VALID 12Z FRI OCT 31 2014 - 12Z TUE NOV 04 2014

...ERN US EARLY SEASON WINTER THREAT AND DEEP TROUGHING/PCPN
INLAND TO THE WEST...

THE WPC MEDIUM RANGE PRODUCT SUITE WAS PRIMARILY DERIVED FROM THE
00 UTC ECMWF ENSEMBLE MEAN. THIS SOLUTION OVERALL MIMICS BUT IS
SLIGHTLY LESS DEVELOPED AND SLIGHTLY MORE PROGRESSIVE THAN THE 00
UTC ECMWF. EVEN SO...THE 00 UTC ECMWF ENSEMBLE MEAN STILL LIES
WELL ON THE AMPLIFIED SIDE OF THE FULL ENVELOPE OF ALL MODEL AND
ENSEMBLE GUIDANCE SYSTEMS. THIS FOLLOWS THE LASTEST GENERAL TREND
TOWARD FLOW AMPLIFICATION FROM MOST GUIDANCE AND LEAD-IN NRN
HEMISPHERIC WATER VAPOR LOOPS...BUT DOES LIMITS BY THE NATURE OF
THE MEAN THE DEEPEST SMALLER SCALE SYSTEM ORGANIZATION/PHASING
CONSIDERING AT LEAST AVERAGE FORECAST SPREAD AND UNCERTAINTY.

THE WEATHER RELATED THREATS HIGHLIGHTED DURING THIS MEDIUM RANGE
FORECAST PERIOD ARE PREDOMINANTLY ASSOCIATED WITH TWO MAIN
DEVELOPING WEATHER FEATURES.

EXPECT STRONG LEAD MID-UPPER LEVEL TROUGH AMPLIFICATION WILL OCCUR
DOWNSTREAM OF AMPLIFYING CENTRAL NOAM RIDGE AS MID AND UPPER
LATITUDE IMPULSE ENERGY DIGS SHARPLY SSEWD FRIDAY INTO THE
WEEKEND...WITH DEVELOPING MODERATELY HEAVY PCPN FROM OFF THE GREAT
LAKES THROUGH THE APPALACHIANS INTO THE MID-ATLANTIC AND
NORTHEAST. THERE IS SOME THREAT OF CLOSING AN ANOMALOUSLY COLD LOW
NEAR THE MID-ATLANTIC BUT REGARDLESS ACTS TO SOLIDIFY AN
ASSOCIATED SURFACE LOW/FRONTAL THEN COASTAL SYSTEM WITH WRAPPING
PCPN INTO THE MID-ATLANTIC/NORTHEAST WITH FREEZING TEMPS POTENTIAL
ALSO TRAILING DOWN THROUGH THE SRN/SERN US. THERE IS A REAL RISK
OF HEAVIER SNOWS ON THE BACKSIDE OF THIS SYSTEM OFF THE LAKES INTO
ESPECIALLY THE APPALACHIANS AND POSSIBLY INTO THE MID-ATLANTIC AND
PORTIONS/TERRAIN ACROSS THE NORTHEAST.

MEANWHILE OUT WEST...GUIDANCE SEEMS TO BE MORE CLOSELY ALIGNING ON
THE CONCEPT OF TRACKING AN AMPLIFIED AND COOLING/UNSETTLING/PCPN
FOCUSING MID-UPPER LEVEL TROUGH AND ASSOCIATED SURFACE LOW/FRONTAL
SYSTEM AND PCPN WELL DOWN THROUGH MUCH OF THE WEST COAST THIS
WEEKEND...LIFTING MORE IN ERNEST THROUGH THE ROCKIES INTO THE
PLAINS EARLY NEXT WEEK. THIS INCLUDES A THREAT FOR HEAVIER SNOWS
DOWN THROUGH THE SIERRA AND NORTHEASTWARD TO THE NORTH-CENTRAL
ROCKIES WITH SYSTEM APPROACH/PASSAGE...EVENTUALLY LEADING TO A
ORGANIZED CONVECTIVE THREAT OVER THE PLAINS INO MIDWEEK.

SCHICHTEL