THE WEATHER PREDICTION CENTER

COLLEGE PARK, MD


EXTENDED FORECAST DISCUSSION




EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 AM EST SAT FEB 28 2015

VALID 12Z TUE MAR 03 2015 - 12Z SAT MAR 07 2015

...GUIDANCE/UNCERTAINTY ASSESSMENT...

GUIDANCE OFFERS REASONABLY SIMILAR MID-LARGER SCALE PATTERN
EVOLUTIONS SO FORECAST CONFIDENCE IS AT LEAST AVERAGE LEVELS. ONE
LINGERING DIFFERENCE HOWEVER REMAINS EVIDENT INTO WED/THU DAYS 4/5
WHEN RECENT GFS AND GEFS MEANS REMAIN LESS AMPLIFIED AND MORE
PROGRESSIVE THAN A CLUSTER OF GUIDANCE FROM THE
ECMWF/UKMET/CANADIAN AND ECMWF/CANADIAN ENSEMBLES. PREFER THIS
LATTER SOLUTION CLUSTER CONSIDERING UPSTREAM ERN PAC/AK MID-UPPER
LEVEL RIDGE AMPLITUDE SHOULD PROMOTE DOWNSTREAM IMPULSE DIGGING.
PREFER BY NEXT FRI/SAT DAYS 6/7 TO USE ANY OF QUITE COMPATABLE
GUIDANCE FROM THE GEFS/NAEFS/ECMWF ENSEMBLE MEANS IN A MUCH MORE
BENIGN/DRY PROLONGED WINTER PATTERN. THIS SOLUTION MAINTAINS GOOD
WPC CONTINUITY.

...PATTERN OVERVIEW AND SENSIBLE WEATHER HIGHLIGHTS...

AMPLIFIED SRN STREAM MID-UPPER LEVEL TROUGHING LINGERING INTO TUE
OVER THE SWRN US FOCUSES A LINGERING WINTER WEATHER THREAT WITH
HEAVIER SNOWS ALSO WORKING INTO THE S-CENTRAL ROCKIES AS AIDED BY
UPSLOPE FETCH THAT LINGERS INTO MIDWEEK WITH NRN STREAM
INTERACTION/PHASING. SIGNIFICANT NRN STREAM IMPULSE DIGGING
THROUGH W-CENTRAL NOAM TO THE LEE OF THE AMPLIFIED ERN PAC/AK
RIDGE. THIS TROUGHING FEEDS INTO THE N-CENTRAL US AND UNCERTAIN
EXTENT OF SUBSEQUENT PHASING WITH SRN STREAM ENERGIES LEADS INTO
AN OVERALL TRANSLATION OF A MEAN TROUGH OVER THE CENTRAL THEN NERN
STATES MID-LATER NEXT WEEK.

COLD NRN STREAM HIGH PRESSURE SINKS ACROSS THE WRN THEN CENTRAL US
DURING THIS PERIOD...EVENTUALLY SPREADING ACROSS THE SRN AND ERN
US. A LEAD AND WAVY FRONT ASSOCIATED WITH PIECES OF ENERGY
EJECTING ENEWD OUT FROM THE SWRN US WILL ACT TO POOL MOISTURE AND
FOCUS A POTENTIALLY LARGE SWATH OF MODERATE TO HEAVIER PCPN
MON-WED ACROSS THE CENTRAL THEN ERN US IN ADVANCE AND WRAPPING
BACK INTO THE TRAILING MAIN ARCTIC AIRMASS. THIS OFFERS YET
ANOTHER SIGNIFICANT WINTER PCPN THREAT ON THE NRN PERIPHERY OF THE
OVERALL PCPN SHIELD AND HEAVY WARM SECTOR RAINS WITH INCREASED
GULF INFLOW.

IN ADDITION IN ADVANCE OF THIS MAIN SYSTEM...MID-UPPER LEVEL
TROUGHING AND SURFACE LOW PRESSURE EJECTION INTO THE CANADIAN
MARITIMES SHOULD MAKE SURFACE BASED HIGH PRESSURE/DAMMED COLD AIR
SLOW TO ERODE FROM NEW ENG INTO THE MID-ATLANTIC IN THE WAKE OF
THE SYSTEM TUE AS WARM AIR AND MOISTURE FEEDS OVERTOP SUGGESTING
AN EMERGING/RECEDING WINTER WEATHER THREAT.

SCHICHTEL





Last Updated: 200 AM EST SAT FEB 28 2015