Prognostic Meteorological Discussion
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000
FXUS02 KWBC 201451
PMDEPD

EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1050 AM EDT SAT SEP 20 2014

VALID 12Z TUE SEP 23 2014 - 12Z SAT SEP 27 2014

...OVERVIEW AND GUIDANCE EVALUATION/PREFERENCES...

DOWNSTREAM FROM INITIAL ERN PAC TROUGHING HGTS ARE FCST TO BE
RELATIVELY HIGH OVER MOST OF THE ERN 2/3 OF THE CONUS THOUGH WITH
TWO OR MORE WEAKNESSES...ONE OVER THE PLAINS CONTAINING ENERGY
FROM A COMPACT NRN HIGH PLAINS UPR FEATURE AND ANOTHER ONE OR MORE
CLOSER TO THE EAST COAST...WHILE THE TROUGH NEAR THE PAC NW
CONTINUES TO MOVE INLAND TOWARD THE END OF THE PERIOD.

GIVEN THE STRENGTH AND NEAR OR ABOVE AVERAGE AMPLITUDE OF THE
DEVELOPING PATTERN...MODEL AGREEMENT THROUGH ABOUT DAY 4 OR 5 IS
NEAR OR ABOVE AVERAGE LEADING TO ABOVE AVERAGE CONFIDENCE IN THE
DETAILS WITH ALMOST ANY MODEL COMBINATION EQUALLY USEFUL TO
ADDRESS ANY LINGERING MODEL DISPARITIES.  HOWEVER...THE EXACT
PLACEMENT AND STRUCTURE OF THE WEAKNESSES DESCRIBED ABOVE ARE
ASSOCIATED WITH BELOW AVERAGE CONFIDENCE.  BY DAYS 6 AND 7...EVEN
THE LARGE-SCALE SOLUTION SPREAD INCREASES APPRECIABLY TO WARRANT A
GRADUAL TRANSITION TO THE GLOBAL ENSEMBLE MEANS IN ALL AREAS WITH
LESS RELIABLY UPON THE DETERMINISTIC SOLUTION...ALTHOUGH THE
SEPARATION OF THE TROUGH ALONG THE WEST COAST SEEN IN THE
DETERMINISTIC GUIDANCE IS LIKELY MORE REALISTIC THAN THE MORE
UNIFIED STRUCTURE OF THE ENSEMBLE MEANS.

...SENSIBLE WEATHER HIGHLIGHTS...

TROUGH ALOFT MOVING INTO THE WEST WILL BRING A PERIOD OF UNSETTLED
WEATHER POSSIBLY INCLUDING SOME HEAVY PRECIPITATION TO AREAS AT
LEAST FROM THE NRN HALF OF THE WEST COAST INTO NRN ROCKIES... AND
BASED ON CURRENT PREFS FARTHER SEWD OVER THE WEST BY LATER IN THE
PERIOD AS WELL.  BEST ENHANCEMENT SHOULD BE ALONG THE NRN CA/PAC
NW COAST.  MID LVL FEATURE OVER THE PLAINS MAY PROMOTE LOCALLY HVY
ACTIVITY OVER THE CNTRL PLAINS PRIMARILY DURING THE FIRST HALF OF
THE PERIOD.  AREAS NEAR THE SRN HALF OF THE EAST COAST AND ALONG
MOST OF THE GULF COAST MAY SEE RNFL OF VARYING INTENSITY THROUGH
MOST OF THE WEEK.  EXPECT THE MOST EXTREME ANOMALIES FOR TEMPS TO
BE OF THE POSITIVE VARIETY ACROSS THE NRN TIER AS SUPPORTED BY
STRONG SRLY FLOW BETWEEN ERN CONUS HIGH PRESSURE AND THE FRONT
EMERGING INTO THE NRN HIGH PLAINS LATE IN THE PERIOD... WITH SOME
PLUS 10-20F ABOVE NORMAL READINGS LIKELY FOR MIN/MAX TEMPS MOST
DAYS.

RAUSCH/JAMES

$$




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