671
FXUS10 KWNH 010518
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
118 AM EDT TUE OCT 01 2019
VALID OCT 01/0000 UTC THRU OCT 04/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z PRELIMINARY MODEL EVALUATION WITH PREFERENCES AND FORECAST
CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..OVERALL PATTERN ACROSS THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: ECENS/ECMWF/UKMET/GEFS
CONFIDENCE: SLIGHTLY BELOW AVERAGE
TWO AREAS OF CONCERN THROUGH THE FORECAST PERIOD AS AN ANOMALOUS
WESTERN TROUGH/EASTERN RIDGE BEGINS TO BREAK DOWN.
THE FIRST IS THE EVOLUTION OF THAT WESTERN TROUGH AS IT FILLS AND
LIFTS NORTHEAST THROUGH THE GREAT LAKES ON D2 AND INTO NEW ENGLAND
ON D3. ALTHOUGH THIS FEATURE IS LIKELY TO WEAKEN AND MOVE QUICKLY
IN THE PINCHED FLOW, THE GFS IS LIKELY MUCH TOO FAST AND OUTPACES
ALL THE AVAILABLE GUIDANCE AS WELL AS ITS OWN ENSEMBLE MEAN. THE
CMC TAKES UP THE OTHER END OF THE SPECTRUM, FALLING WELL BEHIND
THE CONSENSUS MEAN. THIS LEAVES THE UKMET/ECMWF/NAM, AND WHILE THE
NAM LOOKS REASONABLE ALOFT, ITS SURFACE EVOLUTION OF A BACKDOOR
COLD FRONT TOWARDS THE MID-ATLANTIC IS LIKELY TOO STRONG, SO THE
ECMWF/UKMET AS WELL AS THE ECENS/GEFS ARE PREFERRED IN THE EAST.
THE OTHER FEATURE IS A RENEWED LONGWAVE TROUGH DIGGING INTO THE
WEST COAST ON D3 FROM THE GULF OF ALASKA. ONCE AGAIN, THE GFS IS
MUCH TOO FAST, AND IN THIS CASE IT IS CLEARLY DUE TO A MORE ZONAL
PACIFIC JET STREAK SHOWING MUCH LESS EQUATOR-WARD MASS TRANSFER
THAN THE REMAINING GUIDANCE. THIS KEEPS THE TROUGH FLATTER AND
FASTER THROUGH THE WEST. ALTHOUGH THERE IS CONSIDERABLE
LATITUDINAL AND LONGITUDINAL SPREAD, THE UKMET/ECMWF/GEFS/ECENS
ARE IN PRETTY CLOSE AGREEMENT AND SHOW BETTER RUN-TO-RUN
CONSISTENCY THAN THE REMAINING MODELS. FOR THIS REASON, AND SINCE
THAT IS THE PREFERENCE FOR THE EAST AS WELL, BELIEVE THIS BLEND IS
SUFFICIENT FOR THE ENTIRE CONUS.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
WEISS
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