886
FXUS10 KWNH 142107
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
507 PM EDT TUE APR 14 2020
VALID APR 14/1200 UTC THRU APR 18/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH PRELIMINARY PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
CLOSED LOW OVER NORTHEAST U.S. AND OFFSHORE SURFACE LOW EARLY THIS
WEEK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: HIGH
A BROAD UPPER LEVEL LOW OVER NEW ENGLAND, WITH SHORTWAVE ENERGY
PIVOTING AROUND IT, WILL CONTINUE TO SUPPORT OFFSHORE SURFACE LOW
DEVELOPMENT WITH A SECONDARY COLD FRONT EXITING THE EAST COAST
LATER TODAY. THERE IS ENOUGH MODEL AGREEMENT HERE TO MERIT A
DETERMINISTIC MULTI-MODEL BLEND.
CENTRAL PLAINS SHORTWAVE AND SOUTHERN U.S. SURFACE LOW
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/00Z ECMWF
CONFIDENCE: MODERATE-HIGH
A STRONG SOUTHERN STREAM SHORTWAVE EXITING THE ROCKIES AND
EMERGING OVER THE CENTRAL PLAINS WILL SUSTAIN A WELL DEVELOPED
SURFACE LOW ACROSS THE SOUTHERN TIER STATES THROUGH TUESDAY
EVENING. THE LOW THEN EMERGES OVER THE WESTERN ATLANTIC AND THEN
TRACKS TO A POSITION JUST NORTH OF BERMUDA BY WEDNESDAY EVENING.
THERE IS GOOD OVERALL SYNOPTIC SCALE AGREEMENT AS THE SYSTEM
TRACKS EASTWARD ACROSS THE GULF COAST REGION. THE UKMET IS
FARTHER SOUTH WITH THE OFFSHORE TRACK, AND THE CMC BECOMES A
SLOWER SOLUTION. BOTH THE GFS AND ECMWF HAVE GOOD ENSEMBLE
SUPPORT, AND THUS A BLEND OF THESE TWO MODELS IS GOOD.
BROAD UPPER LEVEL GYRE OVER NORTHWEST WITH NORTHERN TIER COLD FRONT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE:
CONFIDENCE: SLIGHTLY BELOW AVERAGE
OVERALL DETERMINISTIC TRENDS SINCE YESTERDAY SHOW GREATER
DEFINITION WITH 2 OR 3 MAIN SHORTWAVE SPOKES TRACKING THROUGH THE
NORTHWEST. THE ENSEMBLE MEANS SHOW RELATIVELY GOOD AGREEMENT WITH
THESE FEATURES WITH THE 00Z NAM, 00Z GFS AND 12Z ECMWF CLOSEST TO
THE MEANS. THE 12Z UKMET IS LESS DEFINED WITH THESE SHORTWAVE
SPOKES WHILE THE 12Z CMC EVOLVES INTO A FAIRLY DIFFERENT PATTERN
ALOFT.
THE MAIN TREND WITH THE 00Z ECMWF/UKMET/CMC COMPARED TO THEIR
PREVIOUS 12Z CYCLES WAS TO BE WEAKER OR TUCKED CLOSE TO THE CENTER
OF THE MAIN CLOSED LOW WITH VARIOUS SHORTWAVES CIRCLING THROUGH
THE NORTHWEST. WHILE THE 00Z ECMWF MEAN MAY JUST FOLLOW THE 00Z
ECMWF TREND ONCE IT BECOMES AVAILABLE, THE PREFERENCE IS TO STAY
TOWARD THE MIDDLE GROUND, AWAY FROM THE EDGES OF THE DETERMINISTIC
GUIDANCE AND TOWARD THE LATEST AVAILABLE ENSEMBLE MEAN BLEND.
TIMING DIFFERENCES AMONG THE 12Z ECMWF, 00Z NAM AND 00Z GFS REMAIN
WITH A BLENDED APPROACH TOWARD THE MIDDLE OF THESE THREE
PREFERRED. THE 00Z GFS IS LIKELY STILL A BIT TOO FAST/EAST WITH A
SHORTWAVE TRACKING INTO SOUTHERN MANITOBA ON WEDNESDAY GIVEN
TRENDS IN THE ENSEMBLES AND THE REMAINING PLACEMENT OF THE
DETERMINISTIC GUIDANCE.
SOUTHWEST SHORTWAVE AND HIGH PLAINS CYCLOGENESIS MIDWEEK
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE:
CONFIDENCE:
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
HAMRICK
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