219
FXUS10 KWNH 150428
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1227 AM EDT FRI MAY 15 2020
VALID MAY 15/0000 UTC THRU MAY 18/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION INCLUDING PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...CLOSED LOW OVER THE NORTHERN PLAINS AND UPPER GREAT LAKES
TONIGHT...CROSSING NORTHERN NEW ENGLAND FRI...
...SURFACE LOW MOVING FROM THE NORTHERN PLAINS TONIGHT INTO
NORTHERN NEW ENGLAND FRI...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z GFS, 12Z ECMWF, 12Z CMC BLEND
CONFIDENCE: ABOVE AVERAGE
SHORTWAVE ENERGY CURRENTLY ALONG THE MINNESOTA/CANADIAN BORDER
WILL QUICKLY SKIRT EASTWARD ACROSS THE NORTHERN GREAT LAKES AND
INTO THE NORTHEAST BY SATURDAY. THE MODEL GUIDANCE HAS CLUSTERED
FAIRLY WELL ON A SOLUTION EXCEPT FOR SOME TIMING ISSUES ON DAY 3
BETWEEN THE SLOWER UKMET AND FASTER NAM 500 SHORTWAVE TIMING.
THESE DIFFERENCES ARE ALSO MANIFESTED AT THE SURFACE WHERE THE NAM
IS A BIT TOO DEEP AND ON THE NORTHERN END OF THE MODEL GUIDANCE
WHILE THE UKMET IS SLOWER AND TO THE SOUTHWEST. FOR THESE REASONS,
THE WPC PREFERENCE IS FOR A BLEND OF THE OTHER DETERMINISTIC
GUIDANCE (00Z GFS, 12Z ECMWF, AND 12Z CMC).
...CLOSED MID LEVEL LOW OFF THE PACIFIC NORTHWEST TODAY
MOVING
TO THE NORTHERN PLAINS SAT AND
THE UPPER GREAT LAKES SUN...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
A LARGE CLOSED MID/UPPER LEVEL LOW IS FORECAST TO MOVE FROM THE
EASTERN PACIFIC TOWARD THE PACIFIC NORTHWEST COAST THROUGH THE
PERIOD. WITH THE HIGHLY AMPLIFIED PATTERN, THE MODEL GUIDANCE
SHOWS REASONABLE AGREEMENT WITH ONLY SOME MINOR DIFFERENCES AT 500
MB ON DAY 3 NOTED (FASTER GFS BIAS). AT THE SURFACE A LOW WILL
APPROACH THE COAST AND THEN WASH OUT BY DAY 3 AS THE OVERALL
SYSTEM SLOWS/STALLS OFF THE COAST. THE MODEL GUIDANCE IS NOW
FAIRLY CLUSTERED AND A GENERAL MODEL BLEND SHOULD SUFFICE THROUGH
THE PERIOD.
...DEVELOPING LONG WAVE TROUGH MOVING FROM NORTHERN MEXICO INTO
CENTRAL TX SAT...THEN INTO
THE LOWER MS VALLEY SUN...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-12Z NAM BLEND
CONFIDENCE: AVERAGE
WEAK SHORTWAVE TROUGHING WILL MOVE ACROSS THE SOUTHERN PLAINS THIS
WEEKEND AND GRADUALLY TAKES THE SLOW MOVING MID LEVEL SLOW INTO
THE LOWER MS VALLEY BY LATE IN THE WEEKEND. THE 00Z NAM IS THE
LEAST FAVORED DETERMINISTIC MODEL, AS IT IS CONSIDERABLY SLOWER
WITH THE WAVE MOVING INTO THE LOWER MS BY SUNDAY COMPARED TO THE
REST OF THE GUIDANCE. THE 12Z UKMET DOES REMAIN ON THE SLOWER SIDE
TOO BUT HAS TRENDED TOWARD THE REST OF THE GUIDANCE
(CMC/ECMWF/GFS) IS PICKING UP THE SYSTEM EASTWARD. AS SUCH, WILL
CONTINUE TO FAVOR A NON-00Z NAM BLEND.
..LOW PRESSURE DEVELOPING NEAR THE BAHAMAS FRIDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/12Z ECMWF/00Z ECMWF MEAN BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE\
WEAK AREA OF LOW PRESSURE IS FORECAST TO DEVELOP OFF THE SOUTHERN
FLORIDA COAST FRIDAY AND GRADUALLY MOVE TOWARD THE BAHAMAS FRIDAY
NIGHT BEFORE TURNING NORTHWARD THIS WEEKEND. FORECAST GUIDANCE
AGREEMENT AND CONFIDENCE REMAINS AVERAGE AT BEST AND BEGINS TO
DIVERGE BEYOND 48 HOURS. THE 12Z UKMET WAS A CLEAR OUTLIER, WELL
EAST OF THE MODEL CONSENSUS AND MOST OF THE DETERMINISTIC
GUIDANCE. MEANWHILE, THE 00Z NAM IS ON THE WESTERN SIDE OF THE
MODEL SPREAD ENVELOPE AS WELL AS A BIT DEEPER WITH THE LOW AS IT
TRACKS TO NEAR THE NC COAST BY 84 HOURS. THE REST OF THE
DETERMINISTIC GUIDANCE (12Z CMC, 12Z ECMWF, AND 00Z GFS) ARE
REASONABLY CLUSTERED THROUGH 3 DAYS AS A MIDDLE GROUND CONSENSUS.
THERE IS ALSO PRETTY GOOD AGREEMENT WITH THE GEFS AND ECENS MEANS.
AS SUCH, THE FAVORED BLEND INCORPORATES THE 00Z GFS, 12Z ECMWF,
18Z GEFS, AND 12Z ECENS. FOR MORE INFORMATION ON THIS SYSTEM AND
POTENTIAL DEVELOPMENT, SEE THE LATEST FROM THE NATIONAL HURRICANE
CENTER.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
TAYLOR
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