545
FXUS10 KWNH 091846
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
245 PM EDT THU APR 09 2020
VALID APR 09/1200 UTC THRU APR 13/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION...WITH LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..DEEP CYCLONE IMPACTING THE NORTHEAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-GFS BLEND
CONFIDENCE: ABOVE AVERAGE
AN ANOMALOUSLY DEEP CLOSED LOW CROSSING THE GREAT LAKES WILL
DEEPEN AND TAKE ON A NEGATIVE TILT AS IT APPROACHES THE NORTHEAST
THIS AFTERNOON/EVENING. MEANWHILE, LOW PRESSURE CROSSING THE
INTERIOR OF NY STATE AND NEW ENGLAND WILL CONSOLIDATE OVER COASTAL
AREAS OF MAINE THIS EVENING AND DEEPEN INTO AN INTENSE LOW CENTER.
THE 12Z GFS IS OVERALL A TAD DEEPER THAN THE 12Z NAM AND THE 12Z
NON-NCEP SOLUTIONS. THE GFS ALSO TRACKS ITS SURFACE LOW A TAD
FARTHER INLAND OVER MAINE VERSUS THE MORE CONCENTRATED LOW CENTER
EVOLUTION ALONG THE MAINE COAST THAT THE REMAINING GUIDANCE
FAVORS. THIS RESULTS IN THE GFS HAVING A SOMEWHAT STRONGER WARM
NOSE WRAPPING FARTHER INLAND. THE PREFERENCE WILL BE TOWARD A
NON-GFS BLEND AT THIS TIME.
..SLOW-MOVING CLOSED LOW ACROSS THE SOUTHWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-GFS BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
THE MODELS GRADUALLY EJECT THE LARGE, SLOW-MOVING CUT-OFF SOUTHERN
STREAM LOW OVER SOUTHERN CALIFORNIA OFF TO THE EAST OVER THE NEXT
COUPLE OF DAYS. THE ENERGY IS EXPECTED TO OPEN UP INTO A
PROGRESSIVE SHORTWAVE TROUGH OVER THE SOUTHERN PLAINS BY SATURDAY
WHICH WILL THEN LIFT NORTHEAST AND GO NEGATIVE TILT OVER LOWER MS
VALLEY AND MID-SOUTH BY SUNDAY AS IT COMES UNDER THE INFLUENCE OF
STRONGER NORTHERN STREAM HEIGHT FALLS DROPPING DOWN OVER THE
MIDWEST. THE 12Z GFS, JUST LIKE ITS PREVIOUS RUNS, CONTINUES TO BE
THE FASTEST SOLUTION AS THE ENERGY EJECTS OUT ACROSS THE SOUTH.
WITH ITS FASTER HEIGHT FALL PROGRESSION, THE GFS IS ALSO FASTER
WITH ITS SURFACE FRONTAL PROGRESSION AND WAVE ACTIVITY, AND
ACTUALLY ENDS UP WITH A SOMEWHAT STRONGER SURFACE LOW COMPARED TO
THE OTHER MODELS BY SUNDAY. THE 12Z NON-NCEP MODELS DID TREND A
TAD MORE PROGRESSIVE WITH THIS CYCLE (AT LEAST MASS FIELD WISE),
BUT STILL TEND TO BE A LITTLE SLOWER THAN THE GFS. THE 12Z NAM
OVERALL TENDS TO BE CLOSE TO THE MODEL CONSENSUS. GIVEN THE LATEST
TRENDS, A MASS FIELD PREFERENCE TOWARD A NON-GFS BLEND WILL STILL
BE MAINTAINED, BUT OVERALL AT LEAST GUIDANCE DOES CLUSTER TOGETHER
A BIT BETTER.
..UPPER LEVEL TROUGH/COLD FRONT REACHING THE NORTHWEST
..DROPPING THROUGH THE NORTHERN PLAINS/MIDWEST ON SUNDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND...LED BY 12Z GEFS/00Z ECENS
CONFIDENCE: AVERAGE
SHORTWAVE ENERGY ALONG THE SOUTHERN COAST OF ALASKA WILL PROGRESS
EASTWARD TO THE YUKON TERRITORY, AND WITH THE ACCELERATING/EXITING
JET, THE UPSTREAM RIDGE WILL BREAK DOWN AND ALLOW FOR GREATER
PROPAGATION EAST AND THEN SOUTHWARD ACROSS SOUTHWESTERN CANADA.
THE HEIGHT-FALLS WILL OVERSPREAD THE LEE OF THE CANADIAN ROCKIES
AND THEN THE NORTHERN HIGH PLAINS, AND SUPPORT A SURFACE COLD
FRONT DROPPING SOUTHEASTWARD ACROSS THE NORTHERN PLAINS AND
MIDWEST BY SUNDAY. THE 12Z NAM AND 12Z GFS BOTH TEND TO BE A
LITTLE FASTER TO ADVANCE THEIR HEIGHT-FALLS TOWARD THE MIDWEST AND
AS SUCH APPEAR TO BE A LITTLE FAST IN ADVANCING THE COLD FRONT
DOWN TO THE SOUTHEAST. THE 12Z NON-NCEP SOLUTIONS ARE ALL JUST A
TAD SLOWER. THE 00Z ECENS AND 12Z CMCE SUITES TEND TO FAVOR THE
MODESTLY SLOWER CAMP, BUT THE 12Z GEFS IS A TAD FASTER. SO, BASED
ON THE LATEST TRENDS, A GENERAL MODEL BLEND WEIGHTED TOWARD A
BLEND OF THE 12Z GEFS MEAN AND 00Z ECENS MEAN WILL BE PREFERRED AS
A COMPROMISE.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
ORRISON
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