304
FXUS10 KWNH 221636
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1236 PM EDT SUN MAR 22 2020
VALID MAR 22/1200 UTC THRU MAR 26/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PHASING STREAMS TODAY ACROSS CENTRAL US, BUILDING TOWARD NORTHEAST
CYCLONE LATE MON/TUES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z CMC/ECENS MEAN/UKMET/ECMWF BLEND WITH SOME NAM
THROUGH 24.00Z
CONFIDENCE: AVERAGE TO SLIGHTLY BELOW AVERAGE
GOES-WV SUITE DEPICT A SHORT-WAVE ACROSS THE SOUTHERN MO VALLEY
CONTINUING AN ENE TRAJECTORY, WHILE THE NORTHERN STREAM SHOWS A
MATURE COMPACT LOW IN BOREAL CANADA, WITH THE NOSE OF SHORTWAVE
ENERGY STARTING TO DESCEND ALONG THE NW PERIPHERY. THESE SYSTEMS
(DOMINATED BY THE SOUTHERN STREAM) WILL CONTINUE TO ADVANCE TOWARD
THE EAST COAST, SUPPORTING A COASTAL LOW DEVELOPING OFF THE NJ
COAST SLIDING NEAR THE BENCHMARK AND SOUTHEAST OF NOVA SCOTIA FROM
LATE MONDAY THROUGH LATE TUESDAY. THE TRENDS CONTINUE TO SHIFT
TOWARD A MORE PHASED AND MATURE CYCLONE, FIRST HINTED BY THE NAM A
FEW DAYS AGO, WITH ONLY THE GFS AND GEFS SOLUTIONS CONTINUING TO
BE WELL SOUTH WITH MUCH LESS NORTHERN STREAM INFLUENCE, THOUGH THE
12Z GFS IS STARTING TO SHOW SOME HINTS TOWARD A STRONGER
COMMAHEAD/WESTERN TROWAL (THOUGH ALSO REMAIN VERY WARM, IN LINE
WITH THIS WINTER'S NEGATIVE BIAS). THE 12Z NAM HOWEVER, DEPICTS
THE STRONGEST NORTHERN STREAM INFLUENCE, TIGHTENING THE OVERALL
GRADIENT AND WITHOUT SIGNIFICANT DOWNSTREAM BLOCKING, IS VERY
RAPID TO ACCELERATE AND NOT SUPPORT A STRONGER SYSTEM (QUITE
ATYPICAL). IT IS SUPPORTED BY THE 00Z CMCE SUITE BUT LESSER SO
THE 00Z OPERATIONAL MODEL WHICH SEEMS TO BE MIDDLE GROUND BETWEEN
THE FASTER NAM AND THE SLOWER/DEEPER WOUND UP UKMET AND ECMWF.
THE 00Z ECENS MEAN, SUGGESTS A SPLIT IN ECENS SOLUTIONS BUT
FAVORING A FASTER, MORE PROGRESSIVE THAN THE OPERATIONAL, CLOSE TO
THE CMC. THOUGH BOTH THE 00Z UKMET/ECMWF SHOW GOOD CONTINUITY.
GIVEN LOWER PREDICTABILITY OF PHASING STREAM SYSTEMS, ESPECIALLY
WITH MESOSCALE INTRODUCED LATENT HEAT RELEASE (SPRING-TIME
MAGNITUDES) THIS MAKES THE UNCERTAINTY STILL QUITE HIGH TO SOLIDLY
CHOOSE ONE CAMP OVER ANOTHER, SO WILL HEDGE TOWARD A 00Z CMC/ECENS
MEAN FOCUSED BLEND WITH SOME UKMET/ECMWF OPERATIONAL BLENDED IN AT
THIS TIME. SOME NAM MAY BE INTRODUCED, ESPECIALLY EARLY ON
MONDAY/TUESDAY BUT TRENDING AWAY AS THE WAVE CONTINUES TO
ACCELERATE AWAY FROM THE TIGHTER CLUSTERING.
CLOSED LOW ENTERING SOCAL TODAY, OPENING AND RAPIDLY CROSSING THE
CONUS: SOUTHWEST/MON, PLAINS/MID-MS TUES, OHIO VALLEY/MID-ATLANTIC
WED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z NAM/NAM-CONEST AND 00Z ECENS/UKMET/ECMWF BLEND
CONFIDENCE: AVERAGE
GOES-W WV SHOWS MATURE CLOSED LOW JUST NORTHEAST OF 30N130W,
ALREADY SHOWING SIGNS OF ELONGATING/SHEARING INTO PROGRESSIVELY
INCREASING ZONAL FLOW THAT WILL DOMINATE FROM BAJA CALIFORNIA TO
THE EAST COAST THOUGH THE FIRST PART OF THE WEEK. BY LATE MONDAY,
THE SMALLER BUT COMPACT SHORTWAVE HAS FLATTENED IN THE FLOW, BUT
THE CMC IS ALREADY STARTING TO LAG THE CONSENSUS, AND IS QUICKLY
REMOVED FROM THE PREFERENCE. THE 12Z GFS, MAY HAVE SOME
LATITUDINAL DIFFERENCES DUE TO ISSUES DOWNSTREAM FROM THE PRIOR
SYSTEM, AND WHILE IT IS BETTER TEMPERED THAN THE 06Z RUN AND LOOKS
MORE IN PHASE MASS WISE WITH THE REMAINING GUIDANCE THROUGH THE
CENTRAL US INTO HE OHIO VALLEY; IT SHOWS A NORTHWARD BIAS IN THE
QPF, FOCUSING ON THE DEFORMATION ZONE/ELEVATED FRONTAL BOUNDARY
WHICH IS NOT HEAVILY PREFERRED GIVEN THE OVERALL PATTERN AND
TRANSITION TO LOWER ROOTED CONVECTION IN THE EARLY SPRING. THE
12Z NAM SHOWS SOME SIMILAR NORTHWARD BIAS, BUT SLIGHTLY SOUTHWARD
FOCUS FOR THE BOUNDARY/MASS FIELDS, THOUGH THE NAM-CONEST APPEARS
A BETTER RESULT FOR QPF THAN THE OPERATIONAL. THE 00Z ECMWF IS
QUITE UNCHARACTERISTICALLY FAST AND ODDLY SOUTH IN THE CLUSTER TO
HAVE TREMENDOUS CONFIDENCE IN ITS QPF AXIS TOO, BUT THE MASS
FIELDS ARE STRONGER AGREED UPON WITH THE REMAINING UKMET, WHICH
HAS SOLID CONTINUITY AND CENTRAL POSITION IN THE OVERALL SUITE.
AS THE SYSTEM TRANSITIONS TO ACROSS THE APPALACHIANS SUPPORTING
ANOTHER EAST COAST CYCLONE, THE OVERALL CLUSTER TIGHTENS AS THE
FASTER UKMET/ECMWF/NAM SOLUTIONS SLOW, AND THE CMC/GFS/GEFS PICK
UP PACE. OVERALL, WILL CONTINUE TO KEEP WITH THE PREFERENCE FROM
THE MS TO OH VALLEYS INTO THE EAST COAST BY THE END OF DAY 3
FOCUSED ON A 00Z UKMET/ECMWF AND 12Z NAM BLEND (THOUGH QPF BLEND
IS GOING TO HAVE OTHER HI-RES CAM INFLUENCES INITIALLY TRENDING
TOWARD ECENS POSITION/TIMING OVER OPERATIONAL. FAST MOVING,
MESOSCALE INFLUENCE LEADS TO LOWER THAN NORMAL PREDICTABILITY,
THOUGH THE MASS FIELD CLUSTERING IS GOOD/SOLID TO SUPPORT AVERAGE
OVERALL CONFIDENCE IN THIS BLEND.
CLOSED LOW INTO PACNW MONDAY; ELONGATING WITH NORTHERN STREAM
CYCLONE CROSSING S CANADA TUES/WED, BASE OF POSITIVE TILT TROF
SLOWLY SLIDING DOWN WEST COAST BY WED
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 24.12Z, NON-GFS THEREAFTER
EXCEPTION: GREATER INFLUENCE OF THE 12Z NAM AND 00Z ECMWF/ECENS,
ACROSS US/CANADA BORDER
CONFIDENCE: ABOVE AVERAGE THROUGH 24.12Z, BECOMING SLIGHTLY ABOVE
THEREAFTER
MODELS CONTINUE TO SHOW SOLID CONTINUITY AND TRACK TO THE CLOSED
LOW HUGGING THE AK PANHANDLE AND BC COAST THROUGH BEFORE AFFECTING
THE PACIFIC NW MONDAY. THE 12Z NAM CONTINUES TO BE A BIT BROADER
WITH THE INNER CORE OF THE CLOSED LOW (NOT AS POINT FOCUSED, MORE
OF A RING) AND SO BY TUESDAY IS A TAD BROADER/LEANING FORWARD
ACROSS BC/S ALBERTA WITH THE NORTHERN PORTION OF THE TROF. STILL
A GENERAL MODEL BLEND IS SUPPORTED THROUGH 24.12Z AT ABOVE AVERAGE
CONFIDENCE.... THEREAFTER THE CLOSED LOW BEGINS TO ELONGATE
SHEDDING THE NORTHERN STREAM WAVE EASTWARD ACROSS THE SOUTHERN
CANADIAN ROCKIES, WHILE THE BASE STRETCHES SW ALONG THE WEST COAST
WITH BROAD DIFFLUENT FLOW IN THE LARGER ZONAL PATTERN ACROSS THE
US ROCKIES. BY THIS TIME THE 12Z GFS, STARTS TO MOVE OUT OF THE
OVERALL GOOD AGREEMENT, LEANING FASTER, BUT ONLY SOUTHWARD AND
THEN EASTWARD...LEAVING THE NORTHERN STREAM SYSTEM MUCH FURTHER
SOUTH OVERALL SO GENERALLY LESS FAVORABLE OVERALL, AND WILL NOT BE
INCLUDED IN PREFERENCE THEREAFTER. THE 12Z NAM/ECMWF ARE A TAD
FASTER AND THEREFORE A BIT FURTHER NORTH WITH THE FORCING/SURFACE
LOW CROSSING SOUTHERN CANADA BY WED, RELATIVE TO THE SLOWER CMC
AND UKMET. THIS IS SIMILAR IN THE SOUTHWEST PORTION OF THE TROF
WITH THE UKMET A BIT BROADER/STRONGER THROUGHOUT ITS LENGTH. SO
OVERALL A 12Z NAM AND 00Z ECMWF IS SUPPORTED ACROSS THE NORTHERN
PORTION OF THE WAVE/ALONG THE NORTHERN TIER, BUT MORE INCLUSION OF
THE UKMET/CMC IS SUPPORTED ACROSS THE CA COAST INTO THE
INTERMOUNTAIN WEST AND LEE OF THE CENTRAL ROCKIES BY 00Z THURSDAY.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
GALLINA
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