225
FXUS10 KWNH 021831
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
230 PM EDT MON SEP 02 2019
VALID SEP 02/1200 UTC THRU SEP 06/0000 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z FINAL MODEL EVALUATION, CONFIDENCE, AND PREFERENCES
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..OVERALL PATTERN ACROSS THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 54/60HRS
12Z GFS/NAM/ECMWF THEREAFTER
CONFIDENCE: ABOVE AVERAGE THROUGH 60HRS
AVERAGE THEREAFTER ESP IN NORTHERN STREAM
19Z UPDATE: THE 00Z ECMWF/CMC WERE SLOW TO BREAK DOWN THE INITIAL
PACIFIC SHORTWAVE, BUT THE 12Z RUNS DO, STILL A BIT SLOWER THAN
THE GFS/UKMET BUT MORE IN LINE WITH TYPICAL SMALLER TIMING
DIFFERENCES/BIASES. HOWEVER, THIS ALSO ALLOWS FOR GREATER
UPSTREAM AMPLIFICATION BY 84HRS OVER CENTRAL CANADA, MORE LIKE THE
CMC. THE 12Z ECMWF/CMC ARE SLOWER THAN THE UKMET WHICH IS TIMED
WITH THE GFS/NAM BUT STILL MUCH DEEPER. SO OVERALL, THE SPREAD IS
REDUCED IN PLACEMENT OF THE WAVES ALONG THE NORTH SIDE OF THE 3H
JET (WHICH ARE STARTING TO AGREE IN STRENGTH), FOR GREATER
AGREEMENT. STILL, FAVOR THE LESS AMPLIFIED SOLUTIONS OF THE
NAM/GFS AND ECMWF BUT WITH INCREASED CONFIDENCE TO AVERAGE AFTER
60HRS.
---PRIOR DISCUSSION---
DEEP INNER CORE/CLOSED LOW ACROSS SOUTHERN HUDSON WILL CONTINUE TO
SHIFT NORTHEAST WITH STRONG SURFACE CYCLONE ACROSS THE NORTHEAST
US/SOUTHEAST CANADA TODAY, WITH FRONTAL ZONE THAT WILL DRAPE
SOUTHWARD ACROSS THE MID-ATLANTIC THROUGH EARLY TUESDAY. A STRONG
SHORT-WAVE CURRENTLY IN CENTRAL ALBERTA WILL DRIVE SOUTHWEST
USHERING IN STRONG NORTHWESTERLY FLOW INTO THE GREAT LAKES,
SUPPORTING A SURFACE WAVE IN THE GREAT LAKES BY LATE TUESDAY/EARLY
WED WITH STRONG MODEL AGREEMENT, PRESSING THE COLD FRONT IN THE
CENTRAL APPALACHIANS BY WED NIGHT. THROUGH THIS TIME (54-60HRS, A
GENERAL MODEL BLEND CAN BE SUPPORTED A ABOVE AVERAGE CONFIDENCE.
THEREAFTER, A COMPACT SHORTWAVE JUST OFF WA COAST WILL SLIDE INTO
THE NORTHWEST FLOW AND CROSS THE NORTHERN TIER, BUT INTO FAIRLY
FLAT TO GLOBAL SCALE WEAK RIDGING AND WEAKENS QUICKLY. THOUGH
THIS WAVE WILL HAVE IMPORTANCE TO TIMING/PLACEMENT OF BAROCLINIC
ENHANCEMENT TO THE JET AND DRAWING DORIAN NORTHWARD. HOWEVER,
THERE IS STRONG MODEL AGREEMENT THAT PACIFIC JET ENERGY WILL
STARTING OVER TOPPING THE RIDGE IN THE CANADIAN ROCKIES AND SPUR
DEEPER SHORTWAVE DEVELOPMENT AT ITS NOSE INTO THE NORTHERN TIER,
WITH ADDITIONAL LEFT ROTOR SHORTWAVES STRUNG OUT INTO BOREAL
SASKATCHEWAN. THE STRENGTH AND TIMING OF THE JET ARE UNCERTAIN
WITH MODERATE TO LARGE MODEL SPREAD ACROSS CANADA INTO THE GREAT
LAKES REGION. THE TYPICALLY SLOWER GUIDANCE, OF THE ECMWF/CMC ARE
SLOWER TO WEAKEN THE INITIAL PACIFIC SHORTWAVE, THOUGH THE CMC IS
MUCH STRONGER WITH THE JET, ALLOWING FOR A GREATER AMPLIFIED
UPSTREAM WAVE. THE UKMET/NAM/GFS ARE FASTER TO WEAKEN THE INITIAL
WAVE, BUT THE UKMET IS VERY STRONG WITH THE JET BUT FURTHER NORTH
BRINGING IT INTO MANITOBA WITH A VERY AMPLIFIED WAVE. THE NAM/GFS
ARE LESS STRONG AND THEREFORE ARE FLATTER, MUCH LIKE THE ECMWF.
GIVEN THE INITIAL SETUP AND ORIENTATION TO THE PACIFIC STREAM, A
FLATTER, SLIGHTLY WEAKER 3H JET SEEM MORE PLAUSIBLE AND FIT WITH
THE LONGER-TERM ENSEMBLE TREND. WHILE THE NAM/GFS ARE MORE
PROGRESSIVE THAN THE ECMWF...A BLEND OF THEM SEEMS A MORE STABLE
YET LOWER CONFIDENCE SOLUTION AT THIS TIME. (60-84HRS FROM
NORTHERN TIER/CENTRAL CANADA, THROUGH THE GREAT LAKES. THIS
TIMING AND THEREFORE PHASING WITH DORIAN FADES INTO THE MEDIUM
RANGE, SO PLEASE REFER TO WPC PMDEPD FOR GREATER DETAIL/PREFERENCE.
..TROPICAL WAVE NEARING MEXICAN EAST COAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM BLEND
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
19Z UPDATE: NO SIGNIFICANT DEPARTURE FROM THE 00Z UKMET/CMC/ECMWF
TO THE 12Z RUNS...THE UKMET REMAINS NORTH PAIRED WITH THE GFS, BUT
STILL WELL DISPLACED FROM THE NAM TO KEEP INITIAL
PREFERENCE/CONFIDENCE.
---PRIOR DISCUSSION---
THE 12Z NAM CONTINUES TO BE QUITE AMPLIFIED TO THE NNW WITH THE
WAVE WHICH LONGER TERM ENSEMBLE TRENDS AND CURRENT FLOW PER WV
SUITE, SUGGEST WOULD CONTINUE SW FOR THE SHORT-TERM PERIOD. WHILE
THE 12Z GFS AND 00Z UKMET ARE SLIGHTLY MORE AMPLIFIED THAN THE 00Z
ECMWF/CMC, A BLEND OF THE FOUR IS FAIRLY TIGHT PROVIDING SLIGHTLY
ABOVE AVERAGE CONFIDENCE IN A NON-NAM BLEND FOR THIS SYSTEM.
..HURRICANE DORIAN
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PLEASE REFER TO THE OFFICIAL NATIONAL HURRICANE CENTER FORECAST
TRACK
19Z UPDATE: THE 12Z UKMET SLOWED SUFFICIENTLY TO NOT BE AS CLOSE
AS THE 12Z GFS TO THE 15Z NHC FORECAST, SO BEST PROXY TO 15Z
FORECAST IS GOING TO BE THE 12Z GFS/GEFS (00Z UKMET). THE ECMWF,
REMAINED THE SLOWEST AND SW COMPARED TO THE GEFS/GFS...BUT STILL
HAS THE CMC AND NOW THE UKMET PAIRED WITH IT.
---PRIOR DISCUSSION---
A BLEND OF THE 12Z GFS/06Z GEFS AND CLOSEST TO THE 00Z UKMET
PROVIDE THE BEST PROXY TO THE OFFICIAL 15Z NHC FORECAST TRACK FOR
DORIAN WITH RESPECT TO MASS FIELDS, ALL BEING SLIGHTLY FASTER THAN
THE 00Z ECMWF/CMC THAT REMAIN SLOW TO LIFT NORTH. THE CMC HAS
STRONGER NORTHWARD FORCING FOR QPF DUE TO PROXIMITY TO THE RIGHT
ENTRANCE TO THE STRONG NORTHERN STREAM JET...SO IS OUT OF PLACE
EVEN COMPARED TO THE CLOSE SURFACE AGREEMENT WITH THE ECMWF. THE
12Z NAM REMAINS OUT OF PHASE WITH THE REMAINING GUIDANCE AND IS
FURTHER EAST AND EVENTUALLY FURTHER NORTHEAST OF THE OTHERWISE
TIGHTER PACKING OF OTHER SOLUTIONS AND IS DISREGARDED IN QPF/MASS
PREFERENCE/PROXY.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
GALLINA
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