360
FXUS10 KWNH 080637
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
236 AM EDT TUE OCT 08 2019
VALID OCT 08/0000 UTC THRU OCT 11/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
12Z MODEL EVALUATION WITH PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..ENERGY AMPLIFYING OVER CENTRAL APPALACHIANS/MID-ATLANTIC
..DEEPENING SURFACE LOW PRESSURE OFF THE EAST COAST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z ECMWF/CMC BLEND
CONFIDENCE: AVERAGE
07Z UPDATE: THE 00Z ECMWF AND CMC TRENDED AWAY FROM THE STRONGER
AND NW AND N SOLUTIONS OF THE 12Z RUNS AND CENTERING CLOSER TO THE
INITIAL PREFERENCE OF THE 12Z ECENS AND CLOSER TO THE WEAKER GFS.
THE 00Z UKMET WAS A BIT SLOWER TO THE OCCLUSION PHASE, AND NOW HAS
SKIPPED PAST TO THE FASTEST GUIDANCE MEMBER BEING VERY STRONG AND
FURTHEST NORTHWEST IN THE NEW YORK BIGHT; SIMILAR TO THE LESS
FAVORED 12Z ECMWF SOLUTION. GIVEN BETTER OVERALL AGREEMENT
TOWARD THE ECENS MEAN AND THE CENTER OF THE TOTAL ENSEMBLE SUITE,
WILL SUPPORT A 12Z ECMWF/CMC BLEND AT AVERAGE CONFIDENCE.
---PRIOR DISCUSSION---
NOW THAT THE TROPICAL SHORTWAVE HAS ROUNDED THE WESTERN EDGE OF
THE SUBTROPICAL RIDGE AND IS WITHIN THE LARGER DEVELOPING WARM
CONVEYOR BELT, THE OVERALL GUIDANCE SUITE IS STARTING TO
CONSOLIDATE ON A SOLUTION. THE LINGERING SHORTWAVE ENERGY IN THE
CENTRAL APPALACHIANS IS STARTING TO ALSO COME INTO BETTER OVERALL
AGREEMENT EVOLVING INTO A WEAK REX FORMATION. THE UNCERTAINTY
REMAINS IN THE DEPTH OF THE CYCLOGENESIS AND HOW FAR THE WOBBLE OF
THE OCCLUDED LOW WILL PRESS TOWARD THE HUDSON CANYON/NEW YORK
BIGHT REGION. THE 12Z ECMWF HAS ONCE AGAIN FLOPPED TO THE
OPPOSITE SIDE OF ENSEMBLE SOLUTIONS WITH A VERY STRONG/DEEP
SOLUTION WITH THE ECENS MEAN/BULK OF ECENS MEMBERS A BIT WEAKER
AND FURTHER SOUTHEAST; THOUGH NOT TO A DRAMATIC DIFFERENCE. THE
ECMWF IS JOINED BY THE EVEN DEEPER 00Z NAM (TYPICAL OF THE DAY 3
OVER-DEEPENING BIAS) AS WELL AS A SLIGHT WESTWARD SHIFT OF THE 12Z
UKMET. THESE SOLUTIONS APPEAR TO HAVE THE GREATEST DEEP
CONVECTION/LATENT HEAT INFLUENCE AND GIVEN THE STRENGTH OF THE
TROPICAL PLUME/MOISTURE FEED, THERE IS GROWING CONFIDENCE TOWARD
THIS EVOLUTION.
THE 00Z GFS HAS SHIFTED NORTH AND WEST WITH SLIGHTLY STRONGER
SOLUTION THAN THE 12Z/18Z RUNS AND WELL WEST OF THE 12Z/18Z GEFS
MEMBERS, BUT ALSO REMAINS THE WEAKEST WITH THE MOST SUBTLE OF
WOBBLES OF THE SURFACE LOW AFTER OCCLUSION. THE CMC CONTINUES TO
SHOW THE GREATEST RUN TO RUN CONSISTENCY BUT IS ALSO A BIT FURTHER
NORTH AND IS A COMPROMISED OF THE UKMET/NAM/ECWMF AND GFS
CLUSTERS. OVERALL, THE CLUSTERING AS REDUCED SUFFICIENTLY TO
FAVOR A GENERAL MODEL BLEND WITH GREATEST WEIGHTING TOWARD THE
MOST CENTRAL MEMBERS (ECENS MEAN/UKMET). CONFIDENCE IS INCREASING
BUT GIVEN THE SMALLER BUT VERY IMPACTFUL DIFFERENCES CONFIDENCE IS
ONLY AVERAGE IN THIS UKMET/ECENS MEAN WEIGHTED GENERAL MODEL BLEND
PREFERENCE.
..DEEP UPPER TROUGH/CLOSED LOW AMPLIFYING OVER THE WEST
..HIGH PLAINS CYCLOGENESIS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
AFTER 11.00Z: LOWER WEIGHT IN THE 00Z GFS
CONFIDENCE: ABOVE AVERAGE
07Z UPDATE: THE 00Z ECMWF TRENDED FASTER CLOSER TO THE INITIAL
PREFERENCE THROUGH 84HRS. THE CMC AND UKMET BOTH TRENDED FAVORABLY
TOWARD TIGHTER OVERALL AGREEMENT. AS SUCH, THIS LEAVES THE GFS A
SMIDGE OFF IN THE MID TO UPPER LEVEL MASS FIELDS ENOUGH TO REDUCE
WEIGHTING AFTER 11.00Z BUT A GENERAL MODEL BLEND CAN BE EMPLOYEES
WITH ABOVE AVERAGE CONFIDENCE.
---PRIOR DISCUSSION---
MODELS CONTINUE TO SHOW VERY STRONG AGREEMENT WITH THE EVOLUTION
OF THE DEEP LATITUDE, POSITIVE TILT TROF THROUGH ABOUT 10.00Z. IT
IS AT THIS POINT, THERE IS INCREASED SHEARING BETWEEN THE CLOSED
LOW LIFTING AWAY IN CONTINENTAL NUNAVUT AND THE AMPLIFYING BASE OF
THE TROF ACROSS THE TERRAIN IN THE CENTRAL ROCKIES. THE 12Z/18Z
GFS WERE BOTH VERY FAST BEING WEAKER/ELONGATED IN THE HIGH PLAINS,
WHICH DID NOT APPEAR RIGHT GIVEN THE VERTICAL VORTICITY STRETCHING
EXPECTED...AS SUCH THE 12Z/18Z GEFS WERE MUCH SLOWER. THE GOOD
NEWS, IS THE 00Z GFS HAS SLOWED DUE TO A MORE COMPACT EVOLUTION TO
THE DEEPENING LOW INTO THE CENTRAL PLAINS. THIS DRAMATICALLY
SLOWED THE FRONTAL ZONE/CONVECTIVE CLUSTERING ACROSS OK/NE TX EVEN
MORE THAN THE UKMET/CMC, EVEN THOUGH THE 5H CLOSED LOW REMAINS A
BIT TOO FAST (SO A BIT MORE VERTICALLY STACKED EARLIER). THIS IS
OPPOSED BY THE 12Z ECMWF WHICH TYPICAL OF ANY POTENTIAL NEGATIVE
BIAS, WOULD BE BEING TOO SLOW; THOUGH THIS BIAS IS BEST NOTED WHEN
THE OPERATIONAL IS MUCH SLOWER/DEEPER THAN THE ECENS MEAN, WHICH
IS NOT THE CASE TODAY PARTICULARLY AFTER 72HRS. HOWEVER, WITH
STRONGER OVERALL AGREEMENT IN THE NAM, UKMET, CMC AND THE SLOWING
OF THE GFS...IT IS HARDER TO HAVE CONFIDENCE IN HIGHER WEIGHTING
IN THE BLEND. SO WPC PREFERENCE IS A GENERAL MODEL BLEND WITH
ABOVE AVERAGE CONFIDENCE BEFORE 72HRS. AFTER 72HRS (11.00Z), WPC
PREFERENCE WOULD BE TO STILL BE A GENERAL MODEL BLEND BUT LOWER
WEIGHTING TO THE OPERATIONAL ECMWF AND GFS.
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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