296
FXUS10 KWNH 050637
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
137 AM EST TUE NOV 05 2019
VALID NOV 05/0000 UTC THRU NOV 08/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
..00Z MODEL EVALUATION WITH PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...OVERALL PATTERN ACROSS THE CONUS THROUGH 08.12Z
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH 07.18Z
00Z GEFS/GFS/ECMWF AND 12Z ECENS MEAN BLEND
CONFIDENCE: ABOVE AVERAGE THRU 07.18Z
BELOW AVERAGE THEREAFTER
07Z UPDATE: THE 00Z ECMWF TRENDED SLOWER WITH THE SHORTWAVE
EMERGING FROM THE SOUTHWEST, PRESSING THE FRONTAL ZONE
SOUTHEASTWARD; ALLOWING FOR THE NORTHERN STREAM TO TREND FASTER,
AND INCREASE PHASING IN A SIMILAR VAIN TO THE 00Z GFS. AS SUCH
THE DEVELOPING COASTAL LOW IS MUCH FURTHER NORTH THOUGH STILL NOT
AS FAR NORTHEAST AS THE GFS. THE UKMET FURTHER DISCONNECTED THE
TROPICAL MOISTURE CONNECTION OFF THE ATLANTIC AND SO BREAKS DOWN
THE CYCLOGENESIS EVEN FURTHER TO THE EAST AND IS NO LONGER WITHIN
THE REALM OF THE ENSEMBLE SUITE. THE 00Z CMC STAYED MOST
CONSISTENT BUT ALSO STARTING ALLUDING TOWARD A NORTHWARD SHIFT
RELATIVE TO THE PRIOR RUN. ALL THIS LEADS TO FURTHER UNCERTAINTY,
ESPECIALLY SINCE THE 12Z GEFS SHOWED GREATER WITHIN ENSEMBLE
AGREEMENT AND IS A SPLIT BETWEEN THE NEW ECMWF AND 00Z GFS.
GIVEN ALL THE GUIDANCE HAS BEEN VARYING FROM RUN TO RUN, AND THE
BETTER VERIFYING GUIDANCE IS STARTING TO AGREE FURTHER NORTH, WILL
ADJUST AND SUPPORT A CHANGE TOWARD A 00Z GEFS/ECWMF/GFS BLEND WITH
SOME 12Z ECENS MEAN TO HANDLE SOME OF THE OTHER UNCERTAINTY AND
KEEP SOME BLEND OF CONTINUITY WITHIN THE PREFERENCE. CONFIDENCE
IS BELOW AVERAGE AFTER 07.18Z
---PRIOR DISCUSSION---
DETERMINISTIC GUIDANCE AND ENSEMBLE SUITE CONTINUE TO BE IN VERY
STRONG AGREEMENT WITH THE CONUS WEATHER PATTERN THROUGH MUCH OF
THE SHORT-RANGE FORECAST PERIOD. HOWEVER, MODEL SPREAD
SIGNIFICANTLY INCREASES ON THE LATTER DAY 3 PERIOD PARTICULARLY
WITH THE EVOLUTION OF A COASTAL SURFACE LOW IN NEW ENGLAND VERY
LATE THURSDAY INTO FRIDAY MORNING. EVOLUTIONARY DIFFERENCES
APPEAR TO BE DRIVEN IN A TYPICAL FASHION BY A WEAKENING/SHEARED
CLOSED LOW EMERGING OUT OF THE SOUTHWEST, ITS
INFLUENCE/INTERACTION WITH GULF MOISTURE TO DEVELOP CONVECTION,
WITH THE SAID CONVECTION FEEDING BACK UPSCALE TO THE UPPER LEVEL
SUBTROPICAL JET STREAK AND ITS INFLUENCE WITH THE POLAR JET
STREAM. AS SUCH, MODEL SPREAD IS ACTUALLY QUITE LARGE AT THE DAY
3 PERIOD ACROSS THE NORTHEAST, AS THE MUCH OF THE CURRENT SYSTEM
IS IN THE DATA ASSIMILATION POOR REGION IN THE COLD CURRENT
REGION OF THE SUBTROPICAL NORTHEAST PACIFIC AND AS A BYPRODUCT,
THE CONVECTION HAS YET TO DEVELOP PROVIDING STRENGTH/UPSCALE
FEED-BACK TO THE SYNOPTIC SYSTEM.
THROUGH DAY 2 INTO EARLY DAY 3, THE GUIDANCE IS VERY WELL AGREED
UPON, PARTICULARLY IN THE AXIS, SPACING OF THE FRONTAL ZONE ACROSS
THE CENTRAL/SOUTHERN PLAINS INTO THE OHIO VALLEY, IT IS THE TIMING
OF CONVECTIVE INITIATION AND THE PLACEMENT OF THE UPSCALE
ASCENT/JET ENHANCEMENT RELATIVE THE TIMING OF THE NORTHERN STREAM
SHORTWAVE (PHASED OR JUST OFFSET) THAT LEADS TO THE VARIATION.
THE 00Z NAM AND 12Z CMC ARE MOST AGGRESSIVE WITH THE CONVECTIVE
DEVELOPMENT PRESSING IT FASTER INTO THE OHIO VALLEY AND AHEAD OF
THE NORTHERN STREAM SHORTWAVE BRING THE 150+KT 250MB JET NEARLY
6-12HRS PRIOR TO OTHER GUIDANCE. THIS ALLOWS FOR GREATER
AMPLIFICATION AND MORE COMPACT DOWNSTREAM EVOLUTION THROUGH THE
NEW YORK BIGHT AND EVENTUALLY THE DEEPEST SURFACE EVOLUTION BY 12Z
FRIDAY. THE PLACEMENT, TIMING IS SUPPORTED BY THE 12Z ECWMF BUT,
THIS MAY BE A BIT OFF, GIVEN THE ECMWF IS UNCHARACTERISTICALLY THE
FASTEST BRINGING THE SHEARED SHORTWAVE OUT OF THE SOUTHWEST, BUT
IS ALSO THE SLOWEST WITH THE NORTHERN STREAM SHORTWAVE, SO THE
UPPER LEVEL JET ENHANCEMENT IS DELAYED. ENSEMBLE TRENDS WOULD
SUPPORT THIS EVOLUTION A BIT MORE THAN THE HIGHLY AGGRESSIVE
CMC/NAM.
THE 00Z GFS, IS VERY FAST EXITING THE PRIOR SHORTWAVE TROF AND IS
UNCHARACTERISTICALLY SLOW BRINGING THE SHORTWAVE OUT OF THE
SOUTHWEST, THIS EVENTUALLY LEADS TO THE MOST PHASED EVOLUTION
ACROSS THE OHIO VALLEY, BUT ALSO WELL NORTH OF THE OTHER
SOLUTIONS, INCLUDING THE BULK OF GEFS MEMBERS, MAKING IT LESS
DESIRABLE TO INCLUDE IN ANY BLEND. THE 12Z UKMET SHOWS A LESS
AMPLIFIED SOLUTION OVERALL, LIKELY AS IT IS MOST DISCONNECTED IN
THE LOW LEVEL STREAM CONFLUENCE, PARTICULARLY THE RETURN ATLANTIC
STREAM LIFTING NORTH ALONG THE EAST COAST, AS SUCH THE SURFACE
EVOLUTION IS MUCH WEAKER BUT IN DECENT PLACEMENT COMPARED TO THE
ECENS MEAN/GEFS MEAN. SO OVERALL, A GENERAL MODEL BLEND IS
SUPPORTED ACROSS DAY 2 AND THROUGH THE CENTRAL PLAINS/MID-MS
VALLEY... BUT A ECMWF, ECENS MEAN BLEND WITH LOW INCORPORATION OF
THE GEFS, UKMET IS PREFERRED THEREAFTER BUT AT MUCH REDUCED
CONFIDENCE (AVERAGE TO SLIGHTLY ABOVE AVERAGE).
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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