690
FXUS10 KWNH 230715
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
315 AM EDT FRI AUG 23 2019
VALID AUG 23/0000 UTC THRU AUG 26/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..OVERALL PATTERN ACROSS THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
EXCEPTIONS: 12Z ECMWF/UKMET BLEND FL TO OFF CAROLINAS DAYS 2/3
CONFIDENCE: ABOVE AVERAGE
07Z UPDATE: THE TWO NORTHERN STREAM SYSTEMS CONTINUE TO BE IN
REMARKABLY STRONG AGREEMENT THROUGH 12Z MONDAY WITH LITTLE CHANGE
IN THINKING/PREFERENCE BUT INCREASE CONFIDENCE TO ABOVE AVERAGE,
THIS INCLUDES THE INTERACTION WITH THE NORTH-CENTRAL GULF WAVE
PHASING WITH THE DIGGING NORTHERN STREAM TROF SUNDAY INTO MONDAY.
AS FOR THE FL/GULF STREAM SURFACE WAVE, THE ECMWF SHIFTED A TAD
SE, BUT THE UKMET TRENDED NEARLY IDENTICAL IN PLACEMENT/DEPTH WITH
THE ECMWF TO BOOST CONFIDENCE IN THE INITIAL THINKING. THE CMC,
WHILE STILL WELL WEAKER THAN THE ECMWF/UKMET, DID SHIFT THE ENERGY
NORTHEASTWARD IN STEP. A SUCH WILL INCREASED CONFIDENCE IN A 00Z
ECMWF/UKMET BLEND TO SLIGHTLY ABOVE AVERAGE.
---PRIOR DISCUSSION---
DETERMINISTIC GUIDANCE CONTINUES TO HAVE VERY STRONG MODEL
AGREEMENT WITH THE SYNOPTIC FLOW ACROSS THE CONUS THROUGH EARLY
MONDAY, WITH THE NORTHERN ROCKIES TROF BEGINNING TO EXPAND ACROSS
THE NORTHERN PLAINS WITH SOME ENERGY LEAKING SOUTHEAST INTO THE MS
VALLEY POTENTIALLY ENHANCING A WEAK SURFACE WAVE/TROF IN THE
WESTERN GULF BY 12Z MONDAY. THE ONLY MINOR DIFFERENCE IN THE MASS
FIELD, IS SEEN IN THE 00Z NAM WHERE, THE UPPER TOR ACROSS S CANADA
IS MUCH BROADER AND THEREFORE A BIT DEEPER THAN THE OTHER
GUIDANCE. ACROSS THE NORTHEAST, THE POSITIVE TILT TROF BEGINS TO
EXIT, BUT WITH ENHANCING RIDGING TO THE SOUTH, THE TRAILING
PORTION OF THE TROF BREAKS INTO A WEAK CLOSED LOW IN THE NORTHEAST
BY 12Z MONDAY, WITH THE 00Z GFS A BIT EAST OF THE REMAINING
GUIDANCE, WITH LITTLE EFFECT IN THE LOWER TROPOSPHERE. THIS LEADS
TO A GENERAL MODEL BLEND WORKING FOR MUCH OF CONUS, WITH PERHAPS
THAT LOWER WEIGHTING OF THE NAM AT THE DAY 3 PERIOD IN THE
NORTHERN PLAINS. CONFIDENCE IS SLIGHTLY ABOVE AVERAGE CONFIDENCE
FOR THIS BLEND.
THE REMAINING UNCERTAINTY CONTINUES WITH THE EVOLUTION OF THE
TROPICAL/SUB-TROPICAL WAVE DEVELOPING IN FLORIDA EARLY SUNDAY AND
DEEPENING AS IT INTERSECTS WITH THE LANGUISHING FRONTAL ZONE ALONG
THE GULF STREAM OFF THE EAST COAST INTO MONDAY. HERE, THE 00Z NAM
HAS TRENDED TOWARD THE EARLIER PREFERENCE OF THE 12Z ECMWF/UKMET
DEPICTING A STRONGER WAVE, YET THE NAM IS SLOWER TO LIFT OUT AND
UP THE COAST, SO THE NAM ADDS CONFIDENCE TO THE SOLUTION BUT WILL
STILL PREFER THE ECMWF/UKMET BLEND HERE. THE 00Z GFS HAD NOT
BUDGED, SUGGESTING MAYBE A WEAK CLOSED LOW AT THE APEX OF THE
TROPICAL WAVE, BUT CONTINUES TO PRESS IT WEST INTO THE GULF, LIKE
THE 00Z CMC. CONFIDENCE IS AVERAGE IN THIS AREA OF THE CONUS.
AS FOR TS IVO IN THE EPAC, THE 00Z GFS CONTINUES TO TRACK CLOSEST
TO THE 03Z NHC FORECAST TRACK THOUGH CLOSER TO THE 00Z NAM AND 12Z
ECMWF, SO A BLEND OF THE 3 MAY BE BEST TO APPROXIMATE THE OFFICIAL
NHC TRACK FOR IVO AND THE MOISTURE IT PUMPS NORTH INTO NW MEXICO
AND THE SOUTHWEST.
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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