981
FXUS10 KWNH 300653
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
252 AM EDT TUE JUL 30 2019
VALID JUL 30/0000 UTC THRU AUG 02/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION AND FINAL PREFERENCES/CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..EAST OF THE MISSISSIPPI RIVER
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
..07Z UPDATE
NO SIGNIFICANT MODEL CHANGES WERE NOTED WITH THE 00Z
ECMWF/UKMET/CMC COMPARED TO THEIR PREVIOUS 12Z CYCLES.
..PREVIOUS DISCUSSION FOLLOWS
MID/UPPER-LEVEL TROUGHING WILL GENERALLY REMAIN OVER THE EASTERN
THIRD OF THE NATION WITH A NORTHERN AND SOUTHERN STREAM COMPONENT.
THE NORTHERN STREAM COMPONENT WILL TRACK FROM THE GREAT LAKES THIS
MORNING TO NEW ENGLAND THURSDAY MORNING, WITH A COLD FRONT
FOLLOWING ALONG AHEAD AT THE SURFACE. A SOUTHERN STREAM COMPONENT
TO TO THE TROUGH WILL EXIST AS A COMPACT CLOSED UPPER LEVEL LOW
OVER THE GULF OF MEXICO OR AN ELONGATED TROUGH EXTENDING NORTHWARD
INTO THE GULF COAST STATES.
WHILE MINOR MODEL DIFFERENCES EXIST WITH THESE FEATURES, THEY ARE
SMALL ENOUGH TO ALLOW FOR A GENERAL MODEL BLEND AS A PREFERENCE.
..PACIFIC NORTHWEST
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 00Z NAM/00Z ECMWF/00Z UKMET BLEND
CONFIDENCE: AVERAGE
..07Z UPDATE
DESPITE ENSEMBLES TRENDING AWAY FROM A STRONGER TROUGH OFFSHORE OF
THE WASHINGTON/OREGON COASTS FRIDAY MORNING, THE 00Z ECMWF/UKMET
TRENDED TOWARD THAT IDEA WHILE THE 00Z CMC STAYED SIMILAR TO ITS
PREVIOUS CYCLE REGARDING STRENGTH. GIVEN SOME OF THESE
DETERMINISTIC TRENDS, INCLUDING THAT OF THE 00Z GFS WHICH IS STILL
LIKELY TOO STRONG, WILL ADJUST THE PREFERENCE TO INCLUDE THESE
RECENT TRENDS.
..PREVIOUS DISCUSSION FOLLOWS
OUTSIDE OF THE 12Z UKMET, THE MODELS HAVE CONVERGED CLOSER WITH
THE EVOLUTION OF THE CLOSED LOW, LOCATED JUST OFF OF THE BRITISH
COLUMBIA COAST THIS MORNING, AS IT REACHES THE WEST COAST. THE
CLOSED LOW IS EXPECTED TO MOVE INLAND INTO CENTRAL BRITISH
COLUMBIA WEDNESDAY NIGHT WHILE A SHORTWAVE TROUGH AXIS, EXTENDING
SOUTHWEST OF THE CLOSED LOW, NEARS THE COASTS OF WASHINGTON AND
OREGON EARLY FRIDAY MORNING. THE 12Z UKMET IS A SLOW OUTLIER WITH
THE SHORTWAVE TROUGH/CLOSED LOW NEARING WASHINGTON/OREGON FRIDAY
MORNING AND THE 00Z GFS IS A STRONG OUTLIER. A BLEND BETWEEN THE
00Z NAM AND 12Z ECMWF IS CLOSEST TO THE RELATIVELY AGREEABLE
ENSEMBLE MEANS AND WILL BE PREFERRED AT THIS TIME.
..SOUTHWEST INTO THE GREAT PLAINS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NEAR THE 00Z ECMWF/UKMET
CONFIDENCE: BELOW AVERAGE
..07Z UPDATE
DESPITE SOME MINOR ADJUSTMENTS, THE 00Z ECMWF/UKMET REMAINED
SIMILAR TO THEIR 12Z CYCLES CONCERNING THE VORTICITY MAX AROUND
THE SOUTHWESTERN U.S. RIDGE AND WITH THE SURFACE LOW/FRONTAL
BOUNDARY IN THE PLAINS. THE 00Z CMC HAD SOME SIMILARITIES TO THE
ECMWF/UKMET, BUT WAS SLOWER IN ITS TIMING OF THE ENERGY REACHING
THE DAKOTAS. THEREFORE, THE PREFERENCE REMAINS THE SAME, BUT JUST
TO UPDATE WITH THE 00Z CYCLES OF THE ECMWF/UKMET OVER THEIR 12Z
RUNS.
..PREVIOUS DISCUSSION FOLLOWS
THERE IS GENERALLY GOOD AGREEMENT ON THE STRENGTH AND POSITION OF
THE SOUTHWESTERN U.S. RIDGE AND ON THE IDEA FOR A CONVECTIVELY
ENHANCED MID-LEVEL VORTICITY MAX TO ROUND THE RIDGE WEDNESDAY INTO
FRIDAY...TRACKING FROM WESTERN AZ TO WY INTO THE DAKOTAS. THE
GFS/ECMWF HAVE HAD THE BEST RUN TO RUN CONSISTENCY ON THE
MID-LEVEL VORTICITY MAX WITH GREATER RUN TO RUN CHANGES NOTED IN
THE NAM, UKMET AND CMC. HOWEVER, DOWNSTREAM INTO THE PLAINS, THE
12Z ECMWF/UKMET SHOW BETTER AGREEMENT WITH AN AREA OF LOW PRESSURE
AT THE SURFACE IN WESTERN KS O THE LATEST ENSEMBLE SCATTER LOW
PLOT CLUSTERING COMPARED TO THE FARTHER SOUTH 00Z NAM/GFS. FOR
THIS REASON, A 12Z ECMWF/UKMET BLEND IS PREFERRED, BUT CONFIDENCE
IS LOW DUE TO THE UNCERTAINTIES WITH CONVECTION AND ITS INFLUENCES
ON IMPULSES ROUNDING THE SOUTHWESTERN RIDGE.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
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