240
FXUS10 KWNH 190740
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
339 AM EDT SUN JUL 19 2020
VALID JUL 19/0000 UTC THRU JUL 22/1200 UTC
...SEE NOUS42 KWNO (ADMSDM) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z FINAL MODEL EVALUATION INCLUDING PREFERENCES AND FORECAST
CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
..NORTHERN TIER OF THE CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM
CONFIDENCE: AVERAGE
THE NORTHERN TIER OF THE CONUS WILL REMAIN ACTIVE WITH FAST FLOW
ATOP AN EXPANSIVE MID-LEVEL RIDGE COVERING MUCH OF THE CENTRAL AND
SOUTHERN U.S. A PAIR OF SHORTWAVE TROUGHS THOUGH WILL BE ADVANCING
ACROSS THE NORTHERN PLAINS AND UPPER MIDWEST GOING THROUGH EARLY
NEXT WEEK.
THE MOST IMPORTANT OF THESE SHORTWAVES WILL DROP OUT OF THE PAC NW
TODAY AND RACE INTO THE NORTHERN PLAINS. AS THIS FEATURE INTERACTS
WITH A SURFACE BAROCLINIC GRADIENT ALONG A STATIONARY BOUNDARY, IT
IS LIKELY TO BECOME CONVECTIVELY ENHANCED AND DIG INTO THE
EXPANSIVE RIDGE TO CAUSE HEIGHT FALLS ACROSS THE CENTRAL PLAINS.
THERE EXISTS CONSIDERABLE SPREAD IN THE AMPLITUDE OF THE
SHORTWAVE, WITH THE NAM POSSIBLY SUFFERING FROM SOME CONVECTIVE
FEEDBACK DUE TO ITS STRENGTH, WHILE THE ECMWF IS ON THE OTHER END
OF THE ENVELOPE WITH A VERY FLAT, BROAD TROUGH LATE MONDAY. WHILE
THE NAM IS LIKELY TOO STRONG, IT DOES HAVE SOME SUPPORT FROM THE
GFS AND GEFS MEAN, AND THE PATTERN APPEARS FAVORABLE FOR AN
MCS/CONVECTIVE ENHANCEMENT OF THE SHORTWAVE. INCLUDING THE
GEFS/GFS WITH THE NON-NCEP SUITE WILL PRODUCE BETTER AMPLIFICATION
OF THE MID-LEVEL HEIGHT FIELD D2 INTO D3, BUT NOT AS ROBUST AS
SHOWN BY THE NAM.
..CALIFORNIA/SOUTHWEST U.S
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM/CMC
CONFIDENCE: AVERAGE
A CLOSED LOW DEVELOPING WITHIN A LARGER TROUGH ACROSS THE
SOUTHWEST WILL MEANDER NEAR THE COAST OF CA MONDAY INTO TUESDAY.
THE NAM IS THE SLOWEST TO DEVELOP THE CUTOFF, WHILE THE CMC IS
MUCH WEAKER THAN THE GLOBAL CONSENSUS SHOWING LITTLE HEIGHT FALLS
OFF CA AT ALL. THE TREND OVER THE PAST FEW RUNS OF THE GLOBALS HAS
BEEN FOR A DEEPER SOLUTION, WITH THE CLOSED LOW MOVING ONSHORE CA
DURING D3. A BLEND OF THE NON-NAM/CMC IS REASONABLE DUE TO GOOD
CLUSTERING, WITH MOST WEIGHT ON THE ECMWF/ECENS DUE TO GOOD
CONTINUITY.
..MID-LEVEL EASTERLY WAVES IMPACTING THE SOUTHERN CONUS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: NON-NAM, LITTLE UKMET D3
CONFIDENCE: AVERAGE
A SERIES OF MID-LEVEL TROUGHS/EASTERLY WAVES WITH AT LEAST A
MODEST SURFACE REFLECTION WILL MOVE ACROSS THE GULF COAST REGION
THROUGH TUESDAY. THE NAM REMAINS STRONG WITH THE 700MB AMPLITUDE
OF THESE FEATURES COMPARED TO CONSENSUS, AND IS ALSO SLOW WITH THE
WESTWARD PROGRESSION. THE UKMET IS A TAD NORTH WITH THESE
FEATURES, ESPECIALLY THE SECONDARY WAVE LIFTING NEAR FL ON D3 WHEN
ITS WEIGHT IN THE BLEND SHOULD BE VERY CONSERVATIVE. THE OTHER
GLOBALS ARE WELL CLUSTERED AND GENERALLY WEAK/FLAT WITH THESE
WAVES AS THEY PUSH TOWARDS THE TX/LA COAST AND INTO FL.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
THIS PRODUCT WILL TERMINATE AUGUST 15, 2020:
WWW.WEATHER.GOV/MEDIA/NOTIFICATION/PDF2/SCN20-58PMDHMD_TERMINATION.
WEISS
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