895
FXUS10 KWNH 220500
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1159 PM EST TUE JAN 21 2020
VALID JAN 22/0000 UTC THRU JAN 25/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z MODEL EVALUATION WITH PRELIMINARY PREFERENCES AND FORECAST
CONFIDENCE
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~~
..CLOSED LOW OFF THE SOUTHEAST COAST
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~~
PREFERENCE: NON-NAM BLEND
CONFIDENCE: ABOVE AVERAGE
CLOSED VERTICALLY STACKED LOW EAST OF FLORIDA WILL MOVE EASTWARD
AWAY FROM THE COAST THROUGH TONIGHT. SUBTLE VORTICITY LOBES
ROTATING AROUND THE MAIN CLOSED FEATURE WILL ALLOW SURFACE
TROUGHINESS TO PERSIST TOWARDS THE FL COAST MUCH OF TODAY, BUT ANY
SIGNIFICANT SENSIBLE WEATHER IMPACTS WILL REMAIN OFFSHORE. THE NAM
IS MOST AGGRESSIVE WITH LAGGING MID-LEVEL ENERGY, KEEPING THE
TROUGH IN PLACE LONGER AND DRIVING A DEEPER SURFACE TROUGH. THIS
IS CLEARLY THE OUTLIER AND NOT-PREFERRED FOR THE BLEND.
...SHORTWAVE MOVING FROM NEW MEXICO TOWARDS THE GULF COAST
TONIGHT...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~
PREFERENCE: NON-NAM BLEND, CMC IS A REASONABLE SURFACE PROXY
CONFIDENCE: SLIGHTLY ABOVE AVERAGE
SHORTWAVE AND ACCOMPANYING WEAK SURFACE LOW WILL DIVE SOUTHEAST
FROM NEW MEXICO THIS MORNING TO THE LOUISIANA GULF COAST TONIGHT,
BEFORE BECOMING ABSORBED IN THE LARGE MID-LEVEL VORTEX DEVELOPING
ON THURSDAY. THE OVERALL AMPLITUDE OF BOTH THE MID-LEVEL FEATURES
AND AT THE SURFACE IS WEAK, AND THERE IS GOOD AGREEMENT IN THE
EVOLUTION AMONG THE VARIOUS GLOBAL MODELS. THE EXCEPTION THE NAM
BEING A FAST OUTLIER DIGGING THE SHORTWAVE SOUTHEAST. THE ECMWF
HAS GOOD SUPPORT FROM ITS ENSEMBLES, AND THE GFS HAS ITS OWN
ENSEMBLE SUPPORT, WITH SOME LATITUDINAL DIFFERENCES SEPARATING THE
TWO CAMPS. THE CMC IS NEARLY IN THE MIDDLE OF THIS CLUSTERING,
SUCH THAT A BLEND OF THE ECMWF/ECENS/GFS/GEFS WOULD LEAD TO A
SOLUTION LIKELY CLOSE TO THE CMC, WHICH IS THE PREFERRED
OPERATIONAL GUIDANCE.
..TROUGH MOVING ONSHORE THE PACIFIC NORTHWEST FRIDAY
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~
PREFERENCE: 12Z ECMWF/UKMET/ECENS
CONFIDENCE: AVERAGE
A PIECE OF ENERGY SHEDDING FROM A CLOSED LOW NEAR THE GULF OF
ALASKA WILL EJECT EASTWARD INTO THE PACIFIC NORTHWEST ON FRIDAY,
ACCOMPANIED BY AN INTENSIFYING, ALTHOUGH STILL MODEST, PACIFIC JET
STREAK BRINGING HEAVY RAINFALL TO THE NORTHWEST. THE NAM CONTINUES
TO BE EXCEPTIONALLY FLAT WITH ITS AMPLITUDE OF THIS FEATURE
COMPARED TO THE GLOBAL CONSENSUS, LIKELY DUE TO A WEAKER
ANTICYCLONIC JET STREAK AND LAGGING MORE RESIDUAL ENERGY BACK INTO
THE MAIN TROUGH. THERE IS A CLEAR DICHOTOMY BETWEEN THE NCEP AND
NON-NCEP CAMPS WITH RESPECT TO THE INTENSIFYING JET STREAK, WITH
THE NCEP CAMP WEAKER AND SLOWER. THE NON-NCEP SOLUTION SEEMS MORE
REASONABLE. FROM THE REMAINING GUIDANCE, THE CMC SQUELCHES THE
MID-LEVEL ENERGY VERY QUICKLY AS IT MOVES ONSHORE, WHICH SEEMS
UNLIKELY IN THE PRESENCE OF CONTINUED JET DYNAMICAL LIFT. THIS
LEAVES THE ECMWF/UKMET AS THE MOST AGREEABLE AND REASONABLE
SOLUTION, WITH SUPPORT FROM THE ECENS MEAN CREATING THE PREFERRED
BLEND.
...BINARY INTERACTION OF CLOSED LOWS THURSDAY-FRIDAY IN THE PLAINS
AND MISSOURI VALLEY...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~
PREFERENCE: 00Z NAM, 12Z ECMWF/ECENS, 12Z CMC
CONFIDENCE: SLIGHTLY BELOW AVERAGE
STILL MANY DETAILS TO IRON OUT WITH TWO MID-LEVEL IMPULSES MOVING
THROUGH THE PLAINS TODAY INTO THURSDAY, AND HOW THEY WILL
DEEPEN/INTERACT THROUGH THE REST OF THE WEEK. THE GFS OVER THE
PAST SEVERAL RUNS CONTINUES TO EXHIBIT MINIMAL RUN-TO-RUN
CONSISTENCY, LEAVING LITTLE CONFIDENCE IN ITS EVOLUTION. MULTIPLE
FEATURES INTERACTING CREATE LOWER THAN USUAL CONFIDENCE, BUT THE
LEADING SHORTWAVE SHOULD EVENTUALLY BECOME DOMINANT AND INTENSE,
ESPECIALLY LATE ON D3 /FRIDAY NIGHT/ ACROSS THE MISSOURI VALLEY
AND INTO THE OHIO VALLEY. THIS SHOULD LEAD TO STRONG CYCLOGENESIS
ALONG A TRIPLE POINT ACROSS THE MID-ATLANTIC D3, WITH THIS TRIPLE
POINT EXTENDING FROM A PRIMARY SURFACE LOW BENEATH THE TRAILING
UPPER TROUGH OVER THE UPPER MIDWEST. MOISTURE DRAWN NORTHWARD
AHEAD OF THIS SYSTEM COULD BE SIGNIFICANT. THE NAM/ECMWF/ECENS ARE
IN GOOD AGREEMENT THROUGH 60 HOURS, WITH THE CMC BECOMING ALIGNED
THEREAFTER DESPITE BEING SLIGHTLY TOO FAST/SOUTH DAYS 1-2.
MODEL TRENDS AT WWW.WPC.NCEP.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML
WEISS
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