Prognostic Meteorological Discussion
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FXUS10 KWNH 191707
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1206 PM EST THU JAN 19 2017

VALID JAN 19/1200 UTC THRU JAN 23/0000 UTC

...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...

12Z NAM/GFS EVALUATION INCLUDING PRELIMINARY MODELS PREFERENCE AND
FORECAST CONFIDENCE

...CLOSED UPPER LOW OVER CNTRL/SRN HIGH PLAINS TRACKING TO UPPER
MS VALLEY/GREAT LAKES FRI WITH
ASSOCIATED SURFACE WAVE INTO THE OHIO VALLEY FRI...

PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE

12Z MODELS WELL RESOLVED WITH THE EVENTUAL EVOLUTION OF CLOSED LOW
CURRENTLY OVER THE CENTRAL/SOUTHERN PLAINS. MODELS ARE IN GOOD
AGREEMENT IN DEPICTING A DAMPENING/OPENING TROUGH SHEARING OUT AND
BECOMING ELONGATED AS IT TAKES ON A NEGATIVE TILT AS IT LIFTS
ACROSS THE OHIO VALLEY FRIDAY AND FRIDAY NIGHT. THE 12Z NAM AND
GFS CONTINUE THE OVERALL GENERAL CONSENSUS OF THIS EVOLUTION AS
PRESENTED BY THE THE PAST COUPLE OF RUNS OF GUIDANCE/ENSEMBLE
SUITE. GIVEN THE CONSISTENCY AND MINIMAL TEMPORAL/SPATIAL
DIFFERENCES AT THIS RANGE...A GENERAL MODEL BLEND IS PREFERRED
WITH AN ABOVE AVERAGE CONFIDENCE.

...LONG WAVE/KICKER UPPER TROUGH DIGGING INTO THE SOUTHWEST US
TONIGHT/FRIDAY...
...DEVELOPING/CLOSING MID LEVEL LOW OVER THE CENTRAL PLAINS BY
EARLY SAT...

PREFERENCE: 12Z GFS/00Z ECMWF
CONFIDENCE: SLIGHTLY ABOVE AVERAGE

PREVIOUSLY REFERENCED UPPER LOW WILL BE EJECTED INTO THE OHIO
VALLEY BY THE NEXT ARRIVING SHORTWAVE. THIS SYSTEM CURRENTLY
CRASHING THE WEST COAST TODAY WILL TRAVERSE ACROSS THE
INTERMOUNTAIN WEST/FOUR CORNERS REGION...EVENTUALLY EMERGING OVER
THE CENTRAL/SOUTHERN HIGH PLAINS BY FRIDAY AFTN/EVENING. GEFS AND
OPERATIONAL 12Z/GFS CONTINUE TO TREND TOWARD THE SLOWER, STRONGER
SOLUTION...WITH THIS SYSTEM LIKELY BECOMING SLOWED BY THE OPENING
WAVE AHEAD OF IT IN THE OHIO VALLEY/GREAT LAKES. IT WILL ALSO
ALLOW FOR THIS SYSTEM TO TAKE ON A NEGATIVE TILT OVER THE
MID-MISSISSIPPI RIVER VALLEY FRIDAY NIGHT AND SATURDAY...BEFORE IT
AND ITS ATTENDANT WEAK SURFACE WAVE EVENTUALLY SLOWLY LIFTING NE
INTO THE UPPER MIDWEST BY LATER SATURDAY/SUNDAY. MODELS HANDLE
THIS FEATURE REASONABLY WELL EVEN INTO DAY 3...WITH BEST OVERALL
ALIGNMENT NOTED WITH THE 00Z ECMWF AND THE 12Z GFS. THE 12Z NAM IS
ALSO QUITE SIMILAR BUT IS A BIT MORE BAGGY/WEAK WITH THE UPPER
TROUGH...AND THEREFORE A BIT FURTHER STRENGTH NORTHWEST/FASTER
WITH LIFTING THE AXIS INTO THE DAKOTAS. A GENERAL MODEL BLEND
WOULD LIKELY BE SUFFICIENT...BUT GIVEN STRENGTH OF ALIGNMENT OF
THE GFS/ECMWF...WILL CONTINUE TO PREFER THESE SOLUTIONS FOR A
TIGHTER BLEND WITH SLIGHTLY ABOVE AVERAGE CONFIDENCE.


...SECONDARY HEIGHT FALLS ACROSS THE WEST LATE FRIDAY/SATURDAY
WHILE BASE ROLLS THROUGH THE SOUTHWEST INTO THE SOUTHERN PLAINS BY
SUN...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: 12Z GFS/00Z ECMWF BLEND
CONFIDENCE: AVERAGE

NEXT WAVE ARRIVES QUICKLY ON THE HEELS OF THE LEAD SHORTWAVE...AND
WILL DIG SOUTH ACROSS THE NORTHWEST COAST LATE FRIDAY...DIGGING
SOUTH TO THE DESERT SOUTHWEST BY SATURDAY MORNING. MODELS REMAIN
IN GOOD AGREEMENT WITH THIS FEATURE AND ITS ASSOCIATED SURFACE LOW
DEVELOPING OVER NV/UT BY DAY 2. A GENERAL MODEL CONSENSUS APPEARS
ACCEPTABLE AT THIS TIME.

BY LATE IN THE PERIOD...A STRONG PUNCH OF UPPER JET ENERGY WILL
DIG SE FROM THE WEST COAST ACROSS THE SOUTHERN PLAINS INTO THE
GULF COAST....SHUNTING THE LEAD SHORTWAVE EAST ALONG WITH IT. THIS
WILL LEAD TO A DEEP CYCLOGENESIS ACROSS TX AND LOWER MS VALLEY BY
LATER SUNDAY. THE 12Z NAM AND 00Z UKMET REMAIN STRONGEST WITH
DEPICTION OF STRONG SHORTWAVE FEATURE...WHICH WOULD PORTEND TO A
MUCH STRONGER SURFACE REFLECTION. HOWEVER...12Z GFS AND 00Z ECMWF
ENSEMBLES ARE BECOMING BETTER CLUSTERED WITH THEIR RESPECTIVE
MEMBER ENSEMBLES...SO WILL CONTINUE TO SUPPORT AN EQUAL GFS/ECMWF
BLEND FOR NOW. FORECAST CONFIDENCE WILL REMAIN ONLY AVERAGE.


...APPROACH OF NEXT STRONG CLOSED LOW NEARING WEST COAST SUNDAY...

PREFERENCE: 00Z ECMWF/UKMET BLEND
CONFIDENCE: AVERAGE

YET ANOTHER STRONG SHORTWAVE APPROACHES THE WEST COAST BY LATE IN
THE PERIOD. MODELS CAN AGREE WITH PUMPING UP WEST COAST UPPER
RIDGING IN ADVANCE OF THIS FEATURE WITH RESULTANT AMPLIFICATION OF
THE UPPER TROUGH AS IT CROSSES EAST OF 150N BY SATURDAY AND
SATURDAY NIGHT. STILL A GOOD AMOUNT OF SPREAD IN THE SOLUTIONS
WITH RESPECT TO THE ORIENTATION OF THE SHORTWAVE/VORTICITY MAXIMA
OF THE PRECEDING WAVE. THE 12Z GFS IS A BIT FASTER AND FLATTER
THAN THE 00Z ECMWF. THE 00Z UKMET IS VERY SIMILAR IN EVOLUTION TO
THE ECMWF, ALBEIT SLIGHTLY FASTER THAN THE ECMWF. THE 00Z CMC IS
ALSO SIMILAR BUT CONTINUED WEAKER AND EVEN FASTER THAN THE
ECMWF...AND WELL AWAY FROM THE ENSEMBLE MEANS. STILL APPEARS THAT
THE PREVIOUS PREFERENCE OF ECMWF/UKMET WILL HOLD TRUE FOR NOW,
WITH THIS BLENDED SOLUTION REMAINING THE BEST REPRESENTATION OF
THE ENSEMBLE SPREAD. GIVEN THE TIME RANGE AND TYPICAL SPATIAL
DIFFERENCES...CONFIDENCE WILL REMAIN AVERAGE AT BEST.

www.wpc.ncep.noaa.gov/html/model2.shtml...

www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

MONTEFUSCO

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