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000
FXUS10 KWNH 110449
PMDHMD

MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1148 PM EST WED FEB 10 2016

VALID FEB 11/0000 UTC THRU FEB 14/1200 UTC

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

00Z GUIDANCE EVALUATION INCLUDING INITIAL MODEL PREFERENCE AND
FORECAST CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

QUICK MOVING S/WV MOVING FROM THE NRN HI PLAINS TO OFF THE
CAROLINA COAST THUR/FRI
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: MODEL BLEND
CONFIDENCE: ABOVE AVERAGE

GUIDANCE IS FAIRLY WELL CLUSTERED HERE WITH VERY CHANNELED S/WV
ENERGY THRU THE PLAINS EARLY DAY 1..SUPPORTING NARROW BAND OF WAA
PCPN..MAINLY LIGHT SNOW THRU PARTS OF THE DAKOTAS INTO THE MO
VALLEY WHERE ENERGY WILL QUICKLY TRANSITION TOWARD DVLPG COASTAL
DVLPMENT NEAR THE S/NC COAST WITH LOW DEEPENING AS IT RACES
QUICKLY TO THE NE FRI NIGHT.  AN OPERATIONAL MODEL BLEND SHOULD
HANDLE THIS SYSTEM WELL.


WEAK LOW ALONG ARCTIC COLD FRONT AFFECTING THE ERN LAKES INTO NEW
ENGLAND FRI/SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: MODEL BLEND
CONFIDENCE: ABOVE AVERAGE

VORT MAX SOUTH OF DEEP ARCTIC VORTEX IS EXPECTED TO SLIDE EWD THRU
THE CNTL/ERN GT LAKES INDUCING WEAK LOW ALONG ASSOCD REINFORCING
ARCTIC COLD FRONT THAT WILL PUSH TOWARD NRN NEW ENGLAND FRI
NIGHT/SAT.  THIS SYSTEM WILL HAVE LIMITED MSTR TO WORK WITH AND
MODELS SUGGEST AND OVERALL WEAKENING AS THE SYSTEM MOVED TOWARD
NEW ENGLAND.  HOWEVER...BY SAT...MODELS ALL SUGGEST THAT THE LOW
LEVEL RESPONSE FROM UPR VORT LIFTING TOWARD ERN NEW ENGLAND WILL
INDUCE INCREASING SURFACE TROFINESS AND MSTR CONNECTION WITH STGR
OFFSHORE LOW (NORLUN TROF) TO SUPPORT INCREASING PCPN AMOUNTS
INVOF TROF AXIS OVER ERN MAINE.  THERE IS A STRONG INDICATION IN
MOST OF THE 12Z AND 00Z GUIDANCE FOR THIS TO OCCUR AND IS
SUPPORTED BY THE 18Z GEFS MEAN AS WELL.  THE OVERALL MODEL SPREAD
WAS RELATIVELY MINOR EVEN AT THIS TIME RANGE SUGGESTING A GENL
MODEL BLEND/ENSEMBLE MEAN WOULD BE WELL SUITED.


SERIES OF SYSTEMS AFFECTING THE NW THUR INTO SAT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: EC/GEFS MEAN
CONFIDENCE: SLIGHTLY BELOW AVERAGE

RATHER COMPLEX CIRC WAS NOTED OFF THE WEST COAST WED EVENING WITH
A SERIES OF S/WVS ROTATING ABOUT A MEAN UPR LOW NEAR 47N/155W.
MODELS BRING A LEAD S/WV AND ASSOCD FRONT TOWARD THE NW COAST THUR
NIGHT/FRI.   THE NAM AND GFS HAD BEEN SLIGHTLY ON THE FASTER END
OF GUIDANCE WITH THIS FEATURE...THOUGH THE GFS HAS TRENDED EVER SO
SLIGHTLY SLOWER DURING THE DAY 1 PD AND CLOSER TOWARD THE SLOWER
MODEL CONSENSUS.  THIS LEAD ENERGY AND FRONT ARE EXPECTED TO
WEAKEN RAPIDLY ENEWD INTO SW CANADA FRI NIGHT WHILE TRAILING
ENERGY...MORE TIED TOWARD INITIAL UPR LOW PUSHES TOWARD THE WA
COAST FRI NIGHT..THEN WEAKENS RAPIDLY INLAND THROUGH THE NRN
INTERMOUNTAIN REGION.  BY DAY 3...SAT NIGHT INTO SUN MRNG...STG
ZONAL FLOW PATRN SETS UP NORTH OF STG UPR RIDGING DVLPG OFF THE
CALIFORNIA COAST WITH QUICK S/WV ENERGY MOVING TOWARD THE B.C.
COAST HELPING TO INITIATE WHICH COULD BE A MULTI-DAY RAIN EVENT
FOR THE PAC NW..SOME OF WHICH WILL BE HEAVY RAINS.  TIMING
DIFFERENCES BEGIN TO SHOW UP BY DAY 2 WITH THE 12Z EC BEING A
LITTLE QUICKER/FLATTER WITH THE 2ND S/WV MOVING INTO WA STATE LATE
FRI NIGHT.  EVEN WITH THE TIMING DIFFERENCES THE 12Z EC AND 18Z
GEFS MEANS MATCHED UP QUITE WELL BY 12Z SUN AND APPEAR TO BE A
GOOD MIDDLE GROUND APCH AT THIS TIME...THOUGH WITH ONLY AVERAGE
CONFIDENCE.

SYSTEM IMPACTING THE NRN PLAINS SAT/SAT NIGHT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GFS/NAM/GEFS MEAN
CONFIDENCE: AVERAGE

SOME AMPLITUDE/TIMING DIFFERENCES BEGIN TO SHOW UP SAT WITH
REMAINS OF ERN PAC UPR LOW THAT QUICKLY DAMPENS OUT INTO THE PAC
NW SAT MRNG BEFORE DIGGING SEWD ACRS THE NRN ROCKIES INTO THE
PLAINS SAT NIGHT.  THE 12Z EC APPEARS TO BE ON THE SOMEWHAT
FASTER/FLATTER END OF GUIDANCE AND IS NORTH OF MOST OF ITS
ENSEMBLE GUIDANCE. CONSIDERING HOW AMPLIFIED THE DOWNSTREAM UPR
TROF IS...THERE APPEARS ROOM FOR THE UPR FLOW TO BUCKLE ACRS THE
PLAINS.   THE 12Z UKMET WAS THE MOST AMPLIFIED AND SLOWER WITH THE
TROF THROUGH THE ROCKIES AND WHILE IT HAD SUPPORT FROM A FEW EC
MEMBERS...THOUGHT A BLEND OF GFS/NAM/GEFS MEAN APPEARED TO BE A
GOOD COMPROMISE AT THIS TIME.

...MODEL TREND GRAPHICS AT
www.wpc.ncep.noaa.gov/html/model2.shtml...

...500 MB FORECASTS AT
www.wpc.ncep.noaa.gov/h5pref/h5pref.shtml...

SULLIVAN

$$




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