095
FXUS10 KWNH 120652
PMDHMD
MODEL DIAGNOSTIC DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
252 AM EDT SAT OCT 12 2019
VALID OCT 12/0000 UTC THRU OCT 15/1200 UTC
...SEE NOUS42 KWNO (ADMNFD) FOR THE STATUS OF THE UPPER AIR
INGEST...
00Z FINAL MODEL EVALUATION WITH LATEST PREFERENCES AND CONFIDENCE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
SUBTROPICAL STORM MELISSA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND AND NHC FORECAST TRACK
CONFIDENCE: ABOVE AVERAGE
SUBTROPICAL STORM MELISSA IS NOW BEGINNING TO ACCELERATE TOWARDS
THE EAST-NORTHEAST AFTER REMAINING NEARLY STATIONARY WELL TO THE
SOUTH OF CAPE COD, MASSACHUSETTS. THE UPPER LEVEL RIDGE THAT HAD
BLOCKED THE STORM IS NOW MOVING OUT OF THE WAY AND THE LARGE SCALE
CIRCULATION AROUND THE UPPER MIDWEST LOW IS INCREASING THE
STEERING FLOW AND CAUSING IT TO GAIN FORWARD SPEED. SIMILAR TO
THE 12Z GUIDANCE ON FRIDAY, THE LATEST GUIDANCE SHOWS GOOD
AGREEMENT WITH THE EVOLUTION AND TIMING OF THIS SYSTEM AND THUS A
GENERAL MODEL BLEND IS PREFERRED.
DEEP PLAINS/UPPER MIDWEST CYCLONE
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND THROUGH SUNDAY NIGHT, THEN
GFS/ECMWF
CONFIDENCE: ABOVE AVERAGE
AN IMPRESSIVE DEEP LAYER CYCLONE OVER THE NORTH-CENTRAL U.S. HAS
REACHED MAXIMUM INTENSITY AS OF FRIDAY NIGHT, AND IS NOW FORECAST
TO GRADUALLY WEAKEN AFTER REMAINING NEARLY STATIONARY ON SATURDAY.
IT SHOULD THEN TRACK IN A GENERAL EASTWARD DIRECTION ACROSS LAKE
SUPERIOR AND THEN NORTHEASTWARD ACROSS ONTARIO. THE COLD FRONT
TRAILING FROM THE PARENT SURFACE LOW WILL CROSS THE APPALACHIANS
SATURDAY MORNING AND THEN EXIT THE EAST COAST BY SATURDAY NIGHT,
ALBEIT NOT NEARLY AS STRONG AS IT WAS OVER THE PLAINS. A
SECONDARY COLD FRONT ASSOCIATED WITH THE STORM SYSTEM WILL LIKELY
DEVELOP AND CROSS THE MIDWEST ON SUNDAY AND THEN MOVE TOWARD THE
EAST COAST ON MONDAY. THE MODELS REMAIN WELL CLUSTERED WITH THE
MASS FIELD EVOLUTION OF THIS SYSTEM THROUGH SUNDAY NIGHT. BY
MONDAY NIGHT, THE 00Z CMC HAS ITS MID LEVEL HEIGHT FIELDS SLIGHTLY
FARTHER SOUTH THAN THE OTHER MODELS AS THE ENERGY CROSSES THE
NORTHEAST U.S., BUT CLOSER TO THE CONSENSUS COMPARED TO ITS 12Z
RUN. THEREFORE, A GENERAL MODEL BLEND IS BEST THROUGH 60 HOURS,
FOLLOWED BY A GFS/ECMWF BLEND.
PACIFIC NORTHWEST TO THE NORTHERN PLAINS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: GENERAL MODEL BLEND
CONFIDENCE: ABOVE AVERAGE
THE NEXT FEATURE OF INTEREST TO AFFECT THE WESTERN U.S. WILL BE A
PROGRESSIVE UPPER-LEVEL TROUGH AND ASSOCIATED COLD FRONT THAT
SHOULD REACH THE WEST COAST BY EARLY SUNDAY, AND THEN ADVANCE
INLAND ACROSS THE NORTHERN ROCKIES ON MONDAY. BY MONDAY NIGHT,
THE HEIGHT FALLS START ARRIVING ACROSS THE HIGH PLAINS AND INDUCES
LEE-SIDE CYCLOGENESIS OVER THE CENTRAL PLAINS TO UPPER MIDWEST.
THE 00Z UKMET HAS TRENDED CLOSER TO THE CONSENSUS COMPARED TO ITS
12Z RUN REGARDING THE LEVEL OF AMPLIFICATION. BY THE END OF THE
FORECAST PERIOD TUESDAY MORNING, THE 00Z GFS IS SLIGHTLY AHEAD
WITH THE TROUGH AXIS OVER THE UPPER MIDWEST AND THE ECMWF SLIGHTLY
SLOWER, BUT CLOSE ENOUGH TO STILL BE INCLUDED IN THE FORECAST
BLEND. THERE IS EXCELLENT AGREEMENT ON THE TIMING OF THE COLD
FRONT ACROSS THE MIDWEST ON TUESDAY MORNING, AND A GENERAL MODEL
BLEND CAN BE INCORPORATED.
SOUTHWESTERN U.S.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
PREFERENCE: ECMWF/EC MEAN
CONFIDENCE: NEAR AVERAGE
A SOUTHERN STREAM SHORTWAVE PERTURBATION IS PROGGED TO REACH
CALIFORNIA SUNDAY NIGHT AND SEPARATES FROM THE NORTHERN STREAM
TROUGH MENTIONED ABOVE. THE CMC AND UKMET APPEAR SLIGHTLY MORE
AMPLIFIED IN THE MID TO UPPER LEVELS AND THE GFS AND NAM BECOME
FASTER AS THE SYSTEM CROSSES THE DESERT SOUTHWEST BY MONDAY. THE
ECMWF APPEARS TO SPLIT THE DIFFERENCE BEST AND HAS SUPPORT FROM
THE EC MEAN.
MODEL TRENDS AT WWW.WPC.NOAA.GOV/HTML/MODEL2.HTML
500 MB FORECASTS AT WWW.WPC.NOAA.GOV/H5PREF/H5PREF.SHTML
HAMRICK
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