Model Diagnostic Discussion
NWS Weather Prediction Center College Park MD
318 AM EDT Thu Oct 17 2019

Valid Oct 17/0000 UTC thru Oct 20/1200 UTC

...See NOUS42 KWNO (ADMNFD) for the status of the upper air
ingest...

00Z Model Evaluation with Preferences and Confidence
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Great Lakes closed low transferring to developing Northeast
coastal surface Low
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: General model blend
Confidence: Above average

Very good agreement now with the synoptic evolution of the
deep/anomalous storm system affecting the Northeast U.S. tonight.
Secondary low along coast will become parent low and deepen
tonight and Thursday morning with the system becoming stacked
later Thursday and Thursday night. There is excellent, above
average agreement with the low position, strength, and track
through the next few days such that a general model blend is
acceptable and the preferred blend.


Developing area of low pressure in the Gulf
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Preference: ECMWF/CMC blend
Confidence: Below average

07Z update: The 00Z ECMWF/CMC did trend toward the faster
solutions like the 00Z GFS/UKMET which now puts the 00Z NAM as the
slowest solution and the dominant outlier. There is still much
uncertainty in how quickly the low lifts as it approaches the
central/northeast Gulf this weekend, but a slight increase in
forward speed from the previous forecast appears likely. With
that, a solution toward the ECMWF/CMC would be a good compromise
to the fast GFS/UKMET at this time, though confidence remains
below average.

---previous discussion---
Broad area of low pressure located over the Bay of Campeche
continues to show increased shower and thunderstorm activity per
satellite IR imagery in the last 6-12 hours. This system is
expected to gradually move northward and then northeastward over
the next day or so as it interacts with a weak mid-level shortwave
vort over Texas. Models have come into slightly better agreement
with the idea that the broad area of low pressure will begin to
move northward, but there remains quite a bit of spread in the
eventual track and intensity as it approaches the central Gulf
Coast by this weekend. The 00Z GFS remains a fast outlier and
should be largely discounted. The 00Z NAM matches fairly well with
the 12Z ECMWF/CMC with speed/position of the low as it crosses the
Southeast U.S., though it is too deep compared to the rest of the
guidance. The 12Z UKMET was discounted as it was too deep/strong
given as the low tracked off the North Carolina coast, and the
latest 0Z UKMET remains fast and too strong (similar to GFS). Its
solution remains discounted for now. All told, the ECMWF/CMC track
remains the closest to the consensus approach and its solutions
are preferred at this time. Forecast uncertainty is high,
especially by Day 2/3.


Model trends at www.wpc.noaa.gov/html/model2.html
500 mb forecasts at www.wpc.noaa.gov/h5pref/h5pref.shtml

Taylor