Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
229 AM EDT Thu Mar 14 2019
Valid 12Z Sun Mar 17 2019 - 12Z Thu Mar 21 2019
...Overview...
Upper ridge/trough pattern over the west/east will slowly slide
eastward next week in a rather dry pattern for the CONUS except
for Florida. Weak northern stream moisture-starved fronts will
sweep through the east early in the week while a cold front stalls
near the Florida Keys. This front will be a focus for rainfall
later next week that may be heavy in places. The west will
initially be protected from a complicated/evolving frontal system
offshore due to the upper ridge, but only until about Wednesday
when it will send a front into California.
...Guidance Assessment/Preferences...
Large scale pattern remains well-forecast but smaller details
remain elusive. Trend in the central/eastern states is a bit
flatter by Tue but would only modulate the weak frontal
positioning in the Southeast back to the southern/central Plains.
Still expect a wave to form along the front near Cuba but that
depends on the strength of the shortwave ejecting out of Mexico
and through the Gulf. Blended solution among the GFS/ECMWF and
their ensemble means was a good starting point.
For the west, issue remains how exactly the eastern Pacific
unfolds in a complicated/meridional pattern. ECMWF has trended
quicker while the GFS has trended slower, and each passed each
other a couple cycles ago. Ensembles followed the lead of each
deterministic model so a blended position (near the 12Z Canadian)
was preferred--mostly in line with continuity.
...Weather Highlights and Hazards...
Florida will see the most rainfall during the period, centered
around Tuesday. Southern third to half of the peninsula will see
more rain than the northern portion. This will keep temperatures
several degrees cooler than average through the period. Larger
negative departures will center over Texas, especially near the
Mexican border. Rest of the lower 48 will be nearly
precipitation-free except for some light rain/snow north of I-40
near the weak surface fronts/upper level shortwaves. California
will see rainfall spread slowly inland starting late Tue into Wed
and increasing in coverage on Thursday as the upper low moves
inland. Areas between San Francisco to San Diego eastward will
likely see at least measurable rain and higher elevation (Sierra
but also San Gabriel/Bernadino/Jacinto peaks) snowfall. This will
also move into Nevada/Utah on Thursday.
Fracasso
Additional 3-7 Day Hazards information can be found on the WPC
medium range hazards chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation, winter weather outlook probabilities
and heat indices are at:
https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml