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Area forecast discussion 
National Weather Service Grand Forks ND
402 am CDT Wednesday may 6 2015

Short term...(today through thursday)
issued at 401 am CDT Wednesday may 6 2015

Timing and amounts of precipitation moving into the area will be
the primary forecast challenge for the period.

The main upper trough is still down over Colorado and western
Kansas...but some scattered showers and thunderstorms have already
moved into the southern counties with some 850mb warm air
advection. This warm air advection should continue to push northward through the
morning hours. The rap has done a decent job of capturing the
leading band...and it has a break in the precipitation behind the
warm air advection band which seems to fit radar over South Dakota at the current
time. Think that the really widespread precipitation will hold off until
this afternoon as the main upper system begins to lift
northeastward into Nebraska/South Dakota and we get more widespread upper
forcing. Continued the trend of holding off on the categorical
probability of precipitation until this afternoon. There is a little bit of elevated cape
a few lightning strikes observed...so will keep showers and
isolated thunder mention for this morning and then match thunder
to showers this afternoon as we get some surface based cape moving
into the region. Clouds and precipitation will keep temperatures from rising a
huge amount today...but given that we are still in the 50s and
even 60s the warm start will help US reach the 70s again.

Tonight...the main upper trough will lift into the County Warning Area...weakening
as it moves through. Even with the weakening upper system there
should still be a decent amount of synoptic scale lift and
continued with high probability of precipitation throughout the overnight hours. The upper
shortwave will move northeast into Canada by Thursday and phase
with the northern branch shortwave. That should help push a cold
front into the County Warning Area for Thursday...and there should be continued
precipitation with the front. The NAM brings a vigorous shortwave behind
the main shortwave which sets off a lot of quantitative precipitation forecast along the
front...but is the odd model out. Will continue to keep high probability of precipitation
transitioning over to the eastern County Warning Area as precipitation should taper off
behind the cold front. Temperatures may actually drop in the northwestern
County Warning Area as the front comes down.

Long term...(thursday night through tuesday)
issued at 401 am CDT Wednesday may 6 2015

Thursday night through Friday night...the models bring through
another weak shortwave trough so continued to linger showers at
least over the eastern County Warning Area. Temperatures will be much cooler as there
seems to be good agreement with 850mb temperatures below zero coming
down...although fortunately after the precipitation ends early Friday
morning. Most of Friday and Friday night should be dry but cool as
surface high pressure extends from southern Canada into the northern
tier of the USA. Temperatures on Friday will be markedly cooler than the
past week and highs should only top out in the 50s and could drop
below freezing for Friday night.

Saturday through Tuesday...split flow was across North America with
northern stream over southern Canada and southern stream over the
central and Southern Plains. Long wave trough/ridge over the Gulf
of Alaska/western Canada will shift east to the West Coast/Central
Plains respectively by the end of the period. Both the GFS and
European model (ecmwf) were in good agreement with low moving into the northern
plains on Mon, but surface features were farther north and slower
on the European model (ecmwf). With the northern stream, the pattern became 180
degrees out of phase for Monday and Tuesday. The GFS has been trending
faster while the GFS has been trending slower over the last couple
runs. Will blend the European model (ecmwf) and GFS.

&&

Aviation...(for the 00z tafs through 00z Wednesday evening)
issued at 644 PM CDT Tuesday may 5 2015

Much of the overnight hours will remain VFR. MVFR (possibly ifr) ceilings
will invade the region from south to north Wednesday morning. -Ra
will become more widespread late Wednesday morning and afternoon.



&&

Fgf watches/warnings/advisories...
ND...none.
Minnesota...none.
&&

$$

Short term...Jr
long term...Jr/hoppes
aviation...tg

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