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Area forecast discussion 
National Weather Service quadrant cities Iowa Illinois
338 am CST Friday Mar 6 2015

Synopsis... corrected typos
issued at 247 am CST Friday Mar 6 2015

The latest surface analysis was indicating passing ridge axis sinking
east-southeastward toward the mouth of the Ohio River valley...allowing
south-southeasterly low level return flow to increase across IA/MO. Surface
trough or even a type of warm front was evident across the central and up
into the northern plains...with pressure falls increasing over much
of the MO River Valley. Surface temperatures which plummeted earlier in the
night/especially over the northern and eastern County Warning Area/ are showing
rising trends from west-to-east along with an approaching deck of
elevated warm air advection/warm air advection clouds. Aloft...water vapor imagery
was indicating a vigorous upper wave rolling eastward across central
into eastern Iowa at this time...with a secondary vorticity lobe noted further
upstream over the Dakotas. The next main vorticity maximum in line was
currently progressing across northern b.C. Canada.

&&

Short term...(today and tonight)
issued at 247 am CST Friday Mar 6 2015

Today...both the current passing vorticity maximum and the Dakota lobe will
be sweeping through a dry air mass today and do little but produce
occasional middle and high level clouds across the region. After the
current incoming warm air advection deck passes east across the County Warning Area this morning...
much of the rest of the day to be mostly sunny until another Wing
of middle clouds pushes in from the northwest later this afternoon and
evening. Gusty south to southwest winds and warm air advection
regime to draw upon plains thermal pool and make for late afternoon
highs generally in the low to middle 30s north of i80...to the upper
30s or around 40 south of i80. Took a blend of the milder European model (ecmwf) and
mav MOS temperature guidance...with the European model (ecmwf) MOS the warmest guidance at
all sites.

Tonight...the above mentioned strong vorticity maximum across b.C. Will clipper
it/S way down across southern Minnesota into northern Iowa by Sat morning.
Again with dry air in place...despite it/S strength see little in the
way of precipitation getting kicked up in the local forecast area with better
chance to the north across Minnesota into WI. More rounds of clouds especially
across the north half of the dvn County Warning Area into Sat morning. Southwest flow
maintaining overnight will keep temperatures steady after a Post-sunset drop
off...with even some steady to slow rise again after midnight in
ongoing warm air advection on the incoming Minnesota/WI clipper/S warm draw. ..12..



Long term...(saturday through next thursday)
issued at 247 am CST Friday Mar 6 2015

Dry conditions with major warming trend to above normal temperatures
for early Spring weather main topic.

Long term forecast confidence assessment...good or slightly above average
with little sensible weather issues. Main challenge is melting of snow
pack with March sunshine. Area highs most days may be 3 or degrees too
low for later shifts to reconsider...especially once snow pack melts
which should be Sunday most areas and some north locations on Monday.

Overview...minor issues with a 70/30 mix of hi-res European model (ecmwf) to GFS preferred
mainly due to GFS too cool and moist in bl. This means warmer temperatures
for highs days 2-7.

Saturday...sunny to mostly sunny and light westerly to northwesterly
winds will allow for highs to reach upper 30s north to possibly some
places in the south the middle 40s. Lows with bl decoupling supports
mins below guidance with upper teens north to lower 20s south.

Sunday...weak disturbance to the north may bring partly to mostly cloudy
skies north with isolated flurries or sprinkles but trends suggest this
is increasingly unlikely for any precipitation. South sections to see
more sunshine suggesting decent thermal gradient of 15 plus degrees
allowing for upper 30s north to around 50 degrees south sections. Sunday
night mins with bl decoupling suggest mins in the upper teens north
to lower 20s south sections.

Monday through Friday...winds to shift to the southwest allowing for
well above normal temperatures for a change with fair skies. Warmest
day looks to be Wednesday with weak trough passage. Low level thermal
fields suggest with snow all melted by then to see upper 50s north
to near 70 degrees south sections...welcome change after the long
cold winter. Weak backdoor cold front Thursday to shift winds to
the east and bring slightly cooler air in with mostly 50s for highs
Thursday and Friday and Friday morning lows in the 30s.

&&

Aviation...(for the 06z tafs through 06z Friday night)
issued at 1147 PM CST Thursday Mar 5 2015

Expect VFR conditions through the taf period with a light
southerly breeze becoming SW Friday morning and becoming gusty. A
band of middle level clouds will traverse the area overnight into
early Friday morning.

&&

Dvn watches/warnings/advisories...
Iowa...none.
Illinois...none.
MO...none.
&&

$$

Synopsis...12
short term...12
long term...Nichols
aviation...rp Kinney

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