Scientific Forecaster Discussion

NWS Discussion
			
				

Area forecast discussion 
National Weather Service Gaylord Michigan 
1010 am EDT Sat may 18 2013 


Synopsis... 
issued at 317 am EDT Sat may 18 2013 


High pressure will exit to the east...allowing for warmer conditions 
along with a chance for showers over the weekend. A storm system 
currently organizing over The Rockies will move into the plains 
today...and into the Great Lakes to start the work week. This will 
generate showers and thunderstorms over northern Michigan beginning 
Monday and continuing through midweek. 


&& 


Update... 
issued at 948 am EDT Sat may 18 2013 


Elevated warm front gradually sliding to the north this morning 
with deepest forcing/moisture remaining west of our area. Despite 
little moisture below 800mb across northern Michigan...still 
enough forcing to create patchy light rain and sprinkles /spotter 
reports up to 0.06 inches of rain/. Forcing will diminish over the 
next several hours as everything gradually pushes to the north. 
Expect current area of light precipitation to gradually diminish through 
early afternoon as it pushes into eastern upper/tip of the mitt. 
Likely still some sprinkles over portions of northern lower into 
the afternoon with lingering forcing and plenty of middle cloud. 
Prevailing cloudy skies today...with some breaks likely over 
southern/SW areas. Lowered temperatures in many areas this afternoon...especially 
Gaylord northward with more clouds and light precipitation. 


Update issued at 650 am EDT Sat may 18 2013 


Isolated light showers continue to impact the SW half of our County Warning Area 
early this morning as limited low/middle level moisture lift into northern 
Michigan north of a warm front. Thunderstorms continue to fire 
well upstream over Minnesota in the vicinity of an 850 mb Theta-E 
ridge and instability axis. Latest NAM still points toward this 
instability and deeper moisture remaining upstream of our County Warning Area through 
the day...with only some isolated showers and mainly cloudy skies 
expected for US today. These isolated showers will gradually lift 
northward into the rest of our County Warning Area through the day as the warm front 
edges closer. No changes are needed to the timing of weather/probability of precipitation for 
now. 


&& 


Short term...(today through tonight) 
issued at 317 am EDT Sat may 18 2013 


On the latest surface weather map...1025 mb high pressure was 
centered over southeast Ontario with 1002 mb low pressure along the 
Front Range of the central rockies. Apx and surrounding radars 
showed a few light rain showers sprinkled across portions of north 
central lower Michigan. The main short term forecast concerns center 
around probability of precipitation and high temperatures today. 


Today into tonight...more of the same with subtle warm front and 
increasing Theta-E ridging (moisture) advecting into the region from 
the southwest. The main forcing/better moisture remain to our west 
closer to parent upper low spinning its wheels across The Rockies. 
Looking at model cross sections...lower levels remain rather dry 
with abundant middle level moisture (from about 850 to just below 500 
mb). So expect mostly cloudy skies with isolated light rain showers 
marching from southwest to northeast through the day. Mainly dry 
tonight with perhaps just a few leftover isolated rain showers 
across the far north. Temperatures are a bit tricky today with 
abundant cloud cover and weak warm advection. Highs expected to 
range from the middle 60s north to the middle 70s south. Lows 
tonight ranging from the middle 40s to lower 50s. 


Long term...(sunday through friday) 
issued at 317 am EDT Sat may 18 2013 


Sunday...will be the best weather day of the weekend. Eastern edge of a 
warm front will lift northward into Upper Michigan. Southerly flow 
south of the warm front will boost temperatures into the low to middle 70s 
across eastern Upper Michigan and into the upper 70s and lower 80s across 
northern lower Michigan. Still appears Sunday will be dry with partly sunny 
skies...and will likely serve as our last completely dry day for 
most of next work week (more on this below). At this point...Sunday 
evening should remain dry...but precipitation chances will begin to 
increase across our western County Warning Area late Sunday night as an initial short 
wave accompanied by better moisture arrive toward daybreak. 


Monday through Wednesday...precipitation chances will continue to increase 
from west to east on Monday as the warm front sags southward into 
northern lower Michigan. Developing low pressure in the plains will begin 
to tap into Gulf moisture...advecting it northward through the lower 
and middle Mississippi Valley and into the western Great Lakes. As this 
deeper moisture begins to interact with the warm front and a series 
of short waves riding NE through Michigan ahead of the deepening upper 
lower...waves of showers and storms will remain the rule beginning 
Monday and continuing through Wednesday night. Surface and closed upper 
low become vertically stacked...thus making very slow eastward 
progress over this time period...and therefore keeping our weather 
unsettled through middle week (at least). Warm temperatures will hold over the 
region on Monday before the warm front sags south on Tuesday and 
Wednesday. High temperatures on Monday will range from around 70 degrees 
across eastern Upper Michigan north of the warm front to the middle 70s to 
lower 80s south of the warm front. High temperatures will only reach into 
the 60s both Tuesday and Wednesday as the warm front continues to 
drop south of our County Warning Area. 


Thursday and Friday...surface and upper low centers will slowly 
slide through lower Michigan on Thursday...exiting east toward New 
England by Friday. Some showers will linger across our County Warning Area Thursday 
around and just north of the surface low center...but should come to 
an end by Friday as drier air filters into the region behind the 
departing low. The colder air behind this system will not arrive 
until Saturday. Neutral temperature advection will lend to high temperatures 
remaining in the 60s for both Thursday and Friday. A first look at 
next weekend looks dry but potentially cooler than normal. 


&& 


Aviation...(for the 12z tafs through 12z Sunday morning) 
issued at 650 am EDT Sat may 18 2013 


Broken/overcast middle cloud will remain over all of northern lower Michigan through 
Sunday morning thanks to middle level moisture north of a warm front 
to our south. Scattered/broken low clouds and a few showers are expected to 
impact portions of northern lower Michigan through the day as well...but VFR 
conditions will remain the rule for the next 24 hours. Southeast 
winds will strengthen to around 10 kts this morning. 




&& 


Marine... 
issued at 317 am EDT Sat may 18 2013 


South-southeast flow slowly increases today through Sunday...and a 
handful of small craft advisories may be needed at some point later 
in the weekend. 




&& 


Apx watches/warnings/advisories... 
Michigan...none. 
LH...none. 
Lm...none. 
Ls...none. 


&& 


$$ 


Update...jk 
synopsis...mr 
short term...as 
long term...mr 
aviation...mr 
marine...as