Scientific Forecaster Discussion

NWS Discussion
			
				

Area forecast discussion 
National Weather Service Grand Rapids Michigan 
121 PM EDT Thursday may 23 2013 


Latest update... 
aviation 


Synopsis... 
issued at 327 am EDT Thursday may 23 2013 


Showers will linger through the morning hours...but then as drier 
air moves in from the northwest the rains will come to an end 
through the afternoon and early evening from northwest to 
southeast. After a gloomy start to the day most areas will see 
some sunshine by late afternoon or early evening. This clearing 
will be the start of quiet period of weather which should last 
throughout the Holiday weekend. 


It will be much cooler today with highs only 55 to 60. Patchy frost 
will be seen tonight north of I-96. However temperatures will 
gradually rebound into the 60s for Friday and Saturday...and mainly 
into the 70s for Sunday through Wednesday. The next chance of rain 
should hold off until Tuesday and Tuesday night. 


&& 


Update... 
issued at 1212 PM EDT Thursday may 23 2013 


Cold front is situated across the far southeast portion of lower 
Michigan stretching from near the Detroit metropolitan area southwest 
into portions of Northeast Indiana. Clouds are in place across the 
entire forecast area with rain showers lingering Post frontal 
across the bulk of the forecast area yet. Heavier showers at this 
point continue from the Interstate 96 corridor south...with 
lighter showers and drizzle to the north. Expect a gradual end of 
the showers from north to south over the course of the next 6 to 8 
hours...with the bulk of the rain over by 800pm or so. Clouds will 
begin to clear as well in the same fashion...with skies turning 
partly cloudy in the northwest toward Ludington this afternoon. 
Clouds will begin clearing out during the evening from Holland to 
Alma and in the southern County Warning Area towards sunset. High temperatures 
will be tempered by the clouds and rain with most sites seeing 
afternoon highs in the upper 40s to middle 50s. 


&& 


Short term...(today through saturday) 
issued at 327 am EDT Thursday may 23 2013 


A cold front cut across the County Warning Area this morning and it will continue to 
sag to the south today. Fgen behind the front was supporting a band 
of showers over eastern WI/Lake Michigan early this. This rain will swing 
through the County Warning Area from northwest to southeast through the course of the day. Upper 
dynamics were also helping this area of rain...and the right 
entrance 
region of the jet will slide over the County Warning Area with the rain. So 
needless to say the band of rain should hold together and it looks 
wet through the morning. Then the back edge of the rain will 
gradually sag southeast through the County Warning Area through the afternoon and early 
evening. Much drier air moves in and skies will clear late today. 
This should give most areas a late afternoon/early evening high temperature 
as a bit of sunshine boosts the temperatures up a bit. 


Will go ahead with a frost advisory across the northern County Warning Area 
tonight. This does not look like a prolong event with the nights 
being so short this time of year. Also with the winds likely 
staying up through the evening the actually time frost will develop 
should only be 3 to 5 hours. Localized areas may fall to below 
freezing in the normally cold low spots...but this should be too 
brief and too isolated to need to consider a freeze warning. 


High pressure and quiet weather prevails for Friday and Saturday. 
Frost potential appear to be lower for Friday night given that some 
middle/hi clouds should be moving in on the heels of warm advection 
aloft. Will mention patchy frost for now and will need to monitor 
cloud trends. Daytime temperatures warming slightly each day. 


Long term...(saturday night through wednesday) 
issued at 327 am EDT Thursday may 23 2013 


A classic Hudson Bay high will visit our area into Monday providing 
little in the way of cloud cover and slightly below normal 
temperatures through Memorial Day. This will block any attempts of 
southern stream shortwaves from bringing any clouds and 
precipitation into the area. 


Beyond Memorial Day the forecast gets more uncertain. While we start 
out with an Omega block type pattern (which is why it should stay 
mostly clear into Memorial day) over time a powerful storm currently 
near Japan crosses the North Pacific gaining support from a system 
in the Bering Sea late in this weekend. The system reaches the West 
Coast in the Wednesday time frame. Now there already a system 
stalled along the West Coast. When the Japan system gets west of the 
dateline... that will force the current system inland and that will 
try to flatten the large ridge (1-2 Standard deviations from normal 
on the 500 mb heights) by midweek. That then sets US up to be in the 
line of fire for shortwaves traveling east on the southern stream 
jet. So just how this plays out is anyone guess... since the 
primary player in all of this has to cross the Pacific Ocean yet. 


So... all that being so I have to admit there will be a chance of 
showers and thunderstorms from Tuesday afternoon on. Thus in 
increased the pop to around 30 percent from then on through the rest of 
the forecast. What this means is the front stalls near US. Another 
aspect to this is it should get warm to hot as the upper ridge is 
pushed east a touch middle to late week. I could see highs well up 
into the 80s from Wednesday on. Again... timing shortwaves and such 
will be an issue with the temperatures... but bottom line Summer 
like weather returns by Wednesday continues well beyond Wednesday. 


&& 


Aviation...(for the 18z tafs through 18z Friday afternoon) 
issued at 116 PM EDT Thursday may 23 2013 


Moisture wrapping around the departing low pressure system will 
lead to a few hours if IFR weather from clouds...fog and rain to start 
the 18z tafs south and east of kgrr. Satellite imagery shows rapid 
clearing pushing southeastward toward kfks and kldm. This will be 
the trend for the taf sites in southwest Michigan later this afternoon. 
VFR weather to prevail tonight and Friday. Mixing will cause some 
gusty winds through 01z...but values should stay under 25 knots. 


&& 


Marine... 
issued at 1212 PM EDT Thursday may 23 2013 


Upgraded the Small Craft Advisory to a Gale Warning as gales have 
been occurring at the northern marine ob sites. Feel this will push 
south this afternoon and affect all marine zones with time. The 
observation at Muskegon and Holland may not show gales on land...but 
believe gales will likely be achieved at the edge of the nearshore 
zone out at 5 miles. Waves have already hit 11 feet at the 
southern Middle Lake buoy. 




&& 


Fire weather... 
issued at 327 am EDT Thursday may 23 2013 


More rain today will keep fire danger low. Much drier air arrives 
for Friday and Saturday with daytime relative humidity values lowering to around 35 
percent. However winds will remain under 10 miles per hour for much of Friday 
and Saturday. 


&& 


Hydrology... 
issued at 327 am EDT Thursday may 23 2013 


Additional rain today will be persistent...but will be on the light 
side. Generally less than a quarter of inch is expected. River 
levels are high with one advisory valid for the Muskegon river near 
Croton. River levels should begin to slowly fall late today as the 
beginning of a dry spell moves in. 


&& 


GRR watches/warnings/advisories... 
Michigan...frost advisory from 1 am to 7 am EDT Friday for miz037>040- 
044>046. 


Lm...Gale Warning until 11 PM EDT this evening for lmz844>849. 


&& 


$$ 


Update...Duke 
synopsis...jk 
short term...jk 
long term...wdm 
aviation...mjs 
fire weather...jk 
hydrology...jk 
marine...Duke