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Area forecast discussion 
National Weather Service Gray ME 
332 PM EDT Sat Mar 20 2010 


Synopsis... 
a cold front will pass through the area from the north tonight 
bringing record warmth to an end. Light precipitation is possible 
behind the front on Sunday and Monday. Low pressure will track 
across the southern United States and move offshore south of New 
England on Tuesday. This will bring more rain and snow to our area 
through Wednesday. Another stronger cold front will move through 
the area on Friday. 


&& 


Near term /through tonight/... 
the surface cold front is dropping through the northern portion of 
the forecast area this afternoon. The frontal zone cloudiness has 
extended into the central zones...but the Canadian radar mosaic 
suggests that the rain showers associated with the front will stay 
in the higher terrain this evening. 


As the short wave that pushes the front south this evening shears 
out to the northeast...the front will slow...and then come to a 
halt south of the area tonight. The cloud band will become nearly 
stationary later tonight...so all areas should become and stay 
mostly cloud. Weak overrunning late tonight may bring light rain 
showers to the southernmost zones...but this may be overdone. For 
the most part...lows were based on the warmer GFS MOS numbers. 


&& 


Short term /Sunday through Sunday night/... 
overrunning begins in earnest ahead of the closed low to the 
southwest Sunday afternoon. Based on the surface and 850 mb warm 
front positions...the best chance of precipitation should be 
across the higher terrain Sunday afternoon and Sunday evening. 
Elsewhere...the forcing may be weak enough to keep southernmost 
areas dry. 


Precipitation type could be problematic across northern zones. The 
airmass should be dry enough for evaporative cooling...meaning 
snow or rain is possible for the terrain. In fact...a few snowflakes 
could fall even across southern sections due to the dryness of the 
column. However...as warm as temperatures reached today...accumulation 
of snow...even in the elevations...could be tough at this point...used 
a blend of MOS numbers for highs Sunday...which will be 20 degrees 
cooler than this afternoon. 


The best forcing exits Sunday evening...but there will be enough 
low level moisture left over for light rain or drizzle in most 
places. The GFS MOS numbers looked better for lows...as the NAM 
numbers looked too cold. 


&& 


Long term /Monday through Friday/... 
the extended forecast will be a tale of three troughs. The first 
will bring the best chance of precipitation. The last will bring a 
return to winter. 


The first low is currently over West Texas...dropping snow on the 
Texas Panhandle. The closed low will track across the southern states 
and then move just offshore of southern New England by Tuesday. 
Moisture will begin streaming northward ahead of the low on Monday 
night. Remnant frontal boundary remains offshore...but does not 
appear that there will be enough cold air in place to provide 
wintry precipitation to most places. Will start off with only a 
rain/snow mix across the northern mountains. Cold air pushing 
southeast out of Canada will slowly pull the rain/snow line 
southeastward. Then as the low passes to the east...cold air 
will be pulled into the system and may be sufficient to cause a 
change over to snow across the whole area before precipitation 
ends on Wednesday. Some accumulations are possible especially in 
the north and the mountains. 


As the first low lumbers slowly into the Canadian Maritimes 
another fast moving trough moves through from the west on 
Thursday. This will bring slightly cooler air and a chance for 
some showers. 


Then the final low will develop over the Great Lakes and track 
across northern New England by Friday morning...dragging an Arctic 
cold front behind it. Much colder air is available behind this 
front than has been seen in several weeks. This far out...exactly 
where the core of this cold air GOES is not certain...and 
therefore the extent of the cold to be felt across Maine and New 
Hampshire is unknown. But it is possible some areas may not make 
it above freezing for high temperatures Friday into 
Saturday...with low temperatures dropping into the teens and 
single numbers in places. The current forecast does not paint such 
a bleak picture as it is still a long ways out and many things 
could change. 


&& 


Aviation /19z Saturday through Thursday/... 
short term... 


Long term...clouds and rain remain through Wednesday. Could see 
periods of MVFR conditions. 


&& 


Marine... 
near term /tonight/...winds are gusting to near 20 knots across 
the southern waters...but the sea breeze circulation has formed 
just offshore and across the eastern waters. This will change with 
the passage of the cold front late this afternoon and this 
evening. Before that...all waters may gust near 20 knots...but 
much warmer air traveling over the much colder surface waters 
should cut down on momentum Transfer. 


After the front pushes south of the waters later this evening...the 
northeast flow behind it could bring the southern waters to near 
small craft winds after 0600 UTC Sunday. For now...kept gusts 
under 25 knots...but this may have to be monitored. It does not 
appear as though the fetch will be long enough for seas to reach 5 
feet...even across the southern waters. 


Short term...the best push of northeast flow should be done by 1500 
UTC Sunday. After this...surface high pressure will build across 
the waters Sunday afternoon and evening. This will bring the 
gradient down...and sea breeze circulations could form in the 
afternoon. 


The surface cold front that passes this evening will move slowly 
north as a warm front Sunday night. This will back winds to the 
east and southeast...but winds and seas are expected to remain 
below small craft levels. 


Long term...as low pressure tracks northeast toward the Gulf of 
Maine...winds will increase out of the east northeast to gale 
force beginning on Tuesday. Will see improving conditions 
beginning Tuesday night and Wednesday. 


&& 


Fire weather... 
a few locations were close to red flag conditions...but most of 
these areas were still fairly wet under the dry surface layer. With 
the passage of the cold front...relative humidities should recover 
the forecast area should go into a wetter regime starting Sunday 
and lasting into the middle of next week. This should mitigate 
fire weather concerns after this evening. 


&& 




Climate... 
Portland, Maine /pwm/ has seen a stretch of 4 days with record 
setting warmth. 


As of 3 PM today...Portland has set the following temperature 
records for March 20th. These record values may change if the 
temperature rises above 69 degrees during the rest of the 
afternoon. 


Record today previous record 
high temperature 69 degrees 62 degrees in 1959 
warmest average temperature. 51 degrees 49 degrees in 1959 


Other temperature records set or tied over the past few days... 


Date record previous record 
17 64 - highest temperature 62 degrees in 1990 
18 43 - warmest low temperature 40 degrees in 1968 
18 53 - warmest average temperature. 48 degrees in 1945 & 1990 
19 56 - highest temperature 56 degrees in 1986 /tied/ 


&& 


Gyx watches/warnings/advisories... 
ME...none. 
New Hampshire...none. 
Marine...none. 


&& 


$$ 

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