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Next 12 Hours

Forecast data from the National Digital Forecast Database.

5 Day Forecast

• Wednesday
• 
• High: 76 °
• Low: 63 °
• T-Storms

• Thursday
• 
• High: 79 °
• Low: 66 °
• T-Storms

• Friday
• 
• High: 81 °
• Low: 66 °
• Chance of T-Storms

• Saturday
• 
• High: 86 °
• Low: 66 °
• Partly Cloudy

• Sunday
• 
• High: 82 °
• Low: 70 °
• Chance of T-Storms

Area forecast discussion 
National Weather Service State College PA 
800 am EDT Wednesday may 23 2012 


Synopsis... 
a broad upper level trough of low pressure will remain over the 
eastern United States through the remainder of this week. Daily 
rounds of showers...and scattered afternoon and early evening 
thunderstorms will continue to affect central Pennsylvania through 
Thursday. A southwest flow of warmer and humid air will follow for 
Friday...and the above normal temperatures will continue through the 
upcoming weekend. A weak cold front will attempt to push southeast 
through the region Saturday afternoon and evening...but could stall 
out across or just to the north of the region. 


&& 


Near term /until 6 PM this evening/... 
kccx radar loop showing scattered...and very slow moving rain 
showers affecting a small portion of far scent Penn /just to the 
west of Gettysburg/ and some communities throughout the middle susq 
valley...east into Schuylkill County. Rainfall will be briefly 
heavy in some of the showers...with pinpoint amounts of 0.25 to 
0.50 inch over the next few hours. 


The relatively high surface dewpoints and tight /0-3 degree f/...T/TD 
spread will combine with the areas of rainfall on Tuesday...to yield 
areas of fog through the middle-morning hours today. The fog could be 
dense at times across the northwest mountains where much of the rain over the 
past 12-18 hours was concentrated...and partial clearing will occur 
at times. 


It will stay fairly mild through daybreak with min temperatures ranging 
from the around 50f over the northwest mountains to around 60f over the southeast. 


The trigger for the showers /and scattered afternoon thunderstorms and rain/ today 
will be a slowly...southeastward moving surface-850 mb front...that 
was situated near the Interstate 81 corridor in Penn early today. 
This front will sag across the lower susq valley and southwestern Poconos 
by late this morning. 


Short range operational models /such as the 07z RUC/...and 21z 
sref paint the prime location for showers and thunderstorms today 
mainly to the east of a line from kipt to kmrb. The sref precipitation 
plumes for kmdt /along and just to the southeast of the aforementioned 
low level frontal boundary/ are somewhat bi-modal...with the lower end 
members accumulating about 0.10 of new rain today...while the 7 or 
8 heavier solutions bring an additional 3-6 tenths of rain by this 
evening. 


Across the northwest mountains and Laurel Highlands...a relatively 
light...north to NE surface-850 mb flow and broad divergence in this 
layer will minimize the chance for convection...except for perhaps a 
few/terrain induced showers. 


Local slow moving heavy rainers will be possible again today...especially 
during the middle to late afternoon hours...especially within the axis 
of anomalously high precipitable water from scent Penn east-northeast across the lower susq 
valley. Will keep probability of precipitation in the high chance...to likely category across 
the southeast half of the County Warning Area today. Convective available potential energy should be slightly higher today 
/compared with Tuesday/...increasing the probability of a storm 
pulsing to strong to severe levels. Afternoon high temperatures will be 
mainly in the middle to upper 70s. The exception will be the higher 
terrain of the northwest mountains and laurels where the Mercury may top out in 
the lower 70s. 


&& 


Short term /6 PM this evening through 6 PM Thursday/... 
isolated to scattered showers and thunderstorms and rain across the southeast 1/2 to 1/3 of the 
County Warning Area will dissipate for the most part after 03z Thursday. 


Any clearing tonight will once again yield patchy fog /and stratus 
straddling the ridges/ thanks to continued moist...albeit 
light...southeasterly flow. 


Low temperatures early Thursday morning will range from the middle 50s across 
the northern and western mountains...to the lower 60s in the southeast. 


For Thursday...the surface boundary lifts north into central New 
York state as a slowly weakening area of low pressure aloft drifts 
north from the virginias. Increasing...south to southeasterly mean surface-850 
mb flow will support plenty of clouds and numerous showers and 
scattered thunderstorms in the afternoon over much of the region to 
the south of Interstate 80. Less numerous showers and scattered thunderstorms and rain will 
develop/advect north across the northern mountains of Penn during the 
afternoon and early evening hours. 


Maximum temperatures Thursday afternoon will increase by a few degree f relative 
to this afternoon/S. 


&& 


Long term /Thursday night through Tuesday/... 
ec and GFS have been switching places on how far south the 
cold front ends up this weekend. Tried to keep forecast similar 
to the last few days...I.E. As consistent as possible. 


The other issue is I did up probability of precipitation a little for Friday. Both 
the NAM and GFS bring up more moisture now...although neither 
model prints out much quantitative precipitation forecast. 


For the weekend into early next week...went with fairly 
warm temperatures...and a mainly dry forecast. Even if the cold front 
moves south...it would not be much more than a wind shift 
line...given rising heights as we head into the later part 
of the weekend. Main chance of showers and storms would be from 
any mesoscale convective system dropping southeast. Will continue to look at the potential for 
this over the next few days. 


&& 


Aviation /12z Wednesday through Sunday/... 
a broad upper level low will remain over the eastern United States 
through the remainder of the week. Daily rounds of showers...and 
scattered afternoon and early evening thunderstorms will continue 
to affect central Pennsylvania through Thursday...in the vicinity 
of a stalled /and gradually weakening/ surface frontal boundary. 


Conditions at 12z are generally MVFR in both ceilings and visibilities as 
abundant low level moisture remains in place. Conds will improve 
to VFR by about 15z. By this afternoon...scattered to numerous 
showers and isolated thunderstorms will bring local reductions - mainly 
to the east of a line from kipt to kmrb /across the southern mountains 
and susq valley/. 


Precipitation becomes more isolated this evening before coming to an end 
by 03z. Clearing tonight will once again yield areas of fog /and 
stratus straddling the ridges/ as moist light southeasterly flow continues. 




Outlook... 
Wednesday night...VFR early...returning to MVFR/IFR after midnight in 
stratocu/fog. 
Thursday...primarily VFR. Scattered rain showers/thunderstorms and rain poss mainly southeast. 
Friday...primarily VFR. Isolated rain showers/thunderstorms and rain poss mainly southeast. 
Sat-sun...VFR. A chance of a rain showers or thunderstorms and rain across the north. 


&& 


Ctp watches/warnings/advisories... 
none. 


&& 


$$ 
Synopsis...Lambert 
near term...Lambert 
short term...Fitzgerald/Lambert 
long term...Lambert/Martin 
aviation...rxr