Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 280109
AFDGYX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
909 PM EDT MON JUL 27 2015

.SYNOPSIS...
WARM AND HUMID AIR WILL REMAIN OVER MAINE AND NEW HAMPSHIRE FOR
THE NEXT SEVERAL DAYS. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE
MAINLY DURING THE AFTERNOON AND EVENING HOURS. SOME STRONGER
STORMS ARE POSSIBLE ON TUESDAY. A COLD FRONT WILL CROSS THE REGION
ON THURSDAY. A WEAK DISTURBANCE MAY BRING A FEW SHOWERS TO THE
MOUNTAINS FRIDAY. UPPER LEVEL TROUGHING REMAINS IN PLACE THROUGH
EARLY NEXT WEEK BRINGING PERIODIC FRONTAL PASSAGES AND UNSETTLED
WEATHER.

&&

.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
9 PM UPDATE: NORTHWEST FLOW ALOFT CONTINUES TO RAISE HAVOC SO HAVE
ADJUSTED POPS HIGHER FOR THE REST OF THE NIGHT AS EXPECTED.
SCATTERED THUNDERSTORMS STILL PERSIST WITH MORE WIDESPREAD
CONVECTION UPSTREAM IN SOUTHERN CANADA ASSOCIATED WITH A SHORT
WAVE DROPPING SOUTHEAST WHICH SHOWS UP NICELY ON WATER VAPOR
IMAGERY. FURTHER DESTABLIZATION OF THIS VERY MOIST AIR MASS
EXPECTED LATER TONIGHT. VERY MOIST AIR MASS OVER THE COOLER
ATLANTIC WATERS IS A FOG GENERATING MACHINE BUT LACK OF AN ONSHORE
WIND FLOW TO PUSH IT INLAND SO CURRENT GUT FEELING IS TO KEEP
WIDESPREAD OCEAN FOG TO DEVELOP ALONG THE COAST WITH PATCHY AREAS
FURTHER INLAND.

705 PM UPDATE: INPUT LATEST OBS DATA AND NEEDED JUST MINOR TWEAKS
TO TEMPERATURES. SCATTERED THUNDERSTORMS CONTINUE ACROSS THE
WESTERN MOUNTAINS OF MAINE AT THIS TIME. DREADED NORTHWEST FLOW
ALOFT COMBINED WITH JUICED UP ATMOSPHERE MEANS MORE CONVECTION
AHEAD LATE TONIGHT AS SOME MODELS INDICATING. TRENDS OF WATER
VAPOR IMAGERY SHOW MORE THUNDERSTORMS TO ARRIVE LATE TONIGHT AS
A SHORT WAVES MOVE SOUTHEAST THROUGH UPPER FLOW. MAY NEED TO
ADJUST POPS FOR LATER TONIGHT ON THE NEXT UPDATE.

PREVIOUS DISCUSSION:

CONVECTION IN SOUTHERN NH LATE THIS AFTERNOON SHOULD WANE BEFORE
SUNSET...BUT SEVERAL CLUSTERS OF CONVECTION WILL MOVE INTO
NORTHERN ZONES AROUND OR SHORTLY AFTER SUNSET...AND THESE SHOULD
TRACK EAST TO SOUTHEAST OVERNIGHT INTO EARLY TUESDAY. MOST OF THIS
ACTIVITY WILL STAY ROUGHLY N AND E OF OF KRKD-KHIE LINE WITH
LITTLE SHRA OR TSRA S OF THERE OVERNIGHT. ONCE AGAIN COASTAL FOG
AND STRATUS WILL DEVELOP THIS EVENING AND PERSIST THRU TUE
MORNING. OVERNIGHT LOWS WILL BE MILD GENERALLY IN THE LOW 60S N TO
MID-UPPER 60S ELSEWHERE.

&&

.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
ANOTHER WEAK WAVE ALOFT PASSES JUST N OF THE CWA...ALTHOUGH
CAPPING INVERSION ALSO WILL BE PRESENT SO THAT WILL LIMIT
CONVECTION TO PLACES THAT CAN GENERATE FORCING. HOWEVER...WILL SEE
DISTINCT SEA BREEZE BOUNDARY DEVELOP...WHICH WILL ACTUALLY BE
SOMEWHAT ENHANCED BY WEAK SFC WINDSHIFT ASSOCIATED WITH THE
WAVE...AND THIS AREA WILL LIKELY BE FOCUS FOR CONVECTION.
ALSO...STRONG SFC BASED INSTABILITY WITH CAPES OF 1K-
2K...COMBINED WITH AT LEAST GOOD VERTICAL SPEED SHEAR WILL HELP
GENERATE GOOD UPDRAFTS AND PULSE STORMS THAT COULD PRODUCE STRONG
WINDS. ALSO...LOCALIZED LOW LEVEL CONVERGENCE ALONG THE SEA BREEZE
AND FRONTAL BOUNDARY REGION WILL BEING HELICITY VALUES INT EH
100-200 RANGE...SO CHANCE FOR A COUPLE ROTATING UPDRAFTS AS
WELL...WILL COULD ADD LARGER HAIL TO THE MIX. MAXES WILL RISE TO
NEAR 90 IN SRN NH...AND 80S MOST OTHER PLACES WITH TDS IN THE MID-
UPPER 60S.

WILL SEE SOME CONVECTION LINGER INTO THE EVENING...BUT SHOULD DIE
OFF SHORTLY AFTER SUNSET...WITH SKIES CLEARING AND FOG FORMING
AGAIN. COULD SEE MINS A DEGREE OR TWO COOLER THAN MON NIGHT AS
SLIGHTLY DRIER AIR WORKS IN BEHIND THE BOUNDARY.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
THE MODELS ARE IN GENERAL AGREEMENT ON THE LONG WAVE PATTERN
THROUGH EARLY NEXT WEEK. WE BEGIN THE PERIOD WITH A SHORTWAVE
RIDGE TRAVERSING THE AREA WEDNESDAY. IT`LL BE A HOT AND HUMID DAY
WITH WIDELY SCATTERED CONVECTION. BY THURSDAY...THE RIDGE SLIDES
OFFSHORE WITH NEXT UPSTREAM IMPULSE DRIVING A WEAK COLD FRONT
ACROSS THE REGION. THURSDAY WILL BE ANOTHER HOT AND INCREASINGLY
HUMID DAY...WITH SCATTERED STRONG CONVECTION DEVELOPING ALONG AND
AHEAD OF THE COLD FRONT. BEHIND THIS LEAD IMPULSE...WE CARVE OUT
A BROAD UPPER TROUGH FOR THE TAIL END OF THE WEEK AND THROUGH THE
FIRST HALF OF NEXT WEEK...THAT WILL FEATURE A SEEMINGLY ENDLESS
PROCESSION OF SHORTWAVE IMPULSES AND ASSOCIATED WEAK SURFACE
FRONTS OR TROUGHS. FRIDAY FEATURES SOME WEAK RIDGING...AND ONLY A
MINIMAL CHANCE OF CONVECTION FOR OUR FAR NORTHERN AND EASTERN
ZONES. THE NEXT IMPULSE WILL DRIVE A WEAK COLD FRONT ACROSS THE
REGION SATURDAY...WITH CONVECTION TO BE STRONGER AND MORE
WIDESPREAD THEN FRIDAY. THE NEXT IMPULSE AND ASSOCIATED WEAK
FRONT/SURFACE TROUGH ARRIVES FOR LATE SUNDAY INTO MONDAY WITH THE
NEXT ROUND OF CONVECTION.

&&

.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
SHORT TERM...ANOTHER ROUND OF COASTAL FOG AND STRATUS EXPECTED
TONIGHT INTO FRI MORNING...WITH SOME VLY FOG POSSIBLE AS WELL.
IMPROVEMENT TO VFR ON TUESDAY...BUT SEVERE STORMS ARE POSSIBLE TUE
AFTERNOON.

LONG TERM...

WED - SAT...SCT MVFR IN SHRA AND TSRA EACH DAY.

&&

.MARINE...
SHORT TERM...WEAK PRESSURE GRADIENT KEEPS WIND FLOW LIGHT AND SEAS
FAIRLY CALM.

LONG TERM...

THU PM - FRI AM...SMALL CRAFT WINDS AND SEAS ARE POSSIBLE.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.

&&

$$
NEAR TERM...MARINE
SHORT TERM...MARINE


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