Area Forecast Discussion
Issued by NWS Portland, ME

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000
FXUS61 KGYX 301354
AFDGYX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
954 AM EDT THU JUL 30 2015

.SYNOPSIS...
A COLD FRONT WILL MOVE INTO THE REGION LATER TODAY... WITH
WIDESPREAD SHOWERS AND THUNDERSTORMS EXPECTED ACROSS THE REGION
THIS AFTERNOON. SOME OF THESE STORMS MAY BE STRONG TO SEVERE.
BEHIND THIS FRONT...DRIER AIR WILL FILTER INTO THE REGION WITH
PARTLY TO MOSTLY SUNNY SKIES EXPECTED FRIDAY. ANOTHER DISTURBANCE
WILL MOVE INTO NEW ENGLAND ON SATURDAY...INCREASING THE CHANCE FOR
SHOWERS AND THUNDERSTORMS ONCE AGAIN.

&&

.NEAR TERM /UNTIL 8 PM THIS EVENING/...

950 AM...WE`RE WARMING QUICKLY IN SOUTHERLY FLOW AHEAD OF THE
COLD FRONT SITUATED ALONG THE INTERSTATE 81 CORRIDOR AT 13Z.
MODIFIED KALB AND KGYX 12Z RAOBS SUGGEST CAPES NEAR 1000 J/KG AND
MODEST SHEAR FOR THIS AFTERNOON AND EARLY EVENING. GREATEST
POTENTIAL WILL BE FOR DAMAGING WIND GUSTS WITH THE STRONGER
CELLS...WHILE FREEZING LEVELS SUGGEST MINIMAL CHANCE FOR LARGE
HAIL. FOR THIS ESTF UPDATE...I MADE MINOR ADJUSTMENTS TO 1ST
PERIOD GRIDS TO REFLECT THE 13Z MESONET. CURRENT TIMING SUGGESTS
THE LINE OF CONVECTION OVER UPSTATE NEW YORK WILL REACH THE
CONNECTICUT VALLEY BETWEEN 1 AND 2 PM...ALTHOUGH SCATTERED
CONVECTION COULD DEVELOP EARLIER IN ADVANCE OF THE LINE.

PREV DISC...
.UPDATE...
NO MAJOR CHANGES FOR THIS UPDATE. INPUT OVERNIGHT TEMPERATURES TO
UPDATE LAST NIGHT`S OVERNIGHT LOWS. FEW SHOWERS JUST OVER THE
CANADIAN BORDER ARE DISSIPATING.

&&

.SHORT TERM /8 PM THIS EVENING THROUGH 6 PM FRIDAY/...
THE MAIN AREA/LINE OF SHOWERS AND EMBEDDED THUNDERSTORMS WILL
MOVE INTO EASTERN MAINE BY TONIGHT. OVERNIGHT LOWS COOL SOMEWHAT
INTO THE UPPER 50S IN THE MOUNTAINS AND THE MID/UPPER 60S SOUTH AS
SKIES CLEAR FROM WEST TO EAST. FRIDAY LOOKS SUNNY WITH WEST WINDS
BRINGING TEMPERATURES INTO THE UPPER 70S NORTH TO UPPER 80S
SOUTH. A DISTURBANCE IN THE UPPER LEVELS MAY BRING A FEW CLOUDS OR
A SPRINKLE TO FAR NORTHERN EAST MAINE.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
HIGH IMPACT WEATHER POTENTIAL: ISOLATED THUNDERSTORMS POSSIBLE EACH
AFTERNOON THROUGH EARLY NEXT WEEK.  A FEW SEVERE STORMS ARE
POSSIBLE...BUT WIDESPREAD SEVERE WEATHER UNLIKELY.

PATTERN SUMMARY: NAEFS/EUROPEAN ENSEMBLE IN GOOD AGREEMENT ON THE
DEVELOPMENT OF LONGWAVE TROUGHING CENTERED NEAR HUDSON BAY...AS
CURRENT POTENT MOBILE SHORTWAVE TROUGH OVER NORTHERN ONTARIO GROWS
IN SCALE AS IT STALLS IN THIS REGION. THIS TROUGH WILL BE THE
PRIMARY GOVERNING FEATURE FOR OUR WEATHER THROUGH THE LONG TERM
FORECAST PERIOD...WITH NUMEROUS SHORTWAVE DISTURBANCES ROTATING
AROUND IT...AND PROVIDING ONGOING CHANCES FOR SHOWER/STORM
ACTIVITY. THIS EASTERN NOAM TROUGHING WON/T BE ANYTHING
SPECTACULAR FROM AN ANOMALY STANDPOINT...WITH TEMPERATURES IN THE
LLEVELS VERY CLOSE TO SEASONAL NORMS. ACCESS TO MOISTURE WILL BE
SOMEWHAT LIMITED...WITH TRAJECTORIES FAVORING A SOURCE REGION OF
AIR THAT REACHES NEW ENGLAND ORIGINATING OVER THE UPPER MIDWEST.
NO SIGNIFICANT STORM SYSTEMS FORESEEN DURING THIS PERIOD...WITH
PRECIPITATION AMOUNTS HIGHLY LOCALIZED /DUE TO THE CONVECTIVE
NATURE OF ANYTHING THAT FALLS/. WITH THE PRIMARY JET AXIS NEARBY
AND SIGNIFICANT WESTERLY FLOW AT MID LEVELS...WILL HAVE TO KEEP AN
EYE OUT FOR THE POTENTIAL OF ISOLATED SEVERE STORMS WITH EACH BOUT
OF CONVECTION THROUGH THE PERIOD...ALTHOUGH INSTABILITY LOOKS TO
BE A LIMITING FACTOR.

DETAILS:

SHORTWAVE IN THE WESTERLY FLOW ALOFT PINWHEELS THROUGH THE REGION
LATE SATURDAY-SATURDAY NIGHT.  MOISTURE WILL BE MORE LIMITED THAN
WITH TODAY/S FRONT...LIMITING INSTABILITY DESPITE ROBUST FLOW AT MID
LEVELS.  THUS...WHILE SCATTERED SHOWER AND EMBEDDED STORM DEVELOPMENT
APPEAR LIKELY...WITH ACTIVITY INITIATING IN THE MOUNTAINS AND THEN
PROGRESSING SOUTH AND EAST.  SEVERE THREAT WILL BE LOW GIVEN THE
LACK OF SIGNIFICANT INSTABILITY...BUT WILL HAVE TO KEEP AN EYE ON
THIS AS WINDS ALOFT WOULD SUPPORT A MORE SIGNIFICANT THREAT GIVEN
IMPRESSIVE WINDS ALOFT.

BEHIND THIS FEATURE...LESS CONVECTIVE COVERAGE APPEARS LIKELY AS THE
COLUMN DRIES ON SUNDAY...WITH ISOLATED SHRA ACTIVITY POSSIBLE DURING
THE AFTERNOON IN THE MOUNTAINS ...WITH DRY CONDITIONS LIKELY
ELSEWHERE.

FORCING/MOISTURE INCREASES AGAIN AS WE REACH NEXT WEEK WITH
REASONABLE AGREEMENT THAT THE LONGWAVE TROUGH AXIS CENTERED OVER
HUDSON BAY WILL SHIFT SOMEWHAT EAST WITH CONFLICTING SIGNALS ON THE
SHARPNESS/TIMING OF ADDITIONAL SHORTWAVE ENERGY ROTATING AROUND THIS
FEATURE.  WITH THE PROXIMITY OF MID LEVEL FORCING...WILL CONTINUE
AFTERNOON SHOWER/STORM CHANCES WITH OVERNIGHTS LIKELY REMAINING DRY.
BY WEDNESDAY /AND BEYOND/...IF THIS EASTWARD SHIFT COMES TO
FRUITION...A DRIER AND SOMEWHAT COOLER PATTERN MAY ARRIVE TO END THE
PERIOD WEDNESDAY.

TEMPERATURES:  WITH TEMPERATURES ALOFT VERY CLOSE TO WHERE THEY
SHOULD BE THIS TIME OF YEAR...EXPECT A PERIOD OF SEASONAL
TEMPERATURES THROUGH THIS PERIOD.

&&

.AVIATION /14Z THURSDAY THROUGH MONDAY/...
SHORT TERM...AREAS OF PATCHY LIFR FOG ALONG THE COAST AND KAUG
WILL IMPROVE AROUND DAYBREAK. SHOWERS AND EMBEDDED THUNDERSTORMS
WILL KEEP TERMINALS IN MVFR CONDITIONS OR LOWER AT TIMES TODAY
INTO THIS EVENING. MORE DENSE FOG EXPECTED TONIGHT.

LONG TERM...WIDESPREAD MVFR/IFR NOT FORESEEN THROUGH THE LONG
TERM PERIOD. RATHER...OCCASIONAL BOUTS OF ISOLATED MVFR/IFR IN
SHRA/TSRA EACH AFTERNOON APPEAR LIKELY...ESPECIALLY HIE/LEB.
PATCHY OVERNIGHT FOG POSSIBLE EACH MORNING GIVEN THIS TYPE OF
PATTERN...PARTICULARLY IN AREAS WHERE AFTERNOON RAIN OCCURS.

&&

.MARINE...
SHORT TERM...THE OUTER WATERS APPROACH 20 KTS AND 5 FT FOR A FEW
HOURS LATE TONIGHT BEHIND A COLD FRONTAL PASSAGE. OPTED NOT TO
ISSUE A SCA FOR THIS.

LONG TERM...SOUTHWESTERLY WINDS WILL GENERALLY REMAIN BELOW SMALL
CRAFT LEVELS THROUGH THE WEEKEND WITH STRONGER WINDS POSSIBLE
EARLY NEXT WEEK AS LOW PRESSURE WORKS THROUGH THE REGION MONDAY-
TUESDAY. WAVES WILL NEAR SMALL CRAFT LEVELS SATURDAY NIGHT...AND
AGAIN EARLY NEXT WEEK COINCIDENT WITH THESE STRONGER WINDS.

&&

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

&&

$$
ES


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