Hello to all….
…SPC and NWS Taunton Are in Agreement on a Slight Risk for Severe Weather for late Tuesday Afternoon and Tuesday Evening for Southern New Hampshire, Western and Central Massachusetts and Northwest/North-Central Connecticut. Damaging Winds and Large Hail are the Primary Threats. Eastern Areas of Southern New England Should Monitor the Situation….
….Threat timeframe is anytime after 2 PM and in particular after 4-5 PM based on current model projections…..
….SKYWARN Activation with Ops at NWS Taunton is Possible for Tuesday….
The Storm Prediction Center has been consistent in their Day-3 Convective Outlook yesterday and the two Day-2 Convective Outlooks issued today that there is a Slight Risk for Severe Weather Across portions of Southern New England. NWS Taunton concurs with this threat. Instability parameters are sufficient for severe weather initiation. Wind field will be much stronger for tomorrow than in the past events. This will result in the possibility of several clusters/lines of thunderstorms with the possibility that these clusters/lines evolve into a “traditional” squall line over the slight risk area. How far east the severe weather reaches will depend on the timing of the convection and what, if any, marine influence does over eastern parts of Southern New England. It is noted that numerous severe reports were received in Michigan as the activity went through that area.
The potential exists for this event to be the first widespread severe weather event in western parts of Southern New England this year. SKYWARN Activation with Ops at NWS Taunton is Possible for Tuesday.
The next coordination message will be issued by 8:30 AM Tuesday. Below is the SPC Day-1 Convective Outlook and the Area Forecast Discussion from NWS Taunton:
[Please press “read more” button ===>]Respectfully Submitted,
Robert Macedo (KD1CY)
ARES SKYWARN Coordinator
Southeast Massachusetts ARES District Emergency Coordinator
SEMARA ARES Emergency Coordinator
Pager #: (508) 354-3142
Home Phone #: (508) 994-1875 (After 6 PM)
Home/Data #: (508) 997-4503 (After 6 PM)
Work Phone #: 1-800-445-2588 Ext.: 72929 (8 AM-5 PM)
Email Address: rmacedo@rcn.com
http://users.rcn.com/rmacedoFXUS61 KBOX 172015
AFDBOX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TAUNTON MA
414 PM EDT MON MAY 17 2004
.SHORT TERM…
TONIGHT THROUGH TUESDAY NIGHT
STRATUS AND FOG SHOULD RETURN TONIGHT AS LIGHT FLOW AND INCREASING
DEWPOINTS WILL ALLOW THE AIR TO RESATURATE. CONVECTION FIRING OVER
PA/MD/DE IS TRENDING EAST…AND MODEL FORECASTS OF THE FLOW SUGGEST
ANY PRECIPITATION WILL PASS TO OUR SOUTH. CONVECTION TO OUR WEST OVER
MICHIGAN EXTRAPOLATES TO OUR WESTERN ZONES AROUND 8 AM. THUS HAVE CUT
POPS FOR TONIGHT TO 20 PERCENT OR LESS WITH INCREASING CHANCES IN
THE WEST AROUND 12Z. TEMPERATURES UPSTREAM THIS MORNING STARTED IN
THE LOW TO MID 50S…AND CURRENT DEWPOINTS OVER NEW ENGLAND ARE IN
THE MID 30S TO MID 50S. SO EXISTING MIN TEMPS FOR TONIGHT WERE EDGED
DOWN A COUPLE OF DEGREES.
MAIN FORECAST CONCERN IS FOR TUESDAY. APPROACH OF COLD FRONT FROM
NORTHWEST TIGHTENS THE PRESSURE GRADIENT…WHICH SHOULD ALLOW
INCREASING S-SW FLOW TO BLOW OUT MUCH OF THE FOG. MODEL CROSS
SECTIONS HOLD IN LOW LEVEL MOISTURE…BUT THIN THE OVERALL MOISTURE
IN THE COLUMN SO THAT WE WOULD EXPECT SKIES TO BECOME AT LEAST
PARTLY SUNNY THROUGH THE CIRRUS VEIL. TEMPERATURES AT H850 ARE
FORECAST TO 13C AND AT H800 TO 10C…SO WITH FULL MIXING ONE MIGHT
EXPECT MAX TEMPERATURES IN THE LOW TO MID 80S. MAX TEMPERATURES
UPSTREAM TODAY HAVE BEEN IN THE UPPER 70S. AM INCLINED TO MOVEMAX
TEMPERATURE FORECAST UP A COUPLE OF DEGREES WITH MAX VALUES AROUND
80 IN THE CONNECTICUT AND MERRIMACK VALLEYS…AND MIN VALUES IN
THE 60S OVER THE CAPE AND ISLANDS. THIS SUGGESTS THE POTENTIAL FOR
MORE SURFACE HEATING THAN INDICATED BY THE MODELS…WHICH IN TURN
WOULD LEAD TO MORE INSTABILITY THAN IS SHOWN BY THE MODEL INDICES
(CAPE/LI/ETC.). SPC CONTINUES TO INDICATE A SLIGHT RISK FOR SEVERE
TSTMS IN OUR NORTH/WEST ZONES…THIS IS QUITE REASONABLE.
THERE IS ALSO A TWIST TO THE TIMING OF THE SHOWERS. BEST CHANCE
SHOULD BE WITH FRONTAL PASSAGE…WHICH WOULD BE DURING TUESDAY
NIGHT. BEST INSTABILITY WILL BE TUESDAY LATE AFTERNOON THROUGH
EVENING. BOTH ETA AND GFS SHOW A SHORTWAVE MOVING THROUGH NEW
ENGLAND BY TUESDAY EVENING…THE GFS IS MORE PRONOUNCED WITH THIS
FEATURE. BOTH MODELS ALSO HINT AT A LEE TROF THIS SIDE OF THE
APPALACHIANS…WHICH WOULD ALSO SERVE TO GENERATE LOW LEVEL
CONVERGENCE. WILL START CHANCE POPS IN THE WEST IN THE MORNING…
BUT RESERVE THE HIGHER POPS FOR THE AFTERNOON AND NIGHT. ENOUGH
POSITIVE FACTORS TO GO WITH CATEGORICAL POPS DURING THIS PERIOD.
&&
.LONG TERM…
12Z WEDNESDAY THROUGH MONDAY
NEARLY ZONAL FLOW ALOFT THROUGH FRIDAY KEEPING COOL AIR TO THEN
NORTH AND REAL HEAT TO THE SOUTH. PATTERN LOOKS TO MAKE A CHANGE FOR
THE UPCOMING WEEKEND WHEN RIDGE RE-ESTABLISHES ITSELF OVER WESTERN
ATLANTIC. WITH UPPER WINDS BECOMING MORE SOUTHWESTERLY…HEAT AND
HUMIDITY WILL GAIN ACCESS INTO NEW ENGLAND.
AT THE SURFACE…LINGERING PRECIPITATION EARLY WEDNESDAY MORNING FOR
SOUTHEAST ZONES BEFORE SUBSTANTIAL DRYING TAKES PLACE WEDNESDAY
AFTERNOON AS HIGH PRESSURE BUILDS OVER NEW ENGLAND. THIS HIGH MOVES
OFFSHORE THURSDAY YIELDING TO A COLD FRONT PROGGED TO MOVE THROUGH
THURSDAY EVENING. BOTH ETA AND GFS NOW SLOWING THIS SYSTEM DOWN WITH
SHOWERS AND POSSIBLE THUNDERSTORMS BREAKING OUT IN THE WEST THURSDAY
EVENING…MOVING AND EXITING EAST BY MIDNIGHT. WEAK HIGH
PRESSURE…COL AREA…FOLLOWS FRIDAY…THEN SET UP OF ELONGATED WEST
TO EAST SURFACE BOUNDARY FRIDAY NIGHT FROM MID WEST TO EAST COAST.
THIS BOUNDARY BETWEEN COOLER AIR TO THE NORTH AND WARMER AIR TO THE
SOUTH BECOMES FOCUS FOR PRECIPITATION. FOR SOUTHERN NEW
ENGLAND…WHILE ON THE COOL DAMP SIDE OF WARM FRONT…STRATIFORM
PCPN POSSIBLE SATURDAY MORNING. THEN MODELS BRING WARM FRONT NORTH
OF REGION SATURDAY DAY AS WESTERN ATLANTIC RIDGE RE-ASSERTS ITSELF.
WENT WITH CHANCE POPS EARLY SATURDAY MORNING NORTH OF SURFACE
BOUNDARY/WARM FRONT. THEN WENT WITH CHANCE POPS SATURDAY AND SUNDAY
AFTERNOON…MAINLY DUE TO SURFACE HEATING. FOR MONDAY…COLD FRONT
MOVES OVER REGION FROM THE WEST AND LINGERS.
&&
.AVIATION…
STRATUS HAS BEEN SLOW TO LIFT ACROSS SOUTHEAST MASS/RI…AND
WHATEVER BREAKAGE THAT OCCURS THIS EVENING SHOULD FILL IN AGAIN
EARLY TONIGHT. WITH SOUTHERLY FLOW AND INCREASING DEWPOINTS…
EXPECT EXTENSIVE FOG/STRATUS OVERNIGHT WITH VSBYS LOCALLY BELOW 1
MILE. THE FOG/STRATUS BURN OFF DURING THE MORNING…FORECAST BREAKS
THE LOW CEILINGS TO A CIRRUS BKN-OVC. CURRENT 18Z-18Z PERIOD ENDS
JUST BEFORE EXPECTED RISK OF SHOWERS/TSTMS. PRECIPITATION WILL MOVE
IN FROM THE NORTHWEST WITH REDUCED CEILINGS AND VSBYS. MHT/BAF/BDL
WOULD BE FIRST TO SEE ANY CONVECTION TUE AFTN.
&&
.MARINE…
IN THE SHORT TERM EXPECT WINDS TO PICK UP FROM THE SOUTHWEST
TUESDAY IN TIGHTENING PRESSURE GRADIENT AHEAD OF ADVANCING COLD
FRONT. BUT WITH WARM ADVECTION OVER THE COLDER WATERS WE WOULD
EXPECT SPEEDS TO REMAIN BELOW SMALL CRAFT LEVELS. WAVE MODEL DOES
BRING SEAS UP TO 5 FT IN THE AFTERNOON/NIGHT…SO THERE IS A
POTENTIAL FOR SMALL CRAFT CRITERIA LATE TUESDAY OR TUESDAY NIGHT.
&&
.BOX WATCHES/WARNINGS/ADVISORIES…
CT…NONE.
MA…NONE.
NH…NONE.
RI…NONE.
MARINE…SMALL CRAFT ADVISORY FOR SEAS MAY BE REQ TUE…
ANZ232>235-237-254-255 ALL WATERS PVC-ACK-MTP EXECPT FOR
NARRAGANSETT BAY
$$
SHORT TERM…WTB
LONG TERM…KAB
SPC AC 171740
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1240 PM CDT MON MAY 17 2004
VALID 181200Z – 191200Z
THERE IS A SLGT RISK OF SVR TSTMS TO THE RIGHT OF A LINE FROM HUL 20
NNE PSM 10 N BDR DOV HGR 20 W MGW EVV HRO 10 SE END GAG EHA 10 SSE
LAA DEN CPR 20 ENE COD 10 NW BIL GDV 20 NW MBG OFK 15 SE OMA 50 NNE
SZL UIN 25 N PIA 20 S ARB 20 SE DTW.
GEN TSTMS ARE FCST TO THE RIGHT OF A LINE FROM 70 NNE DVL FAR 20 SSW
BKX FSD DSM 10 SE JVL MKG 60 ESE OSC …CONT… 35 NNW ORF 10 NE RDU
CAE AGS AYS GNV 55 W ORL 10 SSE SRQ …CONT… 35 S PSX 60 E CLL 35
ESE SHV 40 SSW JBR MKO CSM 10 SE DHT PUB 45 ESE ASE MTJ U17 10 SE
CDC 55 NW MLF 10 SE ENV 20 SE OWY SVE 10 S RBL MFR 10 SE RDM SEA 35
W BLI.
…THERE IS A SLGT RISK OF SVR TSTMS TUESDAY/TUESDAY NIGHT ACROSS A
LARGE PART OF THE NRN/CNTRL U.S….
…OHIO VALLEY/GREAT LAKES INTO NORTHEAST STATES…
SERIES OF SHORT WAVES ARE EVIDENT IN LATEST WATER VAPOR IMAGERY…
PROGRESSING THROUGH BROAD UPPER TROUGH WHICH PERSISTS ACROSS MUCH OF
THE CENTRAL/EASTERN CANADIAN PROVINCES. THIS INCLUDES POSITIVELY
TILTED SHORT WAVE TROUGH OVER MANITOBA/SASKATCHEWAN…WHICH ALREADY
APPEARS TO BE TURNING EASTWARD TOWARD ONTARIO/QUEBEC AND THE UPPER
GREAT LAKES REGION. MODELS SUGGEST THAT AS THIS MOTION CONTINUES…
SYSTEM WILL GRADUALLY MERGE WITH WEAKER SHORT WAVE TROUGH EMANATING
FROM BROADER SCALE NORTHWESTERN U.S. UPPER TROUGH.
BY EARLY TUESDAY …A STRENGTHENING LOW-LEVEL BAROCLINIC ZONE AND
INTENSIFYING MID/UPPER JET STREAK IS PROGGED OVER THE LOWER GREAT
LAKES REGION. AS UPPER TROUGH AXIS CONTINUES EASTWARD INTO/THROUGH
THE ST. LAWRENCE VALLEY DURING THE COURSE OF THE REMAINDER OF THE
FORECAST PERIOD…FRONTAL ZONE WILL ADVANCE SOUTHWARD/SOUTHEASTWARD
INTO THE OHIO VALLEY AND NORTH ATLANTIC COASTAL AREAS. DURING THE
LATE AFTERNOON HOURS…NEAR/SHORTLY AFTER PEAK HEATING…MODELS
SUGGEST FRONT WILL PROGRESS SOUTHEAST OF LAKES
ONTARIO/ERIE…PROVIDING FORCING/FOCUS FOR INCREASING CONVECTIVE
DEVELOPMENT.
THOUGH MID-LEVEL LAPSE RATES DO NOT APPEAR LIKELY TO BECOME
PARTICULARLY STEEP…FAIRLY STRONG SURFACE HEATING SHOULD OCCUR
ACROSS MUCH OF OHIO/PENNSYLVANIA/AND NEW YORK STATE. THIS WILL
CONTRIBUTE TO STEEP LOW-LEVEL LAPSE RATES…WITH SUFFICIENT BOUNDARY
LAYER MOISTURE FOR MEAN MIXED LAYER CAPE IN EXCESS OF 1000 J/KG…
SUPPORTIVE OF VIGOROUS UPDRAFTS WITH POTENTIAL FOR LARGE HAIL.
THERMODYNAMIC ENVIRONMENT WILL ALSO BE FAVORABLE FOR DAMAGING WIND
GUSTS…WITH THIS RISK ENHANCED BY 40 KT MEAN FLOW REGIME ON
SOUTHERN FRINGE OF STRONGER WESTERLIES.
SEVERAL LINES OF STRONG/SEVERE STORMS APPEAR LIKELY TO EVOLVE
THROUGH THE LATE TUESDAY AFTERNOON/EVENING…PERHAPS MERGING INTO
ONE EXTENSIVE SQUALL LINE ORIENTED IN EAST-WEST BAND ALONG FRONTAL
ZONE..FROM NEW ENGLAND AND THE HUDSON VALLEY THROUGH THE OHIO
VALLEY. ACTIVITY WILL CONTINUE SLOWLY SOUTHWARD LATE TUESDAY
NIGHT…BUT SHOULD SLOWLY DIMINISH IN INTENSITY ACROSS THE NORTHERN
MID ATLANTIC COAST REGION/NORTH CENTRAL APPALACHIANS/AND AREAS NEAR
THE OHIO RIVER.
..KERR.. 05/17/2004
…NOTICE…
FOR USERS DECODING THE POINTS PARAGRAPH HEREIN…LATITUDE AND
LONGITUDE POINTS FOR THE CATEGORICAL AND PROBABILISTIC OUTLOOK
GRAPHICS ALSO ARE LOCATED IN A SEPARATE PRODUCT UNDER THE WMO
HEADINGS WUUS01 PTSDY1…WUUS02 PTSDY2…AND WUUS03 PTSDY3. THE
INCLUSION OF POINTS IN THIS PRODUCT WILL EVENTUALLY BE DISCONTINUED.