Temperature-related forecast discussions

QUICK UPDATE TO NC/NE IL AND NW IND ZONES FOR MO CLOUDY SKIES. IR/VIS SAT IMGRY SHOWS EXTENSIVE HIGH CLOUD SHIELD JUST N OF THE IL/WI BORDER...BUT CLOUDS THICK ENOUGH OVR NRN IL/IN TO BLOCK OUT SUN SO HAVE GONE MO CLOUDY. MAY SEE A FEW THIN SPOTS THIS AFTN...BUT GENERAL CHARACTER OF THE DAY SHOULD BE MORE CLOUDS THAN NOT.

ALSO HAVE SHAVED UPPER RANGE FOR MAX TEMPS TODAY GIVEN SAID CLOUD COVER. ACARS SOUNDINGS OUT OF ORD AND MDW INDICATE TEMPS -4 TO -5 DEG C BETWEEN 910 AND 950MB...WHICH SHOULD LIMIT US TO MID 30S GIVEN EASTERLY FLOW AND CLOUDS.

RATZER

CURRENT SAT PIX SHOWS LEAD SHRT/WV OVR THE PANHANDLE OF FL MOVING E. ASSOC MID/HIGH LEVEL CLOUDS WILL MOVE OVR CWA LATER TODAY. WILL GO WITH PARTLY CLOUDY WORDING. TEMPS LOOK TO BE A LITTLE LOW. FFC SOUNDING LOOKS WARM IN THE LOW LEVELS...DRY ADIABATIC TO NEAR 72. ACARS SOUNDINGS FOR CLT SHOWS NR 70. WILL ADJUST ACCORDINGLY FOR CWA AS WELL AS FOR FLO. MODELS STILL CONSISTENT WITH BRINGING PRECIP IN AFTER MIDNIGHT TONIGHT. VIS IMAGES SHOW GOOD ELY FLOW OFF SRN COAST WITH LOW CLDS MVG TWDS THE COASTAL REGIONS. THICKER DECK OF HIGH CLOUDS OVR SRN PORTIONS WILL WARRANT MOSTLY CLOUDY WORDING.

NEW NGM IS IN AND IS A LOT SLOWER THAN PREVIOUS LOOK...WILL WORD AFTER MIDNIGHT FOR ALL ZONES EXCPET WRN SECTIONS.

JDB

SPRING/SUMMER IS HERE TOO BAD IT WONT LAST BEYOND TODAY. ALMOST SUMMER-LIKE PATTERN WITH MARINE ST AND THERMAL SFC LOW MOVING NORTHWARD ALONG NW OREGON COAST. ACARS DATA OFF INTERNET SHOWS VERY WARM AIR OF PLUS 14.4C AT 914MB WITH WIND 136/19 KNOTS. APPEARS THIS WARM AIR TONGUE WILL BE FROM SEATAC NORTHWARD WITH HIGHEST MAX TEMPS TODAY AT UIL AND EAST SUBURBS OF SEA. NEAR 75 AT UIL AND 70 IN SUBURBS OF SEATTLE. ONSHORE FLOW KICKS IN TONIGHT. HOWEVER SATELLITE LOOPER STILL SHOWS HIGH AMPLITUDE RIDGE OVR PACNW. ACTUALLY BETTER CHC OF GETTING SOME PCPN WRN WA FROM UPR LOW TO S AS KICKS INLAND. NGM MOS SENSES THIS BUT I DON'T. WILL LOWER POPS A TAD WRN WA INTERIOR ON SUNDAY. MAX TEMPS LIKELY T COOL 10 DEG OR MORE ON SUNDAY.

ART

QUICK UPDATE TO ZFP FOR NC AND NERN IL. 12Z DVN RAOB SOUNDING...LOCAL WIND PROFILERS AND ORD ACARS SOUNDINGS ALL INDICATE WEAK CAA CONTINUING IN LOW LEVELS. IN ADDITION...SATELLITE LOOPS AND VIEW OUT THE WINDOW SHOW CIRROSTRATUS SHIELD ADVANCING ACROSS NRN IL. ETA 920MB TEMPS SUGGEST IT MAY BE TOUGH TO BREAK THE 30 DEGREE MARK THIS AFTERNOON. BASED ON ABOVE...AND SFC TEMPS RUNNING SOME 2 TO 3 DEG C COLDER THAN THE SAME TIME YESTERDAY...WILL BUMB AFTERNOON MAX TEMPS DOWN A BIT ACROSS THE FA. ONLY EXCEPTION IIS PNT/IKK AND WATSEKA AREAS...WHERE CURRENT TEMPS ARE A BIT HIGHER...AND FORECAST MAX MAY STILL BE REACHED.

RATZER

DISC: 1ST SLUG OF PCPN MOVG OUT OF CWFA ATTM AND SHUD BE GONE BY 18Z OR SO. NXT S/WVS MOVG OUT OF OH VLY AND MID-ATLC SHUD BE INVOF NYC AROUND 00Z PER NEW ETA RUN. RGNL RADARS SHWG A BRK IN PCPN. MORE SLD AREA OVR WV SHUD BE OUR NEXT PROBLEM.

ACARS SNDG FM EWR AROUND 14Z SHWG SUB-FRZG TEMPS JUST OFF DECK TO H850 AND W E-NE WINDS IN SAME RANGE...WILL BE TUFF TO GET TOO MUCH WARMING. WILL LEAVE TEMPS BASICALLY AS-IS...WL UP A TAD OVR ERN LI. PCPN...WL GO PDS OF RA W/ PE MIXED AT TIMES. INLAND...WL KEEP COMBO OF SLOP AND WL CONT WWA THRU THGE AFTERNOON.

REYNOLDS

JET TO THE NORTH OF SOUTH CAROLINA WILL KEEP CLOUDS OVER THE STATE THROUGH SATURDAY. 12Z RUCII TIME SECTION FROM ATL-ILM KEEPS MI AND HIGH LEVEL MOISTURE OVER THE AREA. ALTHOUGH THERE IS SOME INITIAL THINNING AT 15Z ON TIME SECTION...MORE MID LEVEL MOISTURE ARRIVES BY 18Z. THERE IS SOME LIFT AS WELL MAINLY FROM CSRA TO CAE. SO WILL KEEP MENTION OF SPRINKLES AGS AND CAE. WITH CLOUDS...LIKE ILM SUGGESTION OF LOWERING HIGHS PEE DEE-NORTH COAST TO THE MIDDLE 60S. ALSO LOW LEVEL INVERSION ON THE 14Z ACARS SOUNDING FOR CAE GIVES A HIGH OF ABOUT 63F. THIS MAKES SENSE WITH EXPECTED MID LEVEL CLOUD COVER AND SPRINKLES. SO WILL SHAVE MIDLAND HIGHS ONE CATEGORY TO THE LOWER 60S. GSP AND THE FOOTHILLS OKAY AS INDICATED BY GSP. ALSO WILL RE-UNITE THE FOOTHILLS WITH THE PIEDMONT WITH HIGHS AROUND 60F. THE SOUTHEAST SECTION LOOKS OK AS INDICATED BY CHS.

TTH

SFC LOW NE OF GRB WL MV NE IN ONTARIO TODAY AND ALLOW WEAK SFC HIGH TO DROP S FROM SRN CANADA. LOTS OF MOISTURE ON 925MB AND 850MB 00UTC ANALYSES...BUT STRONG SUBSIDENCE AND GOOD MIXING BEHIND SYSTEM TO OUR NE PRODUCING BIG BREAK IN CLDS OVR NRN IA AND SW WI. FCST CHALLENGE OF THE DAY IS CLOUDS AND TEMPERATURES. ACARS SOUNDING DATA FROM ORD AT 0649UTC SHOWS 925MB TEMPS OF -2C AND 850MB TEMP OF -3C. THIS IS A DEG OR TWO THAN NGM AND A BIT MORE LIKE ETA. CAA OVER MOST OF THE STATE TODAY WILL KEEP TEMPS FROM RISING MUCH AT ALL. GOING FCTS LOOK PRETTY GOOD. APPROACHING SHORTWAVE FROM NW TONIGHT FCST TO PRODUCE HIGH SC/LOW AC CLOUDS IN N. WILL GO MOSTLY CLOUDY IN NRN 2/3 AND FAIR TO PARTLY CLOUDY DOWN SOUTH. PARTLY SUNNY LOOKS OKAY FOR TUE...BUT THINK THERE MAY BE LAKE EFFECT CLOUDS IN NE NR LK MICHIGAN. ETA FCST 850MB TEMPS OF -8C (AND LAKE IS +1 OR +2C). NGM IS WARMER. BOTH FCST FAVORABLE WINDS FOR LAKE EFFECT CLOUDS. MAY HEDGE MORE ON CLOUD COVER IN NE.

RDM

COLD FRONT CURRENTLY VICINITY OF CAE. WINDS JUST WENT 300/09KT. DEWPOINT STILL 61. COLD FRONT SHOULD CONTINUE TO MOVE EAST AND HIGH PRESSURE WILL BUILD OVER SOUTH CAROLINA. LATEST ACARS SOUNDING FOR CAE...GIVES HIGH 78F (GOING DOWN DRY ADIABATICALLY FROM TOP OF THE LOW LEVEL INVERSION). THIS HAS WORKED OUT WELL IN THE PAST. 12Z MAPS SOUNDING FORECASTS ALSO GIVES MIDLANDS AND PEE DEE (NORTHEAST PART OF STATE) HIGHS IN THE UPPER 70S. SO CURRENT FCST GOOD FOR THIS PART OF STATE. DOWNSLOPE FLOW SHOULD ALLOW UPSTATE AREA TO WARM UP ABOVE PREVIOUS FORECAST HIGHS AS SUGGESTED BY GSP. WILL INCREASE WINDS A BIT IN UPSTATE TO 10-15 MPH WITH DOWNSLOPE CONDITIONS EXPECTED. THE SOUTH COAST LOOKS OK. OTHERWISE...COASTAL WATERS FORECAST STILL LOOKS OK WITH SCA CONDITIONS POSSIBLE LATER TONIGHT NORTH PORTION AS INDICATED BY ILM.

TTH

PROBLEM OF THE DAY...NRN EXTENT OF RAIN AND COOLING TEMPS.

SYNOPTIC SCALE...IMPRESSIVE VORTEX OVER SE KS THIS MRNG SHUD DEGENERATE INTO MORE SHEARED AFFAIR AS IT MVES INTO MEAN UPR RIDGE INVOF MS RVR AND COMES UNDER INFLUENCE OR PERSISTENT VORTEX OFF EAST COAST. OVERALL PATTERN ACROSS NO AMERICA SHAPING UP AS A BIT COMPLEX YET SIMPLE. MEAN UPR RIDGE SEEMS LIKELY TO STAY PUT THRU MS VLY NWD INTO CENTRAL CANADA WITH PERIODIC OMEGA BLOCK SHOWING UP N OF LK SUPERIOR.

REGIONAL SCOPE AND FCST...RAIN SHIELD HAS BEEN RUNNING JUST S OF CHI PAST 24 HRS. QUITE GOOD MID/LOW LVL FRONTOGENESIS FCST TO OCCUR ACRS CENTRAL IL TDA AS GOOD WAA PATTERN SLIDES EWD FM SRN MO TWD LWR OH VLY. SFC LOW TRYING TO DRIFT EWD BUT SHUD STALL AS THERMAL INFLOW PATTERN SHIFTS EWD TWDS SE STATES TONIGHT AND TUE. EXPECT N NWD ADVANCEMENT OF PCPN PAST CHI TODAY. ACARS SHOWING GOOD INVERSION CONTINUING WITH INCREASED NE FLOW IN LOW LEVELS. SFC DEWPOINTS OVR LWR MI ARE FALLING AND SOME DRYING LIKELY TO FILTER INTO NE IL TODAY BUT NOT ENOUGH TO BREAK CLOUD DECK. LWR DEW POINTS FILTERING INTO CENTRAL IL WL COMBINE WITH FALLING RAIN TO HALT ANY TEMP RISES AND EVEN DRIFT THEM DOWN A BIT.

KML

SATELLITE PICTURES SHOW CI AND HIGH AC MVG ENE WHILE SC/CU MVG WSW BLO! NE SFC WINDS OVR COOL WATERS OF THE NRN LAKES ALL BUT ELIMINATED DIURNAL CU/SC FROM FORMING N OF INTERSTATE 80 IN NR IL TODAY. CLOUDS FORMED ALONG AXIS FROM LK SAINT CLAIR (NR DTW) TO SBN TO KANKAKEE THIS AFTERNOON AS THIS AREA IS BETWEEN COOLING OF NRN LAKES AND LK ERIE. IT IS ALSO A CONVERGENT AREA. THESE CLOUDS MANAGED TO PRODUCE SOME WIDELY SCT LATE AFTERNOON SHOWERS IN THE FAR SERN PTN OF OUR CWA BUT WSR88D SUGGESTS THESE ARE ABOUT DONE. THAT LEAVES US WITH MAINLY CLEAR SKIES FOR THE RFD TO CHI AREA AND PARTLY CLOUDY TO THE SOUTH. SFC DEWPOINTS VARY WIDELY ACROSS THE AREA...FROM 0C NR WI BORDER TO 10C AT CMI. WITH SUCH LOW SFC DEWPOINTS WOULD NORMALLY THINK THAT OUR FCST LOW OF 50F WOULD BE WAY TTO HIGH...BUT ACARS DATA FROM THE VCNTY OF ORD SHOWS WINDS OF 25 TO 30 KNOTS AT 2000MSL. THIS SHOULD KEEP BOUNDARY LAYER STIRRED UP AND KEEP TEMPS FROM FALLING LIKE A ROb> ALSO TRAJECTORY FROM LAKE THAT KEPT AREA COOL TODAY WILL HELP TO KEEP TEMPS FAIRLY STEADY TONIGHT. WILL KEEP LOWS NEAR 50 IN CHI BUT LWR A BIT IN THE RFD AREA.

RDM