468
FXUS63 KGID 161722
AFDGID
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HASTINGS NE
1222 PM CDT WED OCT 16 2013
.UPDATE...
ISSUED AT 900 AM CDT WED OCT 16 2013
OUR MORNING LOW TEMPERATURES HAVE ALREADY BEEN REACHED AND
TEMPERATURES ARE NOW RISING. THEREFORE...THE FROST AND FREEZE
HEADLINES HAVE BEEN ALLOWED TO EXPIRE FOR ALL AREAS. TEMPERATURES
WILL AGAIN BE VERY CHILLY TONIGHT AND FROST MAY AGAIN BE POSSIBLE
IN SOME AREAS BY EARLY THURSDAY MORNING.
UPDATE ISSUED AT 646 AM CDT WED OCT 16 2013
LITTLE CHANGE IN THINKING FROM A FEW HOURS AGO...AS ONE DECK OF
MID CLOUDS CONTINUES SINKING SOUTHWARD ACROSS THE NORTHERN
CWA...WHILE MAINLY THINNER/HIGHER CIRRUS CONTINUES INCREASING INTO
AREAS NEAR/SOUTH OF THE STATE LINE. IN BETWEEN...MOST PLACES
BETWEEN I-80 AND THE STATE LINE ARE ESSENTIALLY CLEAR AT THIS
TIME. ALTHOUGH LIGHT BUT STEADY BREEZES HAVE LIKELY PRECLUDED
TRULY WIDESPREAD FROST DEVELOPMENT IN MANY AREAS...PRESENT
INDICATIONS ARE THAT THE FROST/FREEZE HEADLINES ISSUED YESTERDAY
WERE JUSTIFIED ACROSS MOST AFFECTED AREAS...WITH A FEW LOWS SO FAR
THIS MORNING CONSISTING OF 31 AT LEXINGTON AIRPORT...32 AT
RAVENNA...HOLDREGE AIRPORT AND 4WNW PLAINVILLE KS...AND 33 AT
HASTINGS AIRPORT. WITH CLOUDS ON THE INCREASE...ITS BECOMING
INCREASINGLY UNLIKELY THAT FROST WILL BE OBSERVED IN THE
HAMILTON/YORK AND JEWELL/MITCHELL COUNTY AREAS...BUT GIVEN THAT
TEMPS ARE AT LEAST IN THE BALLPARK OF SUPPORTING FROST AT THIS
TIME WILL DEFER TO ONCOMING DAY SHIFT TO FORMALLY PUT THESE
HEADLINES TO REST. ONCE ALL MORNING TEMPERATURE REPORTS COME
IN...DECISIONS WILL ALSO BE MADE REGARDING WHICH ADDITIONAL
COUNTIES BESIDES VALLEY/GREELEY ARE DEEMED INELIGIBLE FOR FUTURE
FROST/FREEZE HEADLINES...AS WE WILL LIKELY BE ADDING AT LEAST A
FEW.
&&
.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 430 AM CDT WED OCT 16 2013
COMPARED TO THE PAST 48 HOURS OF WIDESPREAD RAIN FOLLOWED BY
FAIRLY STRONG NORTHWEST WINDS...THESE NEXT 24 HOURS ARE GOING TO
BE A BENIGN CHANGE OF PACE...WITH ESSENTIALLY ZERO RISK OF
MEASURABLE PRECIP AND SUSTAINED BREEZES STRUGGLING TO EXCEED 12
MPH AT MOST. HOWEVER...DUE TO FROST/FREEZE SENSITIVITIES THIS TIME
OF YEAR...SKY COVER/CLOUD TRENDS HAVE TAKEN ON AN ENHANCED
FORECAST FOCUS...GIVEN THE PRONOUNCED EFFECT OF CLOUD COVER ON
TEMPERATURES. AS IT IS TURNING OUT...PARTS OF THE CWA ARE GOING TO
FREEZE AND/OR FROST FAIRLY EFFICIENTLY THIS MORNING...WHILE OTHER
PARTS OF THE AREA MAY ACTUALLY SEE MORE FAVORABLE CONDITIONS FOR
FROST/FREEZE WEDNESDAY NIGHT INSTEAD.
07Z OBJECTIVE SURFACE ANALYSIS SHOWS THE LOCAL AREA POSITIONED
BETWEEN A 1003 MILLIBAR LOW THAT HAS DEPARTED WELL EASTWARD INTO
THE GREAT LAKES...AND A 1025 MILLIBAR HIGH CENTERED MUCH CLOSER TO
HOME OVER THE NEB/KS/CO BORDER AREA. WITH THE PRESSURE GRADIENT
CONTINUING TO RELAX...WEST-NORTHWEST BREEZES ACROSS MOST OF THIS
CWA HAVE FINALLY EASED TO 10 MPH OR LESS...BUT WITH SLIGHTLY
STRONGER SPEEDS STILL SHOWING UP NOW AND THEN MAINLY IN THE
NORTHEAST. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA
REVEAL THAT THE CWA IS POSITIONED ALMOST DIRECTLY UNDERNEATH A
BROAD...SEVERELY POSITIVELY TILTED MID/UPPER LEVEL TROUGH AXIS
EXTENDING IN A SOUTHWEST-NORTHEAST ORIENTATION FROM THE 4-CORNERS
AREA THROUGH THE GREAT LAKES AND UP INTO EASTERN CANADA. ALONG THE
SOUTHERN EDGE OF THIS TROUGH AXIS...A 105+ KT JET STREAK IS
EVIDENT AT 300MB OVER THE KS/NEB BORDER.
THE FOLLOWING PARAGRAPH FOCUSES SOLELY ON EXISTING FROST/FREEZE
HEADLINES THIS MORNING...THE REAL HEADACHE THIS MORNING LIES WITH
CLOUD COVER TRENDS PER IR AND 11-3.9 MICRON SATELLITE. ON A
POSITIVE NOTE FOR CURRENT FROST/FREEZE HEADLINES...THE EXPANSIVE
DECK OF LOW STRATUS THAT RULED MOST OF THE CWA ON TUESDAY
CONTINUES TO STEADILY ERODE FROM NORTHWEST-TO-SOUTHEAST...WHICH
MAKES IT NOW LOOK LIKE MUCH OF THE CWA SHOULD SEE AT LEAST A FEW
HOURS OF CLEAR SKIES...POTENTIALLY ALLOWING FROST FORMATION TO
COMMENCE. IN FACT...THIS PROCESS IS LIKELY ALREADY WELL-UNDERWAY
IN/NEAR FAR WESTERN PORTIONS OF THE CWA...WHERE SITES SUCH AS
LEXINGTON/MCCOOK HAVE ALREADY TUMBLED INTO THE LOW 30S THUS
VERIFYING THE EXISTING FREEZE WARNING. HOWEVER...ON THE FLIP
SIDE...PORTIONS OF THE ORIGINAL FROST ADVISORY ACROSS ROUGHLY THE
EASTERN HALF OF THE CWA SEEMS TO BE FACING A GREATER OBSTACLE TO
VERIFY...AS FOLLOWING SHORTLY BEHIND THE VACATING LOW STRATUS IS A
SOUTHWARD-SINKING BAND OF MID LEVEL CLOUDS CENTERED BETWEEN 8-10K
FEET...WHICH HAS ALREADY BRUSHED INTO THE FAR NORTHERN CWA...AND
IS EXPECTED TO SLOWLY DROP SOUTHWARD TO AT LEAST ROUGHLY THE
HIGHWAY 6 CORRIDOR BY SUNRISE. HOWEVER...THESE MID CLOUDS SHOULD
HAVE LITTLE EFFECT ON EARLY MORNING TEMPERATURES ACROSS MOST OF
THE SOUTHERN HALF TO ONE-THIRD OF THE CWA...WITH THESE AREAS
LIKELY HEADED FOR SEVERAL HOURS OF CLEARING IN THE WAKE OF THE
DEPARTING LOWER DECK. THE NET RESULT...AS IT CURRENTLY STANDS AT
09Z/4AM...IS THAT ADVISORIES/WARNINGS WERE CANCELLED FOR 5
COUNTIES NORTH OF INTERSTATE 80...WHILE AT LEAST FOR NOW WILL LET
THE REMAINING 23 COUNTIES STAND AS-IS PER ORIGINAL ISSUANCE...AND
TAKE ANOTHER LOOK FOR POSSIBLE UPDATES IN A FEW HOURS.
TURNING TO OTHER ELEMENTS OF THE FORECAST...RIGHT OFF THE BAT
DECIDED TO SLIP A SLIGHT CHANCE OF SPRINKLES INTO FAR NORTHERN
AREAS UP AROUND ORD/GREELEY PRIOR TO SUNRISE TO ACCOUNT FOR A FEW
WEAK RETURNS SHOWING UP ON RADAR UNDER THE INVADING MID-DECK...BUT
THIS SHOULD BE VERY ISOLATED IN NATURE. BEYOND SUNRISE...ANTICIPATE
A COOLISH BUT SEASONABLY PLEASANT DAY UNDER VARIABLE CLOUD COVER.
ALOFT...THE AFOREMENTIONED ELONGATED MID LEVEL TROUGH AXIS WILL
CONTINUE SLIPPING SOUTHWARD ACROSS THE REGION...AS A SHORTWAVE
CURRENTLY WITHIN THE BASE OF THE TROUGH NEAR THE 4-CORNERS AREA
GRADUALLY EJECTS EASTWARD ALONG THE KS/OK BORDER AS THE DAY WEARS
ON. WHILE ANY SPOTTY RAIN FROM THIS DISTURBANCE SHOULD REMAIN WELL
SOUTH OF THE LOCAL AREA...ESPECIALLY OUR KS ZONES COULD SEE A FAIR
AMOUNT OF MID/UPPER LEVEL CLOUDS STREAMING EAST-NORTHEAST FROM
THIS SYSTEM. MEANWHILE...THE ALREADY-PRESENT MID DECK SLIPPING
INTO NORTHERN COUNTIES WILL CONTINUE TO SLOWLY SINK
SOUTHWARD...AND IS EXPECTED TO PROVIDE A CLOUDY START TO THE DAY
ACROSS THE MAJORITY OF NEB ZONES...BUT THEN ACCORDING TO 700
MILLIBAR RELATIVE HUMIDITY PROGS FROM THE RAP/NAM...SHOULD
GRADUALLY FADE AWAY OR SCATTER OUT BY THE MID-LATE MORNING HOURS.
SO...THE NET RESULT IS BEST PUT AS VARIABLE CLOUD COVER...AS
NORTHERN AREAS SHOULD GENERALLY START OUT RATHER CLOUDY BUT SEE
INCREASING SUN WITH TIME...WHILE SOUTHERN AREAS GENERALLY DO THE
OPPOSITE AND SEE INCREASING CLOUDS WITH TIME. THESE CLOUD COVER
TRENDS WILL BE TOUGH TO CAPTURE IN HOURLY FORECAST GRIDS...AND
PLENTY OF UPDATES ARE LIKELY. OTHERWISE...AS THE CENTER OF THE
SURFACE RIDGE AXIS SINKS SOUTH OF THE AREA TODAY...BREEZES WILL
AVERAGE 10-12 MPH FROM THE WEST-NORTHWEST IN ALL AREAS. HIGH
TEMPERATURES WERE ONLY TWEAKED SLIGHTLY PER A BLEND OF MET/MAV
GUIDANCE AND RAP TEMPS...AND THUS WILL CONTINUE TO CALL FOR A
REMARKABLY UNIFORM RANGE ACROSS THE CWA WITH ALL AREAS TOPPING OUT
BETWEEN 56-59.
FOR THIS EVENING/TONIGHT...THE MAIN STORY ALOFT IS THAT THE
CURRENT SOUTHWEST-TO-NORTHEAST TROUGH AXIS WILL GRADUALLY BE
REPLACED BY A SOUTHWEST-NORTHEAST ORIENTED SHORTWAVE RIDGE AXIS.
THIS IS BECAUSE THE LOCAL AREA WILL BE IN BETWEEN TROUGHS...AS THE
DISTURBANCE CENTERED OVER SOUTHERN KS AT SUNSET DEPARTS EASTWARD
INTO MO...WHILE THE NEXT UPSTREAM TROUGH DROPPING SOUTHEAST TOWARD
THE AREA ONLY REACHES AN AXIS FROM NORTHWEST CO TO NORTH DAKOTA BY
SUNRISE THURSDAY. ALTHOUGH AM EXPECTING SKIES WEDNESDAY NIGHT AS A
WHOLE TO AVERAGE CLEARER THAN THIS ONGOING NIGHT HAS BEEN...THERE
IS AGAIN GOING TO BE VARIABLE CLOUD COVER EXCEPT THIS TIME SOLELY
OF THE MID-UPPER VARIETY. FOR ONE...MAINLY SOUTHERN PARTS OF THE
CWA WILL LIKELY START THE EVENING WITH LINGERING CLOUDS FROM THE
DEPARTING DISTURBANCE...WHILE LATER IN THE NIGHT...MAINLY NORTHERN
AREAS COULD SEE PASSING BATCHES OF CLOUDS OUT AHEAD OF THE
APPROACHING UPSTREAM WAVE. MEANWHILE AT THE SURFACE...WINDS WILL
REMAIN FAIRLY LIGHT AT SUSTAINED SPEEDS GENERALLY LESS THAN 8
MPH...BUT GRADUALLY TRANSITION FROM A SOUTHWESTERLY DIRECTION TO
NORTHWESTERLY IN RESPONSE TO A SUBTLE PASSING TROUGH AXIS. AS FOR
LOW TEMPS...ONCE AGAIN PASSING CLOUDS COULD POSE ISSUES...BUT FOR
NOW STUCK VERY CLOSE TO A MET/MAV GUIDANCE BLEND...WHICH PUTS THE
MAJORITY OF THE CWA DOWN BETWEEN 33-36 DEGREES...WITH THE
TYPICALLY FAVORED DAWSON-TO-VALLEY COUNTY CORRIDOR MOST FAVORED TO
SLIP SLIGHTLY BELOW FREEZING. OBVIOUSLY THESE LOWS ARE AGAIN
SUPPORTIVE OF FROST AND/OR FREEZE DEVELOPMENT. HOWEVER...GIVEN THE
ONGOING COMPLICATIONS/UNCERTAINTY THIS MORNING REGARDING LOW
TEMPS...WILL HOLD OFF ON ANY WEDNESDAY NIGHT FROST
ADVISORIES/FREEZE WARNINGS FOR NOW...NOT ONLY TO AVOID HEADLINE
CONFUSION...BUT ALSO TO ALLOW DAY SHIFT TO IDENTIFY COUNTIES THAT
COULD NOW BE RULED INELIGIBLE FROM FUTURE FROST/FREEZE HEADLINES
BASED ON WHAT HAPPENS THIS MORNING.
.LONG TERM...(THURSDAY THROUGH TUESDAY)
ISSUED AT 430 AM CDT WED OCT 16 2013
MAIN CONCERNS THIS FORECAST PERIOD LOOKS TO BE PRECIPITATION
CHANCES ON FRIDAY.
STARTING OUT THURSDAY MORNING WITH THE BIG PICTURE...THERE SHOULD BE
A HIGH AMPLITUDE RIDGE JUST OFF THE PACIFIC U.S. AND CANADIAN COAST
WITH A LONG WAVE TROUGH AND SEVERAL EMBEDDED SHORT WAVES SITUATED
OVER MUCH OF THE CONUS. THIS PATTERN WILL GRADUALLY SHIFT EAST A BIT
BUT THE CENTRAL PLAINS SHOULD STILL BE SITTING ON THE BACK SIDE OF
THE UPPER TROUGH BY NEXT TUESDAY...PUTTING US IN NORTHWEST FLOW.
AT THE SURFACE ON TUESDAY MORNING...A TROUGH OF LOW PRESSURE
EXTENDING FROM LAKE SUPERIOR TO THE OKLAHOMA PANHANDLE SHOULD BE
JUST ABOUT THROUGH THE CWA WITH A WIND SHIFT FROM SOUTHWEST TO
NORTHWEST. THE COOLER AIR WILL LAG BEHIND THE TROUGH A WAYS AND
THURSDAY SHOULD BE QUITE NICE...JUST A FEW DEGREES LOWER THAN
SEASONAL NORMALS.
THE NEXT IN THE PROGRESSION OF MID LEVEL SHORTWAVES NOTED ABOVE IS
THEN SLATED TO APPROACH THE PLAINS FROM THE NORTHWEST THURSDAY NIGHT
INTO FRIDAY. SEVERAL MODELS SHOW A SIMILAR SOLUTION IN TAKING ONE
WAVE NORTH AND EAST OF US AND DIGGING ANOTHER WAVE TO OUR WEST AND
THEN SOUTH ACROSS KANSAS. INTERESTING TO RUN A TIME HEIGHT SECTION
COMPARING THE GRAND ISLAND AREA TO THE PHILLIPSBURG KANSAS AREA IN
TERMS OF MID LEVEL FORCING. THE NAM IS ONLY PRODUCING 1-2 UBARS PER
SEC OF OMEGA OVER KGRI AT 12Z FRIDAY WHILE AT KPHG IT IS GENERATING
10-12 UBARS PER SEC. THE GFS HAS SIMILAR RESULTS FOR OUR SOUTHERN
CWA WITH THE ONLY DIFFERENCE BEING THE GFS HAS A LITTLE LESS LOW
LEVEL MOISTURE TO WORK WITH AND MAY TAKE A WHILE TO SATURATE THE
COLUMN...WHILE THE NAM IS SATURATED ALL THE WAY FROM NEAR THE
SURFACE TO 300 MB. THE EC FORECAST SOUNDING IS SIMILAR TO THE GFS AS
IT IS NOT QUITE SATURATED UP TO 700MB. NEITHER THE GFS OR EC IS
SHOWING THE LOWER PORTION BECOMING SATURATED BETWEEN 12 AND 18Z
FRIDAY BUT I AM A LITTLE CONCERNED OF THE SCENARIO WHERE SNOW
FALLING FROM ABOVE MOISTENS AND COOLS THE LOWER COLUMN UNTIL IT
REACHES SATURATION. IF THIS WERE TO OCCUR...WE COULD SEE A LITTLE
SNOW FRIDAY MORNING IN THE CWA. WILL NOT INCLUDE SNOW IN THE GRIDS
FOR NOW AS I ONLY HAVE LOW TEMPERATURES FRIDAY MORNING FORECASTED TO
BE AROUND 37 OR 38 DEGREES IN THE KANSAS PART OF OUR CWA...BUT IT
WILL BE WORTH KEEPING AN EYE ON THE NEXT COUPLE OF DAYS.
BUMPED UP POPS IN THE SOUTHERN PART OF THE CWA FOR FRIDAY AND THESE
WILL NEED TO BE RAISED EVEN MORE IF THE MODELS REMAIN CONSISTENT ON
THE TRACK OF THE SHORT WAVE TROUGH.
THE COOLER AIR WILL THEN MAKE IT INTO THE AREA THURSDAY NIGHT AND BY
FRIDAY HIGHS SHOULD BE 5 TO 10 DEGREES COOLER THAN ON THURSDAY. BUT
THE COOLER WEATHER WILL ONLY LAST A DAY AS SATURDAY THROUGH TUESDAY
SHOULD AGAIN BE IN THE UPPER 50S NORTH TO THE MID 60S SOUTH. WILL
LEAVE REST OF FORECAST DRY FOR NOW BUT NOT TOTALLY OUT OF THE
QUESTION THAT ONE OR TWO DISTURBANCES RIDING DOWN THE NORTHWEST FLOW
MAY GIVE US AT LEAST A SLIGHT CHANCE FOR ADDITIONAL PRECIPITATION.
&&
.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)
ISSUED AT 1223 PM CDT WED OCT 16 2013
SATELLITE SHOWS THAT THE BAND OF CLOUDS OVER THE KGRI TERMINAL
AREA HAS BEEN THINNING OUT LATE THIS MORNING AND EARLY THIS
AFTERNOON. EXPECT THERE TO BE SOME SCATTERED MID LEVEL CLOUDS ON
AND OFF DURING THE NIGHT WITH AN INCREASE IN MID LEVEL CLOUDS
LATE IN THE PERIOD.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...NONE.
KS...NONE.
&&
$$
UPDATE...WESELY
SHORT TERM...PFANNKUCH
LONG TERM...EWALD
AVIATION...JCB